692 research outputs found
An archetype-in-neighbourhood framework for modelling cooling energy demand of a city's housing stock
As hot days are getting hotter and more frequent, urban dwelling is expected to increase cooling energy use in current and future climate. The applicability of dynamic building simulation in estimating cooling loads of a cityâs housing stock can be limited due to lack of fine-grained on-site current and future weather inputs. For predicative modelling of residential cooling energy demand to aid a city's energy supply planning resilient to excessive heat conditions, it requires cooling energy demand projection based on a relational account of (1) the thermal-environmental interaction between housing stocks and urban microclimate conditions, (2) the city dwellers' cooling energy use behaviour, and (3) the cityâs climate projections. In this paper, we introduce an âarchetype-in-neighbourhoodâ framework to meet these requirements. Combining empirical urban data modelling and EngeryPlus model calibration, this framework was developed to obtain statistically a maximal cooling energy demand model of a cityâs housing stock during yearly hottest periods. We applied the framework to multiple datasets selected from Seoulâs open urban data sources for the period of 2014-2017 (2014 being the earliest year of data availability, 2017 being the end of the study period), including metered electricity use data of 659 apartment buildings (51,351 households) sampled from 18 city districts. The results show that maximal month cooling energy demand (MMCD, kWh/m2) of Seoulâs housing stock can be expressed as a regression function of two determinants: (1) the city's average outdoor temperature during the hottest month period (Tex, ËC), and (2) estimated indoor cooling temperature set-point (Tin, ËC) of the cityâ housing stock during the same period. Through a k-fold (k=4) validation, the current regression model (2014-17) was evaluated to have an overall coefficient of determination R2=.969. Assuming no housing stock renovation, we applied the model to generate scenarios of maximal month cooling demand in future years according to some of the highest summer temperatures projected for Seoul (RCP8.5 2045, RCP4.5 2047, MM5 2071-2100). We conclude this paper with a brief discussion of the implication for cooling energy supply planning and further work to extend the applicability of this new framework to housing stock adaptation planning and design
Climate change simulation for intelligent green building adaptation design
A climate change simulation framework for intelligent green building adaptation design is proposed. The simulation framework is developed for studying environmental performance of existing or proposed green buildings under present and future urban microclimate conditions. It draws on a synthesis of environmental computer simulation in three areas: (1) overall climate change scenario modelling at city level, (2) outdoor urban microclimate modelling at neighbourhood level, and (3) indoor environmental simulation at building level. A case study of applying the climate change simulation framework to an existing university campus green building is presented for 2012 and 2050. In response to the simulation results, strategies for adapting the case study green building in relation to its changing urban neighbourhood are assessed as an example. The case study shows that the simulation framework can generate requirements for intelligent green building adaptation design by linking urban microclimate change projection to simulated energy demand in maintaining building indoor thermal comfort. © 2014 IEEE
Correlating cooling energy use with urban microclimate data for projecting future peak cooling energy demands: Residential neighbourhoods in Seoul
The paper presents a relational study of correlating cooling energy use with local weather station and
apartment price data in Seoul. The overall analysis at a macro-level shows monthly variations in the correlation
coefficients of cooling energy use and local weather station data during summer months. A further analysis at
a micro-level shows temporal and spatial variations in the correlation. As the August correlation appears the
strongest across all city districts, up to r=.972, a simple bivariate regression (SBR) model is derived to predict
peak cooling energy use for each district. Given the latest climate change projections for Seoul, we use the
SBR models to estimate increases of cooling energy use for each city district in August 2050s. The largest
predicted increase rate (IR) is 96.1% in one city district (from 124.5% in 2012 to 220.6% in 2047). The smallest
IR is 6.0% in another city district (from 51.5% to 57.5%). In 2047, the city district with the highest predicted IR
is up to 292.8%, while the lowest is up to 57.5%. We discuss the implications of the projected future peak
cooling energy demands for sustainable resilience as well as citizenâs health and wellbeing
