High resolution experimental measurement of turbulent flow field in a high pressure homogenizer model and its implications on turbulent drop fragmentation

Particle image velocimetry is performed on a model of a high pressure homogenizer, scaled for qualitative similarity of the one phase turbulent flow field in a production scale homogenizer. Flow fields in gap entrance, gap and gap outlet chamber are obtained with high resolution. The measurements show gap flow development and formation of a turbulent wall adherent jet when exiting into the outlet chamber. Turbulent kinetic energy spectra show how the turbulent energy available for fragmentation is transported over distance along the jet centre axis.The high resolution images are also used together with a Kolmogorov–Hinze theory framework for discussing drop fragmentation together with a direct evaluation of disruptive stresses from measurements. For the turbulent inertial mechanism large drops experience high fragmenting force close to eight gap heights downstream of the gap exit whereas this occurs closer to 20 gap heights for smaller drops. The turbulent viscous mechanism is most efficient at a downstream distance of eight gap heights into the outlet chamber for all drops sizes.     

The effect of oxygen and volatile combustibles on the sulphation of gaseous KCl

Sulphur/sulphate containing additives, such as elemental sulphur (S) and ammonium sulphate (NH₄)₂SO₄), can be used for sulphation of KCl during biomass combustion. These additives convert KCl to an alkali sulphate and a more efficient sulphation is normally achieved for ammonium sulphate compared to sulphur. The presence of SO₃ is thus of greater importance than that of SO₂. Oxygen and volatile combustibles could also have an effect on the sulphation of gaseous KCl. This paper is based on results obtained during co-combustion of wood chips and straw pellets in a 12 MW circulating fluidised bed (CFB) boiler. Ammonium sulphate was injected at three positions in the boiler i.e. in the upper part of the combustion chamber, in the cyclone inlet, and in the cyclone. The sulphation of KCl was investigated at three air excess ratios (λ = 1.1, 1.2 and 1.4). Several measurement tools were applied including IACM (on-line measurements of gaseous alkali chlorides), deposit probes (chemical composition in deposits collected) and gas analysis. The position for injection of ammonium sulphate had a great impact on the sulphation efficiency for gaseous KCl at the different air excess ratios. There was also an effect of oxygen on the sulphation efficiency when injecting ammonium sulphate in the cyclone. Less gaseous KCl was reduced during air excess ratio λ = 1.1 compared to the higher air excess ratios. The optimal position and conditions for injection of ammonium sulphate were identified by measuring KCl with IACM. A correlation was observed between the sulphation of gaseous KCl and reduced chlorine content in the deposits. The experimental observations were evaluated using a detailed reaction mechanism. It was used to model the effect of volatile combustibles on the sulphation of gaseous KCl by SO₃. The calculations supported the proposition that the presence of combustibles at the position of SO₃ injection (i.e. AS) causes reduction of SO₃ to SO₂.     

Photodegradation of DMMP and CEES on zirconium doped titania nanoparticles

The structure and photocatalytic activity of Zr doped TiO₂ nanocrystallites with a varying Zr content between 0 and 15 wt% prepared by an efficient and environmentally benign method has been studied by vibrational spectroscopy, TEM and XRD. It is shown that the presence of Zr⁴⁺ ions stabilizes the anatase structure and delays phase transformation to rutile upon annealing as well as retarding grain coarsening. All TiO₂ samples up to 13 wt% Zr doping concentration show better or similar photoreactivity compared to P25 (Degussa) for decomposition of adsorbed 2-chloroethyl ethyl sulphide (CEES) and dimethyl methylphosphonate (DMMP) in synthetic air at room temperature. The most efficient sample for photodegradation of both CEES and DMMP is shown to be titania doped with 6.8 wt% Zr. The photodegradation of CEES is faster than DMMP under the same experimental conditions. On the undoped TiO₂ sample urea residues are detected spectroscopically. Much less is detected on the Zr doped samples. Mode resolved in situ FTIR surface spectroscopy enables distinction of CEES or DMMP, decomposition products as well as the influence of residues from the particle synthesis. This facilitates extraction of intra-comparable reaction rates. Possible explanations for the improved reactivity of the Zr doped titania are discussed.     

Distributed representations for extended syntactic transformation

This paper shows how the choice of representation substantially affects the generalization performance of connectionistnetworks. The starting point is Chalmers' simulations involving structure-sensitive processing. Chalmers argued that a connectionist network could handle structure sensitive processing without the use of syntactically structured representations. He trained a connectionist architecture to encode/decode distributed representations for simple sentences. These distributed representations were then holistically transformed such that active sentences were transformed into their passive counterpart. However, he noted that the recursive auto-associative memory (RAAM), which was used to encode and decode distributed representations for the structures, exhibited only a limited ability to generalize when trained to encode/decode a randomly selected sample of the total corpus. When the RAAM was trained to encode/decode all sentences, and a separate transformation network was trained to make some active-passive transformations of the RAAMencoded sentences, the transformation network demonstrated perfect generalization on the remaining test sentences. It is argued here that the main reason for the limited generalization is not the ability of the RAAM architecture per se, but the choice of representation for the tokens used. This paper shows that 100% generalization can be achieved for Chalmers' original set up (i.e. using only 30% of the total corpus for training). The key to this success is to use distributed representations for the tokens (capturing different characteristics for differentclasses of tokens, e.g. verbs or nouns).     

