Explicit Routing Research Articles

Using an exact bi-objective decoder in a memetic algorithm for arc-routing (and other decoder-expressible) problems

We address the bi-objective Capacitated Arc Routing Problem (CARP) by considering two levels of solution interpretation: implicit and explicit solutions. An algorithm that translates implicit solutions into explicit solutions is called a decoder. In this work, the decoder takes as input a permutation of the required edges and generates a Pareto frontier of CARP solutions. While bi-objective CARP was our main focus and starting point, we could also use the proposed framework to solve a bi-objective version of the traveling salesman problem by plugging-in a different decoder. Recall that bi-objective CARP asks to service (the demands of) a set of required edges using a fleet of vehicles of limited capacity so as to minimize: (i) the total travelled distance and (ii) the length of the longest route. Any permutation s of the required edges constitutes an implicit CARP solution. The decoder constructs all non-dominated explicit solutions that service the edges in the order indicated by s, i.e., the decoder is an exact algorithm that returns the optimal Pareto frontier subject to the service order s. To achieve competitive CARP results it is also important to reinforce the decoder using a local search operator that acts on explicit routes (and that may change the service order s). For nine instances, the resulting algorithm was even able to find a new total-cost upper bound, improving upon the best solutions reported in the (considerably larger) mono-objective CARP literature. This shows that (some of) the proposed ideas can also be useful in single objective optimization: the second objective can be seen as a guide for the mono-objective search process.

Simulating Groundwater Interaction with a Surface Water Network Using Connected Linear Networks.

Simulating the interaction of groundwater with surface water networks using traditional boundary packages available with MODFLOW-USG can be challenging for complex systems. Often several package types are required as they are typically purpose built. Moreover, these packages generally do not interact with one another which complicates accounting of groundwater discharge at different points within the system. Here, we demonstrate that the connected linear network (CLN) package of MODFLOW-USG, and advances therein in USG-Transport, can be used to simulate groundwater interaction with a complex surface water network comprised of creeks, ponds, wetlands, and springs, in a manner that is comparable with these other packages, but with additional benefits, including explicit routing of water between the features.

Bounds for flag codes

The application of flags to network coding has been introduced recently by Liebhold, Nebe, and Vazquez-Castro. It is a variant to random linear network coding and explicit routing solutions for given networks. Here we study lower and upper bounds for the maximum possible cardinality of a corresponding flag code with given parameters.

A Probabilistic Model for Real-Time Semantic Prediction of Human Motion Intentions from RGBD-Data.

For robots to execute their navigation tasks both fast and safely in the presence of humans, it is necessary to make predictions about the route those humans intend to follow. Within this work, a model-based method is proposed that relates human motion behavior perceived from RGBD input to the constraints imposed by the environment by considering typical human routing alternatives. Multiple hypotheses about routing options of a human towards local semantic goal locations are created and validated, including explicit collision avoidance routes. It is demonstrated, with real-time, real-life experiments, that a coarse discretization based on the semantics of the environment suffices to make a proper distinction between a person going, for example, to the left or the right on an intersection. As such, a scalable and explainable solution is presented, which is suitable for incorporation within navigation algorithms.

Enhancing Performance Of WSN By Utilizing Secure Qos Based Explicit Routing

Wireless sensor networks (WSN) are infrastructure less and self-configured a wireless network that allows monitoring the physical conditions of an environment. Many researchers focus on enhancing the performance of WSN in order to provide effective delivery of data on the network, but still results in lower quality of services like energy consumption, delay and routing. We tackle this problem by introducing a new routing algorithm, QoS-based explicit routing algorithm which helps in transmitting the data from source node to destination node on WSN. We also involve clustering process in WSN based on genetic algorithm and particle swarm optimisation (GA and PSO) algorithm. We proposed identity-based digital signature (IBDS) and enhanced identity-based digital signature (EIBDS) that involves reduction of computation overhead and also increasing resilience on the WSN. We also use advanced encryption standard (AES), for ensuring the security between nodes and avoid hacking of data by other intruders.

