Perception-aware Tag Placement Planning for Robust Localization of UAVs in Indoor Construction Environments

Tag-based visual-inertial localization is a lightweight method for enabling autonomous data collection missions of low-cost unmanned aerial vehicles (UAVs) in indoor construction environments. However, finding the optimal tag configuration (i.e., number, size, and location) on dynamic construction sites remains challenging. This paper proposes a perception-aware genetic algorithm-based tag placement planner (PGA-TaPP) to determine the optimal tag configuration using 4D-BIM, considering the project progress, safety requirements, and UAV's localizability. The proposed method provides a 4D plan for tag placement by maximizing the localizability in user-specified regions of interest (ROIs) while limiting the installation costs. Localizability is quantified using the Fisher information matrix (FIM) and encapsulated in navigable grids. The experimental results show the effectiveness of our method in finding an optimal 4D tag placement plan for the robust localization of UAVs on under-construction indoor sites.Comment: [Final draft] This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers and the Journal of Computing in Civil Engineerin

Reflections on the Cost of Low-Cost Whole Genome Sequencing: Framing the Health Policy Debate

The cost of whole genome sequencing is dropping rapidly. There has been a great deal of enthusiasm about the potential for this technological advance to transform clinical care. Given the interest and significant investment in genomics, this seems an ideal time to consider what the evidence tells us about potential benefits and harms, particularly in the context of health care policy. The scale and pace of adoption of this powerful new technology should be driven by clinical need, clinical evidence, and a commitment to put patients at the centre of health care policy

Longitudinal Study of Two Irish Dairy Herds: Low Numbers of Shiga Toxin-Producing Escherichia coli O157 and O26 Super-Shedders Identified

peer-reviewedThe authors wish to acknowledge The Department of Agriculture, Food and Fisheries in Ireland for its financial contribution to the study under the Food Initiative Research Measure (FIRM) Grant No. 11/F/051.A 12-month longitudinal study was undertaken on two dairy herds to ascertain the Shiga-toxin producing Escherichia coli (STEC) O157 and O26 shedding status of the animals and its impact (if any) on raw milk. Cattle are a recognized reservoir for these organisms with associated public health and environmental implications. Animals shedding E. coli O157 at >10,000 CFU/g of feces have been deemed super-shedders. There is a gap in the knowledge regarding super-shedding of other STEC serogroups. A cohort of 40 lactating cows from herds previously identified as positive for STEC in a national surveillance project were sampled every second month between August, 2013 and July, 2014. Metadata on any potential super-shedders was documented including, e.g., age of the animal, number of lactations and days in lactation, nutritional condition, somatic cell count and content of protein in milk to assess if any were associated with risk factors for super-shedding. Recto-anal mucosal swabs (RAMS), raw milk, milk filters, and water samples were procured for each herd. The swabs were examined for E. coli O157 and O26 using a quantitative real time PCR method. Counts (CFU swab-1) were obtained from a standard calibration curve that related real-time PCR cycle threshold (Ct) values against the initial concentration of O157 or O26 in the samples. Results from Farm A: 305 animals were analyzed; 15 E. coli O157 (5%) were recovered, 13 were denoted STEC encoding either stx1 and/or stx2 virulence genes and 5 (2%) STEC O26 were recovered. One super-shedder was identified shedding STEC O26 (stx1&2). Farm B: 224 animals were analyzed; eight E. coli O157 (3.5%) were recovered (seven were STEC) and 9 (4%) STEC O26 were recovered. Three super-shedders were identified, one was shedding STEC O157 (stx2) and two STEC O26 (stx2). Three encoded the adhering and effacement gene (eae) and one isolate additionally encoded the haemolysin gene (hlyA). All four super-shedders were only super-shedding once during the 1-year sampling period. The results of this study show, low numbers of super-shedders in the herds examined, with high numbers of low and medium shedding. Although four super-shedding animals were identified, no STEC O157 or O26 were recovered from any of the raw milk, milk filter, or water samples. The authors conclude that this study highlights the need for further surveillance to assess the potential for environmental contamination and food chain security

Creative and Stylistic Devices Employed by Children During a Storybook Narrative Task: A Cross-Cultural Study

