Technology capabilities for an automated and connected earthwork roadmap

Purpose: The development of communication and artificial intelligence technologies has raised interest in connectivity and increased autonomy of automated earthmoving equipment for earthwork. These changes are motivating work to reduce uncertainties, in terms of improving equipment object detection capability and reducing strikes and accidents on site. The purpose of this study is to illustrate industrial drivers for automated earthwork systems; identify the specific capabilities which make the transformation happen; and finally determine use cases that create value for the system. These three objectives act as components of a technology roadmap for automated and connected earthwork and can guide development of new products and services. Design/methodology/approach: This paper used a text mining approach in which the required data was captured through a structured literature review, and then expert knowledge was used for verification of the results. Findings: Automated and connected earthwork can enhance construction site and its embraced infrastructure, resilience by avoiding human faults during operations. Automating the monitoring process can lead to reliable anticipation of problems and facilitate real-time responses to unexpected situation via connectedness capabilities. Research findings are presented in three sections: industrial perspectives, trends and drivers for automated and connected earthwork; capabilities which are met by technologies; and use cases to demonstrate different capabilities. Originality/value: This study combines the results of disintegrated and fragmented research in the area of automated and connected earthwork and categorises them under new capability levels. The identified capabilities are classified in three main categories including reliable environmental perception, single equipment decision-making toward safe outcomes and fleet-level safety enhancement. Finally, four different levels of automation are proposed for earthwork technology roadmap

Technologies for safe and resilient earthmoving operations: A systematic literature review

Resilience engineering relates to the ability of a system to anticipate, prepare, and respond to predicted and unpredicted disruptions. It necessitates the use of monitoring and object detection technologies to ensure system safety in excavation systems. Given the increased investment and speed of improvement in technologies, it is necessary to review the types of technology available and how they contribute to excavation system safety. A systematic literature review was conducted which identified and classified the existing monitoring and object detection technologies, and introduced essential enablers for reliable and effective monitoring and object detection systems including: 1) the application of multisensory and data fusion approaches, and 2) system-level application of technologies. This study also identified the developed functionalities for accident anticipation, prevention and response to safety hazards during excavation, as well as those that facilitate learning in the system. The existing research gaps and future direction of research have been discussed

Chronic kidney disease in children as seen in a tertiary hospital in Enugu, South-East, Nigeria

Background: The prevalence of chronic kidney disease (CKD) in children has been reported to be rising locally and globally. There is a dearth of data and inadequate facilities for the management of CKD in children in most of the developing countries like Nigeria.Objectives: The objective of this study is to ascertain the prevalence of CKD among children seen at University of Nigeria Teaching Hospital (UNTH), Enugu, South‑East Nigeria and also to determine the stage of CKD at presentation, possible etiology, treatment options offered and the outcome.Materials and Methods: A retrospective review of pediatric ward admissions in UNTH over a 5 year period (July, 2007 to June, 2012) was done. Information, including the age at presentation, symptoms, level of renal function, management and outcome, were obtained from the medical case notes.Results: There were 3002 pediatric admissions within the period of review, of which 98 (3.3%) had CKD, giving incidence of 3.0 new cases per million‑child population per year and the prevalence of 14.9 per million children population. Majority (54.1%) of those with CKD were over 10 years of age. Edema, oliguria and hypertension were the most frequent clinical features. The most common etiology was glomerular disease (63.6%) and 44.9% presented in CKD stage 4 and 5. Renal replacement therapy (RRT) was offered to 25 (25.5%) of the patients; 6 (24%) of whom had hemodialysis and 3 (12%) had acute peritoneal dialysis while 16 (64%) were managed conservatively. None of the patients had chronic or adequate dialysis. The overall outcome showed that 8 (8.2%) died while on admission, 15 (15.3%) left against medical advice (discharge against medical advice) because of financial constraints and could not access the therapy, 25 (25.5%) were discharged on conservative management and lost to follow‑up while another 50 (51.0%) were discharged and still on follow‑up.Conclusion: CKD in children poses myriad of challenges in management in our setting with late presentation of patients and limited resources being prominent. The majority of patients could not access and sustain RRT and the outcome continues to be daunting.Key words: Children, chronic kidney disease, Enugu, Nigeria, prevalenc

IFN-gamma is associated with risk of Schistosoma japonicum infection in China.

