An Axiomatic Approach to Liveness for Differential Equations

This paper presents an approach for deductive liveness verification for ordinary differential equations (ODEs) with differential dynamic logic. Numerous subtleties complicate the generalization of well-known discrete liveness verification techniques, such as loop variants, to the continuous setting. For example, ODE solutions may blow up in finite time or their progress towards the goal may converge to zero. Our approach handles these subtleties by successively refining ODE liveness properties using ODE invariance properties which have a well-understood deductive proof theory. This approach is widely applicable: we survey several liveness arguments in the literature and derive them all as special instances of our axiomatic refinement approach. We also correct several soundness errors in the surveyed arguments, which further highlights the subtlety of ODE liveness reasoning and the utility of our deductive approach. The library of common refinement steps identified through our approach enables both the sound development and justification of new ODE liveness proof rules from our axioms.Comment: FM 2019: 23rd International Symposium on Formal Methods, Porto, Portugal, October 9-11, 201

Membrane distillation - A technology for resource recovery in communal waste water treatment

In the past years lots of research in the area of membrane distillation (MD) has been conducted, especially in the fields of desalination. Nevertheless there are many new fields with possible applications of MD. With this paper the role of MD in communal wastewater treatment is presented. During the aerobic sewage treatment of a conventional Waste Water Treatment Plant (WWTP) resources such as nitrogen and carbon are destroyed. For this reason membrane distillation was applied for the separation of ammonia. An overall system integration concept could direct the WWTP from being a consumer into a producer – cleaning water while providing resources in form of valuable products. Along with population growth the demand for water, resources and energy will be drastically increased within the next decades. In this study the general stability of a poly tetra fluor ethylene (PTFE) membrane was tested by conducting liquid entry pressure (LEP) tests such as contact angle (CA) measurements with membranes that have been exposed to the waste water before. A spiral wound module was custom-made and a pilot plant (20`- Container, (6058 x 2438 mm)) was designed and constructed. Tests were carried out on-site of a waste water treatment plant for a few month of period. The suitability of the MD configuration for ammonia recovery was proven. Different test- and cleaning conditions were studied in order to evaluate the best-achievable separation factors. The dissociation equilibrium of ammonia-ammonium was taken into account, in terms of temperature and pH value, when conducting the ammonia separation experiments. The paper will present results from field tests at the waste water treatment plant. In the scope of this paper a concept for the integration of the membrane distillation facility into the WWTP will be presented and the potential for the integration of waste heat or solar thermal energy will be pointed out. An essential part is also the calculation of the economic feasibility of this new technology. The result will include detailed knowledge about the operation parameters such as flow rates, temperatures, energy consumption etc

Transparent yttrium hydride thin films prepared by reactive sputtering

Metal hydrides have earlier been suggested for utilization in solar cells. With this as a motivation we have prepared thin films of yttrium hydride by reactive magnetron sputter deposition. The resulting films are metallic for low partial pressure of hydrogen during the deposition, and black or yellow-transparent for higher partial pressure of hydrogen. Both metallic and semiconducting transparent YHx films have been prepared directly in-situ without the need of capping layers and post-deposition hydrogenation. Optically the films are similar to what is found for YHx films prepared by other techniques, but the crystal structure of the transparent films differ from the well-known YH3 phase, as they have an fcc lattice instead of hcp

Surface oxide on thin films of yttrium hydride studied by neutron reflectometry

The applicability of standard methods for compositional analysis is limited for H-containing films. Neutron reflectometry is a powerful, non-destructive method that is especially suitable for these systems due to the large negative scattering length of H. In this work we demonstrate how neutron reflectometry can be used to investigate thin films of yttrium hydride. Neutron reflectometry gives a strong contrast between the film and the surface oxide layer, enabling us to estimate the oxide thickness and oxygen penetration depths. A surface oxide layer of 5-10 nm thickness was found for unprotected yttrium hydride films

NLO QCD corrections to processes with multiple electroweak bosons

The VBFNLO program package is a collection of Monte Carlo programs for the calculation of NLO QCD corrections to vector boson fusion cross sections, double and triple vector boson production, or the production of two electroweak bosons in association with an additional jet. An overview is given of the processes and features implemented in VBFNLO. WWgamma and Wgamma jet production are discussed as examples.Comment: 6 pages, 3 figures; talk given at RADCOR 2009 - 9th International Symposium on Radiative Corrections (Applications of Quantum Field Theory to Phenomenology), October 25 - 30 2009, Ascona, Switzerlan

Ascaroside Signaling Is Widely Conserved among Nematodes

Background: Nematodes are among the most successful animals on earth and include important human pathogens, yet little is known about nematode pheromone systems. A group of small molecules called ascarosides has been found to mediate mate finding, aggregation, and developmental diapause in Caenorhabditis elegans, but it is unknown whether ascaroside signaling exists outside of the genus Caenorhabditis. Results: To determine whether ascarosides are used as signaling molecules by other nematode species, we performed a mass spectrometry-based screen for ascarosides in secretions from a variety of both free-living and parasitic (plant, insect, and animal) nematodes. We found that most of the species analyzed, including nematodes from several different clades, produce species-specific ascaroside mixtures. In some cases, ascaroside biosynthesis patterns appear to correlate with phylogeny, whereas in other cases, biosynthesis seems to correlate with lifestyle and ecological niche. We further show that ascarosides mediate distinct nematode behaviors, such as retention, avoidance, and long-range attraction, and that different nematode species respond to distinct, but overlapping, sets of ascarosides. Conclusions: Our findings indicate that nematodes utilize a conserved family of signaling molecules despite having evolved to occupy diverse ecologies. Their structural features and level of conservation are evocative of bacterial quorum sensing, where acyl homoserine lactones (AHLs) are both produced and sensed by many species of gram-negative bacteria. The identification of species-specific ascaroside profiles may enable pheromone-based approaches to interfere with reproduction and survival of parasitic nematodes, which are responsible for significant agricultural losses and many human diseases worldwide

