Nuclear magnetic resonance dephasing effects in a spherical pore with a magnetic dipolar field

The NMR dephasing behavior of the nuclear spins of a fluid confined in a porous material can be investigated by Hahn spin echoes. Previous experimental results on water in a magnetically doped clay have shown a nonmonoexponentially decaying magnetization, which can be understood neither by the known dephasing rate of freely diffusing spins in a uniform gradient nor by spins diffusing in a restricted geometry. For a better understanding of NMR measurements on these systems, a systematic survey was performed of the various length scales that are involved. The standard length scales for the situation of a uniform gradient are diffusing length, structure length, and dephasing length. We show that for a nonuniform gradient, a new length scale has to be introduced: the magnetic-field curvature length. When a particle diffuses less than this length scale, it experiences a local uniform gradient. In that case the spin-echo decay can be described by the so-called local gradient approximation (LGA). When a particle diffuses over a longer distance than the structure length, the spin-echo decay can be described by the motional averaging regime. For both regimes, scaling laws are derived. In this paper, a random-walk model is used to simulate the dephasing effect of diffusing spins in a spherical pore in the presence of a magnetic dipole field. By varying the dipole magnitude, situations can be created in which the dephasing behavior scales according to the motional averaging regime or according to the LGA regime, for certain ranges of echo times. Two model systems are investigated: a spherical pore in the vicinity of a magnetic point dipole and a spherical pore adjacent to a magnetic dipolar grain of the same size as the pore. The simulated magnetization decay curves of both model systems confirm the scaling laws. The LGA, characterized by a nonmonoexponential magnetization decay, is also investigated by calculating the spatially resolved magnetization in the pore. For this regime, the magnetization is found to be inhomogeneously distributed within the pore, whereas it is homogeneously distributed in the motional averaging regime

Interlaboratory Comparison of the PV Module Energy Rating Standard IEC 61853-3

The IEC 61853 standard series "Photovoltaic (PV) module performance testing and energy rating" aims to provide a standardized measure for PV module performance, namely the Climate Specific Energy Rating (CSER). An algorithm to calculate CSER is specified in part 3 based on laboratory measurements defined in parts 1 and 2 as well as the climate data set given in part 4. To test the comparability and clarity of the algorithm in part 3, we share the same input data, obtained by measuring a standard photovoltaic module, among different research organizations. Each participant then uses their individual implementations of the algorithm to calculate the resulting CSER values. The initial blind comparison reveals differences of 0.133 (14.7%) in CSER between the ten different implementations of the algorithm. Despite the differences in CSER, an analysis of intermediate results revealed differences of less than 1% at each step of the calculation chain among at least three participants. Thereby, we identify the extrapolation of the power table, the handling of the differences in the wavelength bands between measurement and climate data set, and several coding errors as the three biggest sources for the differences. After discussing the results and comparing different approaches, all participants rework their implementations individually and compare the results two more times. In the third intercomparison, the differences are less than 0.029 (3.2%) in CSER. When excluding the remaining three outliers, the largest absolute difference between the other seven participants is 0.0037 (0.38%). Based on our findings we identified four recommendations for improvement of the standard series.Peer reviewe

Really building with BIPV - putting the foundation in place for a successful Dutch BIPV sector (The ‘werkelijk bouwen aan BIPV’ project)

The main result of this project is the organisation of a strong BIPV market and supply chain, to encourage knowledge sharing, and successful business development by collaboration of (SMEs) businesses, R&D knowledge institutions and the solar- and building associations. This should result in a significant increase in the use of BIPV in building projects in Netherlands, and as a result in economic growth. The project runs from 2017 until the end of 2020, and is a follow-up to the national BIPV Roadmap issued in early 2016

Really building with BIPV - putting the foundation in place for a successful Dutch BIPV sector (The ‘werkelijk bouwen aan BIPV’ project)

The main result of this project is the organisation of a strong BIPV market and supply chain, to encourage knowledge sharing, and successful business development by collaboration of (SMEs) businesses, R&D knowledge institutions and the solar- and building associations. This should result in a significant increase in the use of BIPV in building projects in Netherlands, and as a result in economic growth. The project runs from 2017 until the end of 2020, and is a follow-up to the national BIPV Roadmap issued in early 2016