Improving Airline Network Robustness and Operational Reliability by Sequential Optimisation Algorithms

A sequential optimisation algorithm is developed to improve the operational reliability of airline schedules. Simulation results show that departure delays are reduced by 30% after optimisation by using extra 260 min buffer times in the schedule. This also increases the network-wide schedule reliability from 37 to 52% and an estimated delay cost saving of $20 million dollars per annum for a small airline network. The advantage of sequential optimisation is that it considers the delay/punctuality propagation in airline networks, so to prevent airlines from planning excessive buffer times to individual flights by considering aircraft rotation as a whole process.     

Insight to the express transport network

The express delivery industry is developing rapidly in recent years and has attracted attention in many fields. Express shipment service requires that parcels be delivered in a limited time with a low operation cost, which requests a high level and efficient express transport network (ETN). The ETN is constructed based on the public transport networks, especially the airline network. It is similar to the airline network in some aspects, while it has its own feature. With the complex network theory, the topological properties of the ETN are analyzed deeply. We find that the ETN has the small-world property, with disassortative mixing behavior and rich club phenomenon. It also shows difference from the airline network in some features, such as edge density and average shortest path. Analysis on the corresponding distance-weighted network shows that the distance distribution displays a truncated power-law behavior. At last, an evolving model, which takes both geographical constraint and preference attachment into account, is proposed. The model shows similar properties with the empirical results.     

A power consumption sensitivity analysis of circuit-switched versus packet-switched backbone networks

While telecommunication networks have historically been dominated by a circuit-switched paradigm, the last decades have seen a clear trend towards packet-switched networks. In this paper we evaluate how both paradigms (which have also been referred to as optical bypass and non-bypass, respectively) perform in optical backbone networks from a power consumption point of view, and whether the general agreement of circuit switching being more power-efficient holds. We consider artificially generated topologies of various sizes, mesh degrees and – not yet previously explored in this context – transport linerates. We cross-validate our findings with a number of realistic topologies.Our results show that circuit switching is preferable when the average node-to-node demands are higher than half the transport linerates. However, packet switching can become preferable when the traffic demands are lower than half the transport linerate. We find that an increase in the network node count does not consistently increase the energy savings of circuit switching over packet switching, but the savings are heavily influenced by the mesh degree and (to a minor extent) by the average link length. Our results are consistent for uniform traffic demands and realistic traffic demands.A key take-away message for other research on power saving solutions in backbone networks is that the ratio between the average demand and the demand bitrate has considerable effect on the overall efficiency, and should be taken into account.     

A time-varying complex dynamical network model and its controlled synchronization criteria

Today, complex networks have attracted increasing attention from various fields of science and engineering. It has been demonstrated that many complex networks display various synchronization phenomena. In this note, we introduce a time-varying complex dynamical network model. We then further investigate its synchronization phenomenon and prove several network synchronization theorems. Especially, we show that synchronization of such a time-varying dynamical network is completely determined by the inner-coupling matrix, and by the eigenvalues and the corresponding eigenvectors of the coupling configuration matrix of the network.     

Building an IP-based community wireless mesh network: Assessment of PACMAN as an IP address autoconfiguration protocol

Wireless mesh networks are experiencing rapid progress and inspiring numerous applications in different scenarios, due to features such as autoconfiguration, self-healing, connectivity coverage extension and support for dynamic topologies. These particular characteristics make wireless mesh networks an appropriate architectural basis for the design of easy-to-deploy community or neighbourhood networks. One of the main challenges in building a community network using mesh networks is the minimisation of user intervention in the IP address configuration of the network nodes. In this paper we first consider the process of building an IP-based mesh network using typical residential routers, exploring the options for the configuration of their wireless interfaces. Then we focus on IP address autoconfiguration, identifying the specific requirements for community mesh networks and analysing the applicability of existing solutions. As a result of that analysis, we select PACMAN, an efficient distributed address autoconfiguration mechanism originally designed for ad-hoc networks, and we perform an experimental study – using off-the-shelf routers and assuming worst-case scenarios – analysing its behaviour as an IP address autoconfiguration mechanism for community wireless mesh networks. The results of the conducted assessment show that PACMAN meets all the identified requirements of the community scenario.     

Improved trust-aware recommender system using small-worldness of trust networks

The trust network is a social network where nodes are inter-linked by their trust relations. It has been widely used in various applications, however, little is known about its structure due to its highly dynamic nature. Based on five trust networks obtained from the real online sites, we contribute to verify that the trust network is the small-world network: the nodes are highly clustered, while the distance between two randomly selected nodes is short. This has considerable implications on using the trust network in the trust-aware applications. We choose the trust-aware recommender system as an example of such applications and demonstrate its advantages by making use of our verified small-world nature of the trust network.     

