How to certify in offshore wind – Risk mitigation on a new level

This paper introduces the new service specifications for project, type and component certification of wind turbines and power plants including a full overview on standards and recommended practices. The service specification applying to type certification of wind turbines as well as for component certification was published in summer 2016, the one for project certification of power plants at the end of 2015. The experiences gathered from certification projects in on‐ and offshore wind realised over the last years has been taken into account for these new service specifications. Correspondingly the project, type and component certification schemes have been adapted to meet market needs and expectations. But in course of the update of the whole scheme much more effort was taken to get to the next level of certification and standardization; beyond modules and elements of certification this includes all technical aspects laid down in standards and recommended practices.     

Data assimilation in weather forecasting: a case study in PDE-constrained optimization

Variational data assimilation is used at major weather prediction centers to produce the initial conditions for 7- to 10-day weather forecasts. This technique requires the solution of a very large data-fitting problem in which the major element is a set of partial differential equations that models the evolution of the atmosphere over a time window for which observational data has been gathered. Real-time solution of this difficult computational problem requires sophisticated models of atmospheric physics and dynamics, effective use of supercomputers, and specialized algorithms for optimization and linear algebra. The optimization algorithm can be accelerated by using a spectral preconditioner based on the Lanczos method. This paper shows how practical demands of the application dictate the various algorithmic choices that are made in the nonlinear optimization solver, with particular reference to the system in operation at the European Centre for Medium-Range Weather Forecasts.     

Study of intermetallic crystal growth between Nb and molten 52In-48Sn solder

The reactions between Nb and molten, eutectic In-Sn solder have been studied in the temperature range 130–240°C and for times ranging up to 12 months. Hexagonal platelet crystals of NbSn₂ form an intermetallic compound (IMC) layer that provides adhesion between solder and substate, but which grows extremely slowly even at 200°C. A model explaining the observed IMC growth kinetics is developed and relevant activation energies and model parameters are calculated. Applications include high-temperature electronics interconnection, where the device is secured to the substrate via an adhesive component and the solder is designed to melt, preventing fatigue failure by temperture cycling.     

用可编程DSP实现IEEE 802.16 PHY信号处理

IEEE802.16标准的各个版本都规定了PHY(物理层)的多种选项,包括调制、信道编码和天线分集技术。物理信道带宽可以在1.25MHz～20MHz之间变化。上述所有选项都会影响基站的性能和信号处理复杂度。许多客户希望提供一种可以从802.16-2004升级到802.16e标准的方法。上述需求以及对支持互通性(成功部署新标准的关键)的需求,都要求基站的PHY采用可编程的信号处理器件。图1为802.16基站基带信号链路基本框图。因为802.16-2004和802.16e标准都是在OFDM基础上建立的,所以FFT和IFFT起了很大的作用。这两种变换都用于频域副载波(携带编码的数…     

Elastic properties and electronic structure of vanadium silicides-a density functional investigation

Vanadium and silicon form several binary compounds; the most well characterized structures have the compositions V:Si = 3:1, 5:3, 6:5, 1:2. Spin-polarized density functional band-structure calculations using the projector augmented wave method have been carried out for the stable binary compounds in the Si–V system. As many rare earth and early transition metals are refractory materials, the study focuses on the ground state structures and their stabilities by determining their elastic properties. The magnetic properties are also investigated because structurally related Si–Mn compounds exhibit magnetism. All the silicides investigated were found to be refractory, hard, metallic materials and no magnetism was found in the ground state structures.     

Contextual influences on technology use mediation: a comparative analysis of electronic medical record systems

Developing, implementing and assimilating information technologies into organizational practices pose significant technical and social challenges. In this paper, we explore technology use mediation (TUM) processes in two cases of electronic medical record system use in two healthcare organizations. In our analysis, we examine contextual influences on mediation and consider TUM processes and outcomes in projects utilizing modern systems development methods. We found that crucial TUM actions occurred during systems development phases as well as during system use, that mediation was vitally important with these specialized IT artefacts, and that system configuration required changes to software infrastructure and code. Organizational size influenced the availability and the effectiveness of mediation resources; with adequate resources committed to the task, the institutional environment presented substantial, but not insurmountable, challenges to technology use mediation. We consider implications for practice and suggest future research directions.