Purpose: The purpose of this study was to analyze the effects of culture on the creative and stylistic features children employ when producing narratives based on wordless picture books. Method: Participants included 60 first- and second-grade African American, Latino American, and Caucasian children. A subset of narratives based on wordless picture books collected as part of a larger study was coded and analyzed for the following creative and stylistic conventions: organizational style (topic centered, linear, cyclical), dialogue (direct, indirect), reference to character relationships (nature, naming, conduct), embellishment (fantasy, suspense, conflict), and paralinguistic devices (expressive sounds, exclamatory utterances). Results: Many similarities and differences between ethnic groups were found. No significant differences were found between ethnic groups in organizational style or use of paralinguistic devices. African American children included more fantasy in their stories, Latino children named their characters more often, and Caucasian children made more references to the nature of character relationships. Conclusion: Even within the context of a highly structured narrative task based on wordless picture books, culture influences children’s production of narratives. Enhanced understanding of narrative structure, creativity, and style is necessary to provide ecologically valid narrative assessment and intervention for children from diverse cultural backgrounds

RISK AND BENEFITS ASSOCIATED WITH INTERNATIONAL CONSTRUCTION/ CONSULTING JOINT VENTURES IN THE ENGLISH-SPEAKING CARIBBEAN

Research was undertaken to determine the major risk factors associated with international construction–consulting joint ventures (ICJVs) formed in the English-speaking Caribbean (ESC) with construction and consulting firms from Canada and the United States of America. The three highest ranked reasons for forming ICJVs are to improve competitive positions, enter new markets, and share risks and (or) profits. The three highest ranked benefits of the ICJVs are to enhance competitive position, obtain new work, and increase market share. There was some correlation between reasons for entering into these relationships and their perceived benefits. The three highest ranked risks were loss because of bureaucracy for late approvals, project delay, and cash flow problems of the client. The 10 highest ranked risks for both English-speaking Caribbean and North American firms were identical although the ranks changed slightlyGreater Toronto Airports Authority in conjunction with NSERC Industrial Oriented Research Grant 216754-9

Benchmarking airport reconstruction projects

The impact of redevelopment and expansion of airport operations has not received much attention in the literature. Data were collected for 22 North American airports, 26 airport projects, and 107 individual operational years (airport-years) with at least 3.5 million passengers annually, each of which under took a brownfield passenger terminal project between 1991 and 2001. The results indicate that some factors may be indicative of airport redevelopment impacts, such as traffic volume, cargo, and air traffic movements. It was also found that the strategic use of space is critical to operational efficiency, especially with the full range of non-aeronautical services that can be offered at airports. The cost of space may be higher, but it tended to improve overall efficiency. Reconstruction projects that were evaluated as successful tended to show operational recovery within 2 years of completing construction; this result was consistent through a wide range of project sizes, traffic levels, and services.IOR Grant #216754-98 from the Greater Toronto Airports Authority and NSERC. Research support from MGP Project Managers and all of the airport authorities that provided their data for this research

Using Belief Networks to Assess Risk

This paper reviews two commonly used risk assessment tools, namely weighted scores and expected value. The limitations of weighted scores have been outlined. One of the more difficult aspects of the expected value method is to determine the probability of an event. A probabilistic modeling environment called belief networks, has been proposed as an effective means of modeling the situation. An example application has been provided to show how the integrated system may work

Evaluating Risk in Construction-Schedule Model (ERIC-S): Construction schedule risk model

Research was undertaken to develop a method to assist in the determination of the lower and upper activity duration values for schedule risk analysis by PERT (program evaluation and review technique) analysis or Monte Carlo simulation. A belief network was the modeling environment used for this purpose, and the resulting model was named ERIC-S: Evaluating Risk In Construction - Schedule Model. The development of the belief network model consisted of four steps. First, construction schedule risks were identified through a literature review, an expert review, and a group review by a team of experts. Second, cause-effect relationships among these risks were identified through an expert survey. This led to the development of the structure of belief network model. Third, probabilities for various combinations of parents for each risk variable were obtained through an expert interview survey and incorporated into the model. And fourth, sensitivity analysis was performed. The model was tested using 17 case studies with very good results

Time of Sampling Strategies for Asphalt Pavement Quality Assurance

The cost of quality assurance programs in asphalt road construction is high in part because of the need for daily testing. This paper demonstrates the methodology used to investigate the timing of sampling and its effect on the quality assurance program. Fourteen lots over two highway paving projects were tested twice: during construction on a daily basis, and after construction was complete. Three quality measures were compared, namely asphalt content, degree of compaction, and aggregate gradation. The test data during construction were obtained from two sources: the consultant’s quality assurance, and the contractor’s quality control. One-way ANOVA tests and T-tests were used to compare the means. In addition, the arithmetic difference between the means was reviewed to understand how the time of sampling might affect contractor payment adjustments