The body while the vehicle is moving is tilts the longitudinal and transverse directions. Transverse generated mainly by uneven road surface and longitudinal driving processes (acceleration and ...braking). Increasing the weight of the vehicle transported cargo enhances tilt. During cargo delivery vehicles are required to be adequately protected and the distribution of the load area in order to minimize dangerous tilt. Incorrectly secured load during heavy braking can move and change drive trajectory of the vehicle and extend the braking distances. The results of road tests change the inclination of car body of the vehicle a towing car transporting vehicles of different mass.
Following the Paris Accords, the aviation industry aims to become climate neutral by 2050. In this line, electric vehicles that tow aircraft during taxiing are a promising emerging technology to ...reduce emissions at airports. This paper proposes an end-to-end optimization framework for electric towing vehicles (ETVs) dispatchment at large airports. We integrate the routing of the ETVs in the taxiway system where minimum separation distances are ensured at all times, with the assignment of these ETVs to aircraft towing tasks and scheduling ETV battery recharging. For ETV recharging, we consider a preemptive charging policy where the charging times depend on the residual state-of-charge of the battery. We illustrate our model for one day of operations at a large European airport. The results show that the 913 arriving and departing flights can be towed with 38 ETVs, with battery charging distributed throughout the day. The fleet size is shown to increase approximately linear with the number of flights in the schedule. We also propose a greedy dispatchment of the ETVs, which is shown to achieve an optimality gap of 6% with respect to the number of required vehicles and with 22% with respect to the maximum delay during towing. We also show that both algorithms can be leveraged to account for flight delays using a rolling horizon approach, and that over 95% of the flights can be reallocated if delays occur. Overall, we propose a roadmap for ETV management at large airports, considering realistic ETV specifications (battery capabilities, kinematic properties) and requirements for aircraft collision avoidance during towing.
On-road driving emissions of six liquefied natural gas (LNG) and diesel semi-trailer towing vehicles (STTVs) which met China Emission Standard IV and V were tested using Portable Emission Measurement ...System (PEMS) in northern China. Emission characteristics of these vehicles under real driving conditions were analyzed and proved that on-road emissions of heavy-duty vehicles (HDVs) were underestimated in the past. There were large differences among LNG and diesel vehicles, which also existed between China V vehicles and China IV vehicles. Emission factors showed the highest level under real driving conditions, which probably be caused by frequent acceleration, deceleration, and start-stop. NOx emission factors ranged from 2.855 to 20.939 g/km based on distance-traveled and 6.719–90.557 g/kg based on fuel consumption during whole tests, which were much higher than previous researches on chassis dynamometer. It was inferred from tests that the fuel consumption rate of the test vehicles had a strong correlation with NOx emission, and the exhaust temperature also affected the efficiency of Selected Catalytic Reduction (SCR) after-treatment system, thus changing the NOx emission greatly. THC emission factors of LNG vehicles were 2.012–10.636 g/km, which were much higher than that of diesel vehicles (0.029–0.185 g/km). Unburned CH4 may be an important reason for this phenomenon. Further on-road emission tests, especially CH4 emission test should be carried out in subsequent research. In addition, the Particulate Number (PN) emission factors of diesel vehicles were at a very high level during whole tests, and Diesel Particulate Filter (DPF) should be installed to reduce PN emission.
Fig. Portable Emissions Measurement System for test vehicles. a) PC; b) GPS; c) weather station; d) Exhaust flow meter; e) HORIBA OBS ONE for gaseous emissions; f) PPS-M for particulate emission; g) Batteries. Display omitted
The United States Navy owns four salvage ships and four towing ships that will reach the end of their 40-year life expectancy in 2019. The program manager for these vessels has a set of desirable ...performance requirements for a new ship class, T-ARS(X), which combines the capabilities from both the salvage and towing ship classes. The need to develop a recapitalization strategy based on either designing a new ship class based on these desirable requirements or purchasing commercial capabilities based on the salvage and towing community's needs is paramount. Meanwhile, the Department of Defense (DoD) has shifted defense planning from the specific service requirements generating system (RGS) acquisition to the Joint Capabilities Integration and Development System (JCIDS) approach that focuses on requirements generation based on customer need. This thesis explores how to use systems architecting principles in the context of model-based systems engineering (MBSE) to incorporate the capabilities needed for towing and salvage recapitalization into a cohesive framework for developing the T-ARS(X) requirement specification. The CORE design tool is used to implement the MBSE architecting process using the Naval Architecture Elements Reference Guide (NAERG) and standardized operational tasks to create DODAF v1.5 products from system models. The requirements generated from the architecture model are compared with the current, combined towing and salvage-capable commercial platforms for analysis. Based on the methodology presented, the towing and salvage community now has the basis to perform a capabilities-based analysis of alternatives (AoA) for the T-ARS(X) recapitalization.
Commercial towboats in navigable waterways, particularly in confined reaches, generate waves and currents which can be of significant magnitude such that stabilization of the banks with riprap is ...warranted. This paper focuses on stable riprap design for tows under way (here referring to those whose sailing line is parallel to the banks and whose speed is constant). Therefore, return current, wave characteristics, and channel geometry are the governing parameters for sizing the stone. Propeller jet impacts due to maneuvering tows are not addressed. Most of the existing guidance on sizing the riprap on the banks for waves has been based on coastal waves. The riprap design guidance pertaining to waves produced by typical commercial towboats found on US waterways is limited. Based on site-specific needs to address stone sizes due to towboat-induced forces, several studies have been conducted at the US Army Engineer Waterways Experiment Station (WES), Vicksburg, Mississippi. The physical model studies include the Tennessee-Tombigbee Waterway, the Gallipolis Lock approach on the Ohio River, and some general navigation research regarding stone slope stability in confined waterways. Although these studies have been primarily devoted to the evaluation of specific stone sizes and gradations subjected to specific towboat operations, the study results lend themselves to use as general riprap design guidance.
This report documents a study of the horizontal motion of the downstream end of a towed cable when the motion of the towing vessel is known. The dynamic position of the downstream end of the cable is ...a consequence of the random crosstrack meandering of the towing vessel as it imperfectly maintains a constant course. The specific purpose of the study was to supply a method to predict the horizontal motion. Other contributors to cable dynamics, such as ocean current, are not addressed.
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