Zero-Gravity Vortex Vent and PVT Gaging System

Space Station and satellite reservicing will require the ability to vent gas on orbit from liquid supply or storage tanks and to gage liquid quantity under microgravity conditions. In zero gravity, (zero-g) the vortex vent is capable of venting gas from a tank of liquid containing gas randomly distributed as bubbles. The concept uses a spinning impeller to create centrifugal force inside a vortex tube within a tank. This creates a gas pocket and forces the liquid through a venturi and back into the tank. Gas is then vented from the gas pocket through a liquid detector and then out through an exhaust port. If the liquid detector senses liquid in the vent line, the fluid is directed to the low-pressure port on the venturi and is returned to the tank. The advantages of this system is that it has no rotating seals and is compatible with most corrosive and cryogenic fluids. A prototype was designed and built at the NASA Johnson Space Center and flown on the KC-135 zero-g aircraft. During these test flights, where microgravity conditions are obtained for up to 30 sec, the prototype demonstrated that less than 0.10 percent of the volume of fluid vented was liquid when the tank was half full of liquid. The pressure volume temperature (PVT) gaging system is used in conjunction with the vortex vent to calculate the amount of liquid remaining in a tank under microgravity conditions. The PVT gaging system is used in conjunction with the vortex vent to gage liquid quantity in zero or low gravity. The system consists of a gas compressor, accumulator, and temperature and pressure instrumentation. To measure the liquid in a tank a small amount of gas is vented from the tank to the compressor and compressed into the accumulator. Pressure and temperature in the tank and accumulator are measured before and after the gas transfer occurs. Knowing the total volume of the tank, the volume of the accumulator, the volume of the intermediate lines, and initial and final pressures and temperatures, the mass of the gas leaving the tank is equated to the mass of the gas entering the accumulator. The volume of liquid remaining in the tank is calculated using the ideal gas law

The Hardness of Embedding Grids and Walls

The dichotomy conjecture for the parameterized embedding problem states that the problem of deciding whether a given graph $G$ from some class $K$ of "pattern graphs" can be embedded into a given graph $H$ (that is, is isomorphic to a subgraph of $H$) is fixed-parameter tractable if $K$ is a class of graphs of bounded tree width and $W[1]$-complete otherwise. Towards this conjecture, we prove that the embedding problem is $W[1]$-complete if $K$ is the class of all grids or the class of all walls

Reflections on a coaching pilot project in healthcare settings

This paper draws on personal reflection of coaching experiences and learning as a coach to consider the relevance of these approaches in a management context with a group of four healthcare staff who participated in a pilot coaching project. It explores their understanding of coaching techniques applied in management settings via their reflections on using coaching approaches and coaching applications as healthcare managers. Coaching approaches can enhance a manager’s skill portfolio and offer the potential benefits in terms of successful goal achievement, growth, mutual learning and development for both themselves and staff they work with in task focused scenarios

Towards Work-Efficient Parallel Parameterized Algorithms

Parallel parameterized complexity theory studies how fixed-parameter tractable (fpt) problems can be solved in parallel. Previous theoretical work focused on parallel algorithms that are very fast in principle, but did not take into account that when we only have a small number of processors (between 2 and, say, 1024), it is more important that the parallel algorithms are work-efficient. In the present paper we investigate how work-efficient fpt algorithms can be designed. We review standard methods from fpt theory, like kernelization, search trees, and interleaving, and prove trade-offs for them between work efficiency and runtime improvements. This results in a toolbox for developing work-efficient parallel fpt algorithms.Comment: Prior full version of the paper that will appear in Proceedings of the 13th International Conference and Workshops on Algorithms and Computation (WALCOM 2019), February 27 - March 02, 2019, Guwahati, India. The final authenticated version is available online at https://doi.org/10.1007/978-3-030-10564-8_2

Valuing the biodiversity gains from protecting native plant communities from bitou bush (Chrysanthemoides monilifera subsp rotundata (DC.) T.Norl.) in New South Wales: application of the defensive expenditure method