Before the start of the schistosomiasis transmission season, 129 villagers resident on a Schistosoma japonicum-endemic island in Poyang Lake, Jiangxi Province, 64 of whom were stool-positive for S. japonicum eggs by the Kato method and 65 negative, were treated with praziquantel. Forty-five days later the 93 subjects who presented for follow-up were all stool-negative. Blood samples were collected from all 93 individuals. S. japonicum soluble worm antigen (SWAP) and soluble egg antigen (SEA) stimulated IL-4, IL-5 and IFN-gamma production in whole-blood cultures were measured by ELISA. All the subjects were interviewed nine times during the subsequent transmission season to estimate the intensity of their contact with potentially infective snail habitats, and the subjects were all re-screened for S. japonicum by the Kato method at the end of the transmission season. Fourteen subjects were found to be infected at that time. There was some indication that the risk of infection might be associated with gender (with females being at higher risk) and with the intensity of water contact, and there was evidence that levels of SEA-induced IFN-gamma production were associated with reduced risk of infection

Rubber Impact on 3D Textile Composites

A low velocity impact study of aircraft tire rubber on 3D textile-reinforced composite plates was performed experimentally and numerically. In contrast to regular unidirectional composite laminates, no delaminations occur in such a 3D textile composite. Yarn decohesions, matrix cracks and yarn ruptures have been identified as the major damage mechanisms under impact load. An increase in the number of 3D warp yarns is proposed to improve the impact damage resistance. The characteristic of a rubber impact is the high amount of elastic energy stored in the impactor during impact, which was more than 90% of the initial kinetic energy. This large geometrical deformation of the rubber during impact leads to a less localised loading of the target structure and poses great challenges for the numerical modelling. A hyperelastic Mooney-Rivlin constitutive law was used in Abaqus/Explicit based on a step-by-step validation with static rubber compression tests and low velocity impact tests on aluminium plates. Simulation models of the textile weave were developed on the meso- and macro-scale. The final correlation between impact simulation results on 3D textile-reinforced composite plates and impact test data was promising, highlighting the potential of such numerical simulation tools

Foundation punch-through in clay with sand: centrifuge modelling

This paper is concerned with the vertical penetration resistance of conical spudcan and flat footings in layered soils. Centrifuge tests are reported for a clay bed with strength increasing with depth interbedded with dense and medium dense sand. Both non-visualising (full-model) and visualising (half-model) tests were conducted with high-quality digital images captured and analysed using the particle image velocimetry technique for the latter. The load–displacement curves often show a reduction in resistance on passing through the sand layers, which creates a risk of punch-through failure for the foundations when supporting a jack-up drilling unit. For a given foundation, the peak punch-through capacity (qpeak) is dependent on the thickness of both the overlying clay and the sand layer. The failure mechanism associated with the peak resistance in the sand layer involves entrapment of a thin band of top clay above the sand layer that subsequently shears along an inclined failure surface before being pushed into the underlying clay. The top clay height when normalised by the foundation diameter affects the soil failure pattern in this layer and along with the sand layer thickness controls the severity of the punch-through failure (i.e. the additional penetration before the resistance returns to the peak value). Comparisons are made with current industry guidelines for predicting qpeak and the risk of punch-through failure for sand overlying clay. These methods are shown to be conservative in their prediction of qpeak but inconsistent in predicting punch-through.The research presented here forms part of the activities of the Centre for Offshore Foundation Systems (COFS), currently supported as a node of the Australian Research Council Centre of Excellence for Geotechnical Science and Engineering (grant CE110001009) and through the Fugro Chair in Geotechnics, the Lloyd's Register Foundation Chair and Centre of Excellence in Offshore Foundations and the Shell EMI Chair in Offshore Engineering (held by the fourth author). The authors would like to acknowledge the additional support from the Australian Research Council (ARC) through Discovery Project No. 1096764. Thanks are due to the UWA drum centrifuge technicians Bart Thompson and Greg Outridge