Distributed computing power service coordination based on peer-to-peer grids architecture

As computational speed, storage capacity, and communication technologies steadily progress to the advanced levels, many business employments have utilized these improvements to aggregate distributed resources in various enterprise collaborating functionalities. Recently, grid computing has been identified as a critical technology by industry for enterprise computing and business-to-business computing. The concept of peer-to-peer (P2P) network is also evolving to an expanded usage in distributed networks for sharing the resources like the content files or real-time data for enterprise applications. Therefore, it is natural to include the grids and P2P to support environments that have features of both limiting case. In this paper, a new computing design – NaradaBrokering based Computing Power Services (NB-CPS) – has been applied to utilize the P2P grid to integrate the computational grids, distributed objects, P2P networks under the hybrid environment. In this study, the approach has been applied to analyze the robustness of digital watermark by filter bank selection and the performance can be improved in the aspect of speedup, stability and processing time. NB-CPS is not only suitable for executing computing works which are able to run in batches, but also be able to solve current issues in Web Services based Computing Power Service (WS-CPS) such as system resilience, fault tolerance, efficiency of job scheduling and the instability in congested network environment.     

非严格的中枢辐射航线网络设计的鲁棒优化方法

为解决中枢辐射航线网络设计结果易受参数不确定性影响的问题,首先在需求和成本具有不确定性的条件下,建立了非严格意义上的无容量限制的中枢辐射航线网络鲁棒优化模型,并采用鲁棒优化方法对航线网络进行优化设计.然后结合中枢辐射航线网络实际应用中枢纽个数少的特点,对最短路算法加以改进,提出了一种求解航线网络鲁棒优化设计的精确算法,得到了适用于多种可能情景的鲁棒解.最后利用有关的成本和需求数据对该方法进行了验证;结果表明,鲁棒优化设计方法对航空公司构建中枢辐射航线网络具有很好的实用性.     

Softwarization and virtualization of VoIP networks

Nowadays, voice over IP (VoIP) is a cost-effective and efficient technology in the communications industry. Free applications for transferring multimedia on the Internet are becoming more attractive and pervasive day by day. Nevertheless, the traditional, close, and hardware-defined nature of the VoIP networks’ structure makes the management of these networks more complicated and costly. Besides, its elementary and straightforward mechanisms for routing call requests have lost their efficiency, causing some problems, such as SIP servers’ overload. In order to tackle these problems, we introduce VoIP network softwarization and virtualization and propose two novel frameworks in this article. In this regard, we take advantage of the SDN and NFV concepts such that we separate data and control planes and provide the possibility for centralized and softwarized control of this network. This matter leads to effective routing. The NFV also makes this network’s dynamic resource management possible by functions virtualization of the VoIP network. The proposed frameworks are implemented in a real testbed, including Open vSwitch and Floodlight, examined by various scenarios. The results demonstrate an improvement in signaling and media quality in the VoIP network. As an example, the average throughput and resource efficiency increased by at least 28% and the average response time decreased by 34%. The overall latency has also been reduced by almost 39%.

     

A linked data approach to multi-scale energy modelling

Interactions between built infrastructure are complex and nuanced; changes to any one component can have disproportionate effects on the system as a whole. For instance, adoption of heat pumps or electric vehicles by a significant proportion of a population in an urban centre would place new demands on both electricity transmission and distribution networks. It is essential that planners – both national and local – can understand and share information about the resource demands that this type of change places on national and local infrastructure. Access to integrated sources of information – from building component to national levels – is key to supporting policy makers and decision takers. However, over time, information – and as a consequence, the software that manages it – has evolved into functional silos; this has, in turn, affected the definition of data exchange standards. This limits the ability of experts in functional areas to exchange data and implement broader decision support systems. This paper describes the use of linked data approaches to permit queries across large, diverse information sources to provide reasoning about complex questions at multiple scales. The methodology defines a central context to which various external sources can be attached. These distributed sources are, in themselves, registered in a central catalogue; they remain, however, under the control of their source organisations. In this way a large, extensible, interconnected network of distributed data describing, for example, a built environment or electricity transmission network; this network of data resources can be queried centrally to provide customised views of subsets of the data, and so provide a richer view than one source in isolation. The approach was applied to prepare and integrate information about Ireland’s transmission grid and administrative boundaries, along with domestic housing stock into a single data source. The resulting data network is queried by a scenario exploration tool. This tool successfully allows analysis, at a national level by economists, of the effects of the adoption of new technologies on the national grid of Ireland.     

