scholarly journals Testing roundabout capacity models: a practical aid for choosing the right one based on total capacity calculation

2020 ◽  
Vol 80 (ET.2020) ◽  
pp. 1-17
Author(s):  
Raffaele Mauro
Keyword(s):  
Probability Distributions ◽  
Specific Capacity ◽  
Traffic Demand ◽  
Practical Applications ◽  
Capacity Model ◽  
Efficiency Measures ◽  
Capacity Calculation ◽  
Total Capacity ◽  
Capacity Formulation ◽  
The Right

The determination of efficiency measures, under a known traffic demand, is a central aspect of roundabouts analysis. Many capacity formulations have been available for some time in different countries relating to different roundabout layouts. This paper refers to fifteen roundabout entry capacity models used above all in the European countries, highlighting their input requirements and their algorithm complexity. The formulations reviewed are then compared referring to a test roundabout, with a simple and widespread layout. Monte Carlo simulation have been performed considering 5,000 traffic distribution matrices for each capacity model. The results obtained are critically assessed resorting to the calculation of roundabout total capacity. The probability distributions of total capacity allow finding a model that stands out among all as an advisable choice for a suitable capacity formulation, acting as a synthesis of all those examined. This can be of considerable use in view of practical applications, for the design of efficient and safe roundabout intersections in situations in which a country-specific capacity formulation is not available.

The ellipsoidal form of clasts with practical applications to fabric and size analyses of fluvial gravels

1980 ◽  
Vol 17 (12) ◽  
pp. 1725-1739 ◽  
Author(s):  
Emlyn H. Koster ◽  
Brian R. Rust ◽  
Don J. Gendzwill
Keyword(s):  
Statistical Analysis ◽  
Flow Direction ◽  
Probability Distributions ◽  
Size Analysis ◽  
Shape Variation ◽  
Practical Applications ◽  
Flow Interactions ◽  
Typical Range ◽  
Plane Area ◽  
Key Parameter

The widespread assumption that most water-worn gravel clasts approximate ellipsoids is confirmed by a statistical analysis of available data. The analysis demonstrates a Gaussian distribution of V/Ve ratios, centred on unit ratio, where V is clast volume and Ve the volume of a symmetric ellipsoid with equivalent triaxial dimensions. For internally isotropic and unbroken clasts, ellipsoidal form evolves as the rounding due to abrasion reaches its final stages. There appears to be no other major control on the tendency towards ellipsoidal geometry. The ellipsoidal tendency assists the interpretation of fluvial gravel deposits, which depends greatly on accurate description of clast size and fabric.Firstly, it facilitates calculation of Ap, the plane area projected upstream by clasts, a key parameter in bed–flow interactions such as preferred fabric. Formulae are derived to calculate Ap for ellipsoidal clasts with any configuration relative to flow direction. Viewing fabric in terms of the Ap variable supports and explains earlier conclusions concerning the controls on variability of imbrication angle.Secondly, an investigation of the relative merits of six size measures as descriptors of areal trends and predictors of nominal diameter, dn, concludes that (abc)1/3(the formula for dn of an ellipsoid) is superior. Other measures, namely, a, b, c, (a + c)/2, and (a + b + c)/3, are all subject to error in proportion to the degree of shape variation. Also, since downstream fining is typically accompanied by a changing proportion of oblate, bladed, prolate, and equant forms, dn is subject to inconsistent levels of under- or overestimation. The commonly used b dimension is endorsed as an acceptable predictor of dn, but a severely overestimates dn and should be abandoned. Information on errors in size analysis is presented as nomograms in the form of contoured c/b versus b/a plots and as probability distributions based on the typical range of shape variation in fluvial gravel.

scholarly journals Nitrogen-rich covalent organic frameworks with multiple carbonyls for high-performance sodium batteries

