Electric spark discharge as an ultrasonic generator in flow measurement situations

In this paper, a gap discharge approach to create acoustic signals for ultrasonic low pressure gas flow measurements is investigated. The objective is to develop an ultrasonic gas flow meter system that is capable of operation in extreme industrial environments. These environments might have extremely high temperatures (1200 °C), moisture, steam, dust, low gas pressure and large transmission distances.Most other types of ultrasonic transducers found show sensitivity to such conditions: their operation suffers, or they may even stop functioning if exposed to such environments. The development of new transducer technology is therefore crucial to allow ultrasonic flow measurements in extreme industrial environments. In this paper, the gap discharge emitter is evaluated as a candidate to be used in these applications. Its capabilities as a sound source are investigated, and its impact on flow meter performance is estimated. It can be concluded that, despite the uncertainties it introduces to a flow meter system, it stands out as a strong candidate to be used as an acoustic emitter in a gas flow meter system for extreme environments.     

Institutional stability and industry renewal: diverging trajectories in the Cognac beverage cluster

Adding to approaches highlighting network dynamics as a basis for regional economic development, increased attention is paid to institutions as contextual factors contributing to explaining how and why economies change. Research has shown that firms tend to react differently to the same institutional configurations, with the main explanatory factors being their sectoral backgrounds and intra-firm characteristics. This study adds to these insights by examining a regional economy in France, that of Cognac, in which 300 firms are operating under homogeneous institutional preconditions. Despite these similarities, we identify different development trajectories from the 1990s onwards. Our observations illustrate how firms’ responses to external change diverge and bring them on different trajectories due to different positions in the industry hierarchy and different experiences and capabilities among individuals within firms. The study contributes to the better understanding of mechanisms of path dependence, which have gained wide recognition in the literature in the recent decades.     

Experimental evaluation of radiator control based on primary supply temperature for district heating substations

In this paper, we evaluate whether the primary supply temperature in district heating networks can be used to control radiator systems in buildings connected to district heating; with the purpose of increasing the ΔT. The primary supply temperature in district heating systems can mostly be described as a function of outdoor temperature; similarly, the radiator supply temperature in houses, offices and industries can also be described as a function of outdoor temperature. To calibrate the radiator control system to produce an ideally optimal radiator supply temperature that produces a maximized ΔT across the substation, the relationship between the primary supply temperature and outdoor temperature must be known. However, even if the relation is known there is always a deviation between the expected primary supply temperature and the actual temperature of the received distribution media. This deviation makes the radiator control system incapable of controlling the radiator supply temperature to a point that would generate a maximized ΔT.     

Does waterborne citalopram affect the aggressive and sexual behaviour of rainbow trout and guppy?

Citalopram is one of several selective serotonin reuptake inhibitors (SSRIs) commonly found in treated sewage effluents. Accordingly, there are concerns about possible adverse effects of SSRIs on aquatic organisms, particularly behavioural effects similar to those associated with SSRI use in humans. Rainbow trout fry and adult male guppies were therefore exposed to waterborne citalopram, ranging from environmentally relevant to high concentrations (1, 10, 100 μg/L) for 3-7 days. Under these experimental conditions citalopram does not appear to cause significant effects on aggression in rainbow trout fry or on sexual behaviour in male guppies. This may be explained by a relatively low uptake of citalopram from water to fish.     

Experimental verification of a method for estimating energy for domestic hot water production in a 2-stage district heating substation

In this paper we compare our estimate of energy consumption for domestic hot water production in a building with the measured value. The energy consumption for hot water production is estimated from the measured total power consumption. The estimation method was developed using computer simulations, and it is based on the assumption that hot water production causes rapid and detectable changes in power consumption. A comparison of our estimates with measurements indicates that the uncertainty in estimation of hot water energy consumption is ±10%. Thus, the estimate is comparable to class 3 energy meter measurements, which have an uncertainty of ±2-10%.     

