Search

Daylighting and solar availability at urban scale has come to play a crucial role in the perception of discomfort conditions for people, both in outdoor and indoor spaces, and on the energy consumption of buildings. Daylighting and solar analyses are typically done separately. The paper presents a novel method, called the ‘sunlight-daylight signature’ (SDS), which allows the qualitative analysis of urban settings with respect to sunlight and daylight. The method can be used to classify different urban settings in terms of daylight/sunlight access or to test new development proposals by referring to existing locations and confirm whether a certain daylight quality is met. The SDS relies on a new analysis tool, called ‘sunlight-daylight wedge’ (SDW), which combines obstruction (through the vertical sky component VSC) and sunlight access (through the annual probable sunlight hours PASH and the winter probable sunlight hours PWSH). The orientation of the façade at each point is also included as it will affect the times of the day when the sun-hours from PASH and PWSH occur, thus affecting the character of the corresponding sunlight. The SDS approach is based on a clustering technique to subdivide large datasets (in this case, daylight data points across entire cities or major urban areas) into smaller groups, using machine learning by way of the k-medoids clustering technique. This is used to derive typical daylight and sunlight scenarios representing groups of data points with similar conditions. Additional data is included to account for urban density and daylight availability in public areas. Final output of the clustering process consists of a map showing areas with the same daylight signature (SDS), which means areas with the same sunlight and daylight conditions. The SDS can be useful for urban planners and building practitioners to predict the access to both daylight and sunlight of large urban settings to optimize comfort for people and energy usage.

This paper studies the daylighting quality of the indoor prayer-hall in The Great Upper Mosque of Hama city in Syria, highlighting this distinctive historical converted building that has been functioning as a mosque since the entry of Islam in the 6th century AD. The study aims to measure, analyze and comprehend the indoor daylight performance in the main prayer-hall, and to determine the highest and least lighting output time, by carrying out the calculation of three metrics; the illuminance level (E), the uniformity (U0) and daylight factor (DF). And to compare the output with the modern lighting standards. Computational simulation is conducted on the work plane at the floor level, and the Minbar front surface, in clear sky and overcast sky conditions during selected dates in all four seasons based on the climatic data of the case study. Utilization times are defined as per the nature of the Islamic prayer times during day, addressed as al-Zuhr, mid-day time, and al-'Aşr, late afternoon time. Accordingly, it is found that the studied case sets a significant example of employing the daylight to achieve sufficiency; conveying mainly functional, in addition to symbolic purposes. Consequently, it is demonstrated that half of the studied scenarios meet the minimum modern requirements. The study recommends using its simulation outputs to develop a comprehensive artificial lighting design proposal, along with a design proposal for optimizing daylight to align with modern occupants' preferences and to increase opportunities for reducing the use of artificial light during daytime prayers. [ABSTRACT FROM AUTHOR]

Background: For a long older age and the presence of alarm features are regarded as indications for prompt endoscopy in patients with dyspepsia. We aimed to find out the value of alarm features in diagnosing serious organic upper gastrointestinal lesions in patients with dyspepsia. Material & methods: In this observational study clinical variables and endoscopic findings of consecutive patients with dyspepsia were recorded in a semi-structured questionnaire. Univariate and multivariate logistic regression was done stepwise to identify predictors for endoscopic findings. A simplified predictor model was built with the age and the presence of any predictor alarm feature to find out the diagnostic accuracy of this model for the significant endoscopic lesion. Results: Among 304 patients (M=134, F=170) one or more alarm features were present in 193 cases (63.5%). Significant organic lesions were found in 84(27.6%) cases. Age >45 years (OR 2.608), abdominal lump (OR 4.489) and family history of upper gastrointestinal cancer (OR 3.880) were found as independent predictors of major endoscopic findings. Using a simplified predictor model of age e" 45 years or the presence of any predictive alarm feature, sensitivity, specificity, positive predictive value, and negative predictive value were 32.4 %, 82.5 %, 79.8% and 36.4% respectively for a significant endoscopic lesion. For upper gastrointestinal cancers, these values were 6%, 100.0%, 100.0% and 47.3% respectively. Conclusion: The predictive value of the age and the presence of alarm features alone are not optimal for significant endoscopic findings in patients with dyspepsia. A newer and more accurate predictive model is a time demand for organic UGI lesions, especially for malignancies. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced epoxy composites (CFEC) were fabricated infusing 0–0.40 wt% XD-grade carbon nanotube (XD-CNT) using the compression molding process under 16 kips. XD-CNTs were infused into Epon 862 resin using a mechanical stirrer followed by a high intensity ultrasonic liquid processor. The mixture was then placed in a three-roll milling processor for three successive cycles at 140 rpm. Epikure W curing agent was added to the modified resin and mixed using a high-speed mechanical stirrer. Flexural and tensile properties obtained from the flexural and tensile tests were higher in all nanophased composites compared to those of the conventional one. However, samples with 0.3 wt% CNT loading demonstrated the maximum improvement by 27% and 14% in flexural strength and modulus and 19% and 10% in tensile strength and modulus, respectively. Fracture morphology studied by both scanning electron microscopy and optical microscopy revealed better interfacial bonding in the CNT-loaded CFEC. [ABSTRACT FROM AUTHOR]

Investigations were carried out to optimize mechanical and thermal performances of carbon fibre/epoxy composites modified with functionalized carbon nanotubes. For fabricating carbon fibre/epoxy nanocomposites, 0.1-0.4 wt.% carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) were incorporated in an epoxy system. Laminates were cured at a temperature of 65.55 °C. The effects of MWCNT on flexural, interlaminar shear strength (ILSS),tensile and thermo-mechanical properties of carbon fibre/epoxy composites were studied. The results obtained from flexural, ILSS, tensile and dynamic mechanical analysis (DMA) of carbon fibre/epoxy demonstrated a linearly increasing trend in properties up to 0.3 wt.% MWCNT loading. Results obtained from the thermal mechanical analysis showed a linearly decreasing trend in coefficient of thermal expansion up to 0.3 wt.% MWCNT loading. The properties were lower at 0.4 wt.%, due to agglomeration that may have resulted in poor wetting of the carbon fibres. [ABSTRACT FROM AUTHOR]