scholarly journals Distribution Analysis of Freight Transportation with Gravity Model and Genetic Algorithm

2012 ◽  
Vol 2269 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Jun Duanmu ◽  
Peter Foytik ◽  
Asad Khattak ◽  
R. Michael Robinson
Keyword(s):  
Genetic Algorithm ◽  
Friction Factor ◽  
Gravity Model ◽  
Freight Transportation ◽  
Calibration Method ◽  
Gravity Models ◽  
Valuable Insight ◽  
Distribution Analysis ◽  
Friction Factors ◽  
The Impact

The application of a gravity model in freight modeling work on both short-haul and long-haul trips is discussed. A commodity-based gravity model was developed to assess the distribution of freight by long-haul trucks in southeastern Virginia. Although gravity models have been used extensively in transportation studies, little work has been done to address the special characteristics of freight transportation, such as the definition of friction factors and the differences between long-haul and short-haul trips. Results of a recent study of these and similar problems provide valuable insight into freight distribution modeling. A new calibration method that used a genetic algorithm was applied, various commodities were modeled, and the impact of the commodities on the accuracy of the gravity model was studied. Both travel time and travel distance were tested to generate the impedance for friction factors; results showed that for commodity-based long-haul models, travel times were more appropriate for friction factor calculations. In addition, results showed that the gamma function was more suitable than the exponential function for friction factor calculations. Extensive analyses of the causes of variation between observed values and the gravity model outputs are provided. The analyses and conclusions may help modelers better understand characteristics specific to freight transportation and can promote model constructions with greater accuracy and efficiency.

scholarly journals Bilateral Trade and Islamic Sects

2011 ◽  
Vol 2 (3) ◽  
Author(s):  
Rock-Antoine Mehanna ◽  
Leila Sarieddine ◽  
James L. Llorens
Keyword(s):  
Gravity Model ◽  
Bilateral Trade ◽  
Policy Implications ◽  
Gravity Models ◽  
Average Period ◽  
Extended Version ◽  
Control Variables ◽  
Stratified Sample ◽  
Muslim Majority ◽  
The Impact

This paper explores the effects of religion and Islamic sects on bilateral trade activities by employing an extended version of the gravity model. A stratified sample of 33 countries for the average period 1996-99 is selected. Although gravity models have been extensively used in the literature, to the best of our knowledge, they have neither been used to examine the impact of Islamic sects on bilateral trade nor to estimate religion within a model that incorporates oil-exporting countries, culture, regional trading arrangements, and political freedomessential control variables for the specification of the model. Findings reveal that Muslim majority countries trade less than their Christian, Jewish, Buddhist, or other counterparts. In addition, when disaggregating the Muslim sample into Sunni and Shia sects, results show that Sunni majority countries trade more than their Shiite counterparts. Other results and policy implications are discussed.

Gravity models in international trade analysis: testing the country similarity theory 50 years

2020 ◽  
pp. 52-62
Author(s):  
I.S. Smirnov
Keyword(s):  
Developing Countries ◽  
International Trade ◽  
Gravity Model ◽  
Similarity Theory ◽  
Market Competition ◽  
Gravity Models ◽  
Trade Data ◽  
Trade Relations ◽  
Similarity Factor ◽  
The Impact

The article assessed the potential use of gravity models to test the impact of various socio-geographical factors on international and inter-regional trade. The potential of gravitational modeling was estimated based on testing the theory of Linder’s Country similarity theory on recent trade data. This theory was one of the key theories of international trade in the post-war period. The classical gravity model of international trade can be used to test the change in the importance of the country similarity factor over a certain time period. The gravity model will demonstrate more significant results compared to its classical version (excluding the country similarity factor) in the case of a positive effect of the similarity factor on the volume of bilateral trade between countries. The analysis of recent trade data allowed us to assess the extent of change in the country similarity factor over the past 70 years. This period was accompanied by high growth in international trade, as well as the involvement of developing countries in the international division of labor. Vigorous market competition for the production of industrial goods led to the fact that manufacturers were forced to cut costs by moving their main production capacities to developing countries, which significantly differ from them in their level of economic development. The country similarity factor has lost its significance in this new system of international trade relations. As a result, at present the country similarity factor is not a key factor explaining the volume of trade relations between different countries.

