Heavy Metal and PAH Concentrations in Highway Runoff Deposits Fractionated on Settling Velocities

The correlation between settling velocity and associated pollutant concentrations is of major importance for best management practice in designing, redesigning, or evaluation of the efficiency of existing pond facilities for retaining unwanted pollutants. The prospect of this note is to state the relationship between the settling velocity of the runoff particles and the corresponding metal and polyaromatic hydrocarbon (PAH) concentration directly instead of dealing with two unknowns—the density and the shape of a single particle fraction in a settling velocity calculations. The measurements show that the highest cadmium, chromium, zinc, and nickel concentrations is associated with the most slowly falling particles and the lowest concentration associated within the faster falling fraction. This tendency is not clear for some of the sediments due to high content of organic matter and clearly not for lead and copper and there is no significant correlation between PAH concentration and settling velocity. The largest mass of metals and PAH within each pond can be found on the particle fraction with a settling velocity of 5.5–2.5 mm/s.     

Assessment of the performance of organic and mineral-based insulation products used in exterior walls and attics in dwellings

The assessment of the performance of organic and mineral-based insulation products used in exterior walls and attics in traditional Danish housing estate was evaluated. The assessment covered the ability of the materials to be handled on site as well as measurements of the performance of the materials once installed and exposed to normal use of the dwellings and Danish weather conditions over a 2-year period. Evaluations were based on, on-site observations, thermographic observations and measurements of temperature and moisture conditions within the different materials used. Eight different products were used for thermal insulation including six organic and two mineral fibre materials. Loose-fill material and predefined fixed-shape products were used. The eight different products were installed in 16 dwellings, two neighbouring dwellings were insulated with each product. Exterior walls were constructed without PE vapour barriers while ceilings were constructed with PE vapour barriers.     

Refurbishing Faestningens Materialgard： A Heritage Complex

F estningens Materialgard is a listed complex located in downtown Copenhagen. The refurbishment of the listed complex was studied to provide knowledge on how a process for refurbishing heritage buildings can be carried out successfully, as refurbishment of heritage buildings is often a complicated process. The process shows how to choose, evaluate and implement measures creating synergy between the interests of preserving heritage values and to develop affordable refurbishment that meets the requirements for the future use of the building. The refurbishment followed included restoration, energy upgrading and refurbishment of the individual buildings that make up the listed complex. The process focuses on the cooperation and dialogue between the parties involved. F estningens Materialgard is a case study where the Heritage Agency, the Danish Working Environment Authority and the owner as a team cooperated in identifying feasible refurbishment measures. Through the process the owner was supported by architects and engineers. Focus is put on how, to identify potential energy savings and, to decide on energy upgrading measures when refurbishing and restoring listed buildings. The refurbished Faestningens Materialgard is visualized in photos.     

Climate-change impacts on hydrology and nutrients in a Danish lowland river basin

The Mike 11-TRANS modelling system was applied to the lowland Gjern river basin in Denmark to assess climate-change impacts on hydrology and nitrogen retention processes in watercourses, lakes and riparian wetlands. Nutrient losses from land to surface waters were assessed using statistical models incorporating the effect of changed hydrology. Climate-change was predicted by the ECHAM4/OPYC General Circulation Model (IPCC A2 scenario) dynamically downscaled by the Danish HIRHAM regional climate model (25 km grid) for two time slices: 1961-1990 (control) and 2071-2100 (scenario). HIRHAM predicts an increase in mean annual precipitation of 47 mm (5%) and an increase in mean annual air temperature of 3.2 degrees C (43%). The HIRHAM predictions were used as external forcings to the rainfall-runoff model NAM, which was set up and run for 6 subcatchments within and for the entire, Gjern river basin. Mean annual runoff from the river basin increases 27 mm (7.5%, p<0.05) when comparing the scenario to the control. Larger changes, however, were found regarding the extremes; runoff during the wettest year in the 30-year period increased by 58 mm (12.3%). The seasonal pattern is expected to change with significantly higher runoff during winter. Summer runoff is expected to increase in predominantly groundwater fed streams and decrease in streams with a low base-flow index. The modelled change in the seasonal hydrological pattern is most pronounced in first- or second-order streams draining loamy catchments, which currently have a low base-flow during the summer period. Reductions of 40-70% in summer runoff are predicted for this stream type. A statistical nutrient loss model was developed for simulating the impact of changed hydrology on diffuse nutrient losses (i.e. losses from land to surface waters) and applied to the river basin. The simulated mean annual changes in TN loads in a loamy and a sandy subcatchment were, respectively, +2.3 kg N ha(-1) (8.5%) and +1.6 kg N ha(-1) (6.9%). The rainfall-runoff model and the nutrient loss model were chained with Mike 11-TRANS to simulate the combined effects of climate-change on hydrology, nutrient losses and nitrogen retention processes at the scale of the river basin. The mean annual TN export from the river basin increased from the control to the scenario period by 7.7%. Even though an increase in nitrogen retention in the river system of 4.2% was simulated in the scenario period, an increased in-stream TN export resulted because of the simulated increase in the diffuse TN transfer from the land to the surface-waters.     