Enhancing performance of WSN by utilising secure QoS-based explicit routing

Enhancing performance of WSN by utilising secure QoS-based explicit routing

Domestication and Spread of Broomcorn Millet (Panicum miliaceum L.) Revealed by Phylogeography of Cultivated and Weedy Populations

Cultivated broomcorn millet (Panicum miliaceum L.), one of the most ancient crops, has long been an important staple food in the semiarid regions of Eurasia. Weedy broomcorn millet (Panicum ruderale (Kitag.) Chang comb. Nov.), the companion weed of cultivated broomcorn millet, is also widely distributed throughout Eurasia and can produce fertile offspring by crossing with cultivated broomcorn millet. The evolutionary and genetic relationships between weedy and cultivated broomcorn millets, and the explicit domestication areas and detailed spread routes of this cereal are still unclear. The genetic diversity and population structure of 200 accessions of weedy and cultivated broomcorn millets were explored to elucidate the genetic relationship between weedy and cultivated broomcorn millets, and to trace the explicit domestication areas and detailed spread routes of broomcorn millets by using 23 simple sequence repeats (SSR) markers. Our results show that the weedy populations in China may harbor the ancestral variations that gave rise to the domesticated broomcorn millet. The population structure pattern observed in the wild and domesticated broomcorn millets is consistent with the hypothesis that there may be at least two independent domestication areas in China for the cultivated broomcorn millet, the Loess Plateau and the Northeast China, with both following the westward spread routes. These two westward spread routes of cultivated broomcorn millet coincide exactly with the prehistoric Oasis Route and Steppe Route, respectively.

A new approach for traffic matrix estimation in high load computer networks based on graph embedding and convolutional neural network

AbstractIn computer networks, transmitted traffic between origin‐destination nodes has been considered a crucial factor in traffic engineering applications. To date, measuring the traffic directly in high load networks is difficult due to high computational costs. On the other hand, accurate estimation of network traffic by means of link load measurements and routing information is currently a challenging problem. In this paper, we propose a new approach to estimate end‐to‐end traffic, inspired by graph embedding. In the proposed approach, we consider a computer network as a time‐varying graph. Our model provides explicit routing information to a convolutional neural network estimator via link load measurements and network topological structure. When explicit routing information is provided, the learning model is only expected to embed the relations between link loads into a traffic estimation vector, instead of figuring out the routing paths. The experimental results showed that the proposed approach outperforms similar estimators in terms of lower estimation error and better tracking the fluctuations.

Design and Analysis of QoS Routing Framework integrated with OLSR protocol for Multimedia Traffic in Mobile Adhoc Networks

MANETs (Mobile Ad-hoc Networks) is the self organizing wireless structure of mobile hosts. Wireless media is used for communication in MANETs. Considering the developing requirements for multimedia and real-time traffic applications in real world, QoS (Quality-of-Service) support is essential in MANETs. But most of the characteristics of MANETs make QoS support a difficult problem. It is challenging to support QoS routing in MANET due to dynamic behavior and mobility of the hosts. The OLSR (Optimized Link State Routing) protocol can be efficiently used in MANETs to provide QoS routing because of its dynamic MPR (Multi Point Relay) selection criteria and proactive nature. In this paper, a design of QoS routing framework integrated with OLSR protocol is proposed and also analyzed using network simulator. Proposed QoS framework combines a bandwidth estimation algorithm with explicit resource reservation, QoS routing and connection admission control (CAC). OLSR protocol is extended for QoS framework to solve performance issues related to node mobility using cross layer approach. Results after simulation conclude about efficiency of the proposed QoS routing framework.

Sustaining the emergency wireless multihop infrastructure by distributed sharing of energy consumption

ABSTRACTWireless multihop infrastructures (WMIs) facilitate low‐cost and quick deployable network infrastructures for emerging applications in emergency responses and smart cities. Cooperative sharing of energy consumption is essential for network sustainability. This paper studies the problem of cooperative sharing of routing services in an emergency WMI (E‐WMI) by examining the regulation of route switching from perspectives of network‐wide and long‐time energy efficiency. A key idea in the regulation of route switching is employing explicit routing terms among base stations in an E‐WMI, allowing tolerance of temporary imbalance of energy consumption in the network. A routing term refers to a period for a base station to continuously serve routing in an E‐WMI. By taking into account the specific features of E‐WMIs, this paper overcomes the challenging problems of complexity and difficulty in examining the explicit route switching and energy distribution in multihop networks. We find that there exists the optimal routing term and number of route switching for the long‐time energy efficiency. With the optimal routing terms, a network can take a principle of distributed energy sharing by route switching management rather than only applying end‐to‐end energy‐efficient routing that does not have a long‐time management of network energy consumption.

