Design space exploration of a poultry fillet processing system using discrete-event simulation

Developments in the poultry processing industry, such as how livestock is raised and how consumers buy meat, make it increasingly difficult to design poultry processing systems that meet evolving standards. More and more iterations of (re)design are required to optimize the product flow in these systems. This paper presents a method for design space exploration of production systems using discrete-event simulation. This method automates most steps of design space exploration: iterating on the design, model construction, performing simulation experiments, and interpreting the simulation results. This greatly reduces the time and effort required to iterate through different designs. A case study is presented which shows that this method can be effective for design space exploration of poultry processing systems.Comment: FOODOPS 202

Epidemiological patterns of hepatitis B virus (HBV) in highly endemic areas

This paper uses meta-analysis of published data and a deterministic mathematical model of hepatitis B virus (HBV) transmission to describe the patterns of HBV infection in high endemicity areas. We describe the association between the prevalence of carriers and a simple measure of the rate of infection, the age at which half the population have been infected (A50), and assess the contribution of horizontal and perinatal transmission to this association. We found that the two main hyper-endemic areas of sub-Saharan Africa and east Asia have similar prevalences of carriers and values of A50, and that there is a negative nonlinear relationship between A50 and the prevalence of carriers in high endemicity areas (Spearman's Rank, P = 0·0086). We quantified the risk of perinatal transmission and the age-dependent rate of infection to allow a comparison between the main hyper-endemic areas. East Asia was found to have higher prevalences of HBeAg positive mothers and a greater risk of perinatal transmission from HBeAg positive mothers than sub-Saharan Africa, though the differences were not statistically significant. However, the two areas have similar magnitudes and age-dependent rates of horizontal transmission. Results of a simple compartmental model suggest that similar rates of horizontal transmission are sufficient to generate the similar patterns between A50 and the prevalences of carriers. Interrupting horizontal transmission by mass immunization is expected to have a significant, nonlinear impact on the rate of acquisition of new carriers

Robustness of Equations Under Operational Extensions

Sound behavioral equations on open terms may become unsound after conservative extensions of the underlying operational semantics. Providing criteria under which such equations are preserved is extremely useful; in particular, it can avoid the need to repeat proofs when extending the specified language. This paper investigates preservation of sound equations for several notions of bisimilarity on open terms: closed-instance (ci-)bisimilarity and formal-hypothesis (fh-)bisimilarity, both due to Robert de Simone, and hypothesis-preserving (hp-)bisimilarity, due to Arend Rensink. For both fh-bisimilarity and hp-bisimilarity, we prove that arbitrary sound equations on open terms are preserved by all disjoint extensions which do not add labels. We also define slight variations of fh- and hp-bisimilarity such that all sound equations are preserved by arbitrary disjoint extensions. Finally, we give two sets of syntactic criteria (on equations, resp. operational extensions) and prove each of them to be sufficient for preserving ci-bisimilarity.Comment: In Proceedings EXPRESS'10, arXiv:1011.601

Ambient rf energy scavenging: Gsm and wlan power density measurements

Abstract-To assess the feasibility of ambient RF energy scavenging, a survey of expected power density levels distant from GSM-900 and GSM-1800 base stations has been conducted and power density measurements have been performed in a WLAN environment. It appears that for distances ranging from 25m to 100m from a GSM base station, power density levels ranging from 0.1mW/m 2 to 3.0mW/m 2 may be expected. First measurements in a WLAN environment indicate even lower power density values, making GSM and WLAN unlikely to produce enough ambient RF energy for wirelessly powering miniature sensors. A single GSM telephone however has proven to deliver enough energy for wirelessly powering small applications on moderate distances