Investigation of potential extreme load reduction for a two‐bladed upwind turbine with partial pitch

This paper presents a wind turbine concept with an innovative design combining partial pitch with a two‐bladed (PP‐2B) turbine configuration. Special emphasis is on extreme load reduction during storm situations at standstill, but operational loads are also investigated. In order to compare the loads and dynamics of the PP‐2B turbine, a partial pitch three‐bladed (PP‐3B) turbine and a normal pitch regulated three‐bladed (3B) turbine are introduced on the basis of solidity similarity scaling. From the dynamic comparisons between two‐ and three‐bladed turbines, it has been observed that the blade vibrations are transferred differently from the rotor to the tower. For a three‐bladed turbine, blade vibrations seen in a fixed frame of reference are split with ±1P only. A two‐bladed turbine has a similar split of ±1P but also includes contributions on higher harmonics (±2P, ±3P, … etc.). Further on, frequency split is also seen for the tower vibrations, where an additional ±2P contribution has been observed for the two‐bladed turbine. Regarding load comparisons, the PP‐2B turbine produces larger tower load variations because of 2P excitation during the operational cases. However, extreme loads are reduced by approximately 20% for the PP‐2B and 18% for the PP‐3B compared with the 3B turbine for the parked condition in a storm situation. Moreover, a huge potential of 60% is observed for the reduction of the extreme tower bottom bending moment for the PP‐2B turbine, when the wind direction is from ±90° to the turbine, but this also requires that the turbine is parked in a T‐configuration. © 2014 The Authors. Wind Energy published by John Wiley & Sons, Ltd.     

UTRA/FDD RF Transceiver Requirements

Unified RF requirements are derived for an UMTS Terrestrial RadioAccess/Frequency Division Duplex (UTRA/FDD) compliant mobile transceiver. Aset of transceiver requirements are proposed with consideration to systemissues including duplex aspects. From these design-compatible requirements areproposed for each functional block in the transceiver.     

Clocked power control circuit for inductively powered devices

Inductively powered devices are finding increasing use in many applications, such as biomedical implants and radio frequency identification (RFID) tags. In these systems, because of transmitter and receiver movements, the receiver coil may get close to the transmitter coil, which results in more than needed power delivered to the receiver load. This increases heat dissipated in the receiver circuit. In order to avoid overheating the receiver in such a high magnetic field (short coil separation distance) condition, the received power should be monitored and controlled. This paper introduces a clocked power control circuit integrated in the implant receiver, which is an independent, automatic power adjustment solution to limit heat dissipation with response to the coil separation distance. In this circuit, the rectified voltage across the load is monitored, and converted to a digital representation to selectively detune the receiver inductor-capacitor (LC) tank. To demonstrate this concept, a design example applied to inductively powered implants is given. Measurements on the prototype with a varied coil separation distance validate the desired power control functionality. Less power dissipation is achieved for the receiver compared to no power control condition.     

On the existence of statistically hiding bit commitment schemes and fail-stop signatures

We show that the existence of a statistically hiding bit commitment scheme with noninteractive opening and public verifiability implies the existence of fail-stop signatures. Therefore such signatures can now be based on any one-way permutation. We also show that genuinely practical fail-stop signatures follow from the existence of any collision-intractable hash function. These are the weakest assumptions known to be sufficient for fail-stop signatures. Conversely, we show that any fail-stop signature scheme with a property we call thealmost unique secret key property can be transformed into a statistically hiding bit commitment scheme. All previously known fail-stop signature schemes have this property. We even obtain an equivalence, because we can modify the construction of fail-stop signatures from bit commitments such that it has this property.     

The dispersion model for hydration of portland cement I. General concepts

This paper introduces an analytical mathematical model for development of the hydration of Portland cement: t₀ + t₁A + t₂A² = t t is time, and t₀, t₁ and t₂ are time-constants depending on temperature, cement type, admixtures etc. A is the hydration ratio, i.e. the ratio of hydrated to unhydrated cement. The dispersion model has been derived on basis of the typical particle size distribution for tube-milled products. Earlier findings by us have proven the particle size distribution to be a dominant factor in the correct modelling of cement hydration. The parameterization of hydration curves, which is easily performed with this dispersion model, gives a sufficient characterization of these for purposes of practical interpretations of the effects of factors decisive for the development of hydration.     

An impedance-measurement setup optimized for measuring relaxations of glass-forming liquids

An electronics system has been assembled to measure frequency-dependent response functions of glass-forming liquids in the extremely viscous state approaching the glass transition. We determine response functions such as dielectric permittivity and shear and bulk moduli by measuring electrical impedances of liquid-filled transducers, and this technique requires frequency generators capable of producing signals that are reproducible over the span of several days or even several weeks. To this end, we have constructed a frequency generator that produces low-frequency (1 mHz-100 Hz) sinusoidal signals with voltages that are reproducible within 10 ppm. Two factors that partly account for this precision are that signals originate from voltages stored in a look-up table and that only coil-less filters are used in this unit, which significantly reduces fluctuations of output caused by changes of temperatures of circuits. This generator also includes a special triggering facility that makes it possible to measure up to 512 voltages per cycle that are spaced apart at uniform phase intervals. Fourier transformations of such data yield precise determinations of complex amplitudes of voltages and currents applied to a transducer, which ultimately allows us to determine electrical impedances of transducers with a reproducibility error that is only a few parts per hundred thousand. This equipment is used in tandem with a commercial LCR meter and/or impedance analyzer that give(s) impedance measurements at higher frequencies, up to 1 MHz. The experimental setup allows measurements of the transducer impedance over nine decades of frequency within a single run.