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruijuan Shi ◽  
Luojia Liu ◽  
Yong Lu ◽  
Chenchen Wang ◽  
Yixin Li ◽  
...  
Keyword(s):  
High Performance ◽  
Density Functional ◽  
Specific Capacity ◽  
Density Functional Theory Calculations ◽  
Rechargeable Batteries ◽  
High Rate ◽  
Ex Situ ◽  
Covalent Organic Frameworks ◽  
Rate Performance ◽  
Practical Applications

AbstractCovalent organic frameworks with designable periodic skeletons and ordered nanopores have attracted increasing attention as promising cathode materials for rechargeable batteries. However, the reported cathodes are plagued by limited capacity and unsatisfying rate performance. Here we report a honeycomb-like nitrogen-rich covalent organic framework with multiple carbonyls. The sodium storage ability of pyrazines and carbonyls and the up-to twelve sodium-ion redox chemistry mechanism for each repetitive unit have been demonstrated by in/ex-situ Fourier transform infrared spectra and density functional theory calculations. The insoluble electrode exhibits a remarkably high specific capacity of 452.0 mAh g−1, excellent cycling stability (~96% capacity retention after 1000 cycles) and high rate performance (134.3 mAh g−1 at 10.0 A g−1). Furthermore, a pouch-type battery is assembled, displaying the gravimetric and volumetric energy density of 101.1 Wh kg−1cell and 78.5 Wh L−1cell, respectively, indicating potentially practical applications of conjugated polymers in rechargeable batteries.

Some new approaches to probability distributions

1980 ◽  
Vol 12 (04) ◽  
pp. 903-921 ◽  
Author(s):  
S. Kotz ◽  
D. N. Shanbhag
Keyword(s):  
Probability Distributions ◽  
Random Variables ◽  
Representation Theorems ◽  
Practical Applications ◽  
New Approaches ◽  
Characterization Of Distributions ◽  
Stability Theorems ◽  
Conditional Expectations

We develop some approaches to the characterization of distributions of real-valued random variables, useful in practical applications, in terms of conditional expectations and hazard measures. We prove several representation theorems generalizing earlier results, and establish stability theorems for two general characteristics introduced in this paper.

scholarly journals Improving the Performance of a Graphite Foil/Polyaniline Electrode Material by a Thin PEDOT:PSS Layer for Application in Flexible, High Power Supercapacitors

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5791
Author(s):  
Zuzanna Zarach ◽  
Konrad Trzciński ◽  
Marcin Łapiński ◽  
Anna Lisowska-Oleksiak ◽  
Mariusz Szkoda
Keyword(s):  
High Power ◽  
Electrode Material ◽  
Specific Capacity ◽  
Protective Layer ◽  
High Specific Capacitance ◽  
Specific Power ◽  
Potential Range ◽  
Graphite Foil ◽  
Practical Applications ◽  
Symmetric Supercapacitor

In this study, we present a novel strategy for enhancing polyaniline stability and thus obtaining an electrode material with practical application in supercapacitors. A promising (graphite foil/polyaniline/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) GF/PANI/PEDOT:PSS) electrode material was characterized and used in the construction of a symmetric supercapacitor that provides an outstanding high power density. For this purpose, the electropolymerization of PANI was carried out on a graphite foil and then a thin protective layer of PEDOT:PSS was deposited. The presence of the nanometer PEDOT:PSS layer made it possible to widen the electroactivity potential range of the electrode material. Moreover, the synergy between materials positively affected the amount of accumulated charge, and thus the thin PEDOT:PSS layer contributed to enhancing the specific capacity of the electrode material. The electrochemical performance of the GF/PANI/PEDOT:PSS electrode, as well as the symmetrical supercapacitor, was investigated by cyclic voltammetry and galvanostatic charge/discharge cycles in 1 M H2SO4 at room temperature. The fabricated electrode material shows a high specific capacitance (Csp) of 557.4 Fg−1 and areal capacitance (Careal) of 2600 mF·cm−2 in 1 M H2SO4 at a current density of 200 mA·cm−2 (~4 A·g−1). The supercapacitor performance was studied and the results show that a thin PEDOT:PSS layer enables cycling stability improvement of the device from 54% to 67% after 10,000 cycles, and provides a high specific capacity (159.8 F·g−1) and a maximum specific power (18,043 W·kg−1) for practical applications.

