14,879 research outputs found
MESURE Tool to benchmark Java Card platforms
The advent of the Java Card standard has been a major turning point in smart
card technology. With the growing acceptance of this standard, understanding
the performance behavior of these platforms is becoming crucial. To meet this
need, we present in this paper a novel benchmarking framework to test and
evaluate the performance of Java Card platforms. MESURE tool is the first
framework which accuracy and effectiveness are independent from the particular
Java Card platform tested and CAD used.Comment: International Journal of Computer Science Issues, Volume 1, pp49-57,
August 200
Sparse Automatic Differentiation for Large-Scale Computations Using Abstract Elementary Algebra
Most numerical solvers and libraries nowadays are implemented to use
mathematical models created with language-specific built-in data types (e.g.
real in Fortran or double in C) and their respective elementary algebra
implementations. However, built-in elementary algebra typically has limited
functionality and often restricts flexibility of mathematical models and
analysis types that can be applied to those models. To overcome this
limitation, a number of domain-specific languages with more feature-rich
built-in data types have been proposed. In this paper, we argue that if
numerical libraries and solvers are designed to use abstract elementary algebra
rather than language-specific built-in algebra, modern mainstream languages can
be as effective as any domain-specific language. We illustrate our ideas using
the example of sparse Jacobian matrix computation. We implement an automatic
differentiation method that takes advantage of sparse system structures and is
straightforward to parallelize in MPI setting. Furthermore, we show that the
computational cost scales linearly with the size of the system.Comment: Submitted to ACM Transactions on Mathematical Softwar
Port-City Development: The Spanish Case
[Abstract]: The objective of this paper is to try to evaluate the port-city
relationship from its onset, taking into account the challenges
of port 4.0. Indicators such as the percentage of employees
participating in training programs, the percentage of female
employees in Galician ports, the percentage of merchandise
moved by private operators and the percentage of companies
with quality certification in Galician ports are evaluated. The
fourth revolution is based on the transition from current
fossil fuel-based energy models to alternative energy sources,
changes in the logistics and transport parameters and finally,
on the elimination of intermediation. The key component of
the third pillar of new Economy 4.0 is complete digitalization.
The optimum port-city solution must address the need of both
the urban planner and the port manager to evaluate potential
measures that would alleviate the pressure of dedicated port
facilities on the city and vice versa to the greatest extent possible
An evaluation of Nigerian ports post-concession performance
Purpose: The quest for efficiency is claimed to be the major objective of port privatisation and this has led many ports in Africa to undertake port reforms. Based on this, Nigerian ports were concessioned and operations were handed over in one scoop to private operators between 2006 and 2007. This paper is looking to investigate in the reform that took place in a very short period of time improved the performance of Nigerian ports. This paper is also looking to provide a model for future evaluation.
Research Approach: A window based DEA model with panel data will be employed to measure pre- and post concession Nigerian ports' performance to determine efficiency gains from port reform. Secondly, to demonstrate how concession influence efficiency, a DEA based Malmquist productivity Insex will be used to determine the sources of (in)efficiency by decomposing the efficiency into frontier shift effects and catch-up effects.
Findings and Originality: The results revealed that none of the ports is hundred percent efficient before and after concession but rather a tremendous increase in throughput and ship traffic after the reform in most of the ports. Apapa port is the most efficient while Calabar and Warri are inefficient although there were fluctuations in efficiency in all the ports. The research is inconclusive because it is still ongoing
Although some studies have investigated the relationship between port efficiency and privatisation however several gaps still exist as the studies are skewed in favour of container ports in the developed world, mainly in Europe. Therefore, the need arises to critically look at the overall efficiency of national port system to enhance the efficiency of global transport chain.
