scholarly journals Archimedes Screw Design: An Analytical Model for Rapid Estimation of Archimedes Screw Geometry

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7812
Author(s):  
Arash YoosefDoost ◽  
William David Lubitz
Keyword(s):  
Single Equation ◽  
Relative Difference ◽  
Hydropower Plant ◽  
Local Flow ◽  
Rapid Estimation ◽  
Screw Design ◽  
Initial Design ◽  
Flow Duration Curves ◽  
A Site

In designing Archimedes screws, determination of the geometry is among the fundamental questions that may affect many aspects of the Archimedes screw powerplant. Most plants are run-of-river and highly depend on local flow duration curves that vary from river to river. An ability to rapidly produce realistic estimations for the initial design of a site-specific Archimedes screw plant helps to facilitate and accelerate the optimization of the powerplant design. An analytical method in the form of a single equation was developed to rapidly and easily estimate the Archimedes screw geometry for a specific site. This analytical equation was developed based on the accepted, proved or reported common designs characteristics of Archimedes screws. It was then evaluated by comparison of equation predictions to existing Archimedes screw hydropower plant installations. The evaluation results indicate a high correlation and reasonable relative difference. Use of the equation eliminates or simplifies several design steps and loops and accelerates the development of initial design estimations of Archimedes screw generators dramatically. Moreover, it helps to dramatically reduce one of the most significant burdens of small projects: the nonscalable initial investigation costs and enables rapid estimation of the feasibility of Archimedes screw powerplants at many potential sites.

Development of a regional model for hydropower potential in western Greece

2013 ◽  
Vol 14 (4) ◽  
pp. 442-449
Keyword(s):  
Regional Model ◽  
Flow Duration Curve ◽  
Drainage Basins ◽  
Flow Duration ◽  
Hydropower Potential ◽  
Flow Duration Curves ◽  
A Site ◽  
Northwestern Greece ◽  
Climatic Characteristics

A regional model was developed in the present study for the determination of the flow duration curve at ungaged catchments, in western and northwestern Greece, which is a hydrologically homogenous region. A flow duration curve indicates the water availability at a site and is important for the estimation of the hydropower potential. A flow duration curve was generated for each of seven available stations at different rivers and then the parameters of the flow duration curves were correlated with geomorphological and climatic characteristics of the drainage basins for the derivation of the equations of the regional model. The model was verified using three hold out stations, in which the error ranged from 0.3 to 1.1%.

RNA secondary structure dependence in METTL3–METTL14 mRNA methylation is modulated by the N-terminal domain of METTL3

2020 ◽  
Vol 402 (1) ◽  
pp. 89-98
Author(s):  
Nathalie Meiser ◽  
Nicole Mench ◽  
Martin Hengesbach
Keyword(s):  
Secondary Structure ◽  
Rna Binding ◽  
Specific Protein ◽  
Structure Dependence ◽  
Terminal Domain ◽  
Methylation Assay ◽  
A Site ◽  
Methylation Activity

AbstractN6-methyladenosine (m6A) is the most abundant modification in mRNA. The core of the human N6-methyltransferase complex (MTC) is formed by a heterodimer consisting of METTL3 and METTL14, which specifically catalyzes m6A formation within an RRACH sequence context. Using recombinant proteins in a site-specific methylation assay that allows determination of quantitative methylation yields, our results show that this complex methylates its target RNAs not only sequence but also secondary structure dependent. Furthermore, we demonstrate the role of specific protein domains on both RNA binding and substrate turnover, focusing on postulated RNA binding elements. Our results show that one zinc finger motif within the complex is sufficient to bind RNA, however, both zinc fingers are required for methylation activity. We show that the N-terminal domain of METTL3 alters the secondary structure dependence of methylation yields. Our results demonstrate that a cooperative effect of all RNA-binding elements in the METTL3–METTL14 complex is required for efficient catalysis, and that binding of further proteins affecting the NTD of METTL3 may regulate substrate specificity.