Normalized Cuts Revisited: A Reformulation for Segmentation with Linear Grouping Constraints

Indisputably Normalized Cuts is one of the most popular segmentation algorithms in pattern recognition and computer vision. It has been applied to a wide range of segmentation tasks with great success. A number of extensions to this approach have also been proposed, including ones that can deal with multiple classes or that can incorporate a priori information in the form of grouping constraints. However, what is common for all these methods is that they are noticeably limited in the type of constraints that can be incorporated and can only address segmentation problems on a very specific form. In this paper, we present a reformulation of Normalized Cut segmentation that in a unified way can handle linear equality constraints for an arbitrary number of classes. This is done by restating the problem and showing how linear constraints can be enforced exactly in the optimization scheme through duality. This allows us to add group priors, for example, that certain pixels should belong to a given class. In addition, it provides a principled way to perform multi-class segmentation for tasks like interactive segmentation. The method has been tested on real data showing good performance and improvements compared to standard normalized cuts.     

Incidence of primary malignancies other than breast cancer among women treated with radiation therapy for benign breast disease

In addition to left ventricular pump failure and low cardiac output, structural and metabolic alterations of skeletal muscle are thought to contribute to exercise intolerance seen in patients with CHF. Studies using cardiac myocytes have implicated nitric oxide elaborated by inducible nitric oxide synthase (iNOS) as a potential agent associated with the genesis of dilated cardiomyopathy. The present study was designed to locate iNOS in the working skeletal muscle of patients with congestive heart failure. Specific antibodies were used to detect iNOS by immunohistochemistry in skeletal muscle biopsies (m. vastus lateralis) of 37 patients with left ventricular pump failure and 8 normal controls. The expression was restricted to skeletal muscle myocytes and was increased five- to ninefold in patients with chronic heart failure. There was no statistically significant difference in iNOS expression between patients with dilated cardiomyopathy and those with ischemic cardiomyopathy. The finding of a locally increased expression of iNOS and the experimental evidence that NO attenuates the contractile performance of the skeletal muscle suggest that the expression of iNOS may be responsible for the exercise intolerance seen in patients with chronic heart failure.     

Evaluation of on-line flue gas measurements by MISiCFET and metal-oxide sensors in boilers

Metal insulator silicon carbide field-effect transistor sensors, metal-oxide sensors, and a linear Lambda sensor in an electronic nose was used to measure on-line in hot flue gases from a boiler. Flue gas from a 100-MW pellets-fuelled boiler has been used to feed the experimental setup. Several reference instruments, which measure the flue gases in parallel to the sensor array, are connected to the electronic nose. Data was collected during six weeks and then evaluated. Using principal component analysis as the data evaluation method, different operating modes for the boiler have been identified in the data set. The different modes could be described in terms of high or low O/sub 2/ and CO concentration. Furthermore, we have shown that it seems possible to use a sensor array to determine the operating mode of the boiler and, by partial least-squares models, measure the CO concentration when the boiler operates in its optimum mode.     

An integrated model of residential and employment location in a metropolitan region

The purpose of this paper is to improve the tools available for analyzing and evaluating land-use and transport policies in a regional planning context. A normative residential location submodel is combined with a predictive submodel for the location of employment. The demand side of the residential location submodel is formulated as a nested multinomial logit model of the joint choice of residential location and transportation mode. The cost of commuting is assumed to be a major determinant of locational choice. The employment location submodel is based on the assumption that accessibility to the labor force is the strategic location factor. Two versions of the submodels are proposed corresponding to a post- and pre-distribution modal split in the familiar four-step transport model. Policy tests of a newly proposed, large-scale traffic investment program in the Stockholm region are reported.An earlier version of this paper was presented at the 30th European Congress, Istanbul, August 1990.     

Experimental study of heat transfer additive influence on the absorption chiller performance

The influence of 2-methyl-1-pentanol (2MP) on the cooling effect of pilot absorption chiller has been studied experimentally. In one experimental series the additive was injected into LiBr solution. The enhancement ratio up to 20% was observed at the optimum additive concentration. In the second experimental series the additive was injected into the refrigerant. The enhancement ratio became 32% at higher additive concentration. Different additive concentrations have been tested in both series. These experimental results clearly showed that the presence of the additive in the vapour phase, even in very small amounts, favours the enhancement more than the additive in the LiBr solution. Also, it has been noticed, that the additive travels around the absorption cycle during long-term operation.