Human vs. Machine, the Eyes Have It. Assessment of Stemphylium Leaf Blight on Onion Using Aerial Photographs from an NIR Camera

Aerial surveillance could be a useful tool for early detection and quantification of plant diseases, however, there are often confounding effects of other types of plant stress. Stemphylium leaf blight (SLB), caused by the fungus Stemphylium vesicarium, is a damaging foliar disease of onion. Studies were conducted to determine if near-infrared photographic images could be used to accurately assess SLB severity in onion research trials in the Holland Marsh in Ontario, Canada. The site was selected for its uniform soil and level topography. Aerial photographs were taken in 2015 and 2016 using an Xnite-Canon SX230NDVI with a near-infrared filter, mounted on a modified Cine Star—8 MK Heavy Lift RTF octocopter UAV. Images were taken at 15–20 m above the ground, providing an average of 0.5 cm/pixel and a field of view of 15 × 20 m. Photography and ground assessments of disease were carried out on the same day. NDVI (normalized difference vegetation index), green NDVI, chlorophyll index and plant senescence reflective index (PSRI) were calculated from the images. There were differences in SLB incidence and severity in the field plots and differences in the vegetative indices among the treatments, but there were no correlations between disease assessments and any of the indices.

THE CLASSIFICATION OF PIPE-LAY VESSELS AND HEAVY-LIFT CRANE VESSELS

Pipe-lay vessels, heavy-lift crane vessels and dual purpose heavy-lift and pipe-lay vessels are distinct in many ways from other types of ships or offshore units. The unique functions that these vessels carry out can impact directly on the overall safety of the vessel, the personnel on-board and the potential to pollute the environment. This paper outlines some of the hull and machinery safety assurance considerations for classification and design pertinent to pipe-lay and heavy-lift operations. The considerations that are discussed in this paper include the implications of classing the vessel as a ship or an offshore unit; the interaction between classification and marine warranty; general arrangement; station-keeping; structural assessment and the interaction between safety critical systems. Specific hazards for pipe-lay vessels and their use of chemicals on-board are also discussed.

Installation of Long Span Boat Landing on Float Over Platforms - A Case Study

Fixed offshore platforms are normally provided with landing platforms that enable berthing of supply vessels, crew boats etc. These landing platforms or ‘Boat landings’ are energy absorption structures provided on substructures (jackets) of offshore platforms. Their purpose is to facilitate personnel access from vessel to platforms for performing various tasks including manning the platform, its maintenance etc. Vessel also approach the platforms for providing supplies in case of a manned platform and for providing bunkers, spares etc. As such, boat landing is an integral part of offshore platform and its design and installation becomes equally important. They are preferably located at leeward direction as far as practical, to avoid accidental vessel drift into the platform. For smaller standalone offshore platforms installed with Heavy Lift Crane Vessels, boat landing is installed after the jacket is piled to seabed. Since sequence of installation of boat landing is prior to that of Topside, such installations are straightforward and without obstructions from the Topside. For the bigger accommodation, production, process platforms located in super-complex (or standalone) with topsides installed by float over method, boat landings sometimes are in the wide float over barge slots. In such cases, installation of boat landing becomes very critical due to the post installation after the Topside and associated obstructions from the Topside. This is similar or more critical than a boat landing removal / refurbishment activity carried for a brownfield project. This paper explores the challenges and associated steps adopted to execute the safe installation of these critical structures underneath a newly installed Topside. This case study details the installation of ∼300mt boat landings onto recently installed Greenfield platforms in Arabian Gulf using efficient rigging, suiting the EPC Contractors’ crane assets.

Onshore Yard Readiness for Upcoming Oil and Gas Offshore Structure Decommissioning Projects in Indonesia

More than a thousand fixed oil and gas offshore structures were installed in the Southeast Asia region. Indonesia currently has more than 600 offshore oil and gas platforms, nearly half of which need to be decommissioned within the next few years. While the regulators and operators are developing procedures and regulations for the decommissioning process of the offshore platforms, there is also a need to ensure that onshore facilities are available to receive the decommissioned structures and equipment and subsequently process them safely. At the moment, there is no yard in Indonesia that is well-placed to undertake onshore decommissioning activities. The aim of this study is to develop recommendations for yard owners to assure their yards are ready for the upcoming decommissioning projects. Research data was collected directly from field survey in an offshore fabrication yard, owned by PT. Meitech Eka Bintan, Indonesia. In the current study, research data was analyzed by comparing with decommissioning yard facilities in ABLE Seaton Port, United Kingdom which was used as offshore structure decommissioning yard since 1985. Recommendations include the work required to assure the yard comply with respective guidelines and industry best practices. The research begun with identifying the yard's potential to receive onshore decommissioning work based on current primary facilities which are quay and fabrication area properties. After that, a yard modernization assessment was carried out as to identify the best location for the upgrade on the missing required facilities. The results indicate that the primary facilities of the yard are comparable to ABLE Seaton Port with both having similar depth at quayside, capable of mooring barges and Heavy Lift Vessel (HLV), both having liquid containment system at the fabrication area and the large fabrication area at PT. Meitech Eka Bintan yard is sufficient similar to the area utilized by ABLE Seaton Port for Brent Delta topside decommissioning works. However, since the yard's main business is currently on offshore structure fabrication, hence there is a lack of waste handling facilities such as waste handling workshop and covered waste storage area to fulfill the respective guidelines and regulations. A case study was carried out to identify the onshore decommissioning working area and the location of the waste handling facilities on the yard. This study is expected to assist towards improving the readiness of yards to carry out onshore decommissioning not only in Indonesia but also in Southeast Asia region.

COAA* — An Optimized Obstacle Avoidance and Navigational Algorithm for UAVs Operating in Partially Observable 2D Environments

Obstacle avoidance and navigation (OAN) algorithms typically employ offline or online methods. The former is fast but requires knowledge of a global map, while the latter is usually more computationally heavy in explicit solution methods, or is lacking in configurability in the form of artificial intelligence (AI) enabled agents. In order for OAN algorithms to be brought to mass produced robots, more specifically for multirotor unmanned aerial vehicles (UAVs), the computational requirement of these algorithms must be brought low enough such that its computation can be done entirely onboard a companion computer, while being flexible enough to function without a prior map, as is the case of most real life scenarios. In this paper, a highly configurable algorithm, dubbed Closest Obstacle Avoidance and A* (COAA*), that is lightweight enough to run on the companion computer of the UAV is proposed. This algorithm frees up from the conventional drawbacks of offline and online OAN algorithms, while having guaranteed convergence to a global minimum. The algorithms have been successfully implemented on the Heavy Lift Experimental (HLX) UAV of the Autonomous Robots Research Cluster in Taylor’s University, and the simulated results match the real results sufficiently to show that the algorithm has potential for widespread implementation.