Explicit Path Control in Commodity Data Centers: Design and Applications

Many data center network (DCN) applications require explicit routing path control over the underlying topologies. In this paper, we present XPath, a simple, practical and readily-deployable way to implement explicit path control, using existing commodity switches. At its core, XPath explicitly identifies an end-to-end path with a path ID and leverages a two-step compression algorithm to pre-install all the desired paths into IP TCAM tables of commodity switches. Our evaluation and implementation show that XPath scales to large DCNs and is readily-deployable. Furthermore, on our testbed, we integrate XPath into four applications to showcase its utility.

Implicit and Explicit Routes to Recognize the Own Body: Evidence from Brain Damaged Patients.

Much research suggested that recognizing our own body-parts and attributing a body-part to our physical self-likely involve distinct processes. Accordingly, facilitation for self-body-parts was found when an implicit, but not an explicit, self-recognition was required. Here, we assess whether implicit and explicit bodily self-recognition is mediated by different cerebral networks and can be selectively impaired after brain lesion. To this aim, right- (RBD) and left- (LBD) brain damaged patients and age-matched controls were presented with rotated pictures of either self- or other-people hands. In the Implicit task participants were submitted to hand laterality judgments. In the Explicit task they had to judge whether the hand belonged, or not, to them. In the Implicit task, controls and LBD patients, but not RBD patients, showed an advantage for self-body stimuli. In the Explicit task a disadvantage emerged for self-compared to others' body stimuli in controls as well as in patients. Moreover, when we directly compared the performance of patients and controls, we found RBD, but not LBD, patients to be impaired in both the implicit and explicit recognition of self-body-part stimuli. Conversely, no differences were found for others' body-part stimuli. Crucially, 40% RBD patients showed a selective deficit for implicit processing of self-body-part stimuli, whereas 27% of them showed a selective deficit in the explicit recognition of their own body. Additionally, we provide anatomical evidence revealing the neural basis of this dissociation. Based on both behavioral and anatomical data, we suggest that different areas of the right hemisphere underpin implicit and explicit self-body knowledge.

Iterated Local Search and Column Generation to solve Arc-Routing as a permutation set-covering problem

We propose a method that combines Column Generation (CG) and Iterated Local Search (ILS) to solve the Capacitated Arc-Routing Problem (CARP). One of the goals is to integrate into the ILS (some of) the duality information that underpins the CG paradigm. The CARP is expressed in a space of permutations and sub-permutations (sequences, routes) of the set of required edges. For this, the ILS uses an exact decoder that maps any permutation s to a list of sequences (routes) of minimum cost servicing all edges in the order s(1), s(2), s(3), etc. This permutation space is explored both by an ILS process and a CG process that run in parallel and that communicate by exchanging sequences. The first use of the CG paradigm in ILS is the following: all sequences discovered by CG are sent to the ILS process that can inject them into the current ILS solution. The second application of CG in ILS is a “CG improver” operator that acts on the current ILS solution, so as to (try to) improve it by running several CG iterations. The first half of the paper describes the method in a general framework based on sequences, permutations and set covering. The second part is devoted to more specialized Arc-Routing techniques. For instance, the CG convergence could be accelerated by factors of tens or even hundreds by exploiting two ideas in the Dynamic Programming (DP) pricing: (i) avoid as much as possible to traverse edges without service, and (ii) record only non-dominated DP states using a fast-access data structure mixing an array and a red-black tree. Regarding the ILS, we show that the permutation-level search can be substantially improved if the exact decoder is reinforced by a deterministic post-decoder acting on explicit routes. The general results are competitive (reducing the best-known gap of five instances) and certain ideas could be potentially useful for other set-covering or permutation problems.