scholarly journals Investigating Factors Affecting the U.S. National Nursery Trade: The Implications of a Gravity Model

HortScience ◽  
2011 ◽  
Vol 46 (11) ◽  
pp. 1518-1522 ◽  
Author(s):  
Xiaofang Guo ◽  
Chengyan Yue ◽  
Charles R. Hall
Keyword(s):  
Survey Data ◽  
Gravity Model ◽  
National Survey ◽  
Gravity Models ◽  
Factors Affecting ◽  
Domestic Trade ◽  
Nursery Crops ◽  
The Impact ◽  
The U.S ◽  
Over Time

Literature on the domestic trade of nursery crops is sparse. Based on national survey data collected in years 1999, 2004, and 2009, we used augmented gravity models to investigate the primary factors affecting the value of trade for both large and small nurseries. We found that the impact of distance on trade value was different between large nurseries and small nurseries; the impact of distance on national nursery trade has been decreasing over time; and the level of impact of distance on nursery trade differs across regions. Additionally, the value of nursery trade was affected by plant types the nurseries produced and other business characteristics.

MAGNETIC FIELD IMPACT UPON TRIBOTECHNICAL CHARACTERISTICS OF PERMANENT CONNECTIONS IN RELATION TO FRICTION SHOCK ABSORBERS

2020 ◽  
Vol 2020 (10) ◽  
pp. 4-11
Author(s):  
Victor Tikhomirov ◽  
Aleksandr Gorlenko ◽  
Stanislav Volohov ◽  
Mikhail Izmerov
Keyword(s):  
Magnetic Field ◽  
Friction Factor ◽  
Physical Contact ◽  
Active Centers ◽  
Press Fit ◽  
Electro Magnetic Field ◽  
Investigation Methods ◽  
Electro Magnetic ◽  
The Impact ◽  
The Magnetic Field

The work purpose is the investigation of magnetic field impact upon properties of friction steel surfaces at fit stripping with tightness through manifested effects and their wear visually observed. On the spots of a real contact the magnetic field increases active centers, their amount and saturation with the time of dislocation outlet, and has an influence upon tribo-mating. The external electro-magnetic field promotes the increase of the number of active centers at the expense of dislocations outlet on the contact surface, and the increase of a physical contact area results in friction tie strengthening and growth of a friction factor. By the example of friction pairs of a spentonly unit in the suspension of coach cars there is given a substantiation of actuality and possibility for the creation of technical devices with the controlled factor of friction and the stability of effects achieved is also confirmed experimentally. Investigation methods: the fulfillment of laboratory physical experiments on the laboratory plant developed and patented on bush-rod samples inserted with the fit and tightness. The results of investigations and novelty: the impact of the magnetic field upon the value of a stripping force of a press fit with the guaranteed tightness is defined. Conclusion: there is a possibility to control a friction factor through the magnetic field impact upon a friction contact.

scholarly journals Optimized Strategic Planning of Future Norwegian Low-Voltage Networks with a Genetic Algorithm Applying Empirical Electric Vehicle Charging Data

Electricity ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 91-109
Author(s):  
Julian Wruk ◽  
Kevin Cibis ◽  
Matthias Resch ◽  
Hanne Sæle ◽  
Markus Zdrallek
Keyword(s):  
Genetic Algorithm ◽  
Electric Vehicle ◽  
Electric Vehicles ◽  
Low Voltage ◽  
Network Planning ◽  
Voltage Regulation ◽  
Electric Vehicle Charging ◽  
Vehicle Charging ◽  
The Impact