Microclimate change outdoor and indoor coupled simulation for passive building adaptation design
How to deploy passive building design strategy adaptive to climate change scenarios at urban neighbourhood level is currently not well understood. A microclimate change outdoor and indoor coupled simulation assessment framework for passive building adaptation design in an urban neighborhood context is proposed. Based on computational modelling, it was developed to investigate summer overheating and to apply to a passive design strategy in an existing green building case study, taking into account the seasonal conditions in 2012 and 2050 as projected by a current climate change scenario. Through a series of numerical modelling and prognostic visualization, the results from applying the framework show how building indoor thermal performance interacts with specific outdoor microclimates. This study shows the importance of outdoor and indoor coupled assessment at microclimate level to deploy passive design features to changing climate. © 2014 Published by Elsevier B.V
Modelling urban dwellersâ indoor heat stress to enhance heat-health warning and planning
Due to climate change, the intensity, duration and frequency of heatwaves are likely to increase in the coming years. Excessive heat events can increase local urban heat island intensity affecting the health and wellbeing of urban dwellers vulnerable to heat stress. Heat-Health Warning Systems (HHWSs) have been developed to warn the public of impending heat events and to advise on preventable negative health outcomes. However, metrics upon which action triggers are made in HHWSs rely on reported critical outcomes, such as heat-related excess death. Thus, human exposure to heat is underestimated in current metrics and consequently, their capacity to prevent heat-related health risks remains uncertain, particularly indoors. This study investigates how indoor heat stress in urban dwellings at a city-scale can be modelled to enhance Heat-Health Warning and Planning. First, the effects of housing typologies on indoor thermal conditions are quantified in a local urban microclimate context. We then model the dynamic relationships between outdoor climate and indoor heat exposure to identify specific outdoor climatic thresholds as action triggers for alerting urban dwellersâ indoor heat stress. Based on urban microclimate data available for a city of Birmingham UK, a proof-of-principle study is presented. The result shows the presence of large variances in the heat-health action triggers across different housing typologies. This is further extended to consider the Birmingham climate projection scenarios provided by the UKCP18. Compared to the current UK Heat-Health Alert Service, we show how indoor heat stress warnings may look like and the implications for long-term heat-health planning
Added Value of Computed Tomography Virtual Intravascular Endoscopy in the Evaluation of Coronary Arteries with Stents or Plaques
Coronary computed tomography angiography (CCTA) is a widely used imaging modality for diagnosing coronary artery disease (CAD) but is limited by a high false positive rate when evaluating coronary arteries with stents and heavy calcifications. Virtual intravascular endoscopy (VIE) images generated from CCTA can be used to qualitatively assess the vascular lumen and might be helpful for overcoming this challenge. In this study, one hundred subjects with coronary stents underwent both CCTA and invasive coronary angiography (ICA). A total of 902 vessel segments were analyzed using CCTA and VIE. The vessel segments were first analyzed on CCTA alone. Then, using VIE, the segments were classified qualitatively as either negative or positive for in-stent restenosis (ISR) or CAD. These results were compared, using ICA as the reference, to determine the added diagnostic value of VIE. Of the 902 analyzed vessel segments, CCTA/VIE had sensitivity, specificity, accuracy, positive predictive value, and negative predictive value (shown in %) of 93.9/90.2, 96.2/98.2, 96.0/97.7, 70.0/83.1, and 99.4/99.0, respectively, in diagnosing ISR or CAD, with significantly improved specificity (p = 0.025), accuracy (p = 0.046), and positive predictive value (p = 0.047). VIE can be a helpful addition to CCTA when evaluating coronary arterie
Narrow ridge waveguide high power single mode 1.3-ÎŒm InAs/InGaAs ten-layer quantum dot lasers
Ten-layer InAs/In0.15Ga0.85As quantum dot (QD) laser structures have been grown using molecular beam epitaxy (MBE) on GaAs (001) substrate. Using the pulsed anodic oxidation technique, narrow (2 ÎŒm) ridge waveguide (RWG) InAs QD lasers have been fabricated. Under continuous wave operation, the InAs QD laser (2 Ă 2,000 ÎŒm2) delivered total output power of up to 272.6 mW at 10 °C at 1.3 ÎŒm. Under pulsed operation, where the device heating is greatly minimized, the InAs QD laser (2 Ă 2,000 ÎŒm2) delivered extremely high output power (both facets) of up to 1.22 W at 20 °C, at high external differential quantum efficiency of 96%. Far field pattern measurement of the 2-ÎŒm RWG InAs QD lasers showed single lateral mode operation