Design and implementation of WiMesh: A tool for the performance evaluation of multi-radio wireless mesh networks

In this paper we present WiMesh, a software tool we developed during the last few years of research conducted in the field of multi-radio wireless mesh networks. WiMesh serves two main purposes: (i) to evaluate and compare different algorithms for the static configuration of a wireless mesh network (assignment of channels, transmission rate and power to the available network radios, explicit routing); (ii) to automatically setup and run packet level simulations (by using the ns-3 network simulator) based on the network configuration returned by such algorithms. WiMesh consists of a core library, three libraries dedicated to distinct functionalities of WiMesh and three corresponding utilities that allow us to easily conduct experiments. To ensure ease of use and flexibility, all such utilities accept as input an XML configuration file where various options and parameters can be specified. WiMesh is freely available to the research community as open source software, with the purpose of easing the development of new algorithms and the verification of their performances. In this paper, we first present the architecture of WiMesh and its features and capabilities by illustrating the design and the usage of each of the provided utilities. Then, to the benefit of those willing to implement their own solution within WiMesh or extend its functionalities, we illustrate the design of the WiMesh libraries. Finally, we report some of the results, which we were able to show in previous research work thanks to the use of WiMesh.

Load Balancing in IP Networks Using Generalized Destination-Based Multipath Routing

Intradomain traffic engineering (TE) has become an indispensable tool for Internet service providers (ISPs) to optimize network performance and utilize network resources efficiently. Various explicit routing TE methods were recently proposed and have been able to achieve high network performance. However, explicit routing has high complexity and requires large ternary content addressable memories (TCAMs) in the routers. Moreover, it is costly to deploy explicit routing in IP networks. In this paper, we present an approach, called generalized destination-based multipath routing (GDMR), to achieve the same high performance as explicit routing. The main contribution of this paper is that we prove that an arbitrary explicit routing can be converted to a loop-free destination-based routing without any performance penalty for a given traffic matrix. We present a systematic approach including a heuristic algorithm to realize GDMR. Extensive evaluation demonstrates the effectiveness and robustness of GDMR.

A Comparative Analysis of the Effects of Dynamic Optical Circuit Provisioning on IP Routing

We analyze the effects of dynamic optical circuit setup on IP routing in general and on two routing mechanisms in particular, i.e., explicit routing and shortest-path-first routing. We present analytical models for computing the size and placement of optical circuits and propose model adaptations driven by the IP router system design. The results show that without careful consideration of intrinsic capabilities of IP routing protocol and forwarding, the size and location of optical circuits used can be vastly underestimated, also leading to significant disruptions in real networks. We present the Optical Bypass mechanisms and show that these methods, unlike traditional IP routing-based solutions, affect a comparatively lower number of IP routes and can be computed near-optimally, even under unknown traffic matrix conditions, making them effective and feasible.

Class-Based Constraint-Based Routing with Implemented Fuzzy Logic in MPLS-TE Networks

The paper deals with constraint-based routing (CBR) in MPLS-TE networks and proposes a new CBR algorithm based on fuzzy logic called Fuzzy Class-Based Algorithm (FCBA). Multiprotocol label switching with traffic engineering (MPLS-TE) networks represent a popular mechanism to effectively use resources of service providers’ core networks. The paths can be either built by administrators (explicit routing) or built by using existing routing algorithms which mostly decide based on the shortest paths towards the destination which might not be sufficient in nowadays’ multimedia networks. To address this problem various CBR algorithms have emerged which take into consideration various aspects important to existing traffic like QoS parameters or administrative policies. FCBA makes routing decisions based on traffic classes and by using fuzzy logic we can assign normalized values to various constraints based on the traffic class’ preferences (e.g., low delay paths for voice traffic) and network administrator’s preferences (e.g., avoiding congested links). The paper provides comparison of FCBA with existing CBR approaches based on their ability to provide QoS parameters loss. The simulations show that FCBA provides the best results for the highest priority traffic where it uses lower priority traffic to efficiently utilize the network.

QoS measurement of workflow-based web service compositions using Colored Petri net.

