An experimental investigation of the influence of inter-turbine spacing on the loads and performance of a co-planar tidal turbine fence

Multi-rotor tidal turbine systems offer engineering benefits through shared infrastructure and improved opportunities for maintenance. Additionally, the ability to specify accurately the inter-turbine spacing in co-planar arrays allows rotors to be designed and deployed to benefit from the constructive interference effects available from neighbouring rotors. In this work we consider the effect of inter-turbine spacing and control of this spacing for a fence of turbines in low overall levels of global blockage (4.5%). We conduct experiments in a towing tank using two tidal turbine models that were previously designed to benefit from constructive interference effects at high local blockage, i.e. close inter-turbine spacing. The turbines were towed in a side-by-side configuration by suspending them from above. By making use of the tank’s side wall to act as a symmetry plane we were able to emulate a fence of four laterally arrayed turbines. As indicated by theory, decreasing inter-turbine spacing is shown to have a positive effect on fence performance. By reducing the inter-turbine spacing from one diameter to a quarter of a diameter, we observe an overall 1.4% performance increase, which is driven by a 2.8% increase in the inboard turbine’s power coefficient. This research is a first attempt to quantify constructive interference effects for a four turbine fence; the methods and results will be used to instruct further studies to aid the development of such multi-rotor tidal turbine systems

On the recent elevation changes at the Flade Isblink Ice Cap, northern Greenland

This is the final version of the article. Available from AGU via the DOI in this record.We have used Radar Altimeter 2 (RA-2) onboard ESA's EnviSAT and Geosciences Laser Altimeter System (GLAS) onboard NASA's ICESat to map the elevation change of the Flade Isblink Ice Cap (FIIC) in northern Greenland. Based on RA-2 data we show that the mean surface elevation change of the FIIC has been near zero (0.03±0.03 m/a) between fall 2002 and fall 2009. We present the elevation change rate maps and assess the elevation change rates of areas above the late summer snow line (0.09±0.04 m/a) and below it (-0.16±0.05 m/a). The GLAS elevation change rate maps show that some outlet glaciers, previously reported to have been in a surge state, are thickening rapidly. Using the RA-2 measured average elevation change rates for different parts of the ice cap we present a mass change rate estimate of 0.0±0.5 Gt/a for the FIIC. We compare the annual elevation changes with surface mass balance (SMB) estimates from a regional atmospheric climate model RACMO2. We find a strong correlation between the two (R = 0.94 and P < 0.002), suggesting that the surface elevation changes of the FIIC are mainly driven by net SMB. The correlation of modeled net SMB and measured elevation change is strong in the southern areas of the FIIC (R = 0.97 and P < 0.0005), but insignificant in the northern areas (R = 0.38 and P = 0.40). This is likely due to higher variability of glacier flow in the north relative to the south. Copyright 2011 by the American Geophysical Union

Activities of National Hellenic Documentation Centre and the National Network of Scientific and Technological Libraries

Περιέχει το πλήρες κείμενοThe mission of National (Hellenic) Documentation Centre (NDC)is to ensure the flow of the scientific and technological information to the Hellenic scientific community. This is achieved by establishing online access to 17 international hosts and 1.300 databases, acting as the major information intermediary in the country offering bibliographic references to 10.000 scientst per year, producing 8 national databases and hosting 40 databases produced by other national or international organisations. Concerning libraries NDC supports them by developing and disseminating ABEKT, the most popular library automation software in the country numbering more than 700 copies installed, developing, in close collaboration with 206 libraries, the Union Catalogue of Periodicals including 22.790 unique journal titles, creating and coordinating the National Network of Hellenic Scientific Libraries with 107 libraries supporting interlibrary loan through the online document ordering system provided by the host computer of NDC, developing its own digital library having access to more than 230 electronic journals via internet and about 1.000 installed locally, organising seminars, workshops and information days focusing on the electronic information services and technologies

An agent-based approach to assess drivers’ interaction with pre-trip information systems.

This article reports on the practical use of a multi-agent microsimulation framework to address the issue of assessing drivers’ responses to pretrip information systems. The population of drivers is represented as a community of autonomous agents, and travel demand results from the decision-making deliberation performed by each individual of the population as regards route and departure time. A simple simulation scenario was devised, where pretrip information was made available to users on an individual basis so that its effects at the aggregate level could be observed. The simulation results show that the overall performance of the system is very likely affected by exogenous information, and these results are ascribed to demand formation and network topology. The expressiveness offered by cognitive approaches based on predicate logics, such as the one used in this research, appears to be a promising approximation to fostering more complex behavior modelling, allowing us to represent many of the mental aspects involved in the deliberation process

A model for integrating home-work tour scheduling with time-varying network congestion and marginal utility profiles for home and work activities.

