Diffusion of building information modeling in building projects and firms in Singapore

Building information modeling (BIM) implementation has been mandated in building projects in Singapore, but a wider adoption is still desired. This study aims to investigate the factors influencing BIM diffusion and examine how the factors influence firms with different project roles, firm sizes, and BIM implementation experience. The results of a pilot study, a questionnaire survey with 89 professionals, and five post-survey interviews showed that hindrances related to inadequate multi-party collaboration (whether formal or informal), conservative mindset, limited skills, costly infrastructure and training, and multi-discipline model integration were the most influential, whereas drivers associated with project leadership team’s strategic consensus, multi-disciplinary design coordination, training, and government regulations were top-ranked. Subgroup analyses between pairs of firms with different characteristics revealed that while construction firms and less experienced stakeholders tended to underestimate BIM implementation difficulties, small-medium contractors might underestimate relevant benefits. The findings and managerial recommendations help different types of firms prioritize resources to overcome hindrances, seize opportunities (such as gaining a competitive edge from BIM practical experience), and obtain support from workers executing BIM daily. With major stakeholders’ recognition and implementation, BIM can be successfully diffused in building projects and firms. The Singapore government and other countries can refer to this study when further issuing BIM diffusion policies

Hydrogenated amorphous silicon films with significantly improved stability

NRC publication: Ye

Reducing non-value-adding BIM implementation activities for building projects in Singapore: Leading causes

The use of building information modeling (BIM) has been mandated by the Singapore government, but at the same time, non-value-adding (NVA) implementation practices are prevalent. However, little is known about the factors contributing to NVA BIM implementation practices from different stakeholders’ viewpoints. This study aims to identify the leading contributors to NVA BIM implementation activities in BIM-based building project delivery in Singapore, compare perceptions among stakeholders with different roles, firm sizes, and BIM implementation experience, and propose strategies for NVA implementation activity reduction. An extensive literature review and a pilot study were conducted to determine causes. The results of a questionnaire survey, statistical analyses, and four postsurvey interviews found that all 49 causes categorized by major stakeholders were critical. Among the most influential causes were “design models do not fit for intended downstream uses” (for architect/engineers) and “design changes are expensive once fabrication has commenced” (for manufacturer/supplier). The subgroup analysis indicated that contractors, especially those of small to medium size, perceived that the leading causes related to consultancy firms’ reluctance to enhance design-construction integration and consider incremental changes, whereas stakeholders without much BIM practical experience probably underestimated the difficulties of conducting value-adding BIM diffusion activities. This study extends the concept of NVA activities to BIM implementation and recommends management strategies for each project role to implement BIM-based collaborative practices. The findings enable practitioners to better understand BIM diffusion and reduce their NVA BIM implementation activities for enhanced construction productivity

Potential Role of Circulating microRNA-21 for Hepatocellular Carcinoma Diagnosis: A Meta-Analysis.

Circulating microRNA-21 (miR-21) is known to be aberrantly expressed in hepatocellular carcinoma (HCC) patients, and this implies that microRNA-21 is a promising and novel indicator of HCC. However, a systematic evaluation of the performance of microRNA-21 as a diagnostic marker for HCC has yet to be conducted. Therefore, the test performance of circulating miR-21 for HCC was assessed in this study.Three common international databases and a Chinese electronic database were used to search for literature on the diagnostic accuracy of microRNA-21 for HCC. The pooled results included the sensitivity and specificity of microRNA-21 for HCC detection and were analyzed with a random effect model. The area under summary receiver operating characteristic curve (AUC) was used to estimate overall test performance.A total of 339 HCC patients and 338 controls without HCC from four published studies were eligible for the meta-analysis and included in our study. The test performance of circulating miR-21 in HCC detection was assessed with the summary estimates of sensitivity and specificity, which were 81.2% (95% CI: 70.8% to 88.4%) and 84.8% (95% CI: 75.1% to 91.2%), respectively. The value of AUC was 0.90 (95% CI: 0.87 to 0.92). Significant inter-study heterogeneity was detected by our analysis, and sub-group analyses suggested that the type of control group was probably a source of heterogeneity.Our current findings suggested that circulating miR-21 can serve as a potential co-biomarker for early-stage HCC diagnosis. Thorough large-scale studies are needed to confirm the generalizability of our findings

Impacts of nano-structures in p- and i-layer on the performances of amorphous silicon solar cells

Fine-grained nano-structures were introduced in p- and i-layers of n-i-p type hydrogenated amorphous silicon (a-Si:H) based solar cells deposited on stainless steel substrate, and their impacts on the cell performances were characterized. It is found that the hydrogenated nanocrystalline silicon (nc-Si:H) p-layer with a certain nanocrystalline volume fraction leads to a higher V oc of 1.042 V. For the intrinsic layer, introducing a middle-range ordered-like structure and a small amount of nanosized silicon crystallites may decrease the light-induced degradation and increase the stabilized efficiency of n-i-p a-Si:H based solar cells up to 10% for single junction nano-structured a-Si:H solar cells with an area of 0.25 cm 2 , AM1.5, 100 mW/cm 2 . (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62060/1/696_ftp.pd

STUDY OF MICROSTRUCTURE AND DEFECTS IN HYDROGENATED MICROCRYSTALLINE SILICON FILMS

Microcrystalline silicon films were deposited by very high frequency (VHF) plasma-enhanced chemical vapor deposition (PECVD) with different hydrogen dilution. The microstructure of these films was investigated using Raman spectroscopy and infrared absorption (IR) spectra. The crystalline, amorphous, and grain boundary volume fractions X-c, X-a and X-gb were estimated from Raman measurements. An interface structure factor (R-if) is proposed to characterize the grain boundary volume fractions in IR spectroscopy. The density of states (DOS) of the microcrystalline crystalline silicon films were studied by phase-shift analysis of modulated photocurrent (MPC) and photoconductivity spectroscopy. It was observed that DOS increases with increasing grain boundary volume fractions, while the values of electron mobility-lifetime product mu T-e(e) disease