Photobleaching of Fluorescent Dyes under Conditions Used for Single-Molecule Detection: Evidence of Two-Step Photolysis

The photostability of fluorescent dyes is of crucial importance for the statistical accuracy of single-molecule detection (SMD) and for the image quality of scanning confocal microscopy. Concurrent results for the photostability were obtained by two different experimental techniques. First, the photostabilities of several coumarin and rhodamine derivatives in aqueous solution were obtained by monitoring the steady-state fluorescence decay in a quartz cell. Furthermore, an epi-illuminated microscope, continuous wave (CW) excitation at 514.5 nm, and fluorescence correlation spectroscopy (FCS) with a newly developed theory were used to study the photobleaching characteristics of rhodamines under conditions used for SMD. Depending on the rhodamine structure, the probability of photobleaching, p(b), is in the order of 10(-)(6)-10(-)(7) for irradiances below 10(3) W/cm(2). However, a considerable increase of p(b) for irradiances above this level was observed which can only be described by photobleaching reactions from higher excited states (two-step photolysis). In view of these observations, the probability of photobleaching, p(b), as well as a closed expression of its dependence on the CW excitation irradiance considering a five-level molecular electronic state model with the possibility of photobleaching from higher excited electronic states, is derived. From this model, optimal conditions for SMD with respect to the number of emitted fluorescence photons and to the signal-to-background ratio are discussed, taking into account both saturation and photobleaching. The additional photobleaching due to two-step photolysis limits the applicable irradiance.     

A web application for follow-up of results from a mobile device test battery for Parkinson's disease patients

Contrast-enhanced ultrasound (CEU) is an ultrasound imaging technique used to assess tissue perfusion. Analysis of microvascular recruitment necessitates the definition of a region of interest (ROI) containing exclusively the tissues to be studied. Conventional ROI selection requires examining the images and drawing the ROI by hand, making the analysis of CEU images non-reproducible and analyst-dependent. We have designed a systematic ROI selection method that is both reproducible and analyst-independent. Microvascular blood volume (MBV) assessed in 21 sequences of images was used to correlate the systematic ROI selection method with the conventional method performed by two independent analysts (correlation of 0.88 and 0.87 respectively) and the MBV sample distribution from the systematic method was not significantly different from those obtained from the conventional one. Using the systematic method, we found no significant insulin-induced capillary recruitment in subjects with type 1 diabetes mellitus, which might be related to the observed low glucose uptake during the hyperinsulinemic euglycemic clamp compared to healthy patients.     

Simulation of flow meter calibration factors for various installation effects

The determination of flow meter calibration factors has been made using a computer simulation approach. The proposed technique is based on computational fluid dynamics (CFD). The CFD tools were used to determine the flow field in a flow meter as developed by three different pipe configurations. These flow fields were used to determine the calibration factor for an ultrasonic flow meter. The results have been compared with calibration factors obtained by CFD using detailed LDV input boundary data, analytical calculations and experimental data. Tests were made for reference conditions of 10013 straight-pipe and for single- and double-elbow pipe configurations using Reynolds numbers from 100 to 100,000. For reference conditions good agreement is shown. For disturbed flow conditions the simulations well resembled the experimental data. However we find differences for transitional and swirl flows.     

Water Savings Through Improved Irrigation Techniques: Basin-Scale Quantification in Semi-Arid Environments

In many semi-arid and arid regions of the world, water saving strategies need to be implemented in the agricultural sector in order to increase the resilience to water scarcity. We investigate basin-scale hydrological impacts of possible irrigation technique improvements, considering extensive cotton fields in the Aral Sea drainage basin (ASDB), Central Asia. We use a distributed hydrologic model that combines basin-scale, calibrated discharge and evapotranspiration quantifications with experimental results of (on-farm) water application needs for different irrigation techniques. This allows for quantification of how return flows contribute to river discharge through coupled groundwater-surface water-systems at the basin scale, under different regional climatic conditions. Results show that an implementation of improved irrigation techniques can yield water savings that increase the discharge to the Aral Sea by between 1 and 6 km³/year. Such water savings could contribute to mitigation of the acute water scarcity in the lower ASDB. The basin-scale water savings are about 60% lower than corresponding on-farm reductions in irrigation water application, since water is re-used and, hence, return flows decrease when less water is applied. Spatial analysis of regional differences in climatic conditions shows that implementation of more efficient irrigation systems would result in much larger (up to a factor 4) water savings in the more arid downstream regions than in the colder, upstream mountainous regions.