Rainwater in Egypt: quantity, distribution and harvesting

Egypt has limited water resources, and it will be under water stress within the year 2030. Therefore, Egypt should consider the natural and non-conventional water resources to overcome such problem. Rain harvesting is one solution; but not all; particularly on the north coast by the Mediterranean Sea and the Red sea. In this paper, the rainwater issue is reviewed and discussed in terms of the quantities and distribution at different selected areas in Egypt. The amount of rain falls at different location in Egypt was collected for a period of 16 months. The data indicated that rainfall in Egypt is very scarce, with an annual average of 12 mm and ranges from 0 mm/year in the desert to 200 mm/year in the north coastal region. The maximum total amount of rain does not exceed 1.8 billion m3per year. However, the average annual amount of rainfall water that is effectively utilized for agriculture purposes is estimated to be 1 billion m3. Harvesting pilot plant was constructed and implemented in Alexandria directly on the Mediterranean Sea. The harvested rain was used for irrigation and treated for drinking. It was, therefore, recommended to develop sustainable catchments at appropriate locations in the rain-fed areas at the north coast as well as cost effective grafting of the indigenous technologies with the innovative techniques

Trombe walls with nanoporous aerogel insulation applied to UK housing refurbishments

There is an opportunity to improve the efficiency of passive Trombe walls and active solar air collectors by replacing their conventional glass covers with lightweight polycarbonate panels filled with nanoporous aerogel insulation. This study investigates the thermal performance, energy savings, and financial payback period of passive Aerogel Trombe walls applied to the existing UK housing stock. Using parametric modeling, a series of design guidance tables have been generated, providing estimates of the energy savings and overheating risk associated with applying areas of Trombe wall to four different house types across the UK built to six notional construction standards. Calculated energy savings range from 183 kWh/m2/year for an 8 m2 system retrofitted to a solid walled detached house to 62 kWh/m2/year for a 32 m2 system retrofitted to a super insulated flat. Predicted energy savings from Trombe walls up to 24 m2 are found to exceed the energy savings from external insulation across all house types and constructions. Small areas of Trombe wall can provide a useful energy contribution without creating a significant overheating risk. If larger areas are to be installed, then detailed calculations would be recommended to assess and mitigate potential overheating issues.The EPSRC, Brunel University, and Buro Happold Lt

Extending Hybrid CSP with Probability and Stochasticity

Probabilistic and stochastic behavior are omnipresent in computer controlled systems, in particular, so-called safety-critical hybrid systems, because of fundamental properties of nature, uncertain environments, or simplifications to overcome complexity. Tightly intertwining discrete, continuous and stochastic dynamics complicates modelling, analysis and verification of stochastic hybrid systems (SHSs). In the literature, this issue has been extensively investigated, but unfortunately it still remains challenging as no promising general solutions are available yet. In this paper, we give our effort by proposing a general compositional approach for modelling and verification of SHSs. First, we extend Hybrid CSP (HCSP), a very expressive and process algebra-like formal modeling language for hybrid systems, by introducing probability and stochasticity to model SHSs, which is called stochastic HCSP (SHCSP). To this end, ordinary differential equations (ODEs) are generalized by stochastic differential equations (SDEs) and non-deterministic choice is replaced by probabilistic choice. Then, we extend Hybrid Hoare Logic (HHL) to specify and reason about SHCSP processes. We demonstrate our approach by an example from real-world.Comment: The conference version of this paper is accepted by SETTA 201

The role of health determinants in the influenza vaccination uptake among older adults (65+): a scope review

Background: Although the burden of influenza infection is the highest in older adults, vaccination coverage remains low, despite this age group being more vulnerable than others. Aims: Given the current pandemic of SARS-CoV-2, it was the aim of this scope review to update knowledge on factors affecting seasonal influenza vaccine uptake among older adults to strengthen prevention approaches in the context of an overall burden of infectious diseases. Methods: We searched bibliographic databases from 2012 to 2019. All studies reviewed one or more social determinant of health listed by WHO, or factors affecting the decision-making process whether to accept influenza vaccine or not. Results: Overall, 44 studies were included, 41 determinants were extracted and summarized into six categories. Older age and constitutional factors including multiple chronic diseases as well as preventive lifestyle and frequent routine healthcare utilization positively affected vaccination uptake (VU). Living and working conditions are also researched determinants of influenza vaccine uptake. A small number of studies explored the role of social inclusion and system-based interventions. Discussion and conclusions: This scope review provides a comprehensive overview on factors affecting seasonal influenza vaccination uptake among older citizens. The review also clearly shows gaps for evidence on system-based level or political strategies to improve vaccination uptake