This paper examines the statistical properties and the quality of the speed through water (STW) measurement based on data extracted from almost 200 container ships of Maersk Line’s fleet for 3 years of operation. The analysis uses high-frequency sensor data along with additional data sources derived from external providers. The interest of the study has its background in the accuracy of STW measurement as the most important parameter in the assessment of a ship’s performance analysis. The paper contains a thorough analysis of the measurements assumed to be related with the STW error, along with a descriptive decomposition of the main variables by sea region including sea state, vessel class, vessel IMO number and manufacturer of the speed-log installed in each ship. The paper suggests a semi-empirical method using a threshold to identify potential error in a ship’s STW measurement. The study revealed that the sea region is the most influential factor for the STW accuracy and that 26% of the ships of the dataset’s fleet warrant further investigation.
In this report we study mathematical models for predicting when ice may form and fall from vertical steel hangers of suspension bridges down onto the road below. This is an important problem to study, not only because of the economic costs related to closing a bridge due to the risk of falling ice, but also the human cost if the bridge is still open to traffic when ice falls down. In the report we present two main categories of models for predicting falling times: 1) models based on heat transfer from the surrounding air, and 2) models based on heating due to radiation from the sun. A flow chart is furthermore presented together with tables for determining which model to use and quickly estimating time of failure based on a set of simple conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.