Valuation of the gains from protection of biodiversity is difficult because the services that provide the benefits do not normally pass through markets where prices can form. But the services sometimes pass through markets where consumers or producers behave in a market-oriented manner, and so the values implicit in this behaviour can be identified and derived. Estimates of the benefits of biodiversity protection are derived from the costs of protecting native plant communities from a major weed in Australia, by following this approach. In 1999, invasion of coastal areas of New South Wales by bitou bush (Chrysanthemoides monilifera subsp. rotundata (DC.) T. Norl.) was listed as a key process threatening native plants under the NSW Threatened Species Conservation Act 1995. In accordance with the Act, the Department of Environment and Climate Change prepared a Threat Abatement Plan (TAP) to reduce the impacts of bitou bush on biodiversity at each threatened site. The costs of protecting sites vary closely with the number of priority native species and communities at each site. Following standard economic assumptions about market transactions, these costs are interpreted to provide values the benefits of protecting extra species, communities, and sites. Key words: Bitou bush, Chrysanthemoides monilifera, threat abatement plan, valuation of biodiversity, benefit-cost analysis, weed control, defensive-expenditure method.Bitou bush, Chrysanthemoides monilifera, threat abatement plan, valuation of biodiversity, benefit-cost analysis, weed control, defensive-expenditure method, Demand and Price Analysis, Environmental Economics and Policy,

On-Orbit Validation of a Framework for Spacecraft-Initiated Communication Service Requests with NASA's SCaN Testbed

We design, analyze, and experimentally validate a framework for demand-based allocation of high-performance space communication service in which the user spacecraft itself initiates a request for service. Leveraging machine-to-machine communications, the automated process has potential to improve the responsiveness and efficiency of space network operations. We propose an augmented ground station architecture in which a hemispherical-pattern antenna allows for reception of service requests sent from any user spacecraft within view. A suite of ground-based automation software acts upon these direct-to-Earth requests and allocates access to high-performance service through a ground station or relay satellite in response to immediate user demand. A software-defined radio transceiver, optimized for reception of weak signals from the helical antenna, is presented. Design and testing of signal processing equipment and a software framework to handle service requests is discussed. Preliminary results from on-orbit demonstrations with a testbed onboard the International Space Station are presented to verify feasibility of the concept

Assessing the psychosocial factors associated with adherence to exercise referral schemes: a systematic review

This paper aimed to systematically review the evidence base to uncover the key psychosocial factors that underpin adherence to an exercise referral scheme (ERS). Databases PsycINFO, MEDLINE, SPORTDiscus, Web of Science, PubMed, PsycARTICLES, Open Grey, and PsycEXTRA were systematically searched. A parallel results-based convergent synthesis was performed by identifying key themes from quantitative and qualitative studies separately. After applying inclusion and exclusion criteria, the review included 24 eligible studies. Key findings showed intrinsic motivation, psychological need satisfaction, social support, and self-efficacy to be the prominent psychosocial factors associated with ERS adherence. In addition, lower expectations for change when entering the scheme was associated with ERS adherence. This review should serve as a catalyst to provide evidence-based ERS and as such ERS providers should seek to place an emphasis on participants’ expectations and beliefs when entering the scheme. Moreover, targeting the key factors of intrinsic motivation, psychological need satisfaction, social support, and self-efficacy throughout the duration of an ERS should serve to facilitate adherence

Counting dependent and independent strings

The paper gives estimations for the sizes of the the following sets: (1) the set of strings that have a given dependency with a fixed string, (2) the set of strings that are pairwise \alpha independent, (3) the set of strings that are mutually \alpha independent. The relevant definitions are as follows: C(x) is the Kolmogorov complexity of the string x. A string y has \alpha -dependency with a string x if C(y) - C(y|x) \geq \alpha. A set of strings {x_1, \ldots, x_t} is pairwise \alpha-independent if for all i different from j, C(x_i) - C(x_i | x_j) \leq \alpha. A tuple of strings (x_1, \ldots, x_t) is mutually \alpha-independent if C(x_{\pi(1)} \ldots x_{\pi(t)}) \geq C(x_1) + \ldots + C(x_t) - \alpha, for every permutation \pi of [t]