A two-stage,two-organism process for biohydrogen from glucose

_H2${\mathrm{H}}_2$ can potentially be produced in a two-stage biological process: the fermentation of glucose by Escherichia coli HD701 and the photofermentation of the residual medium by Rhodobacter sphaeroides O.U. 001. In a typical batch fermentation, E. coli   consumed glucose and produced _H2${\mathrm{H}}_2$, organic end-products and biomass. Organic end-products and residual glucose were removed during subsequent photofermentation by R. sphaeroides  , with associated growth and neutralization of pH. However, photoproduction of _H2${\mathrm{H}}_2$ did not occur during photofermentation of the residual liquor per se due to the presence of fixed nitrogen compounds. Nevertheless, this two-stage approach could be applied to dispose of sugar-containing industrial wastes, _H2${\mathrm{H}}_2$ being used for on-site power generation.     

Diagnostic considerations for optical laser-extinction measurements of soot in high-pressure transient combustion environments

Laser-extinction diagnostics can provide spatially and temporally resolved measurements of attenuation from combustion-generated soot within the path of the beam. When laser-extinction techniques are utilized in high-pressure combustion environments, however, a number of complications may be encountered that are not present in low-pressure environments. Several of these experimental difficulties were investigated in diesel engine environments, and solutions that facilitated acquisition of reliable laser-extinction data were demonstrated. Beam steering due to refractive index gradients within the combusting gases was observed, and a full-angle beam divergence of over 100 mrad was measured. A spatial-filtering scheme was employed to reduce the collection of forward-scattered light and background combustion luminosity while ensuring full collection of the steered beam. To further reject combustion luminosity, a narrow-bandpass laser-line filter was employed, after diffusing the transmitted light sufficiently to avoid the effects of significant spatial non-uniformities of the filter. As the windows were subjected to thermal and mechanical stresses, dynamic etaloning effects due to the photoelastic properties of synthetic fused silica were observed. Dynamic changes in the polarization of the exit beam were also observed, as stress-induced birefringence in the windows caused dynamic phase retardation of the transmitted beam. Although these photoelastic effects could not be eliminated, they were mitigated by introducing curvature to the wavefronts in the laser-extinction beam and using polarization-insensitive elements in the detection optics. Soot deposits on window surfaces were removed ablatively using a coaxial, high-energy, pulsed Nd:YAG laser beam.     

Comfort criteria for passively cooled buildings a pascool task

The application of passive cooling techniques to buildings in warm climates creates the need for appropriate comfort criteria. Conventional comfort criteria, usually based upon laboratory experiments, seem to be unnecessarily severe. The paper describes preliminary findings of the PASCOOL Thermal Comfort task which, responding to renewed interest in behavioural aspets of thermal comfort, sets out to establish appropriate limits by field studies and theoretical considerations.     

Silicon‐Modified Rare‐Earth Transitions—A New Route to Near‐ and Mid‐IR Photonics

Silicon underpins microelectronics but lacks the photonic capability needed for next‐generation systems and currently relies on a highly undesirable hybridization of separate discrete devices using direct band gap semiconductors. Rare‐earth (RE) implantation is a promising approach to bestow photonic capability to silicon but is limited to internal RE transition wavelengths. Reported here is the first observation of direct optical transitions from the silicon band edge to internal f‐levels of implanted REs (Ce, Eu, and Yb); this overturns previously held assumptions about the alignment of RE levels to the silicon band gap. The photoluminescence lines are massively redshifted to several technologically useful wavelengths and modeling of their splitting indicates that they must originate from the REs. Eu‐implanted silicon devices display a greatly enhanced electroluminescence efficiency of 8%. Also observed is the first crystal field splitting in Ce luminescence. Mid‐IR silicon photodetectors with specific detectivities comparable to existing state‐of‐the‐art mid‐IR detectors are demonstrated.     

Effective image retrieval based on hidden concept discovery in image database.