This article outlines methods to facilitate the assessment of the impact of electric vehicle charging on distribution networks at planning stage and applies them to a case study. As network planning is becoming a more complex task, an approach to automated network planning that yields the optimal reinforcement strategy is outlined. Different reinforcement measures are weighted against each other in terms of technical feasibility and costs by applying a genetic algorithm. Traditional reinforcements as well as novel solutions including voltage regulation are considered. To account for electric vehicle charging, a method to determine the uptake in equivalent load is presented. For this, measured data of households and statistical data of electric vehicles are combined in a stochastic analysis to determine the simultaneity factors of household load including electric vehicle charging. The developed methods are applied to an exemplary case study with Norwegian low-voltage networks. Different penetration rates of electric vehicles on a development path until 2040 are considered.

scholarly journals Detecting Convergence Trends among EU Universities

Economies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 42
Author(s):  
Maria Adamakou ◽  
Dimitris Kallioras ◽  
George Petrakos
Keyword(s):  
Methodological Approach ◽  
Basic Research ◽  
Valuable Insight ◽  
Traditional Role ◽  
University Ranking ◽  
Convergence Clubs ◽  
Development Processes ◽  
The Impact ◽  
The Empirical Analysis ◽  
Insight Into

Universities are emerging growth determinants. This is so as, in addition to the fulfillment of their traditional role in teaching and (basic) research, universities, as aptly described within the helix framework, are expected to engage in regional development processes. The paper aims to detect trends of convergence among EU universities in terms of performance. To the best of our knowledge, this topic has not hitherto been examined. The empirical analysis of the paper covers the period 2014–2021, utilizes data obtained from URAP (University Ranking by Academic Performance), and employs the methodological approach of convergence clubs. The findings of the paper provide valuable insight into both theory and policy-making. We conclude that despite the unification of EU educational space, trends of divergence among EU universities are still present, and notable divisions still remain. Consequently, this indicates that the impact of EU universities on the formation of spatial disparities across EU space is not neutral.

Numerical and Experimental Analysis of Turbulent Flow in Corrugated Pipes

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Henrique Stel ◽  
Rigoberto E. M. Morales ◽  
Admilson T. Franco ◽  
Silvio L. M. Junqueira ◽  
Raul H. Erthal ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Velocity Magnitude ◽  
Geometric Configurations ◽  
Corrugated Surfaces ◽  
Friction Factors

This article describes a numerical and experimental investigation of turbulent flow in pipes with periodic “d-type” corrugations. Four geometric configurations of d-type corrugated surfaces with different groove heights and lengths are evaluated, and calculations for Reynolds numbers ranging from 5000 to 100,000 are performed. The numerical analysis is carried out using computational fluid dynamics, and two turbulence models are considered: the two-equation, low-Reynolds-number Chen–Kim k-ε turbulence model, for which several flow properties such as friction factor, Reynolds stress, and turbulence kinetic energy are computed, and the algebraic LVEL model, used only to compute the friction factors and a velocity magnitude profile for comparison. An experimental loop is designed to perform pressure-drop measurements of turbulent water flow in corrugated pipes for the different geometric configurations. Pressure-drop values are correlated with the friction factor to validate the numerical results. These show that, in general, the magnitudes of all the flow quantities analyzed increase near the corrugated wall and that this increase tends to be more significant for higher Reynolds numbers as well as for larger grooves. According to previous studies, these results may be related to enhanced momentum transfer between the groove and core flow as the Reynolds number and groove length increase. Numerical friction factors for both the Chen–Kim k-ε and LVEL turbulence models show good agreement with the experimental measurements.

scholarly journals Delineating the Polarized and Unpolarized Parton Structure of the Nucleon

2015 ◽  
Vol 37 ◽  
pp. 1560053
Author(s):  
Pedro Jimenez-Delgado
Keyword(s):  
Parton Distribution ◽  
Distribution Functions ◽  
Distribution Analysis ◽  
Coupling Constant ◽  
Parton Distribution Functions ◽  
Careful Treatment ◽  
Future Data ◽  
The Impact

Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.

Sign in / Sign up

Export Citation Format

Share Document