scholarly journals Survey of entomopathogenic nematodes and fungi in agricultural areas

2020 ◽  
Vol 56 (No. 3) ◽  
pp. 214-225
Author(s):  
Magdalena Dzięgielewska ◽  
Iwona Adamska
Keyword(s):  
Entomopathogenic Nematodes ◽  
Plant Protection ◽  
Abiotic Factors ◽  
Field Studies ◽  
Natural Resistance ◽  
Steinernema Feltiae ◽  
Practical Applications ◽  
Taxonomic Groups ◽  
The Right ◽  
Biological Methods

In 2016-2018, in north-western Poland, field studies were carried out on the coexistence of various taxonomic groups, such as soil nematodes and fungi, including beneficial species that comprise the environment’s natural resistance to pests in agrocenoses. The research aimed to find a connection between select biotic and abiotic factors in the chosen crops which could have practical applications in plant protection. Entomopathogenic nematodes Steinernema feltiae Filipiev, 1934 and entomopathogenic fungi Cordyceps fumosorosea and Metarhizium anisopliae (Metschn.) Sorokin were found to be present in all studied agrocenoses; however, they showed clear preferences for some types of crops or soil. The research shows that the effectiveness of the biological methods of plant protection depends on the selection of the right biopreparations, which strengthen the local populations of the beneficial organisms present in specific agriculture areas.

scholarly journals Estimating the Capacity of Urban Transportation Networks with an Improved Sensitivity Based Method

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Muqing Du ◽  
Xiaowei Jiang ◽  
Lin Cheng
Keyword(s):  
Sensitivity Analysis ◽  
Large Scale ◽  
Transportation Network ◽  
Network Capacity ◽  
Combined Model ◽  
Practical Applications ◽  
Large Scale Problems ◽  
Capacity Model ◽  
High Efficient ◽  
Equilibrium Constraint

The throughput of a given transportation network is always of interest to the traffic administrative department, so as to evaluate the benefit of the transportation construction or expansion project before its implementation. The model of the transportation network capacity formulated as a mathematic programming with equilibrium constraint (MPEC) well defines this problem. For practical applications, a modified sensitivity analysis based (SAB) method is developed to estimate the solution of this bilevel model. The high-efficient origin-based (OB) algorithm is extended for the precise solution of the combined model which is integrated in the network capacity model. The sensitivity analysis approach is also modified to simplify the inversion of the Jacobian matrix in large-scale problems. The solution produced in every iteration of SAB is restrained to be feasible to guarantee the success of the heuristic search. From the numerical experiments, the accuracy of the derivatives for the linear approximation could significantly affect the converging of the SAB method. The results also show that the proposed method could obtain good suboptimal solutions from different starting points in the test examples.

On the distribution of records in a finite sequence of observations, with an application to a road traffic problem

1973 ◽  
Vol 10 (03) ◽  
pp. 556-571 ◽  
Author(s):  
Dariush Haghighi-Talab ◽  
Christopher Wright
Keyword(s):  
Experimental Observation ◽  
Road Traffic ◽  
Probability Distributions ◽  
Finite Sequence ◽  
Simple Application ◽  
Practical Applications ◽  
Record Time ◽  
Lower Records

Probability distributions relating to the number and positions of lower records in a finite sequence of observations are obtained by methods involving the permutation of ranks. Some new results, and results of earlier authors, are expressed in a form thought to be useful for direct practical applications. Expressions are also given for the distribution of the length of a ‘record run’, which consists of the observations following and including a given record either up to the next record, or, if a further record does not occur, up to the end of the sequence of observations. This quantity, whose distribution is closely related to that of the inter-record time, has a direct and simple application to road traffic leaving a signal which has been confirmed by experimental observation.

