Solid-phase microextraction (SPME) as a tool to predict the bioavailability and toxicity of pyrene to the springtail, Folsomia candida, under various soil conditions

The porewater concentrations of pyrene were estimated by a negligible depletive solid-phase microextraction (SPME) method. The effects of organic matter (OM) and soil aging on the bioavailability of pyrene in soil were investigated by generation of reproductive effect concentrations (EC50) for the euedaphic springtail, Folsomia candida, under various test conditions. The soil used was a sandy loam soil with natural OM content of 2.6% (Askov soil). It was enriched with increasing organic matter concentrations of 5%, 10%, and 20% and was aged for 0, 56, and 112 days. The EC50 values of the springtails increased with increasing OM and aging of the soil. The increase of the OM content in the soil reduced the extractability of pyrene by SPME, as well as the toxicity of pyrene. An aging effect was demonstrated in Askov soil, EC50 values increased with increased contact time. The amounts of pyrene extracted by SPME were significantly affected by the soil concentration. Porewater concentrations determined by SPME decreased with increasing OM and aging. However, the pyrene EC50 porewater concentration remained largely constant at approximately 23 microg L(-1). The results demonstrated that the SPME method is a useful indicator for bioavailability to soil microarthropods.     

Modeling and control of a SOFC-GT-based autonomous power system

In this article, a dynamic, lumped model of a solid oxide fuel cell (SOFC) is described, as a step towards developing control relevant models for a SOFC combined with a gas turbine (GT) in an autonomous power system. The model is evaluated against a distributed dynamic tubular SOFC model. The simulation results confirm that the simple model is able to capture the important dynamics of the SOFC and hence it is concluded that the simple model can be used for control and operability studies of the hybrid system. Several such lumped models can be aggregated to approximate the distributed nature of important variables of the SOFC. Further, models of all other components of a SOFC-GT-based autonomous power system are developed and a control structure for the total system is developed. The controller provides satisfactory performance for load changes at the cost of efficiency.     

Levoglucosan as a Tracer for Smouldering Fire

Detecting fires at an early stage is crucial for mitigating and extinguishing fires. The increased use of biofuels in Northern Europe has led to an increased number of fires in storage facilities. These fires are often caused by self-heating in the interior of the stored materials and slowly develop to smouldering fires. Consequently, these smouldering fires are usually detected several days or weeks after the initial smouldering fire had started. At this point, measures to extinguish the smouldering fire inside the material are difficult as the fire has grown for a long time and is located inside the material. This makes it difficult to gain a successful effect of any extinguishing agents. This paper presents a pilot study in lab scale suggesting levoglucosan as an early tracer for smouldering fires using 600 g cotton as the biomass source. The advantage of detecting levoglucosan as a fire signature is that it serves as a tracer compound for biomass burning and is produced at temperatures of 200–400°C reducing the risk of false alarms from emissions produced at lower temperatures. In this paper, levoglucosan was detected in aerosols emitted in an early stage from smouldering fires and was analyzed by ultrasonic assisted extraction followed by gas chromatographic separation and mass spectrometric detection. First detection of levoglucosan was made in the first sample, collected after 30 min when the smouldering fire was only a few cubic centimeters of the cotton package. In addition, levoglucosan was found in the solid residues of carbonized cotton after the initial smouldering process had moved through the material. The findings should be regarded as screening results to be used for the development of sensors and technology for smouldering fire detection.     

The revised Tennessee Eastman process simulator as testbed for SPC and DoE methods

Engineering process control and high-dimensional, time-dependent data present great methodological challenges when applying statistical process control (SPC) and design of experiments (DoE) in continuous industrial processes. Process simulators with an ability to mimic these challenges are instrumental in research and education. This article focuses on the revised Tennessee Eastman process simulator providing guidelines for its use as a testbed for SPC and DoE methods. We provide flowcharts that can support new users to get started in the Simulink/Matlab framework, and illustrate how to run stochastic simulations for SPC and DoE applications using the Tennessee Eastman process.     

Decoupling,re‐engaging: managing trust relationships in implementation projects

An important aspect of the successful implementation of large information systems (such as Enterprise Resource Planning (ERP) systems) is trust. These implementations impact the legitimate interests of many groups of stakeholders, and trust is a critical factor for success. Trust in the project is contingent upon many factors, is likely to vary over time and should not be taken for granted. Previous studies have identified the relationship between trust and project outcomes and suggested trust‐building strategies but have largely ignored the dynamic quality of trust relations through the life of a major project and the complex demands of managing those fluctuations. We investigate evolving trust relationships in a longitudinal case analysis of a large integrated hospital system implementation for the Faroe Islands. Trust relationships suffered various breakdowns, but the project was able to recover and eventually meet its goals. Based on concepts from Giddens' later work on modernity, we develop two approaches for managing dynamic trust relationships in implementation projects: decoupling and re‐engaging.     

Energy system analysis of utilizing hydrogen as an energy carrier for wind power in the transportation sector in Western Denmark

Hydrogen is an energy carrier that can potentially be used for introducing renewably generated electricity into the transportation sector. This paper presents a methodology for an overall energy system analysis of a hydrogen infrastructure, which meets a transportation hydrogen demand profile. The methodology starts by building a mathematical model for optimizing the economic operation of electrolyzers on the electricity market by use of Genetic Algorithms. Demand profiles from the optimization are then included in an overall energy system analysis model studying the electricity market and power balance system effects. A sample 2030 scenario analysis of Western Denmark is presented to demonstrate the applicability of the devised methodology. It is shown that Genetic Algorithms is a flexible tool that can be adapted to optimization problems involving energy storage. On the other hand, it is found that the ability of Genetic Algorithms to find a solution is highly dependent on initial variables and the storage constraint. Further analysis is required in order to test and expand the methodology and scenario results.     

Using Multispectral Imaging for Spoilage Detection of Pork Meat

The quality of stored minced pork meat was monitored using a rapid multispectral imaging device to quantify the degree of spoilage. Bacterial counts of a total of 155 meat samples stored for up to 580 h have been measured using conventional laboratory methods. Meat samples were maintained under two different storage conditions: aerobic and modified atmosphere packages as well as under different temperatures. Besides bacterial counts, a sensory panel has judged the spoilage degree of all meat samples into one of three classes. Results showed that the multispectral imaging device was able to classify 76.13 % of the meat samples correctly according to the defined sensory scale. Furthermore, the multispectral camera device was able to predict total viable counts with a standard error of prediction of 7.47 %. It is concluded that there is a good possibility that a setup like the one investigated will be successful for the detection of spoilage degree in minced pork meat.     

Parameter ranking by orthogonalization—Applied to nonlinear mechanistic models

The paper addresses methods for parameter sensitivity analysis in a large, nonlinear, mechanistic model which is to be run in an on-line estimation scheme. The parameter sensitivity has been obtained by numeric approximation. The paper proposes and applies successive orthogonalization of the sensitivity derivative for parameter ranking. The method is easy to implement and the results are easily interpreted. Orthogonalization of the sensitivity matrix gives a triangular form of the squared sensitivity. The paper shows how the triangular form of the sensitivity derivative gives a particularly easy form of the variance contribution of individual parameters, provided the model error can be assumed Gaussian. This information has been used to decide how many parameters from the ranked set are to be selected for on-line estimation.