Workflow-based web service compositions (WB-WSCs) is one of the main composition categories in service oriented architecture (SOA). Eflow, polymorphic process model (PPM), and business process execution language (BPEL) are the main techniques of the category of WB-WSCs. Due to maturity of web services, measuring the quality of composite web services being developed by different techniques becomes one of the most important challenges in today's web environments. Business should try to provide good quality regarding the customers' requirements to a composed web service. Thus, quality of service (QoS) which refers to nonfunctional parameters is important to be measured since the quality degree of a certain web service composition could be achieved. This paper tried to find a deterministic analytical method for dependability and performance measurement using Colored Petri net (CPN) with explicit routing constructs and application of theory of probability. A computer tool called WSET was also developed for modeling and supporting QoS measurement through simulation.

Explicit routing schemes for implementation of cellular automata on processor arrays

Massively parallel processor array (MPPA) architectures are becoming widely available computing platforms. Because of formal similarities, they are good candidates for implementing cellular automata (CA). An essential difference still remains regarding the freedom in communications. In MPPA there is a fixed on-chip network interconnection topology but every CA has its own definition of neighbourhood. While a cell in a CA can be considered as directly connected to its neighbours, these connections correspond to paths in the network of the MPPA. The communications need to be routed and scheduled to reach their proper destination. In previous work we introduced a formal data-flow process network model named KRG (for K-periodically Routed Graph). Its main feature is to allow regular switching directives. In the present paper we will use it to represent the proper local sequences of routing directives that will efficiently propagate values from cells to cells so as to implement the required CA neighbourhood. We present the neighbourhood broadcasting algorithm that computes these routing directives. One should note here that the problem is made more complex as data traffic between distinct source and target cells must be merged, while multicast may save a tremendous amount of communications when values are required in multiple locations. We demonstrate the expressive power of our formalism on the case of a 2D CA where the neighbourhood consists of all cells at Moore distance at most n. Further potential applications of our framework are hinted.

Foreword: cellular automata and applications

This special issue contains four papers presented during the workshop, ‘‘18th International Workshop on Cellular Automata and Discrete Complex Systems’’ (Automata 2012), held in La Marana, Corsica island (France) in the period September 19–21th, 2012. The aim of this workshop is to establish and maintain a permanent, international, multidisciplinary forum for the collaboration of researchers in the field of Cellular Automata (CA) and Discrete Complex Systems (DCS), provide a platform for presenting and discussing new ideas and results, and support the development of theory and applications of CA and DCS. Typical, but not exclusive, topics of the workshop are: dynamics aspects, algorithmic, computational and complexity issues, emergent properties, formal language processing, models of parallelism and distributed systems, phenomenological descriptions, scientific modeling and practical applications. After an additional review process, four papers were selected and included in this special issue. They are now presented in an extended and improved form with respect to the already refereed workshop version that appeared in the proceedings of Automata 2012. The paper ‘‘Computation of Functions on n Bits by Asynchronous Clocking Cellular Automata’’ by Michael Vielhaber aims at proving that different functions on binary vectors can be computed by changing the updating scheme from a fully synchronous to an asynchronous one on some fixed CA local rule. In their paper ‘‘Solving the Parity Problem in One– Dimensional Cellular Automata’’, Heather Betel, Pedro P. B. de Oliveira, and Paola Flocchini deal with the parity problem in one–dimensional cellular automata (CA): a CA local rule solves the parity problem if, starting from any initial configuration, the CA converges to the 0–configuration (resp., the 1–configuration) if and only if the initial configuration contains an even number of 1s (resp., an odd number of 1s). In particular, authors focus on the neighborhood size of CA rules solving the problem. Murillo G. Carneiro and Gina M. B. Oliveira present in the paper ‘‘Synchronous Cellular Automata-Based Scheduler initialized by Heuristic and modeled by a Pseudolinear neighborhood’’ two approaches based on CA to the task scheduling problem in multiprocessor systems. The implementation of cellular automata on processor arrays is considered by Jean-Vivien Millo and Robert de Simone in the paper ‘‘Explicit routing schemes for implementation of cellular automata on processor arrays’’. They deal with the trade-offs between the generality of the CA neighborhood and the limited expressive power provided by physical platforms. This is an extremely hot topic which will help in turning CA towards real extended applications. We would like to warmly thank the authors for their work and effort which made this special issue possible. Special thanks go to all referees for their valuable contributions both during the selection and the final review process. Finally, we also want to thank Professor Grzegorz Rozenberg for offering us the opportunity to publish this special issue in Natural Computing.