The existing literature on activity-based modeling emphasizes that individuals schedule their activities by keeping the whole-day activity pattern in mind. Several attempts have been made to integrate this with network congestion; however, for explicit explanation of travel behavior of individuals, further improvements are required. The proposed model is a combined model that addresses the scheduling of the home-work tour with time-varied network congestion in a fixed-point problem frame-work. Marginal utility profiles that represent individual time-of-day preferences and satiation effect of the activities are incorporated for the measurement of the utility of activity engagement along with the disutility of travel. Consideration of only time-of-day dependent marginal utility profiles of activities in the utility function does not appropriately integrate activities and travel within the tour. The proof is shown analytically and numerically. This finding contradicts earlier research into integration of morning and evening commutes with network congestion. Additionally, the results of two numerical experiments are presented. In the first experiment, an arbitrary dynamic tolling strategy is assumed, and then a detailed analysis is performed to show variation in the balance of trade-offs involved in the process. The second experiment assesses the sensitivity of the combined model through incorporation of different dynamic traffic loading models. Some meaningful observations are drawn from these experiments and are discussed with the identification of avenues for future research

A protocol for periprosthetic joint infections from the Northern Infection Network for Joint Arthroplasty (NINJA) in the Netherlands

Periprosthetic joint infection (PJI) is a devastating complication of joint arthroplasty surgery. Treatment success depends on accurate diagnostics, adequate surgical experience and interdisciplinary consultation between orthopedic surgeons, plastic surgeons, infectious disease specialists and medical microbiologists. For this purpose, we initiated the Northern Infection Network for Joint Arthroplasty (NINJA) in the Netherlands in 2014. The establishment of a mutual diagnostic and treatment protocol for PJI in our region has enabled mutual understanding, has supported agreement on how to treat specific patients, and has led to clarity for smaller hospitals in our region for when to refer patients without jeopardizing important initial treatment locally. Furthermore, a mutual PJI patient database has enabled the improvement of our protocol, based on medicine-based evidence from our scientific data. In this paper we describe our NINJA protocol

How do I want the city council to spend our budget? Conceiving MaaS from a citizen's perspective … (as well as biking infrastructure and public transport)

While several governmental and research efforts are set upon mobility-as-a-service (MaaS), most of them are driven by individual travel behavior and potential usage. However, considering only individuals’ preferences carries the risk of neglecting societal benefits going beyond individual travel behavior. This study addresses the valuation of different features of MaaS-services from a social desirability perspective as compared to social investments in biking infrastructure and in public transport, and aims at eliciting trade-offs between different features of such projects. This analysis is conducted on the basis of Participatory Value Evaluation (PVE). In PVE-experiments, individuals select their preferred portfolio of government projects given a constrained public budget and societal preferences for (the impacts of) government projects can be determined based on these choices. The results show that the population of Rotterdam exhibits a willingness to allocate public resources to all types of investment projects considered in the analysis. However, the willingness to allocate resources to bike infrastructure projects and public transport seems to be higher than the willingness to dedicate resources to MaaS subsidies. Within the different types of MaaS subsidies considered, subsidies aimed at sustainability exhibit a larger social valuation. Strong negative synergies among similar projects exist, signalizing that individuals prefer diversifying the use of public resources across different types of investment projects

Developing institutional capacity for reproductive health in humanitarian settings: A descriptive study

© 2015 Tran et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Introduction. Institutions play a central role in advancing the field of reproductive health in humanitarian settings (RHHS), yet little is known about organizational capacity to deliver RHHS and how this has developed over the past decade. This study aimed to document the current institutional experiences and capacities related to RHHS. Materials and Methods. Descriptive study using an online questionnaire tool. Results. Respondents represented 82 institutions from 48 countries, of which two-thirds originated from low-and middle-income countries. RHHS work was found not to be restricted to humanitarian agencies (25%), but was also embraced by development organizations (25%) and institutions with dual humanitarian and development mandates (50%). Agencies reported working with refugees (81%), internally-displaced (87%) and stateless persons (20%), in camp-based settings (78%), and in urban (83%) and rural settings (78%). Sixtyeight percent of represented institutions indicated having an RHHS-related policy, 79% an accountability mechanism including humanitarian work, and 90% formal partnerships with other institutions. Seventy-three percent reported routinely appointing RH focal points to ensure coordination of RHHS implementation. There was reported progress in RHHSrelated disaster risk reduction (DRR), emergency management and coordination, delivery of the Minimum Initial Services Package (MISP) for RH, comprehensive RH services in post-crisis/recovery situations, gender mainstreaming, and community-based programming. Other reported institutional areas of work included capacity development, program delivery, advocacy/policy work, followed by research and donor activities. Except for abortion-related services, respondents cited improved efforts in advocacy, capacity development and technical support in their institutions for RHHS to address clinical services, including maternal and newborn health, sexual violence prevention and response, HIV prevention, management of sexually-transmitted infections, adolescent RH, and family planning. Approximately half of participants reported that their institutions had experienced an increase in dedicated budget and staff for RHHS, a fifth no change, and 1 in 10 a decrease. The Interagency RH Kits were reportedly the most commonly used supplies to support RHHS implementation. Conclusion. The results suggest overall growth in institutional capacity in RHHS over the past decade, indicating that the field has matured and expanded from crisis response to include RHHS into DRR and other elements of the emergency management cycle. It is critical to consolidate the progress to date, address gaps, and sustain momentum