scholarly journals On the probability distribution of daily streamflow in the United States

2017 ◽  
Vol 21 (6) ◽  
pp. 3093-3103 ◽  
Author(s):  
Annalise G. Blum ◽  
Stacey A. Archfield ◽  
Richard M. Vogel
Keyword(s):  
United States ◽  
Probability Distribution ◽  
The United States ◽  
Good Representation ◽  
Lognormal Distributions ◽  
Daily Streamflow ◽  
The Us ◽  
Flow Duration Curves ◽  
A Site ◽  
Physiographic Regions

Abstract. Daily streamflows are often represented by flow duration curves (FDCs), which illustrate the frequency with which flows are equaled or exceeded. FDCs have had broad applications across both operational and research hydrology for decades; however, modeling FDCs has proven elusive. Daily streamflow is a complex time series with flow values ranging over many orders of magnitude. The identification of a probability distribution that can approximate daily streamflow would improve understanding of the behavior of daily flows and the ability to estimate FDCs at ungaged river locations. Comparisons of modeled and empirical FDCs at nearly 400 unregulated, perennial streams illustrate that the four-parameter kappa distribution provides a very good representation of daily streamflow across the majority of physiographic regions in the conterminous United States (US). Further, for some regions of the US, the three-parameter generalized Pareto and lognormal distributions also provide a good approximation to FDCs. Similar results are found for the period of record FDCs, representing the long-term hydrologic regime at a site, and median annual FDCs, representing the behavior of flows in a typical year.

Isolation of radioactive iodothyronines for kinetic studies: a comparison of two methods

1982 ◽  
Vol 99 (1) ◽  
pp. 64-71 ◽  
Author(s):  
Jens Faber ◽  
lb Bo Lumholtz ◽  
Carsten Kirkegaard ◽  
Kaj Siersbæk-Nielsen ◽  
Thorkild Friis
Keyword(s):  
Radioactive Iodine ◽  
Single Injection ◽  
Kinetic Studies ◽  
Acid Precipitation ◽  
Relative Difference ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Minor Degree ◽  
A Minor

Abstract. A method based on the principle of gel separation followed by antibody extraction (GSAE) has been developed for isolation of radioactive thyroxine (T4), 3,5,3'-triiodothyronine (T3), 3,3',5'-triiodothyronine (rT3), 3,3'-diiodothyronine (3,3'-T2), 3',5'-diiodothyronine (3',5'-T2) and 3'-monoiodothyronine (3'-T1) in serum. This method was used for the estimation of the metabolic clearance rate (MCR) of the iodothyronines using the single injection, non-compartmental approach, and was compared to the conventional trichloroacetic acid precipitation/ethanol extraction (TCA-E) technique. The GSAE method excluded the co-determination of radioactive iodine and iodoproteins, whereas the co-determination of radiolabelled daughter iodothyronines was found negligible. The relative difference of duplicate estimations of MCR was approximately 10%. Using the TCA-E method for isolation of tracer, the MCR of T4, T3 and rT3 was underestimated to a minor degree (20%), whereas the MCRs of 3,3'-T2, 3',5'-T2 and 3'-T1 were 20–40% of those estimated by the GSAE method. In conclusion the GSAE method was found suitable for kinetic studies of iodothyronines, whereas the TCA-E method cannot be used for turnover studies of 3,3'-T2, 3',5'-T2 or 3'-T1.

scholarly journals I. On the motion of fluid, part of which is moving rotationally and part irrotationally

1883 ◽  
Vol 36 (228-231) ◽  
pp. 276-284 ◽  
Keyword(s):  
Single Equation ◽  
Plane Motion ◽  
Vortex Lines ◽  
Irrotational Motion

