The Diffuse Interstellar Cloud Experiment: a high-resolution far-ultraviolet spectrograph

We have designed, assembled, and launched a sounding rocket payload to perform high-resolution far-ultraviolet spectroscopy. The instrument is functionally a Cassegrain telescope followed by a modified Rowland spectrograph. The spectrograph was designed to achieve a resolving power (R=λ/δλ) of 60,000 in a compact package by adding a magnifying secondary optic. This is enabled by using a holographically ruled grating to minimize aberrations induced by the second optic. We designed the instrument to observe two stars on opposing sides of a nearby hot/cold gas interface. Obtaining spectra of the O VI doublet in absorption toward these stars can provide new insight into the processes governing hot gas in the local interstellar medium. Here we present the optical design and alignment of the telescope and spectrograph, as well as flight results.     

Sports analytics for professional speed skating

In elite sports, training schedules are becoming increasingly complex, and a large number of parameters of such schedules need to be tuned to the specific physique of a given athlete. In this paper, we describe how extensive analysis of historical data can help optimise these parameters, and how possible pitfalls of under- and overtraining in the past can be avoided in future schedules. We treat the series of exercises an athlete undergoes as a discrete sequence of attributed events, that can be aggregated in various ways, to capture the many ways in which an athlete can prepare for an important test event. We report on a cooperation with the elite speed skating team LottoNL-Jumbo, who have recorded detailed training data over the last 15 years. The aim of the project was to analyse this potential source of knowledge, and extract actionable and interpretable patterns that can provide input to future improvements in training. We present two alternative techniques to aggregate sequences of exercises into a combined, long-term training effect, one of which based on a sliding window, and one based on a physiological model of how the body responds to exercise. Next, we use both linear modelling and Subgroup Discovery to extract meaningful models of the data.     

Automated determination of organic sulphur in coal: Use of scanning electron microscopy and energy-dispersive X-ray microanalysis

Scanning electron microscopy combined with energy-dispersive X-ray microanalysis in fully automated form was used for the determination of organic sulphur in coal. The values found by this technique are in good agreement with those found by the usual classical methods, provided the coal has a low content of pyrite. For coals high in pyrite, however, SEM/XRMA gives considerably lower values of organic sulphur. The discrepancy is probably due to the incomplete extraction of pyrite inclusions in the wet analysis leading to a low value for the pyrite content, and consequently, a high value for organic sulphur. Apart from primarily being a method for the determination of organic sulphur, the method presented affords additional information; for example, it may enable a differentiation to be made between a single coal sample and a blend of several types of coal.     

Ultraviolet groove efficiency of a holographic grating: implications for a dual-order spectrograph

The ultraviolet groove efficiency for a holographically ruled diffraction grating with a trapezoidal profile has been measured. The efficiencies for the +/-1 and the zero orders are in good agreement with those derived from scalar theory. The +/-1 orders have equal efficiency as a function of wavelength. The peak of the sum of fitted groove efficiency functions is 76%, a level that is competitive with the groove efficiency of a mechanically blazed grating. We suggest that a normal-incidence grating mount with detectors at both orders will offer a system with twice the efficiency and provide a built-in redundancy. We discuss design considerations for reducing astigmatism equally in both orders in such dual-order mountings.     

A linear differential equation with a time-periodic damping coefficient: stability diagram and an application

In this paper the second-order differential equation with time-dependent damping coefficientx + cos (2t) x + x = 0,will be studied. In particular the coexistence of periodic solutions corresponding with the vanishing of domains of instability is investigated. The coexistence of -periodic solutions occurs for 4n ² where n is integer. This implies that the instability area which is emanating from =4n ² in the – stability diagram disappears. In applications, this equation can be considered as a model equation for the study of rain-wind-induced vibrations of a special oscillator.on leave as a PhD reseacher at Delft University of Technology, The Netherlands     

Planning by Parameters

With increasing pressure on available land for development, planning parameters continue to intensify. Since the early 1990s, such constraints on urban sites have provided a significant focus for MRVDV's design and research. The practice has worked on the creation of interactive software that enables designers to interact with the limits and opportunities highlighted by the visualisation and evaluation of these parameters. Jeroen Zuidgeest and Sanne van der Burgh of MVRDV and Bas Kalmeyer of think tank The Why Factory describe how parametric models are now being applied, leading the way to a whole new generation of open-source planning tools.