Gone with the wind? Newspaper discourse of eutrophication and blue‐green algae blooms in Finland

The mass media shape the public and policy agenda by giving prominence to certain ecosystem changes and risks, as well as by framing some policy measures as the preferred ones. Based on longitudinal analysis of the leading Finnish newspaper, this study considers the media coverage of eutrophication. The results show an increase of reporting in the late 1990s as a result of intertwined ecological and social factors – i.e. intense algal occurrences and establishment of a national communication system. The news coverage has highlighted the harmful algal blooms and health risks of algal toxins and has framed short‐term weather conditions as the key factor regulating algal occurrences. This creates a challenge for environmental management aimed at reduction in the nutrient discharges that influence the state of the environment in the long term.     

A fast modelling tool for plate heat exchangers based on depth-averaged equations

In this study, the depth-averaged flow and energy equations for plate heat exchangers are presented. The equations are derived by integrating the original 3D flow and energy equations over the height of the gap between the bottom and top plates. This approach reduces the equations from 3D to 2D but still takes into account the frictions on the surfaces and heat transfer through the plates. The depth-averaging reduces the elapsed time of CFD simulations from hours to minutes. Thus, it is very practicable modelling method in real time design work. 2D CFD simulations with depth-averaged equations are compared with full 3D models for five different corrugation angles and corrugation lengths. The simulation results show that the 2D model predicts with relatively good accuracy the profile of the pressure drop and the temperature change as a function of the corrugation angle and the function of the corrugation length. In order to get more extensive information about the significance of the different geometry parameters on the efficiency of the heat exchanger, we simulated 30 different geometries with the fast 2D model. The results suggest that the temperature change is not as sensitive for the geometrical modifications as the pressure drop.     

Ante- and perinatal factors and child characteristics predicting parenting experience among formerly infertile couples during the child's first year: A controlled study.

In this prospective controlled study, the authors examined (a) parenting experiences among couples with successful assisted reproduction treatment (ART; n = 367) and fertile spontaneously conceiving controls (n = 371) and (b) the impact of ante- and perinatal factors and child characteristics on parenting experiences. The results show that positive mothering experiences increased more during the 1st year of parenting and were generally higher among ART mothers than control mothers. No differences were found between ART fathers and controls in their fathering experience. Unpleasant birth experiences, low birth weight, and difficulty soothing the child were associated with high levels of parental stress in the control group, but this was not so among the ART parents. Psychosocial interventions in maternal care should take into account the various meanings that couples give to the history of infertility and conception and ante- and perinatal experiences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simulation of light propagation by local spherical interface approximation

A new local elementary interface approximation is introduced for the modeling of wave propagation through interfaces between homogeneous media. The incident wave and the surface profile are approximated locally by a spherical wave and a spherical surface, respectively. The wave field travels through the modulated structure according to the laws of geometrical optics, being refracted by the surface and propagating to the output plane locally as a geometric spherical wave. Diffraction theory is applied to propagate the field from the output plane onwards. We provide comparisons of the method with the thin-element approximation, the local plane-wave and interface approach, and rigorous diffraction theory using a sinusoidal surface-relief grating as an example. We illustrate the power of the new method by applying it to the analysis of a diffractive beam splitter.     

An efficient variable neighborhood search heuristic for very large scale vehicle routing problems

In this paper, we present an efficient variable neighborhood search heuristic for the capacitated vehicle routing problem. The objective is to design least cost routes for a fleet of identically capacitated vehicles to service geographically scattered customers with known demands. The variable neighborhood search procedure is used to guide a set of standard improvement heuristics. In addition, a strategy reminiscent of the guided local search metaheuristic is used to help escape local minima. The developed solution method is specifically aimed at solving very large scale real-life vehicle routing problems. To speed up the method and cut down memory usage, new implementation concepts are used. Computational experiments on 32 existing large scale benchmarks, as well as on 20 new very large scale problem instances, demonstrate that the proposed method is fast, competitive and able to find high-quality solutions for problem instances with up to 20,000 customers within reasonable CPU times.     

