Seventh International Workshop on Simulation, 21-25 May, 2013, Department of Statistical Sciences, Unit of Rimini, University of Bologna, Italy. Book of Abstracts

Seventh International Workshop on Simulation, 21-25 May, 2013, Department of Statistical Sciences, Unit of Rimini, University of Bologna, Italy. Book of Abstract

Seventh International Workshop on Simulation, 21-25 May, 2013, Department of Statistical Sciences, Unit of Rimini, University of Bologna, Italy. Book of Abstracts

Seventh International Workshop on Simulation, 21-25 May, 2013, Department of Statistical Sciences, Unit of Rimini, University of Bologna, Italy. Book of Abstract

Gaining Insight into Determinants of Physical Activity using Bayesian Network Learning

Contains fulltext : 228326pre.pdf (preprint version ) (Open Access) Contains fulltext : 228326pub.pdf (publisher's version ) (Open Access)BNAIC/BeneLearn 202

Spectrum Sharing, Latency, and Security in 5G Networks with Application to IoT and Smart Grid

The surge of mobile devices, such as smartphones, and tables, demands additional capacity. On the other hand, Internet-of-Things (IoT) and smart grid, which connects numerous sensors, devices, and machines require ubiquitous connectivity and data security. Additionally, some use cases, such as automated manufacturing process, automated transportation, and smart grid, require latency as low as 1 ms, and reliability as high as 99.99\%. To enhance throughput and support massive connectivity, sharing of the unlicensed spectrum (3.5 GHz, 5GHz, and mmWave) is a potential solution. On the other hand, to address the latency, drastic changes in the network architecture is required. The fifth generation (5G) cellular networks will embrace the spectrum sharing and network architecture modifications to address the throughput enhancement, massive connectivity, and low latency. To utilize the unlicensed spectrum, we propose a fixed duty cycle based coexistence of LTE and WiFi, in which the duty cycle of LTE transmission can be adjusted based on the amount of data. In the second approach, a multi-arm bandit learning based coexistence of LTE and WiFi has been developed. The duty cycle of transmission and downlink power are adapted through the exploration and exploitation. This approach improves the aggregated capacity by 33\%, along with cell edge and energy efficiency enhancement. We also investigate the performance of LTE and ZigBee coexistence using smart grid as a scenario. In case of low latency, we summarize the existing works into three domains in the context of 5G networks: core, radio and caching networks. Along with this, fundamental constraints for achieving low latency are identified followed by a general overview of exemplary 5G networks. Besides that, a loop-free, low latency and local-decision based routing protocol is derived in the context of smart grid. This approach ensures low latency and reliable data communication for stationary devices. To address data security in wireless communication, we introduce a geo-location based data encryption, along with node authentication by k-nearest neighbor algorithm. In the second approach, node authentication by the support vector machine, along with public-private key management, is proposed. Both approaches ensure data security without increasing the packet overhead compared to the existing approaches

Reliability and Efficiency of Vehicular Network Applications

The DSRC/WAVE initiative is forecast to enable a plethora of applications, classified in two broad types of safety and non-safety applications. In the former type, the reliability performance is of tremendous prominence while, in the latter case, the efficiency of information dissemination is the key driving factor. For safety applications, we adopt a systematic approach to analytically investigate the reliability of the communication system in a symbiotic relationship with the host system comprising a vehicular traffic system and radio propagation environment. To this aim, the¬ interference factor is identified as the central element of the symbiotic relationship. Our approach to the investigation of interference and its impacts on the communication reliability departs from previous studies by the degree of realism incorporated in the host system model. In one dimension, realistic traffic models are developed to describe the vehicular traffic behaviour. In a second dimension, a realistic radio propagation model is employed to capture the unique signal propagation aspects of the host system. We address the case of non-safety applications by proposing a generic framework as a capstone architecture for the development of new applications and the efficiency evaluation of existing ones. This framework, while being independent from networking technology, enables accurate characterization of the various information dissemination tasks that a node performs in cooperation with others. As the central element of the framework, we propose a game theoretic model to describe the interaction of meeting nodes aiming to exchange information of mutual or social interests. An adaptive mechanism is designed to enable a mobile node to measure the social significance of various information topics, which is then used by the node to prioritize the forwarding of information objects

Euromech Colloquium 509: Vehicle Aerodynamics. External Aerodynamics of Railway Vehicles, Trucks, Buses and Cars - Proceedings