A RISK-ANALYTIC APPROACH TO CONTROL OF LARGE-VOLUME OIL SPILLS

1975 ◽  
Vol 1975 (1) ◽  
pp. 301-306 ◽  
Author(s):  
A. S. Paulson ◽  
A. D. Schumaker ◽  
W. A. Wallace
Keyword(s):  
Large Volume ◽  
Oil Spills ◽  
Probability Distributions ◽  
Data File ◽  
Coast Guard ◽  
New Approach ◽  
Appropriate Treatment ◽  
Coefficients Of Variation ◽  
The Right ◽  
Thick Tails

ABSTRACT The frequency of large-volume oil spills is considerably greater than is consistent with prediction based upon traditional methods. The reason for this phenomenon is that standard probability distributions of magnitude of spills do not have the flexibility to admit of very large coefficients of variation, especially for distributions which are highly skewed to the right. Hence, distributions which have large means relative to the median and which have long thick tails are prerequisites for an appropriate treatment of the problem. The class of stable laws provides a convenient method for investigating the empirical oil spill experience: several large spills dominate the total volume of spillage in virtually all accounting periods; e.g., quarterly. Our methodology involves a statistical assessment of “accident-proneness component;” if one exists, the data is further examined to identify insofar as is possible the genesis of the component (s); if none exists, we assess the frequency and severity of discharge for various geographic areas. A new approach has been utilized to fit these long, thick-tailed probability distribution to a U.S. Coast Guard data file on oil spills, the pollution incident reporting system (PIRS), with considerable success. We pay particular attention to the fitted upper tail vis-a-vis the actual upper tail. The agreement, where our methodology is deemed applicable, is very good We also indicate improvements to methodology and applications.

Model Test Research of Surcharge Contribution to Ground Bearing Capacity

2013 ◽  
Vol 353-356 ◽  
pp. 815-818
Author(s):  
Le Yi Chen
Keyword(s):  
Bearing Capacity ◽  
Failure Mode ◽  
Model Test ◽  
Shear Failure ◽  
Theoretical Solution ◽  
Capacity Factor ◽  
Ground Failure ◽  
Capacity Model ◽  
Capacity Calculation ◽  
Bearing Capacity Factor

To investigate the influence of surcharge on bearing capacity, model tests were performed. In the tests, 5 kPa and 10 kPa surcharge was applied on silt respectively. The bearing capacity factor Nq is smaller than theoretical solution, and is only of 60.3% and 80.5% of theoretical solution. Model test show that the ground failure mode is not general shear failure mode in condition of ground under surcharge. In bearing capacity calculation, if bearing capacity factor theoretical solution which is from general shear failure mode is applied, the result will be overestimate.

scholarly journals Signal Control Strategy for Supersaturated Traffic at Urban Road Intersections with a Large Technical Grade Gap

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Baiqun Ding ◽  
Liu Yang ◽  
He Xu ◽  
Yongming He
Keyword(s):  
Control Strategy ◽  
Queue Length ◽  
Control Method ◽  
Signal Control ◽  
Main Road ◽  
Traffic Demand ◽  
The Road ◽  
Capacity Model ◽  
Minor Road ◽  
Remaining Capacity

To reduce the risk of queuing overflow on the urban minor road at the intersection under supersaturation where the capacity of the arterial and minor roads shows extreme disparity, reduce the adverse effects caused by long queues of vehicles on the minor road, and comprehensively balance the multiobjective requirements such as priority of the main road, queuing restrictions, and delay on the minor road, the minor road queue model at the end of red, a road remaining capacity model, and multiparameter coordinated signal control model were established, and a multiobjective genetic algorithm was used to optimize this solution. As an example, the multiparameter coordinated control strategy decreased the delay per vehicle by approximately 17% and the queue length by approximately 30%–50% on the minor road and slightly increased the delay per vehicle at the intersection and the length on the main road queue. This control strategy can make full use of the capacity of the main road to control the queue length on the minor road, effectively reduce the risk of minor road queue overflow blocking local road network traffic operation involved, and comprehensively balance the traffic demand between arterial and minor roads. It provides a reference control method for coping with the transfer of the main traffic contradiction under the oversaturated state of the road intersection with large disparity.

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