Foundation punch-through in clay with sand: Analytical modelling

Severe punch-through of jack-up rig foundations can occur due to the presence of a stronger sand layer in a bed of relatively soft clay. Analytical estimation of the bearing capacity and leg load-penetration response on such multi-layer stratigraphies is challenging. Accurate mechanism-based models need to be established in each of the layers involved and the effects of the mechanisms in each of the layers on the response in the other layers must be captured. Based on the recently developed failure stress-dependent punch-through models for sand-clay stratigraphies, an extended model is proposed for clay-sand-clay stratigraphies. Half-spudcan particle image velocimetry centrifuge tests and fullspudcan centrifuge tests are used in developing and validating the extended model. The centrifuge test results were discussed in a companion paper and this paper focuses on the analytical developments and prediction assessment. Both spudcan peak resistance (qpeak) and spudcan punch-through depth (dpunch) can be estimated using the model. The predictions by the extended model and by the current industry guidelines are compared against the centrifuge test data. The extended model proposed in this paper outperforms the approaches suggested in the guidelines. An advantage of the proposed approach is that it can be used for either sand-clay or clay-sand-clay scenarios and exhibits excellent performance compared to the model testing dataset considered in this work for both cases. The resulting penetration resistance model is a useful design tool for routine punch-through risk assessment.the research presented here forms part of the activities of the Centre for Offshore Foundation Systems (COFS), currently supported as a node of the Australian Research Council Centre of Excellence for Geotechnical Science and Engineering (grant CE110001009) and through the Fugro Chair in Geotechnics, the Lloyd's Register Foundation Chair and Centre of Excellence in Offshore Foundations and the Shell EMI Chair in Offshore Engineering (held by the fourth author). The authors would like to acknowledge the financial contribution of the Australian Research Council (ARC) through Discovery Project DP1096764

Dynamics of one-dimensional tight-binding models with arbitrary time-dependent external homogeneous fields

The exact propagators of two one-dimensional systems with time-dependent external fields are presented by following the path-integral method. It is shown that the Bloch acceleration theorem can be generalized to the impulse-momentum theorem in quantum version. We demonstrate that an evolved Gaussian wave packet always keeps its shape in an arbitrary time-dependent homogeneous driven field. Moreover, that stopping and accelerating of a wave packet can be achieved by the pulsed field in a diabatic way.Comment: 8 pages, 6 figure

Emergence of scale-free close-knit friendship structure in online social networks

Despite the structural properties of online social networks have attracted much attention, the properties of the close-knit friendship structures remain an important question. Here, we mainly focus on how these mesoscale structures are affected by the local and global structural properties. Analyzing the data of four large-scale online social networks reveals several common structural properties. It is found that not only the local structures given by the indegree, outdegree, and reciprocal degree distributions follow a similar scaling behavior, the mesoscale structures represented by the distributions of close-knit friendship structures also exhibit a similar scaling law. The degree correlation is very weak over a wide range of the degrees. We propose a simple directed network model that captures the observed properties. The model incorporates two mechanisms: reciprocation and preferential attachment. Through rate equation analysis of our model, the local-scale and mesoscale structural properties are derived. In the local-scale, the same scaling behavior of indegree and outdegree distributions stems from indegree and outdegree of nodes both growing as the same function of the introduction time, and the reciprocal degree distribution also shows the same power-law due to the linear relationship between the reciprocal degree and in/outdegree of nodes. In the mesoscale, the distributions of four closed triples representing close-knit friendship structures are found to exhibit identical power-laws, a behavior attributed to the negligible degree correlations. Intriguingly, all the power-law exponents of the distributions in the local-scale and mesoscale depend only on one global parameter -- the mean in/outdegree, while both the mean in/outdegree and the reciprocity together determine the ratio of the reciprocal degree of a node to its in/outdegree.Comment: 48 pages, 34 figure

The extreme vulnerability of interdependent spatially embedded networks

Recent studies show that in interdependent networks a very small failure in one network may lead to catastrophic consequences. Above a critical fraction of interdependent nodes, even a single node failure can invoke cascading failures that may abruptly fragment the system, while below this "critical dependency" (CD) a failure of few nodes leads only to small damage to the system. So far, the research has been focused on interdependent random networks without space limitations. However, many real systems, such as power grids and the Internet, are not random but are spatially embedded. Here we analytically and numerically analyze the stability of systems consisting of interdependent spatially embedded networks modeled as lattice networks. Surprisingly, we find that in lattice systems, in contrast to non-embedded systems, there is no CD and \textit{any} small fraction of interdependent nodes leads to an abrupt collapse. We show that this extreme vulnerability of very weakly coupled lattices is a consequence of the critical exponent describing the percolation transition of a single lattice. Our results are important for understanding the vulnerabilities and for designing robust interdependent spatial embedded networks.Comment: 13 pages, 5 figure