An efficient memetic, permutation-based evolutionary algorithm for real-world train timetabling

Train timetabling is a difficult and very tightly constrained combinatorial problem that deals with the construction of train schedules. We focus on the particular problem of local reconstruction of the schedule following a small perturbation, seeking minimisation of the total accumulated delay by adapting times of departure and arrival for each train and allocation of resources (tracks, routing nodes, etc.). We describe a permutation-based evolutionary algorithm that relies on a semi-greedy heuristic to gradually reconstruct the schedule by inserting trains one after the other following the permutation. This algorithm can be hybridised with ILOG commercial MIP programming tool CPLEX in a coarse-grained manner: the evolutionary part is used to quickly obtain a good but suboptimal solution and this intermediate solution is refined using CPLEX. Experimental results are presented on a large real-world case involving more than one million variables and 2 million constraints. Results are surprisingly good as the evolutionary algorithm, alone or hybridised, produces excellent solutions much faster than CPLEX alone

On the Benefits of Inoculation, an Example in Train Scheduling

The local reconstruction of a railway schedule following a small perturbation of the traffic, seeking minimization of the total accumulated delay, is a very difficult and tightly constrained combinatorial problem. Notoriously enough, the railway company's public image degrades proportionally to the amount of daily delays, and the same goes for its profit! This paper describes an inoculation procedure which greatly enhances an evolutionary algorithm for train re-scheduling. The procedure consists in building the initial population around a pre-computed solution based on problem-related information available beforehand. The optimization is performed by adapting times of departure and arrival, as well as allocation of tracks, for each train at each station. This is achieved by a permutation-based evolutionary algorithm that relies on a semi-greedy heuristic scheduler to gradually reconstruct the schedule by inserting trains one after another. Experimental results are presented on various instances of a large real-world case involving around 500 trains and more than 1 million constraints. In terms of competition with commercial math ematical programming tool ILOG CPLEX, it appears that within a large class of instances, excluding trivial instances as well as too difficult ones, and with very few exceptions, a clever initialization turns an encouraging failure into a clear-cut success auguring of substantial financial savings

Artificial Agents and Speculative Bubbles

Pertaining to Agent-based Computational Economics (ACE), this work presents two models for the rise and downfall of speculative bubbles through an exchange price fixing based on double auction mechanisms. The first model is based on a finite time horizon context, where the expected dividends decrease along time. The second model follows the {\em greater fool} hypothesis; the agent behaviour depends on the comparison of the estimated risk with the greater fool's. Simulations shed some light on the influent parameters and the necessary conditions for the apparition of speculative bubbles in an asset market within the considered framework

Capacitated Hub Routing Problem in Hub-and-Feeder Network Design: Modeling and Solution Algorithm

International audienceIn this paper, we address the Bounded Cardinality Hub Location Routing with Route Capacity wherein eachhub acts as a transshipment node for one directed route. The number of hubs lies between a minimum anda maximum and the hub-level network is a complete subgraph. The transshipment operations take place atthe hub nodes and flow transfer time from a hub-level transporter to a spoke-level vehicle influences spoketo-hub allocations. We propose a mathematical model and a branch-and-cut algorithm based on Bendersdecomposition to solve the problem. To accelerate convergence, our solution framework embeds an efficientheuristic producing high-quality solutions in short computation times. In addition, we show how symmetrycan be exploited to accelerate and improve the performance of our method

Local probing of the field emission stability of vertically aligned multiwalled carbon nanotubes

Metallic cantilever in high vacuum atomic force microscope has been used as anode for field emission experiments from densely packed vertically aligned multi-walled carbon nanotubes. The high spatial resolution provided by the scanning probe technique allowed precise setting of the tip-sample distance in the submicron region. The dimension of the probe (curvature radius below 50nm) allowed to measure current contribution from sample areas smaller than 1um^2. The study of long-term stability evidenced that on these small areas the field emission current remains stable (within 10% fluctuations) several hours (at least up to 72 hours) at current intensities between 10-5A and 10-8A. Improvement of the current stability has been observed after performing long-time Joule heating conditioning to completely remove possible adsorbates on the nanotubes.Comment: 15 pages, 7 figure

Hubungan Pengetahuan Ibu Tentang Manfaat Bermain Dengan Perkembangan Anak Usia Prasekolah Di Taman Kanak-kanak Anugerah Tumaratas Dua Kecamatan Langowan Barat

: Knowledge and mother's roles are very useful for child development thoroughly because parents could recognize the excess of child development process earlier and possibly to give stimulate to child growth including physically, mentally and social. The purpose of this study was to determine the relationship of mother's knowledge about the benefits of playing with the development of preschool childrens in Anugerah Kindergarten Tumaratas Two District of West langowan. The design of this study used cross sectional method. The population in this study were all mothers and children in the Anugerah Kindergarten Tumaratas Two District west Langowan, who have met the inclusion criteria. The sampling technique used is Saturated Samples. Instrument used was a questionnaire. The conclusion is that knowledge of mothers about the benefits of playing with the child's development have gained value (p =0.004<α 0.05). Good knowledge of parents about the benefits of play for childrens can affect the development of children so that children achieve optimal development of the appropriate age. Advice through research that the mothers can apply the benefits of play to childrens in accordance with the age of the child