Research Impact: The study will contribute to existing literature on port performance being the first to evaluate the post concession performance of a major maritime player in Sub-Saharan Africa. It will contribute to the never- ending debate by the Academia on the effect of ownership or privatisation on efficiency from the perspective of port institutional reforms in the third world countries
Practical Impact: It will benefit the Federal Government of Nigeria as a reference document of the first five years of the port reform policy and help the Government to intervene in areas of observed inefficiencies and make adjustments where possible. On the part of the "Landlord" NPA it will help them in the performing their regulatory role by identifying the operators who are making inefficient use of the resources allocated to them and provide the basis for future evaluation. Finally, it will give the various stake holders in the Maritime Industry a full grasp of the effect of concession in a Nation's port as Nigeria is the first country in the world to hand over terminal operations in all her ports in one scoop
High-Level Object Oriented Genetic Programming in Logistic Warehouse Optimization
DisertaÄnĂ prĂĄce je zamÄĹena na optimalizaci prĹŻbÄhu pracovnĂch operacĂ v logistickĂ˝ch skladech a distribuÄnĂch centrech. HlavnĂm cĂlem je optimalizovat procesy plĂĄnovĂĄnĂ, rozvrhovĂĄnĂ a odbavovĂĄnĂ. JelikoĹž jde o problĂŠm patĹĂcĂ do tĹĂdy sloĹžitosti NP-teĹžkĂ˝, je vĂ˝poÄetnÄ velmi nĂĄroÄnĂŠ nalĂŠzt optimĂĄlnĂ ĹeĹĄenĂ. MotivacĂ pro ĹeĹĄenĂ tĂŠto prĂĄce je vyplnÄnĂ pomyslnĂŠ mezery mezi metodami zkoumanĂ˝mi na vÄdeckĂŠ a akademickĂŠ pĹŻdÄ a metodami pouĹžĂvanĂ˝mi v produkÄnĂch komerÄnĂch prostĹedĂch. JĂĄdro optimalizaÄnĂho algoritmu je zaloĹženo na zĂĄkladÄ genetickĂŠho programovĂĄnĂ ĹĂzenĂŠho bezkontextovou gramatikou. HlavnĂm pĹĂnosem tĂŠto prĂĄce je a) navrhnout novĂ˝ optimalizaÄnĂ algoritmus, kterĂ˝ respektuje nĂĄsledujĂcĂ optimalizaÄnĂ podmĂnky: celkovĂ˝ Äas zpracovĂĄnĂ, vyuĹžitĂ zdrojĹŻ, a zahlcenĂ skladovĂ˝ch uliÄek, kterĂŠ mĹŻĹže nastat bÄhem zpracovĂĄnĂ ĂşkolĹŻ, b) analyzovat historickĂĄ data z provozu skladu a vyvinout sadu testovacĂch pĹĂkladĹŻ, kterĂŠ mohou slouĹžit jako referenÄnĂ vĂ˝sledky pro dalĹĄĂ vĂ˝zkum, a dĂĄle c) pokusit se pĹedÄit stanovenĂŠ referenÄnĂ vĂ˝sledky dosaĹženĂŠ kvalifikovanĂ˝m a trĂŠnovanĂ˝m operaÄnĂm manaĹžerem jednoho z nejvÄtĹĄĂch skladĹŻ ve stĹednĂ EvropÄ.This work is focused on the work-flow optimization in logistic warehouses and distribution centers. The main aim is to optimize process planning, scheduling, and dispatching. The problem is quite accented in recent years. The problem is of NP hard class of problems and where is very computationally demanding to find an optimal solution. The main motivation for solving this problem is to fill the gap between the new optimization methods developed by researchers in academic world and the methods used in business world. The core of the optimization algorithm is built on the genetic programming driven by the context-free grammar. The main contribution of the thesis is a) to propose a new optimization algorithm which respects the makespan, the utilization, and the congestions of aisles which may occur, b) to analyze historical operational data from warehouse and to develop the set of benchmarks which could serve as the reference baseline results for further research, and c) to try outperform the baseline results set by the skilled and trained operational manager of the one of the biggest warehouses in the middle Europe.
The Impacts of Airport Centrality in the EU Network and Inter- Airport Competition on Airport Efficiency
In this paper we study the relationship between airport efficiency and two factors: an airportâs centrality in the EU network, and the intensity of competition from alternative airports in the same catchment area. We apply a two-stage econometric model based on the Simar & Wilson (2007) bootstrap procedure to a balanced sample of 57 European airports. We also design and compute our own measures of airport centrality and competition. The results show that efficiency is positively related to centrality in the European network, as measured by a weighted sum of minimal paths passing through the airport in question. The intensity of competition between airports also has a positive effect on efficiency. Our analysis suggests that air transportation policies should focus on increasing competition within important catchment areas (e.g., by investing in infrastructure facilitating access to alternative airports) and enhancing the connectivity of the EU network (e.g., by subsidizing new point-to-point connections between airports with capacity to spare).air transportation, efficiency, network centrality, inter â airports competition.
- âŚ