Lost in translation: Hybrid-time flows vs. real-time transitions

Recently, hybrid-time flow systems have been introduced as an extension to timed transition systems, hybrid automata, continuous time evolutions of differential equations etc. Furthermore, a number of notions of bisimulation have been defined on these flow systems reflecting abstraction from certain timing properties. In this paper, we research the difference in abstraction level between this new semantic model of flow systems, and the more traditional model of real-time transition systems. We explore translations between the old and new semantic models, and we give a necessary and sufficient condition, called finite-set refutability, for these translations to be without loss of information. Finally, we show that differential inclusions with an upper-semicontinuous, closed and convex right-hand side, are finite-set refutable, and easily extend this result to impuls differential inclusions and hybrid automata

Analysis of an industrial system

Abstract. Studying industrial systems by simulation enables the designer to study their dynamic behaviour and to determine characteristics of the system. Unfortunately, simulation also has some disadvantages. These can be overcome by using formal methods. Formal methods allow a thorough analysis of the possible behaviours of a system, parameterised system analysis and a modular approach to the analysis of systems. We present a case study in which a model of an industrial system is studied in a formal way. For this purpose, the model is first specified and simulated using the CSP-based executable specification language χ . The model is translated into a model in the process algebra µCRL. This enables us to give a correctness proof of the parameterised model and to study the model in isolation

Submesoscale dispersion in the vicinity of the Deepwater Horizon spill

Reliable forecasts for the dispersion of oceanic contamination are important for coastal ecosystems, society and the economy as evidenced by the Deepwater Horizon oil spill in the Gulf of Mexico in 2010 and the Fukushima nuclear plant incident in the Pacific Ocean in 2011. Accurate prediction of pollutant pathways and concentrations at the ocean surface requires understanding ocean dynamics over a broad range of spatial scales. Fundamental questions concerning the structure of the velocity field at the submesoscales (100 meters to tens of kilometers, hours to days) remain unresolved due to a lack of synoptic measurements at these scales. \textcolor{black} {Using high-frequency position data provided by the near-simultaneous release of hundreds of accurately tracked surface drifters, we study the structure of submesoscale surface velocity fluctuations in the Northern Gulf Mexico. Observed two-point statistics confirm the accuracy of classic turbulence scaling laws at 200m$-$50km scales and clearly indicate that dispersion at the submesoscales is \textit{local}, driven predominantly by energetic submesoscale fluctuations.} The results demonstrate the feasibility and utility of deploying large clusters of drifting instruments to provide synoptic observations of spatial variability of the ocean surface velocity field. Our findings allow quantification of the submesoscale-driven dispersion missing in current operational circulation models and satellite altimeter-derived velocity fields.Comment: 9 pages, 6 figure

Observations of velocities, sand concentrations, and fluxes under velocity-asymmetric oscillatory flows

Peer reviewedPublisher PD

On the Nature of the Frontal Zone of the Choctawhatchee Bay Plume in the Gulf of Mexico

River plumes often feature turbulent processes in the frontal zone and interfacial region at base of the plume, which ultimately impact spreading and mixing rates with the ambient coastal ocean. The degree to which these processes govern overall plume mixing is yet to be quantified with microstructure observations. A field campaign was conducted in a river plume in the northeast Gulf of Mexico in December 2013, in order to assess mixing processes that could potentially impact transport and dispersion of surface material near coastal regions. Current velocity, density, and Turbulent Kinetic Energy Values, ε, were obtained using an Acoustic Doppler Current Profiler (ADCP), a Conductivity Temperature Depth (CTD) profiler, a Vertical Microstructure Profiler (VMP), and two Acoustic Doppler Velocimeters (ADVs). The frontal region contained ε values on the order of 10−5 m2 s−3, which were markedly larger than in the ambient water beneath (O 10−9 m2s−3). An energetic wake of moderate ε values (O 10−6 m2 s−3) was observed trailing the frontal edge. The interfacial region of an interior section of the plume featured opposing horizontal velocities and a ε value on the order of 10−6 m2 s−3. A simplified mixing budget was used under significant assumptions to compare contributions from wind, tides, and frontal regions of the plume. The results from this order of magnitude analysis indicated that frontal processes (59%) dominated in overall mixing. This emphasizes the importance of adequate parameterization of river plume frontal processes in coastal predictive models