This paper addresses content-based image retrieval in general, and in particular, focuses on developing a hidden semantic concept discovery methodology to address effective semantics-intensive image retrieval. In our approach, each image in the database is segmented into regions associated with homogenous color, texture, and shape features. By exploiting regional statistical information in each image and employing a vector quantization method, a uniform and sparse region-based representation is achieved. With this representation, a probabilistic model based on statistical-hidden-class assumptions of the image database is obtained, to which the expectation-maximization technique is applied to analyze semantic concepts hidden in the database. An elaborated retrieval algorithm is designed to support the probabilistic model. The semantic similarity is measured through integrating the posterior probabilities of the transformed query image, as well as a constructed negative example, to the discovered semantic concepts. The proposed approach has a solid statistical foundation; the experimental evaluations on a database of 10000 general-purposed images demonstrate its promise and effectiveness.     

Detecting and classifying delay Data Exceptions on communication networks using rule based algorithms

Network performance monitoring is essential for managing a network efficiently and for ensuring reliable operation of the network. Monitored network performance changes reflect events in the network, such as faults, significant changes in usage patterns or planned alterations. Network managers are interested in how and when the performance of a network changes; however it is inefficient to analyse all the data resulting from the monitoring operation manually. In this paper a rule based algorithm to automate detection of the changes in one of the network performance parameters, namely delay, is presented and described in detail. The nature of the delay pattern in a commercial communication network was the key issue in developing this algorithm. The approach was tested with monitored delay data generated from three different networks and showed good results. Also, the algorithm was tested with sets of delay data which have been already input to a previously developed detector based on a different approach, and the results between the two detectors are compared. In addition to a noticeable improvement in detection performance, the new approach provides more generality and independency of the source of the delay data, making the approach generally applicable to other networks. Copyright © 2004 John Wiley & Sons, Ltd.     

Half-time image reconstruction in thermoacoustic tomography

Thermoacoustic tomography (TAT) is an emerging imaging technique with great potential for a wide range of biomedical imaging applications. In this paper, we propose and investigate reconstruction approaches for TAT that are based on the half-time reflectivity tomography paradigm. We reveal that half-time reconstruction approaches permit for the explicit control of statistically complementary information that can result in the optimal reduction of image variances. We also show that half-time reconstruction approaches can mitigate image artifacts due to heterogeneous acoustic properties of an object. Reconstructed images and numerical results produced from simulated and experimental TAT measurement data are employed to demonstrate these effects.     

The European project trust—reconfigurable terminals and supporting networks

To date, research into reconfigurable mobile communications has predominantly focussed on the software radio concept, and specifically on the hardware technologies required to move physical layer processing into a programmable environment [1, 2, 3]. Although an interesting and necessary challenge, this only represents a fraction of the overall support and technology required to realise the potential of the concept. Other necessary developments include network/terminal cooperation for seamless inter-standard handoff, QoS management for software download and reconfiguration, a secure software download mechanism, terminal software and mobile radio network architecture supporting terminal reconfiguration, management for software downloads, configuration management, capability negotiation, radio resource management and spectrum allocation policies etc… This paper describes results from the EuropeanIst Trust (Transparently Reconfigurable UbiquitouS Terminal) [4] project concerning user and operator requirements, the proposed overall system environment, security issues, concerted radio resource management, and expected time frame for the development of reconfigurable terminals.     

Synthesis,characterisation and use of 2-tetradecylcyclobutanone together with other cyclobutanones as markers for irradiated liquid whole egg

The synthesis and characterisation of 2-tetradecylcyclobutanone (TCB) is described. Both 2-dodecykyclobutanone and TCB were shown to be present in liquid whole egg irradiated at doses of 2.5 and 10.0 kGy. These compounds were absent from the unirradiated pasteurised samples. Using gas chromatography and infrared spectroscopy, there was also evidence for the presence in irradiated egg of 2-tetradeccnyl- and 2-tetradecadienylyclobutanone which are formed from oleic and linoleic acids, respectively. Authentic standards for these unsaturated cyclobutanones were not available commercially but the presence of 2-tetra-decenylcyclobutanone was substantiated by hydrogenating the egg extracts so converting this unsaturated cyclobutanone to TCB. Saturated and unsaturated cyclobutanones appear to be specific products of irradiation and are potential markers for detection of irradiated liquid egg and probably other fat-containing foods.