Scheduling of Multiple Chillers in Trigeneration Plants

The scheduling of both absorption cycle and vapour compression cycle chillers in trigeneration plants is investigated in this work. Many trigeneration plants use absorption cycle chillers only but there are potential performance advantages to be gained by using a combination of absorption and compression chillers especially in situations where the building electrical demand to be met by the combined heat and power (CHP) plant is variable. Simulation models of both types of chillers are developed together with a simple model of a variable-capacity CHP engine developed by curve-fitting to supplier’s data. The models are linked to form an optimisation problem in which the contribution of both chiller types is determined at a maximum value of operating cost (or carbon emission) saving. Results show that an optimum operating condition arises at moderately high air conditioning demands and moderately low power demand when the air conditioning demand is shared between both chillers, all recovered heat is utilised, and the contribution arising from the compression chiller results in an increase in CHP power generation and, hence, engine efficiency

Numerical modelling of multiple standing column wells for heating and cooling buildings

A model for simulating clusters of standing column wells (SCWs) for use in geothermal heating and cooling systems is described in this paper. The model is three-dimensional, dynamic and solves the governing equations using a finite volume discretisation scheme with a fully implicit algorithm. The slower-acting field equations are solved using a wider time interval than that used for the faster-acting well equations and the two sets of equations are coupled through the field equation source terms. A groundwater bleed feature is incorporated. The model is applied to two evaluative test cases the first of which involves heating only and the second, heating and cooling. Results of the applications suggest that SCWs can deliver substantially higher rates of heat transfer than conventional closed loop borehole heat exchanger arrays especially when groundwater bleed is operational. An important practical consequence of this is that far less geotechnical drilling is needed when using SCWs than is the case with closed loop arrays

A biologically relevant rapid quantification of physical and biological stress profiles on rocky shores.

Different combinations and intensities of physical (e.g. thermal) and biological (e.g.competition or predation) stress operate on organisms in different locations. Variation in these stresses can occur over small to medium spatial scales (cm to 10s m) in heterogeneous environments such as rocky shores, due to differences in sun and wave exposure, shore topography and/or recruitment. In this study we demonstrate how simple measurements can be taken that represent physical and biological stresses (stress profiles)in a given location. Using a bootstrapped principal component analysis, we identified significantly different stress profiles at four sites separated by only 10s to 100s of metres on the Shek O peninsula in Hong Kong. We then measured response to thermal stress, as determined by detachment temperature, in the limpet Cellana grata (which is known to be a sensitive indicator species to thermal stress) from each location. Significant differences in stress profile between locations were also seen in thermal stress tolerance of limpets from those locations. At locations where the major stresses are likely to be more physical or less biological in nature (e.g. southerly facing aspect or lower density of grazers), the mean detachment temperature was higher, whereas detachment temperature was lower at sites with more biological or less physical stress. This method is, therefore, able to determine biologically meaningful differences in stress profiles over small to medium spatial scales, and demonstrates that localised adaptation (i.e. post planktonic settlement) or acclimation of species may occur in response to these different stress profiles. The technique can be adapted to different environments and smaller or larger spatial scales as long as the stress experienced by the study species is relevant to these scales

Installation of the MAXIMUM microscope at the ALS

The MAXIMUM scanning x-ray microscope, developed at the Synchrotron Radiation Center (SRC) at the University of Wisconsin, Madison was implemented on the Advanced Light Source in August of 1995. The microscope`s initial operation at SRC successfully demonstrated the use of multilayer coated Schwarzschild objective for focusing 130 eV x-rays to a spot size of better than 0.1 micron with an electron energy resolution of 250meV. The performance of the microscope was severely limited, because of the relatively low brightness of SRC, which limits the available flux at the focus of the microscope. The high brightness of the ALS is expected to increase the usable flux at the sample by a factor of 1,000. The authors will report on the installation of the microscope on bending magnet beamline 6.3.2 at the ALS and the initial measurement of optical performance on the new source, and preliminary experiments with surface chemistry of HF etched Si will be described

Androgen receptor phosphorylation at serine 515 by Cdk1 predicts biochemical relapse in prostate cancer patients

<br>Background:Prostate cancer cell growth is dependent upon androgen receptor (AR) activation, which is regulated by specific kinases. The aim of the current study is to establish if AR phosphorylation by Cdk1 or ERK1/2 is of prognostic significance.</br> <br>Methods: Scansite 2.0 was utilised to predict which AR sites are phosphorylated by Cdk1 and ERK1/2. Immunohistochemistry for these sites was then performed on 90 hormone-naive prostate cancer specimens. The interaction between Cdk1/ERK1/2 and AR phosphorylation was investigated in vitro using LNCaP cells.</br><br>Results:Phosphorylation of AR at serine 515 (pAR(S515)) and PSA at diagnosis were independently associated with decreased time to biochemical relapse. Cdk1 and pCdk1(161), but not ERK1/2, correlated with pAR(S515). High expression of pAR(S515) in patients with a PSA at diagnosis of ≤20 ng ml(-1) was associated with shorter time to biochemical relapse (P=0.019). This translated into a reduction in disease-specific survival (10-year survival, 38.1% vs 100%, P<0.001). In vitro studies demonstrated that treatment with Roscovitine (a Cdk inhibitor) caused a reduction in pCdk1(161) expression, pAR(S515)expression and cellular proliferation.</br> <br>Conclusion: In prostate cancer patients with PSA at diagnosis of ≤20 ng ml(-1), phosphorylation of AR at serine 515 by Cdk1 may be an independent prognostic marker.</br&gt

Automated quantification of mitral valve anatomy using anatomical intelligence in three-dimensional echocardiography

postprin

Optical Fibre Sensors for Monitoring Phase Transitions in Phase Changing Materials

A platinum coated singlemode-multimode (SM) structure is investigated in this paper as an optical fibre sensor (OFS) to monitor the phase transition of a phase change material (PCM). Paraffin wax has been used as an example to demonstrate the sensor\u27s performance and operation. Most materials have the same temperature but different thermal energy levels during the phase change process, therefore, sole dependency on temperature measurement may lead to an incorrect estimation of the stored energy in PCM. The output spectrum of the reflected light from the OFS is very sensitive to the bend introduced by the PCM where both liquid and solid states exist during the phase transition. The measurement of strain experienced by the OFS during the phase change of the PCM is utilized for identifying the phase transition of paraffin wax between the solid and liquid states. The experimental results presented in this paper show that the OFS with a shorter multimode fibre section has better performance for monitoring the phase transition of paraffin wax with a measured phase transition temperature range of 41.5 °C–57.7 °C for the SM based OFS with a 5 mm long multimode fibre section