Specialized Trial Courts in Patent Litigation: A Review of the Patent Pilot Program\u27s Impact on Appellate Reversal Rates at the Five-Year Mark

Do specialized trial court judges make more accurate decisions in patent law cases? In 2011, Congress passed a law setting up a ten-year patent law pilot program to enhance expertise in patent litigation by funneling more trial court decisions to fourteen selected district courts. Now that the five-year mark has passed, has the program had its intended effect of increasing accuracy, as measured by less reversal by the appellate court? In this Article, I analyze over 20,000 trial-court patent cases filed from late 2011 to 2016, focusing specifically on whether cases heard by district court judges participating in the patent law pilot program differ from those before non-pilot judges. I find that the types of cases heard before pilot judges differ. Pilot judges are less likely to rule in favor of the patentee and they are more likely to take cases to trial. Pilot judges also make different kinds of “mistakes” than non-pilot judges. Of the near three-hundred cases where the Federal Circuit rules on the substantive patent law issues on appeal, my results indicate that even controlling for other factors, judges that are part of the pilot program are not less likely to be overturned on appeal by the Federal Circuit. After discussing the empirical results, the Article proposes suggestions for reform. Patent law is unique in that it is one of the only areas of law where Congress delegates policymaking to the courts. The current piecemeal approach to patent reform by changing institutions in isolation to solve specific problems is misplaced. Multi-institutional reform of the patent system — focused on giving policymaking power to the bureaucracy to allow for less biased and more expert decision making — is needed in order to properly position courts as interpreters of the law rather than as being the vehicle primarily responsible for fashioning policy on an ad hoc basis

Specialized Trial Courts in Patent Litigation: A Review of the Patent Pilot Program\u27s Impact on Appellate Reversal Rates at the Five-Year Mark

Do specialized trial court judges make more accurate decisions in patent law cases? In 2011, Congress passed a law setting up a ten-year patent law pilot program to enhance expertise in patent litigation by funneling more trial court decisions to fourteen selected district courts. Now that the five-year mark has passed, has the program had its intended effect of increasing accuracy, as measured by less reversal by the appellate court? In this Article, I analyze over 20,000 trial-court patent cases filed from late 2011 to 2016, focusing specifically on whether cases heard by district court judges participating in the patent law pilot program differ from those before non-pilot judges. I find that the types of cases heard before pilot judges differ. Pilot judges are less likely to rule in favor of the patentee and they are more likely to take cases to trial. Pilot judges also make different kinds of “mistakes” than non-pilot judges. Of the near three-hundred cases where the Federal Circuit rules on the substantive patent law issues on appeal, my results indicate that even controlling for other factors, judges that are part of the pilot program are not less likely to be overturned on appeal by the Federal Circuit. After discussing the empirical results, the Article proposes suggestions for reform. Patent law is unique in that it is one of the only areas of law where Congress delegates policymaking to the courts. The current piecemeal approach to patent reform by changing institutions in isolation to solve specific problems is misplaced. Multi-institutional reform of the patent system — focused on giving policymaking power to the bureaucracy to allow for less biased and more expert decision making — is needed in order to properly position courts as interpreters of the law rather than as being the vehicle primarily responsible for fashioning policy on an ad hoc basis

The study of magnetic properties of the bilayer Ising model in an external magnetic field

Bu çalışmada, en düşük dereceli kümesel değişim metodunu kullanarak ferromagnetik A ve B tek tabakalarında aynı ve farklı spin durumlarını ve tabakalar arasında farklı bir etkileşme ile çiftlenimli iki katmanlı Ising modelinin magnetik özellikleri en düşük dereceli kümesel değişim metodunun kullanılmasıyla incelendi. Tabaka ve toplam magnetizasyonun termal değişimleri kapsamlıca incelendi ve durumunda sadece ikinci derece faz dönüşümü elde edildi. Diğer taraftan, tek tabakalardaki spin değerleri için hem birinci derece hem de ikinci derece faz dönüşümü elde edilir. Tek iyon anizotropisinin sadece B tek tabakası üzerideki etkisi incelendi. Tek tabaka magnetizasyonlarının sıcaklık değişimleri incelendi ve sistemi faz diyagramları farklı düzlemlerde verildi. Ayrıca toplam magnetizasyonun sıcaklığa göre davranışı ve dış magnetik alanın tüm sistem üzerindeki etkisi incelendi. Sistemde komşu tabakalar arası etkileşme ve tek iyon anizotropi parametresi arasındaki etkileşmeye bağlı olarak üçlü kritik nokta ve kompansasyon davranışı gibi ilginç magnetik özellikler bulundu.In this study, we study magnetic properties of a ferromagnetic bilayer Ising system consisting of two monolayers (A and B) with different spins and different interaction constants coupled together with an interlayer interaction by using the lowest approximation of the cluster variation method. The thermal variations of the layer and total magnetizations are investigated extensively and obtained only second order phase transition in the case of . On the other hand, both the first and second order phase transitions are observed for the spin values on the monolayers. The effect of single-ion anisotropy on the only B monolayer is also studied. The phase transitions of monolayer magnetizations are studied and the phase diagrams of the system are given in different planes. The temperatures dependence of the total magnetization and the influence of the external magnetic field on the all system is also examined. We find interesting magnetic properties in the system, such as tricritical point and compensation behavior, depending on the competition between the interlayer interaction and single-ion anisotropy parameter