Valuation of online social networks taking into account users’ interconnectedness

Online social networks have been gaining increasing economic importance in light of the rising number of their users. Numerous recent acquisitions priced at enormous amounts have illustrated this development and revealed the need for adequate business valuation models. The value of an online social network is largely determined by the value of its users, the relationships between these users, and the resulting network effects. Therefore, the interconnectedness of a user within the network has to be considered explicitly to get a reasonable estimate for its economic value. Established standard business valuation models, however, do not account for these aspects sufficiently. Thus, we propose an economic model for the valuation of online social networks, which takes into account the users’ interconnectedness within the network. Furthermore, we analyze different centrality measures, which can be used to quantify users’ interconnectedness in online social networks and propose a measure which is based on the PageRank-algorithm. Finally, the practical application of the model is illustrated by an example of the European online social network XING.com.     

Vulnerability of Regional Aviation Networks Based on DBSCAN and Complex Networks

To enhance the accuracy of performance analysis of regional airline network, this study applies complex network theory and Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm to investigate the topology of regional airline network, constructs node importance index system, and clusters 161 airport nodes of regional airline network. Besides, entropy power method and approximating ideal solution method (TOPSIS) is applied to comprehensively evaluate the importance of airport nodes and complete the classification of nodes and identification of key points; adopt network efficiency, maximum connectivity subgraph and network connectivity as vulnerability measurement indexes, and observe the changes of vulnerability indexes of key nodes under deliberate attacks and 137 nodes under random attacks. The results demonstrate that the decreasing trend of the maximum connectivity subgraph indicator is slower and the decreasing trend of the network efficiency and connectivity indicators is faster when the critical nodes of the regional airline network are deliberately attacked. Besides, the decreasing trend of the network efficiency indicator is faster and the decreasing trend of the maximum connectivity subgraph indicator is slower when the nodes of four different categories are randomly attacked. Finally, it is proposed to identify and focus on protecting critical nodes in order to better improve the security level of regional airline system.     

Airline planning benchmark problems—Part I:: Characterising networks and demand using limited data

This paper is the first of two papers entitled “Airline Planning Benchmark Problems”, aimed at developing benchmark data that can be used to stimulate innovation in airline planning, in particular, in flight schedule design and fleet assignment. While optimisation has made an enormous contribution to airline planning in general, the area suffers from a lack of standardised data and benchmark problems. Current research typically tackles problems unique to a given carrier, with associated specification and data unavailable to the broader research community. This limits direct comparison of alternative approaches, and creates barriers of entry for the research community. Furthermore, flight schedule design has, to date, been under-represented in the optimisation literature, due in part to the difficulty of obtaining data that adequately reflects passenger choice, and hence schedule revenue. This is Part I of two papers taking first steps to address these issues. It does so by providing a framework and methodology for generating realistic airline demand data, controlled by scalable parameters. First, a characterisation of flight network topologies and network capacity distributions is deduced, based on the analysis of airline data. Then a multi-objective optimisation model is proposed to solve the inverse problem of inferring OD-pair demands from passenger loads on arcs. These two elements are combined to yield a methodology for generating realistic flight network topologies and OD-pair demand data, according to specified parameters. This methodology is used to produce 33 benchmark instances exhibiting a range of characteristics. Part II extends this work by partitioning the demand in each market (OD pair) into market segments, each with its own utility function and set of preferences for alternative airline products. The resulting demand data will better reflect recent empirical research on passenger preference, and is expected to facilitate passenger choice modelling in flight schedule optimisation.     

Design of bifurcation junctions in artificial vascular vessels additively manufactured for skin tissue engineering

Construction of an artificial vascular network ready for its additive manufacturing is an important task in tissue engineering. This paper presents a set of simple mathematical algorithms for the computer-aided design of complex three dimensional vascular networks. Firstly various existing mathematical methods from the literature are reviewed and simplified for the convenience of applications in tissue engineering. This leads to a complete and step by step method for the construction of an artificial vascular network. Secondly a systematic parametric study is presented to illustrate how the various parameters in the vascular junction model affect the key factors that have to be controlled when designing the bifurcation junctions of a vascular network. These results are presented as a set of simple design rules and a design map which serve as a convenient guide for tissue engineering researchers when constructing artificial vascular networks.     

Modeling honeybee communication using network of spiking neural networks to simulate nectar reporting behavior

The paper presents the findings of the research that attempted to mathematically model the cognitive behavior that could arise due to the interaction between honeybees in a colony during forager recruitment process. The model defines a honeybee as a spiking neural network, and colony as a network of spiking neural networks. The proposed mathematical model has been evaluated by analyzing the cognitive behavior generated by the main network which represents honeybees’ interaction as interactions of component networks (i.e. spiking neural networks). Accordingly, behavior of the component network, that represents an unemployed forager in the colony, was examined under different scenarios by setting networks’ parameters to simulate ecological situations in the colony. The reporting of different level of quantity of nectar sources by scouts to the colony, an attempt made by a scout to attract more unemployed foragers for foraging, and influence by dancing foragers to attract other unemployed foragers for foraging are those ecological colony states that have been tested in this research. The results of all these cases have supported that the proposed mathematical model can sufficiently simulate the unemployed forager’s behavior during recruitment process.     

