LEO and the Big Blue Marble, a Bad Combination for Albedo Errors

Almost all satellites fly Sunsensors for launch and early orbit (LEOP) and safe mode operations. More than 90% of these are analogue Sunsensors with either an analogue or digital interface. The later are quite often referred to as digital Sunsensors but contrary to a true digital Sunsensor, analogue Sunsensors with a digital interface are still largely affected by albedo generated error signals. Depending on the positioning of the sensor on the satellite, the satellites altitude, and the local node time, albedo errors can lead to significant measurement inaccuracies. This paper describes some research into albedo induced errors in analogue fine Sunsensors as performed while using the data generated by the NAPA-2 satellite. This Satellite was built and is operated by ISISpace. This 6 unit Cubesat has one Auriga startracker and three MAUS Sunsensors on board allowing to compare the startracker determined attitude with the Sunsensor determined attitude. Although the study results are far from complete, preliminary results shown a strong influence of the Earth’s albedo on the measurement accuracy of the Sunsensor

Conquering the Solar System with CubeSat Technology – First Results of CubeSat Hardware Beyond Low Earth Orbit

This paper sets out to show the in-flight results of The Netherlands-China Low-Frequency Explorer (NCLE) – one of the first times CubeSat hardware has left low Earth Orbit. The Netherlands-China Low-Frequency Explorer (NCLE), is a low-frequency payload which is part of the Chinese Chang’e 4 mission. The NCLE instrument consists of three 5-meter long monopole antennas mounted on the Queqiao satellite and will be measuring in the 80 kHz - 80 MHz radio frequency range. The instrument is designed to address a multitude of high-profile science cases, but predominantly NCLE will open up the low-frequency regime for radio astronomy and will prepare for the ground-breaking observations of the 21-cm line emission from the Dark Ages and the Cosmic Dawn, considered to be the holy grail of cosmology. The design of the instrument began in May 2016, with a launch scheduled May 2018. This left only 2 years to develop, build and test the instrument. Given the short development time the design is based on COTS and space qualified components as much as possible, and a design and model philosophy common to nano-satellites was adopted. Even so, special care had to be taken as one of the main challenges of this mission is EMC. This is an area which is only marginally considered during a typical CubeSat project and required a different approach. Following the delivery in March 2018, less than 2 years after the project started, the instruments was successful launched in the 21st of May 2018 and saw its first return of telemetry January 2019. In this paper, the design of the instrument will be covered, as well as the first in flight results which were obtained. These results indicate NCLE is performing admirably after having spent over a year in interplanetary space. The NCLE instrument represents one of the first times the CubeSat methodology and hardware left Low Earth Orbit. This, together with the strict EMC requirements have resulted in CubeSat hardware which can be used in future interplanetary missions. The promising results give strong confidence in the technology and enables new mission opportunities which could not be served by CubeSats in the past. This will fuel the next phase of the CubeSat revolution where they will venture out into interplanetary space in support of bigger missions

Bistability in a Metabolic Network Underpins the De Novo Evolution of Colony Switching in Pseudomonas fluorescens

Phenotype switching is commonly observed in nature. This prevalence has allowed the elucidation of a number of underlying molecular mechanisms. However, little is known about how phenotypic switches arise and function in their early evolutionary stages. The first opportunity to provide empirical insight was delivered by an experiment in which populations of the bacterium Pseudomonas fluorescens SBW25 evolved, de novo, the ability to switch between two colony phenotypes. Here we unravel the molecular mechanism behind colony switching, revealing how a single nucleotide change in a gene enmeshed in central metabolism (carB) generates such a striking phenotype. We show that colony switching is underpinned by ON/OFF expression of capsules consisting of a colanic acid-like polymer. We use molecular genetics, biochemical analyses, and experimental evolution to establish that capsule switching results from perturbation of the pyrimidine biosynthetic pathway. Of central importance is a bifurcation point at which uracil triphosphate is partitioned towards either nucleotide metabolism or polymer production. This bifurcation marks a cell-fate decision point whereby cells with relatively high pyrimidine levels favour nucleotide metabolism (capsule OFF), while cells with lower pyrimidine levels divert resources towards polymer biosynthesis (capsule ON). This decision point is present and functional in the wild-type strain. Finally, we present a simple mathematical model demonstrating that the molecular components of the decision point are capable of producing switching. Despite its simple mutational cause, the connection between genotype and phenotype is complex and multidimensional, offering a rare glimpse of how noise in regulatory networks can provide opportunity for evolution

Controlling and supervising the nuclear (core) power of a PWR in relation to nuclear safety and economics

Knowing exactly the nuclear core power of a nuclear reactor is one of the most important parameters for the operator; it is vital for safety as well as for economical matters. The secondary calorimetric is the only one where one can pilot on; it is a combination of measured parameters, of which the feedwater (FW) flow towards the steam generators is the most significant one. This feedwater flow can be measured by means of an ultrasonic flow meter, “LEFM CheckPlus™ system” instead of the commonly used venturis or diaphragms. In the Belgian Nuclear Power Plant (NPP) Doel 4, a new ultrasonic “LEFM CheckPlus™” feedwater flow measuring system has been installed in April 2008. The paper describes the consequences of the installation, as the total error on the secondary calorimetric decreases from the previous 1,3 % to the current 0,8 % with a possibility of further reduction to 0,4 %. Additionally, the economical effects of the installation are calculated for a 1000 MWe power plant with venturi meters undergoing fouling. For the NPP Doel 4 it was an economically interesting investment since the payback period was only 45 days. Finally, the possibility of consuming the margin on the secondary calorimetric for a mini-power uprate is inspected, technically and economically. It is concluded that such a mini-power uprate is an interesting option for the NPP owner

Exploring new operational research opportunities within the Home Care context: the chemotherapy at home

Health service, Home care, Operations planning, Anti-cancer drug supply chain, Scheduling,

Bistability in a metabolic network underpins the de novo evolution of colony switching in Pseudomonas fluorescens

Phenotype switching is commonly observed in nature. This prevalence has allowed the elucidation of a number of underlying molecular mechanisms. However, little is known about how phenotypic switches arise and function in their early evolutionary stages. The first opportunity to provide empirical insight was delivered by an experiment in which populations of the bacterium Pseudomonas fluorescens SBW25 evolved, de novo, the ability to switch between two colony phenotypes. Here we unravel the molecular mechanism behind colony switching, revealing how a single nucleotide change in a gene enmeshed in central metabolism (carB) generates such a striking phenotype. We show that colony switching is underpinned by ON/OFF expression of capsules consisting of a colanic acid-like polymer. We use molecular genetics, biochemical analyses, and experimental evolution to establish that capsule switching results from perturbation of the pyrimidine biosynthetic pathway. Of central importance is a bifurcation point at which uracil triphosphate is partitioned towards either nucleotide metabolism or polymer production. This bifurcation marks a cell-fate decision point whereby cells with relatively high pyrimidine levels favour nucleotide metabolism (capsule OFF), while cells with lower pyrimidine levels divert resources towards polymer biosynthesis (capsule ON). This decision point is present and functional in the wild-type strain. Finally, we present a simple mathematical model demonstrating that the molecular components of the decision point are capable of producing switching. Despite its simple mutational cause, the connection between genotype and phenotype is complex and multidimensional, offering a rare glimpse of how noise in regulatory networks can provide opportunity for evolution.BionanoscienceApplied Science

Mutations causing capsule switching.

<p>Mutations causing capsule switching.</p