Cyclophosphamide induces NR2B phosphorylation-dependent facilitation on spinal reflex potentiation
Chang CH, Peng HY, Wu HC, Lai CY, Hsieh MC, Lin TB. Cyclophosphamide induces NR2B phosphorylation-dependent facilitation on spinal reflex potentiation. Am J Physiol Renal Physiol 300: F692-F699, 2011. First published November 24, 2010; doi:10.1152/ajprenal.00531.2010.-It is well-established that cyclophosphamide (CYP) can sensitize the pelvic afferent nerve arising from the urinary bladder and therefore induce suprapubic pain. To test the possibility that CYP might mediate the development of visceral hypereflexia/hyperalgesia by facilitating spinal activity-dependent neural plasticity, we compared the pelvic-urethra reflex activity and spinal N-methyl-D-aspartate receptor NR2B subunit (NR2B) phosphorylation in rats treated with vehicle solution and CYP. Compared with vehicle solution, when accompanied by upregulation of phosphorylated NR2B expression in the lumbosacral (L6-S2) dorsal horn, CYP increased the evoked spikes in spinal reflex potentiation induced by repetitive stimulation (1 stimulation/1 s). Moreover, intraperitoneal pretreatments with N(G)-nitro-L-arginine methyl ester and roscovitine, nitric oxide synthase and cyclin-dependent protein kinase 5 (Cdk5) antagonists, respectively, overwrote CYP-enhanced reflex potentiation and NR2B phosphorylation. When compared with the untreated group, the treatment with small-interfering RNA of NR2B, which decreased the expression of NR2B expression, abolished CYP-dependent reflex facilitation and spinal NR2B phosphorylation. These results suggested that CYP might facilitate spinal reflex potentiation mediated by N-methyl-D-aspartate receptors and participate in the development of visceral hypereflexia/hyperalgesia through nitric oxide-and Cdk5-dependent NR2B phosphorylation at the lumbosacral dorsal horn
Further investigations of linear trirhodium complexes: experimental and theoretical studies of Rh-3(dpa)(4)Cl-2 and Rh-3(dpa)(4)Cl-2 (BF4) dpa = bis(2-pyridyl)amido anion
The linear trirhodium compound, Rh-3(dpa)(4)Cl-2 (1), and its one-electron oxidation product, [Rh-3(dpa)(4)Cl-2]BF4 (2), have been synthesized and studied extensively. The magnetic measurement for compound 1 shows that it possesses one unpaired electron that is assigned to occupy the sigma(nb) orbital ((2)A(2)) by DFT calculations. Upon oxidation, a beta-spin electron of 1 is removed, that causes compound 2 to exhibit a triplet ground state. DFT calculations indicate that the two unpaired electrons of 2 occupy sigma(nb) and delta* orbitals (B-3(1)), which is supported by H-1 NMR spectrum. Unlike their isoelectronic analogues [Co-3(dpa)(4)Cl-2] (3) and [Co-3(dpa)(4)(Cl)(2)]BF4 (4), both compound 1 and 2 do not display the spin-crossover phenomenon. The reason may be attributed to the relative large energy gap between B-3(1) and open-shell singlet B-1(1) states
EphrinB2 induces pelvic-urethra reflex potentiation via Src kinase-dependent tyrosine phosphorylation of NR2B
Wu HC, Chang CH, Peng HY, Chen GD, Lai CY, Hsieh MC, Lin TB. EphrinB2 induces pelvic-urethra reflex potentiation via Src kinase-dependent tyrosine phosphorylation of NR2B. Am J Physiol Renal Physiol 300: F403-F411, 2011. First published December 8, 2010; doi:10.1152/ajprenal.00520.2010.-Recently, the role of EphB receptor (EphBR) tyrosine kinase and their ephrinB ligands in pain-related neural plasticity at the spinal cord level have been identified. To test whether Src-family tyrosine kinase-dependent glutamatergic N-methyl-D-aspartate receptor NR2B subunit phosphorylation underlies lumbosacral spinal EphBR activation to mediate pelvic-urethra reflex potentiation, we recorded external urethra sphincter electromyogram reflex activity and analyzed protein expression in the lumbosacral (L(6)-S(2)) dorsal horn in response to intrathecal ephrinB2 injections. When compared with vehicle solution, exogenous ephrinB2 (5 mu g/rat it)-induced reflex potentiation, in associated with phosphorylation of EphB1/2, Src-family kinase, NR2B Y1336 and Y1472 tyrosine residues. Both intrathecal EphB1 and EphB2 immunoglobulin fusion protein (both 10 mu g/rat it) prevented ephrinB2-dependent reflex potentiation, as well as protein phosphorylation. Pretreatment with PP2 (50 mu M, 10 mu l it), an Src-family kinase antagonist, reversed the reflex potentiation, as well as Src kinase and NR2B phosphorylation. Together, these results suggest the ephrinB2-dependent EphBR activation, which subsequently provokes Src kinase-mediated N-methyl-D-aspartate receptor NR2B phosphorylation in the lumbosacral dorsal horn, is crucial for the induction of spinal reflex potentiation contributing to the development of visceral pain and/or hyperalgesia in the pelvic area
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