Clebsch has show that the components of the velocity of a fluid u, v, w , parallel to rectangular axes x, y, z , may always be expressed thus— u = dX / dx + λ dψ / dx . v = dX / dy + λ dψ / dy , w = dX / dz +λ dψ / dz ; Where λ, ψ are systems of surfaces whose intersections determine the vortex lines; and the pressure satisfies an equation which is equivalent to the following— p /ρ + V = - dX / dt -1/2{( dX / dx ) 2 + ( dX / dy ) 2 + ( dX / dz ) 2 } + 1/2 λ 2 {( dψ / dx ) 2 + ( dψ / dy ) 2 + ( dψ / dz ) 2 } where p is the pressure, ρ the density, and V the potential of the forces acting on the liquid. It is shown in this paper that an equation in λ only can be obtained in the following cases (that is to say, as in cases of irrotational motion, the determination of the motion depends on the solution of a single equation only):— (1.) Plane motion, referred to rectangular co-ordinates x , y .

Deadhead Minimization with a Flexible Facility Locator Tool

2021 ◽  
pp. 036119812110444
Author(s):  
Kara Todd ◽  
Freyja Brandel-Tanis ◽  
Daniel Arias ◽  
Kari Edison Watkins
Keyword(s):  
Open Source Software ◽  
Operating Cost ◽  
Bus Rapid Transit ◽  
Rapid Transit ◽  
Flexible Tool ◽  
The Subject ◽  
Transit Agencies ◽  
A Site

As transit agencies expand, they may outgrow their existing bus storage and service facilities. When selecting a site for an additional facility, an important consideration is the change in bus deadhead time, which affects the agency’s operating costs. Minimizing bus deadhead time is the subject of many studies, though agencies may lack the necessary software or programming skill to implement those methods. This study presents a flexible tool for determination of bus facility location. Using the R dodgr package, it evaluates each candidate site based on a given bus network and existing depots and calculates the network minimum deadhead time for each potential set of facilities. Importantly, the tool could be used by any transit agency, no matter its resources. It runs on open-source software and uses only General Transit Feed Specification (GTFS) and data inputs readily available to transit agencies in the U.S.A., filling the accessibility gap identified in the literature. The tool is demonstrated through a case study with the Metropolitan Atlanta Rapid Transit Authority (MARTA), which is considering a new bus depot as it builds its bus rapid transit network. The case study used current MARTA bus GTFS data, existing depot locations, and vacant properties from Fulton County, Georgia. The tool evaluated 17 candidate sites and found that the winning site would save 29.7 deadhead hours on a typical weekday, which translates to more than $12,000 daily based on operating cost assumptions. The output provides important guidance to transit agencies evaluating sites for a new bus depot.

AN EVALUATION OF SEVERAL METHODS OF ESTIMATING SITE INDEX OF IMMATURE STANDS

1952 ◽  
Vol 28 (3) ◽  
pp. 63-74 ◽  
Author(s):  
John W. Ker
Keyword(s):  
Basal Area ◽  
Site Index ◽  
Site Quality ◽  
Average Height ◽  
Office Procedure ◽  
Minimum Sample ◽  
A Site ◽  
The University ◽  
Site Classes

The use of dominant heights for the estimation of site index is compared with the use of the average of dominant and codominant heights. Data collected on the University Research Forest are presented to illustrate the variability in tree heights and diameters within the two upper crown classes in well-stocked stands of immature Douglas fir.HeightIt is shown that the use of dominant heights reduces considerably the number of measurements required for a site index determination of given accuracy. Minimum sample sizes are given for three limits of accuracy for use in different site qualities. A general field and office procedure is outlined for the determination of minimum sample size in stands other than those described.DiameterThe use of diameter in site determination is discussed. Site indices based on the height of the tree of mean diameter, the height of the tree of mean basal area, and mean height are compared.ConclusionsQuick estimates of site quality can best be obtained by the measurement of total height of sample dominant trees, selected at random. For this purpose, tables are presented which list the average height of dominant trees by age and site classes for use in stands of Douglas fir, and western hemlock, respectively.

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