During the 509th Colloquium of the Euromech society, held from March 24th & 25th at TU Berlin, fifty leading researchers from all over europe discussed various topics affecting both road vehicle as well as railway vehicle aerodynamics, especially drag reduction (with road vehicles), cross wind stability (with trains) and wake analysis (with both). With the increasing service speed of modern high-speed railway traffic, aerodynamic aspects are gaining importance. The aerodynamic research topics comprise both pure performance improvements, such as the continuous lowering of aerodynamic drag for energy efficiency, as well as safety relevant topics, such as cross-wind stability. The latter topic was most recently brought to attention when a swiss narrow-gauge train overturned during the severe storm Kyrill in january 2007. The shape of the train head usually has largest influence on cross wind stability. Slipstream effects of passing trains cause aerodynamic loads on objects and passengers waiting at platforms. The strength of the slipstream is determined by both the boundary layer development along the length of the train and the wake developing behind the tail of the train. Since high-speed trains can be considered to be as smooth as technically possible, attention is drawn to the wake region. The wake of the train again is also one important factor for the total drag of a train. Due to the fact that trains are bidirectional, optimisation of the leading car of a train with respect to drag and cross wind performance while simultaneously minimising the wake of the train for drag and slipstream performance is a great challenge. Modern optimisation tools are used to aid this multi-parameter multi-constraint design optimisation in conjunction with both CFD and wind tunnel investigations. Since many of the aerodynamic effects in the railway sector are of similar importance to road vehicles, the aim of the colloquium is to bridge the application of shape optimisation principles between rail- and road vehicles. Particular topics to be addressed in the colloquium are: Drag, Energy consumption and emissions: Due to increase in energy cost, drag reduction has gained focus in the past years and attention will grow in the future. Pressure induced drag is of common importance for both rail- and road vehicles. The optimisation of head- and tail shape for road vehicles as well as for bi-directional vehicles (trains) is in the focus. Interference drag between adjacent components shall also be treated. Slipstream Effects: Are a safety issue for high-train operation (Prams sucked into track due to train-induced draught flows) when trains passing platforms at high speeds. For Road vehicles, the ride stability of overtaking cars is influenced by the wake of the leading trucks and busses. Common interest is the minimisation of wake effects for both rail and road vehicles. Cross-Wind Safety, Ride stability under strong winds: Both are safety issues for rail- and road vehicles. Aerodynamic forces shall be minimised (roll moment for trains and also yaw moment for road vehicles). Strategies for Vehicle shape optimisation (head, tail and roof shape) in order to minimise aerodynamic moments. Possibilities of Flow control. Optimisation strategies: Parametrisation, analyses (CFD), Optimisation tools and methods, Application to Drag, Cross-Wind, Ride stability and Snow issue

Essays on the causes of migration

This thesis consists of three chapters. All three are linked by our desire to better understand the determinants of labour migration; that is, the motivation for a person to change his or her location of residence for a period of at least a year. While immigration receives much public discourse, the economic evidence on how migrants self-select is still lacking. In particular, we have little evidence on the relative importance of determinants. We focus on three areas that have received substantially less attention in the migration literature: the importance of relative versus absolute income motives for migration; the effect of wealth and intertemporal choice on return migration; and the role of place attachment as an obstacle to labour mobility. Common to all three chapters is an emphasis on counterbalancing forces that tend to offset spatial income differentials in determining migration. The first chapter examines the extent to which relative income – that is, one’s position in the income distribution – matters in migration choice. Virtually all studies of migration focus on absolute income. This is at odds with the mounting evidence that suggests people care about their relative position in the income distribution. We argue that, in order to test between the absolute income and relative income theories of migration, one needs individual-level panel data on before and after migration outcomes. Indeed, since one has to estimate counterfactual migrant earnings of non-migrants, if migrants are selected on unobservables then cross-sectional estimates will systematically bias the predicted migrant earnings of non-migrants. We estimate the relative importance of the two main theories in explaining interstate migration in the U.S. using a panel of individuals. Relative income is calculated with respect to those persons in the same U.S. state. We find that, although migration leads to a substantial rise in absolute income, the trigger for migration is low relative income and not low absolute income. In the second chapter we show analytically that, under some conditions, return migration is optimal. We build a model where consumers choose either to never migrate, permanently migrate or, migrate and subsequently return. To generate an incentive for return migration, the model assumes a nominal income differential between the source and destination and a compensating differential – which exerts a counterbalancing force to the income differential. Examples of compensating differentials may include differences between the source and destination in climate, place attachment, price levels, unemployment and average consumption. We characterise the optimal migration decision space with respect to the three key variables: initial wealth, the income differential and the compensating differential between the source and destination. The marginal utility of consumption is assumed to be location-dependent due to a non-separable nonpecuniary preference for the source. Consequently, when the region with the best economic opportunities is not the source region, there is a trade-off between income maximisation on the one hand and the marginal utility of consumption on the other. We find that, all else equal, those with low wealth are more likely to migrate and, conditional on migration, those with higher wealth are more likely to return migrate. The third chapter seeks to estimate a key obstacle to migration: place attachment. Place attachment refers to the emotional bonds a person feels towards the place (or area) he or she resides. We estimate place attachment within a tructural model of spatial job search where migration is a by-product of accepting a job offer from another region. The chapter can broadly be split into two parts. The first takes a standard job search model and adapts it to allow search in many potential destinations. Acceptance of an offer from a destination necessarily involves migration to that destination and its associated costs. We consider two types of costs: a cost of migration that is related to distance-to-destination and a non-pecuniary cost of leaving the current region. The latter is deemed to be the negative of place attachment. In the second part, we estimate the structural model for a sample of individual durations in a U.S. state. Our estimates suggest that place attachment is steeply increasing in duration for our reduced-form model; however, the opposite is true for our structural model. We also find that for half the population, the dollar values of place attachment are prohibitively large

Quantitative prediction of quality attributes for component-based software architectures

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