Phytoplankton periodicity in a new reservoir, Lake Anna, Virginia

1975 ◽  
Vol 19 (3) ◽  
pp. 1814-1819 ◽  
Author(s):  
Brian Armitage ◽  
George M. Simmons
Keyword(s):  
Lake Anna ◽  
New Reservoir

scholarly journals Early Science from POSSUM: Shocks, turbulence, and a massive new reservoir of ionised gas in the Fornax cluster

2021 ◽  
Vol 38 ◽  
Author(s):  
C. S. Anderson ◽  
G. H. Heald ◽  
J. A. Eilek ◽  
E. Lenc ◽  
B. M. Gaensler ◽  
...  
Keyword(s):  
X Ray ◽  
Main Cluster ◽  
Rotation Measure ◽  
Sky Survey ◽  
Low Mass ◽  
Fornax Cluster ◽  
Depth Enhancement ◽  
Projected Distance ◽  
Density Regime ◽  
New Reservoir

Abstract We present the first Faraday rotation measure (RM) grid study of an individual low-mass cluster—the Fornax cluster—which is presently undergoing a series of mergers. Exploiting commissioning data for the POlarisation Sky Survey of the Universe’s Magnetism (POSSUM) covering a ${\sim}34$ square degree sky area using the Australian Square Kilometre Array Pathfinder (ASKAP), we achieve an RM grid density of ${\sim}25$ RMs per square degree from a 280-MHz band centred at 887 MHz, which is similar to expectations for forthcoming GHz-frequency ${\sim}3\pi$ -steradian sky surveys. These data allow us to probe the extended magnetoionic structure of the cluster and its surroundings in unprecedented detail. We find that the scatter in the Faraday RM of confirmed background sources is increased by $16.8\pm2.4$ rad m−2 within 1 $^\circ$ (360 kpc) projected distance to the cluster centre, which is 2–4 times larger than the spatial extent of the presently detectable X-ray-emitting intracluster medium (ICM). The mass of the Faraday-active plasma is larger than that of the X-ray-emitting ICM and exists in a density regime that broadly matches expectations for moderately dense components of the Warm-Hot Intergalactic Medium. We argue that forthcoming RM grids from both targeted and survey observations may be a singular probe of cosmic plasma in this regime. The morphology of the global Faraday depth enhancement is not uniform and isotropic but rather exhibits the classic morphology of an astrophysical bow shock on the southwest side of the main Fornax cluster, and an extended, swept-back wake on the northeastern side. Our favoured explanation for these phenomena is an ongoing merger between the main cluster and a subcluster to the southwest. The shock’s Mach angle and stand-off distance lead to a self-consistent transonic merger speed with Mach 1.06. The region hosting the Faraday depth enhancement also appears to show a decrement in both total and polarised radio emission compared to the broader field. We evaluate cosmic variance and free-free absorption by a pervasive cold dense gas surrounding NGC 1399 as possible causes but find both explanations unsatisfactory, warranting further observations. Generally, our study illustrates the scientific returns that can be expected from all-sky grids of discrete sources generated by forthcoming all-sky radio surveys.

Field Measurements on Side Arms of Lake Anna, Va.

1984 ◽  
Vol 110 (6) ◽  
pp. 773-793 ◽  
Author(s):  
E. Eric Adams ◽  
Scott A. Wells
Keyword(s):  
Field Measurements ◽  
Lake Anna

scholarly journals New Reservoir Grading Method for Tight Gas Reservoir – One Case Study in Kekeya Block, Tuha Basin, China

2015 ◽  
Vol 8 (1) ◽  
pp. 167-171
Author(s):  
Fangfang Wu ◽  
Jinchuan Zhang ◽  
Liuzhong Li ◽  
Jinlong Wu
Keyword(s):  
Flow Unit ◽  
Reservoir Evaluation ◽  
Flow Units ◽  
Core Dataset ◽  
Tight Gas Reservoir ◽  
Set Up ◽  
Productivity Prediction ◽  
Hydraulic Flow Units ◽  
New Reservoir

Tight sand reservoir is usually characterized by high heterogeneity and complex pore structure, which makes the permeability calculation a big challenge and leads to difficulties in reservoir classification and productivity evaluation. First, five different Hydraulic Flow Units and respective Porosity-permeability relations were built based on core dataset from Kekeya block, Tuha Basin; and then with BP Neutron Network method, flow unit was classified for un-cored intervals using normalized logging data, and permeability was calculated accordingly. This improved the accuracy of permeability calculation and helped a lot on un-cored reservoir evaluation. In addition, based on porosity, permeability and flow unit type, a new reservoir grading chart was set up by incorporating the testing or production data, which provides important guidance for productivity prediction and reservoir development.

