Part two: Control of a novel HTPEM-based micro combined heat and power fuel cell system

A novel micro combined heat and power system and a dynamic model thereof were presented in part one of the publication. In the following, the control system and dynamic performance of the system are presented. The model is subjected to a measured consumption pattern of 25 Danish single family houses with measurements of heat, power and hot water consumption every 15th minute during one year.     

Genetic parameter estimation for milk yield over multiple parities and various lengths of lactation in Danish Jerseys by random regression models

The objectives of this study were to test for heterogeneity of genetic and environmental variance among completed and extended records from different lactations or different days in milk (DIM) and to build a model that accounts for this heterogeneity. A total of 147,457 305-d milk yield records from Danish Jersey cows calving between 1984 and early 1999 from two regions of Denmark were used in this study. Results showed that DIM and parity influenced parameters estimated from an animal model with repeated records. Therefore, the data were analyzed using random-regression models that allow the covariance between measurements to change gradually with DIM and parity. Random regressions were fitted for additive genetic effects and permanent environmental effects using second- or third-order normalized Legendre polynomials for DIM and parity. Variances of random-regression coefficients associated with all orders of the polynomials were significant. Based on these parameter estimates, a covariance function (CF) was defined. The CF showed that the heritability decreases over parities, but within each parity heritability increases with DIM, whereas variance of permanent environmental effects increases over parities and decreases with DIM. Generally, genetic correlations were higher between records with similar DIM and parity. The results indicate that there are problems with the extension procedure used to predict 305-d milk yields. Using the covariance functions estimated in this study, breeding values could be predicted that take into account the covariance structure between records from different parities and different DIM.     

Formation of a Nanocrystalline Layer on the Surface of Stone Wool Fibers

In the present paper, we report a simple approach for creating a nanocrystalline layer on the surface of stone wool fibers (SWFs) with a basalt-like composition. The approach is based on a preoxidation process of the SWFs in atmospheric air at a temperature around the glass transition temperature ( T _g) for various durations. During preoxidation, the network-modifying ions diffuse from the interior toward the surface of SWFs and react with oxygen on the surface to form oxides. This diffusion process is accompanied by an inward diffusion of electron holes via the oxidation process of Fe²⁺ to Fe³⁺. It is found that the diffusion of Mg²⁺ is dominant in the overall diffusion process. The main phase of the nanocrystalline layer is identified to be periclase (MgO) crystals. The thickness of the nanocrystalline layer can be varied by adjusting the temperature and the duration of preoxidation. The nanocrystalline layer plays a significant role in enhancing the high-temperature stability of the SWFs.     

Analytical model of heat transfer in porous insulation around cold pipes

A thermal insulation system is analysed that consists of a cold tube insulated with a porous material faced with a vapour retarding foil.Water vapour will diffuse through the vapour retarding foil and condense on the cold tube. To avoid build-up of water in the insulation a hydrophilic wicking cloth is wrapped around the cold tube and extended through a slit in the tubular insulation and a slot in the facing to the ambient so that condensed water can evaporate into the air. Some of the moisture in that part of the wicking cloth situated in the slit in the tubular insulation will diffuse backwards to the cold pipe and contribute to the heat uptake of the cold tube. This part is calculated for the stationary case and compared with the sensible heat transfer through the tubular shaped insulation material, using measured dry λ values and measured fictitious moist λ values.     

Dimensioning of the solar heating system in the zero energy house in Denmark

The paper describes the project for a Zero Energy House constructed at the Technical University of Denmark. The house is designed and constructed in such a way that it can be heated all winter without any “artificial” energy supply, the main source being solar energy. With energy conservation arrangements, such as high-insulated constructions (30–40 cm mineral wool insulation), movable insulation of the windows and heat recovery in the ventilating system, the total heat requirement for space heating is calculated to 2300 kWh per year. For a typical, well insulated, one-storied, one-family house built in Denmark, the corresponding heat requirement is 20,000 kWh. The solar heating system is dimensioned to cover the heat requirements and the hot water supply for the Zero Energy House during the whole year on the basis of the weather data in the “Reference Year”. The solar heating system consists of a 42 m² flat-plate solar collector, a 30 m³ water storage tank (insulated with 60 cm of mineral wool), and a heat distribution system. A total heat balance is set up for the system and solved for each day of the “Reference Year”. Collected and accumulated solar energy in the system is about 7300 kWh per yr; 30 per cent of the collected energy is used for space heating, 30 per cent for hot water supply, and 40 per cent is heat loss from the accumulator tank. For the operation of the solar heating system, the pumps and valves need a conventional electric energy supply of 230 kWh per year (corresponding to 5 per cent of the useful solar energy).     

On The Role of Wetting,Structure Width,and Flow Characteristics in Polymer Replication on Micro‐ and Nanoscale

The replication of functional polymeric micro‐ and nanostructures requires a deep understanding of material and process interrelations. In this investigation the dewetting potential of a polymer is proposed as a simple rationale for estimation of the replicability of functional micro‐ and nanostructures by injection molding. The dewetting potential of a polymer is determined by integrating the spreading coefficient over the range from melt temperature to no‐flow temperature. From all polymers tested, the lowest dewetting potential is calculated for PP and the highest for polymethylmethacrylate. The dewetting potential correlates well with the replicated height of four different structures covering both the micro‐ and the nanorange on two different surfaces (brass and fluorocarbon modified nickel) and polymers with different spreading coefficients. It is clearly shown that a lower dewetting potential of a polymer leads to a better replication accuracy. Additionally a parabolic relationship is demonstrated between filled height and structure width.

     

Distraction as a measure of presence: using visual and tactile adjustable distraction as a measure to determine immersive presence of content in mediated environments

To assess and improve the user experience in entertainment products, developers need results of evaluation methods, which in detail measure the relationship between the mediated content and the resulting media experience. This paper proposes a method applying adjustable distraction (AD) to determine presence as immersion (Lombard and Ditton in At the heart of it all: the concept of presence, Department of Broadcasting, Telecommunications and Mass Media, Temple University, 1997) at selectable events (approximated real-time). Two experiments were conducted to investigate its applicability in computer games and movies with respectively visual and tactile AD. The first experiment examined whether the experienced intensity in a survival-shooter game, measured through questionnaires, was proportional to results from the AD method. The intrusiveness of the AD method was also addressed in the experiment by comparing the immersive presence ratings in a between-groups design. The second experiment investigated whether heart rate measurements, intensity ratings and the results of the AD method with vibration as the distraction signal were proportional when test participants watched a movie clip. The outcome of the first experiment indicated that no significant intrusion is caused by the method. In addition, results showed no proportionality between the AD method and intensity ratings. However, as the AD measurements were supported by flow theory, it might be that the results from the AD method using visual distraction are giving a more comprehensive indication of presence as immersion (rather than just the intensity dimension). The second experiment revealed proportionality between the intensity ratings and the heart rate measurements, while the results from the tactile AD method were not proportional. We suspect that this was caused by the great variance found across the test participants’ thresholds of perceivable vibration. Because of this, it is suggested that a thorough screening process is conducted pre-test if the AD method should apply vibration as the distracting stimulus.