Thomas Noël

Climate change impacts on the power generation potential of a European mid-century wind farms scenario

Wind energy resource is subject to changes in climate. To investigate the impacts of climate change on future European wind power generation potential, we analyze a multi-model ensemble of the most recent EURO-CORDEX regional climate simulations at the 12 km grid resolution. We developed a mid-century wind power plant scenario to focus the impact assessment on relevant locations for future wind power industry. We found that, under two greenhouse gas concentration scenarios, changes in the annual energy yield of the future European wind farms fleet as a whole will remain within ±5% across the 21st century. At country to local scales, wind farm yields will undergo changes up to 15% in magnitude, according to the large majority of models, but smaller than 5% in magnitude for most regions and models. The southern fleets such as the Iberian and Italian fleets are likely to be the most affected. With regard to variability, changes are essentially small or poorly significant from subdaily to interannual time scales.

Climate variability and trends in downscaled high-resolution simulations and projections over Metropolitan France

In order to fulfill the society demand for climate information at the spatial scale allowing impact studies, long-term high-resolution climate simulations are produced, over an area covering metropolitan France. One of the major goals of this article is to investigate whether such simulations appropriately simulate the spatial and temporal variability of the current climate, using two simulation chains. These start from the global IPSL-CM4 climate model, using two regional models (LMDz and MM5) at moderate resolution (15–20xa0km), followed with a statistical downscaling method in order to reach a target resolution of 8xa0km. The statistical downscaling technique includes a non-parametric method that corrects the distribution by using high-resolution analyses over France. First the uncorrected simulations are evaluated against a set of high-resolution analyses, with a focus on temperature and precipitation. Uncorrected downscaled temperatures suffer from a cold bias that is present in the global model as well. Precipitations biases have a season- and model-dependent behavior. Dynamical models overestimate rainfall but with different patterns and amplitude, but both have underestimations in the South-Eastern area (Cevennes mountains) in winter. A variance decomposition shows that uncorrected simulations fairly well capture observed variances from inter-annual to high-frequency intra-seasonal time scales. After correction, distributions match with analyses by construction, but it is shown that spatial coherence, persistence properties of warm, cold and dry episodes also match to a certain extent. Another aim of the article is to describe the changes for future climate obtained using these simulations under Scenario A1B. Results are presented on the changes between current and mid-term future (2021–2050) averages and variability over France. Interestingly, even though the same global climate model is used at the boundaries, regional climate change responses from the two models significantly differ.

Anticipated handover over IEEE 802.11 networks

The recent success of IEEE 802.11 networks and the increasing demand for real time services suggest a new usage of wireless devices. In particular, mobility management between access points and IPv6 networks must be fast enough to avoid loss of packets. In this paper, we propose a new mechanism to anticipate handovers. The movement anticipation consists of new potential access points discovery before the handover has even started. It also allows a station to set up in advance a new IPv6 configuration for the next location. We show by simulation that the anticipation mechanism strongly enhances both link and network layers handovers and significantly reduces the loss of packets.

Bias correction of precipitation through Singularity Stochastic Removal: Because occurrences matter

This study focuses on how the treatment of the rainfall occurrences in bias correction (BC) contexts may affect the resulting precipitation, both in terms of occurrence and intensity. Three methodologies are compared—the “direct approach” (DA), the “Threshold Adaptation” approach (TA), and the “Positive Approach” (Pos)—as well as a method called “Singularity Stochastic Removal” (SSR) specifically developed for precipitation, all based on the same adjustment technique. Unlike the three other models, SSR allows dealing in the same way with the situations where the precipitation model has too many wet days or not with respect to the reference data. SSR also avoids separating the correction of the occurrence from that of the intensity, which constitutes a flexible tool. First, the four approaches are applied to a historical regional climate model precipitation run. Evaluations are realized through occurrence- and intensity-related criteria. Although SSR, DA, and Pos may be close to each other depending on the criterion, in general, SSR provides the best results when all criteria are accounted for. This is even more true when the classical assumption that “the model precipitation had too many wet days” does not hold. The BC methods are also intercompared over the 2071–2100 period. The different BC methods are in agreement with previous studies, with relatively equivalent evolutions from 1976–2005 to 2071–2100, although nuances are present from one BC method to another. As a global conclusion, the SSR method for precipitation is a good compromise to correct both occurrences and intensities.

Layered Architecture for Mobility Models LEMMA

We introduce a generic layered architecture that can be used to construct a wide variety of mobility models, including the majority of models used in wireless network simulations. Each mobility model is divided in five distinct layers that communicate via interfaces, thus allowing their easy replacement and recombination. We review 18 layers that can form 304 different mobility models. Additionally, we discuss how to aggregate some of the layers into new ones, and how to define hybrid and group mobility models. Numerous studies performed in various research fields (e.g. traffic engineering, crowd dynamics) turned out to be directly applicable to the different layers, which further supports the pertinence of our proposition.

Interoperability, Safety and Security in IoT

This book constitutes the refereed post-conference proceedings of the Third International Conference on Interoperability, InterIoT 2017, which was collocated with SaSeIoT 2017, and took place in Valencia, Spain, in November 2017. The 14 revised full papers were carefully reviewed and selected from 22 submissions and cover all aspects of the latest research findings in the area of Internet of Things (IoT)

Active Networks for IPv6 Communication Redirection

In this article, we propose an Active Network mechanism based on IPv6 to forward communications. Indeed, with the use of the Internet Protocol improvements in its version 6, especially the concepts introduced in IPv6 mobility, we can use active nodes to perform the redirection of the packets of a unicast and UDP communication that we choose in advance. This redirection can be done transparently of one of the correspondents of this communication.

IPv6 addressing scheme and self-configuration for multi-hops wireless ad hoc network

Next generation mobile communication systems will comprise both WLAN technologies and ad hoc networks. Ad hoc networks are formed by the spontaneous collaboration of wireless nodes. When communication to the Internet is desired, one or more nodes must act as gateways for the ad hoc network. In this case, global addressing of ad hoc nodes is required. In this paper, we present an IPv6 addressing architecture in order to be able to support “pure” spontaneous IPv6 ad hoc networks but also to allow seamless integration between wireless LANs and ad hoc networks. It implies the possibility to discover a gateway/prefix pair which is used in order to build an IPv6 global address and, when necessary, to maintain a default route towards the Internet.

Overcoming the IEEE 802.11 paradox for realtime multimedia traffic

In this paper, we introduce a replacement Medium Access Control layer for wireless communications using the IEEE 802.11 standard. We justify this replacement by the performances achieved using the ratified Medium Access Control protocol which has several flaws although its design is based on fairness. We will especially focus on power consumption because it is a widely required feature and is not dealt with efficiently in the current protocol. To solve the energy-efficiency problem while still maintaining good quality of service, we propose a TDMA-based Medium Access Control protocol, with enhanced features allowing to save energy such as deterministic scheduling and frame aggregation.