Estimation of tree crown volume from airborne lidar data using computational geometry

Although simple geometrical shapes are commonly used to describe tree crowns, computational geometry enables calculation of the individual crown properties directly from airborne lidar point clouds. Our objective was to calculate crown volumes (CVs) using this technique and validate the results by comparing them with field-measured values and modelled ellipsoidal crowns. The CVs of standing trees were obtained by measuring the crown radii at different heights, integrating the obtained crown profiles as solids of revolution, and finally averaging the volumes obtained from the four separate profiles. With the lidar data, the CVs were extracted using 3D alpha shape and 3D convex hull techniques. Crown base heights (CBHs) were also estimated from the lidar data and used to exclude echoes from the understory, which was also done using field-based CBHs to exclude this error source. The results show that the field-measured CVs had a high correlation with lidar-based estimates (best R ² = 0.83), but the lidar-based estimates were generally smaller than the field values. The best correspondence (root mean square difference (RMSD) = 45.0%, average difference = –24.7%) was obtained using the convex hull of the point data and field-measured CBH. The CBHs were consistently overestimated (RMSD = 37.3%; average difference = –20.0%), especially in spruces with long crowns. Thus using lidar-based CBH also increased the inaccuracy of the CV estimates. While the underestimation of CV is mainly explained by the inadequate number of echoes from the lower regions of the crowns, the CVs obtained from the lidar were better than those obtained with ellipsoids fitted by using general models for crown dimensions. The utility of the estimated CVs in the prediction of stem diameter is also demonstrated.     

Bi-level optimization for a dynamic multiobjective problem

In this article, a bi-level optimization problem covering upper (design) and lower (operation) levels is defined and a solution procedure for bi-level optimization problems is presented. This is devised as a dynamic multiobjective optimization problem, i.e. the values of the control and state variables change over a predefined time horizon and several competing criteria are optimized simultaneously. Moreover, the interaction between the upper and lower levels is analysed. The benefits of bi-level dynamic multiobjective optimization are illustrated in detail by examining an industrial case in which the design of a paper mill (upper level) and the mill operation (lower level) are optimized at the same time. However, the problem definition and the solution procedure are not limited to any specific application but can be exploited in many different industrial areas.     

Study on process parameters in metallocene polymerizations,I. Apparent viscosity and macro-scale mass transfer

A heat balance reaction calorimeter was used to obtain information about the most informative process parameters in polymerizations carried out with Et[Ind]₂ZrCl₂-methylaluminoxane catalyst. The viscosity of the reaction mixture was found to increase dramatically during the homopolymerization of ethylene, but it could be controlled through appropriate selection of the reaction mixture medium. The mass transfer between the gas and liquid phases was the rate-determining step for the polymerization when the reaction mixture-based Reynolds number was below 2.500. The limited mass transfer between the gas and liquid phases was caused by the intensive activity of the metallocene catalyst and the increased viscosity of the reaction mixture.     

Thermoplastic 0–3 Ceramic–Polymer Composites With Adjustable Magnetic and Dielectric Characteristics for Radio Frequency Applications

Magnetic and electrical properties of thermoplastic ceramic-polymer 0–3 composites with Z-type hexaferrite, and MnZn ferrite inclusions were investigated. The complex permeability and permittivity were measured up to 1 GHz where maximum values of ɛ′_r=30.47 and μ′_r=4.32 and ɛ′_r=10.95 and μ′_r=1.80 were obtained for MnZn-ER182 and Co₂Z-ER182 composites with ∼44.7 vol% and 43.0 vol% filler loadings, respectively. MnZn and Co₂Z composites exhibit miniaturization factors as low as 0.09 and 0.23, together with reduced magnetic losses and frequency dispersion. The results indicate that the composites offer novel possibilities for wider feasible frequency bandwidth and adjustable impedance matching and magnetic and dielectric properties.     

Estimation of the number of trays for natural gas triethylene glycol dehydration column

The paper deals with the tray-to-tray method for determining the required number of trays in columns with intensive entrainment of liquid when the operating line of the “dry working regime” is not straight and with a small concentration of diffusing component in gas. Presented calculations show that the number of transfer units for gas and liquid should be calculated using the AIChE method accompanied with longitudinal mixing according to Gilbert properly transformed for case of diffusion through stagnant film. The suggested method can be applied for TEG dehydration absorbers-columns for dehydration of natural gas using triethylene glycol with system factor SF = 0.5.