Development of a module based service family design for mass customization of airline sector using the coalition game

The Airline industry faces various issues and difficulties related to its management, which have a peculiar and a complex solution. The objective of this paper is to introduce new and simplified methodologies for improving the airline sector by introducing cost efficient and relatively high payout services. In this paper, we have applied strategic sharing of modules in service family design using coalition game and Cournot game theories to model the related situations. Service family design is a cost-effective way for achieving mass customization by developing highly differentiated products from a common platform while laying emphasis on individual products. A coalitional game is applied which is used to model the potential module sharing and thus determines which modules that are being used in the platform proves to be the most beneficial ones. The empirical evidence suggests that convenience, safety and service quality also have a major influence on the choice of airline passengers. In a Cournot model, new services are predicted to be introduced by an airline and the effect of that service on its profits and thus response from other competitor airlines are carefully examined and result of this, decides the layout of the service in the functionality of the airline. This research can be efficiently used to assist the working of airline companies and help them to select services and have a better understanding of the role of quality of different services in the airline sector as a whole, thus giving them an edge over its competitors.     

Editorial

Wireless sensor network(WSN)is characterized by the dense deployment of sensor nodes that continuously observe physical phenomenon.The main advantages of WSN include its low cost,rapid deployment,self-organization,and fault tolerance.WSN has received tremendous interests of various research communities,and significant progresses have been made in various aspects including sensor platform development,wireless communication and networking,signal and information processing,as well as network performance eva...     

Configuring a transportation route network via the method of successive approximation

In every transportation network problem, there are two subproblems: networksynthesis and networkanalysis. The author takes up the problem of structuring airline route networks as an example and devises an enumerative type algorithm coupling synthesis and analysis, as defined by the following steps: Step 1: Synthesize a route network configuration; Step 2: Analyze the synthesized route network by flowing passengers on it—whereby the figureof-merit for the network is obtained; and Step 3: Based on the analysis (step 2), go back to step 1 and suggest a new route configuration which would improve on the figure-of-merit. The repeated execution of these three algorithmic steps, following the method of successive approximation, would incrementally improve the network until optimality or until a satisfactory configuration is obtained. Part of the algorithm was implemented in a 40-routine software package. A case study with American Airlines shows a potential 3.6 per cent improvement in net revenue. The programs execute at least seven times faster than a comparable package.     

On the use of open-source firewalls in ICS/SCADA systems

ABSTRACT

Firewalls are one of the most widely used security devices to protect a communications network. They help secure it by blocking unwanted traffic from entering or leaving the protected network. Several commercial vendors have extended their firewall capabilities to support SCADA protocols or designed SCADA-specific firewalls. Although open-source firewalls are used successfully in IT networks, their use in SCADA networks has not been properly investigated. In this research we investigate the major open-source firewalls for their use in SCADA networks and identify Linux iptables’ potential as an effective SCADA firewall. Iptables is a powerful open-source firewall solution available as part of most Linux distributions in use today. In general, use of iptables as a network-level firewall for SCADA systems has been limited to basic port and host filtering, without further inspection of control messages. We propose and demonstrate a novel methodology to use iptables as an effective firewall for SCADA systems. This is achieved by utilizing advanced iptables features that allow for dynamic inspection of packet data. It is noteworthy to mention that the proposed solution does not require any modification to the netfilter/iptables framework, making it possible to turn a Linux system into an effective SCADA firewall. The approach has been tested by defining filtering rules for the Modbus TCP protocol and validating its ability to defend against various attacks on the protocol.     

Reconstruction of graphs based on random walks

The analysis of complex networks is of major interest in various fields of science. In many applications we face the challenge that the exact topology of a network is unknown but we are instead given information about distances within this network. The theoretical approaches to this problem have so far been focusing on the reconstruction of graphs from shortest path distance matrices. Often, however, movements in networks do not follow shortest paths but occur in a random fashion. In these cases an appropriate distance measure can be defined as the mean length of a random walk between two nodes — a quantity known as the mean first hitting time.In this contribution we investigate whether a graph can be reconstructed from its mean first hitting time matrix and put forward an algorithm for solving this problem. A heuristic method to reduce the computational effort is described and analyzed. In the case of trees we can even give an algorithm for reconstructing graphs from incomplete random walk distance matrices.