Reprocessed time-lapse seismic data provides new reservoir information on the Njord field

First Break ◽  
2021 ◽  
Vol 39 (2) ◽  
pp. 87-93
Author(s):  
Patrick Smith ◽  
Paul Glenister ◽  
Marianne Yanez ◽  
Kristoffer Sundøy ◽  
Øyvind Kvam
Keyword(s):  
Seismic Data ◽  
Time Lapse ◽  
New Reservoir

scholarly journals A New Reservoir Operation Chart Drawing Method Based on Dynamic Programming

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3355 ◽  
Author(s):  
Zhiqiang Jiang ◽  
Yaqi Qiao ◽  
Yuyun Chen ◽  
Changming Ji
Keyword(s):  
Power Generation ◽  
Dynamic Programming ◽  
Global Convergence ◽  
Local Convergence ◽  
Reservoir Operation ◽  
Optimization Methods ◽  
Simulation Results ◽  
Conventional Methods ◽  
Drawing Method ◽  
New Reservoir

A reservoir operation chart is an important tool in guiding actual reservoir operation at present. There are mainly two kinds of methods in drawing the operation chart, i.e., conventional methods and optimization methods, but each of them has some shortcomings, such as the repeated empirical inspection and correction of conventional methods, and the sensitivity to the initial trajectories of some optimization algorithms. In view of this, based on the principle of dynamic programming (DP), this paper coupled the reservoir operation chart drawing model and the DP model, and proposed a new reservoir operation chart drawing method which has no empirical inspection and correction, no requirement for initial solution, no problem of premature convergence and local convergence. In addition, this method can guarantee the global convergence of the results to a certain extent because of the global convergence of DP. Ya Yangshan reservoir in the Li Xianjiang River of China was selected as the research object to derive the operation chart by the drawing method. The simulation results show that the proposed method in this paper presents better performance compared with the conventional method on power generation, guaranteed output, and assurance rate, especially on the latter, which has a 2.68% increase. In addition, compared with the deterministic optimization results of DP, it is found that the results of the proposed method are very close to that of deterministic DP, the differences are only 1.8 GWh (0.36% decline) and 1.6 GWh (0.32% decline). So, the validity and rationality of the proposed method are further verified by the simulation results.

scholarly journals Alternative Woods in Enology: Characterization of Tannin and Low Molecular Weight Phenol Compounds with Respect to Traditional Oak Woods. A Review

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1474 ◽  
Author(s):  
Ana Martínez-Gil ◽  
Maria del Alamo-Sanza ◽  
Rosario Sánchez-Gómez ◽  
Ignacio Nevares
Keyword(s):  
Molecular Weight ◽  
Prunus Avium ◽  
Robinia Pseudoacacia ◽  
Castanea Sativa ◽  
Low Molecular Weight ◽  
New Materials ◽  
Castanea Sativa Mill ◽  
Robinia Pseudoacacia L ◽  
New Reservoir

Wood is one of the most highly valued materials in enology since the chemical composition and sensorial properties of wine change significantly when in contact with it. The need for wood in cooperage and the concern of enologists in their search for new materials to endow their wines with a special personality has generated interest in the use of other Quercus genus materials different from the traditional ones (Q. petraea, Q. robur and Q. alba) and even other wood genera. Thereby, species from same genera such as Q. pyrenaica Willd., Q. faginea Lam., Q. humboldtti Bonpl., Q. oocarpa Liebm., Q. stellata Wangenh, Q. frainetto Ten., Q. lyrata Walt., Q. bicolor Willd. and other genera such as Castanea sativa Mill. (chestnut), Robinia pseudoacacia L. (false acacia), Prunus avium L. and P. cereaus L. (cherry), Fraxinus excelsior L. (European ash) and F. americana L. (American ash) have been studied with the aim of discovering whether they could be a new reservoir of wood for cooperage. This review aims to summarize the characterization of tannin and low molecular weight phenol compositions of these alternative woods for enology in their different cooperage stages and compare them to traditional oak woods, as both are essential to proposing their use in cooperage for aging wine.

A rare cause of infection, Raoultella planticola: emerging threat and new reservoir for carbapenem resistance

Infection ◽  
2016 ◽  
Vol 44 (6) ◽  
pp. 713-717 ◽  
Author(s):  
Tayfur Demiray ◽  
Mehmet Koroglu ◽  
Ahmet Ozbek ◽  
Mustafa Altindis
Keyword(s):  
Carbapenem Resistance ◽  
Raoultella Planticola ◽  
New Reservoir

Influence of a reservoir with surface release on the life history of the mayfly Heterocloeon curiosum (McDunnough) (Ephemeroptera: Baetidae)

1981 ◽  
Vol 59 (2) ◽  
pp. 305-314 ◽  
Author(s):  
Boris C. Kondratieff ◽  
J. Reese Voshell Jr.
Keyword(s):  
Life History ◽  
Benthic Macroinvertebrates ◽  
Temperature Regime ◽  
Life Histories ◽  
Second Generation ◽  
Larval Instars ◽  
History Of ◽  
Lake Anna

The life history of Heterocloeon curiosum was compared in the impounded North Anna River (NAR) and the free-flowing South Anna River (SAR) in Virginia, U.S.A. The study site on the NAR was 32 km below Lake Anna, a surface-release reservoir. Heterocloeon curiosum was bivoltine in both rivers with two summer generations and probable overwintering in the egg stage. It passed through 10 larval instars (range 9–12) in both rivers. The density of larvae was twice as great in the SAR as the NAR. Factors which may have contributed to the lesser success of H. curiosum in the NAR included bottom scouring produced by sudden increases in discharge, absence of the macrophyte Podostemum, quality of available food, and alterations of the temperature regime. Of these four factors, temperature probably had the most significant effect. The emergence of the second generation was 1 month later in the NAR because the reservoir delayed the normal seasonal cooling of the river. The nonoptimal temperature regime appeared to significantly reduce the fecundity of H. curiosum in the NAR. Our data indicate that surface-release reservoirs may have subtle but significant effects on the life histories of benthic macroinvertebrates.

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