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Technical Paper

Space Life Support from the Cellular Perspective

2001-07-09
2001-01-2229
Determining the fundamental role of gravity in vital biological systems in space is one of six science and research areas that provides the philosophical underpinning for why NASA exists. The study of cells, tissues, and microorganisms in a spaceflight environment holds the promise of answering multiple intriguing questions about how gravity affects living systems. To enable these studies, specimens must be maintained in an environment similar to that used in a laboratory. Cell culture studies under normal laboratory conditions involve maintaining a highly specialized environment with the necessary temperature, humidity control, nutrient, and gas exchange conditions. These same cell life support conditions must be provided by the International Space Station (ISS) Cell Culture Unit (CCU) in the unique environment of space. The CCU is a perfusion-based system that must function in microgravity, at unit gravity (1g) on earth, and from 0.1g up to 2g aboard the ISS centrifuge rotor.
Technical Paper

An EVA Mission Planning Tool based on Metabolic Cost Optimization

2009-07-12
2009-01-2562
An extravehicular activity (EVA) path-planning and navigation tool, called the Mission Planner, has been developed to assist with pre-mission planning, scenario simulation, real-time navigation, and contingency replanning during astronaut EVAs, The Mission Planner calculates the most efficient path between user-specified waypoints. Efficiency is based on an exploration cost algorithm, which is a function of the estimated astronaut metabolic rate. Selection of waypoints and visualization of the generated path are realized within a 3D mapping interface through terrain elevation models. The Mission Planner is also capable of computing the most efficient path back home from any point along the path.
Technical Paper

Optimization of Gear Shifting and Torque Split for Improved Fuel Efficiency and Drivability of HEVs

2013-04-08
2013-01-1461
Decreasing fuel consumption and emissions in automobiles has been an active research topic in recent years. Vehicles with alternative powertrain systems, especially hybrid-electric vehicles (HEVs), have shown significant reduction in fuel consumption and emissions, and therefore have attracted many researchers to this field. The focus is usually on the development of optimal power management control methods. For parallel HEVs, the primary control variable is the torque split between the internal combustion engine and the electric motor. More advanced approaches also simultaneously search for the optimal gear number and engine on/off state, which can further reduce the fuel consumption but also complicate the problem. In the literature on HEVs, the emphasis is typically only on fuel efficiency and sometimes the emissions. The drivability of the vehicle is usually not considered during the optimization process.
Technical Paper

Turbocharger Speed Estimation via Vibration Analysis

2016-04-05
2016-01-0632
Due to demanding legislation on exhaust emissions for internal combustion engines and increasing fuel prices, automotive manufacturers have focused their efforts on optimizing turbocharging systems. Turbocharger system control optimization is difficult: Unsteady flow conditions combined with not very accurate compressor maps make the real time turbocharger rotational speed one of the most important quantities in the optimization process. This work presents a methodology designed to obtain the turbocharger rotational speed via vibration analysis. Standard knock sensors have been employed in order to achieve a robust and accurate, yet still a low-cost solution capable of being mounted on-board. Results show that the developed method gives an estimation of the turbocharger rotational speed, with errors and accuracy acceptable for the proposed application. The method has been evaluated on a heavy duty diesel engine.
Technical Paper

An Experimental Study of Piston Skirt Roughness and Profiles on Piston Friction Using the Floating Liner Engine

2016-04-05
2016-01-1043
The piston skirt is an important contributor of friction in the piston assembly. This paper discusses friction contributions from various aspects of the piston skirt. A brief study of piston skirt patterns is presented, with little gains being made by patterning the piston skirt coating. Next the roughness of the piston skirt coating is analyzed, and results show that reducing piston skirt roughness can have positive effects on friction reduction. Finally, an introductory study into the profile of the piston skirt is presented, with the outcome being that friction reduction is possible by optimizing the skirt profile.
Technical Paper

Multi-objective Optimization of a Multifunctional Structure through a MOGA and SOM based Methodology

2013-09-17
2013-01-2207
A Multi-Objective Optimization (MOO) problem concerning the thermal control problem of Multifunctional Structures (MFSs) is here addressed. In particular the use of Multi-Objective algorithms from an optimization tool and Self-Organizing Maps (SOM) is proposed for the identification of the optimal topological distribution of the heating components for a multifunctional test panel, the Advanced Bread Board (ABB). MFSs are components that conduct many functions within a single piece of hardware, shading the clearly defined boundaries that identify traditional subsystems. Generally speaking, MFSs have already proved to be a disrupting technology, especially in aeronautics and space application fields. The case study exploited in this paper refers to a demonstrator breadboard called ABB. ABB belongs to a particular subset of an extensive family of MFS, that is, of thermo-structural panels with distributed electronics and a health monitoring network.
Technical Paper

Axiomatic Design of Automobile Suspension and Steering Systems: Proposal for a Novel Six-Bar Suspension

2004-03-08
2004-01-0811
The existing vehicle designs exhibit a high level of coupling. For instance the coupling in the suspension and steering systems manifests itself through the change in wheel alignment parameters (WAP) due to suspension travel. This change in the WAP causes directional instability and tire-wear. The approach of the industry to solve this problem has been twofold. The first approach has been optimization of suspension link lengths to reduce the change in WAP to zero. Since this is not possible with the existing architecture, the solution used is the optimization of the spring stiffness K to get a compromise solution for comfort (which requires significant suspension travel and hence a soft spring) and directional stability (which demands least possible change in wheel alignment parameters and hence a stiff spring).
Technical Paper

Developing Design Guidelines for an SCR Assembly Equipped for RF Sensing of NH3 Loading

2018-04-03
2018-01-1266
The Cu-zeolite (CuZ) SCR catalyst enables higher NOx conversion efficiency in part because it can store a significant amount of NH3. “NH3 storage control”, where diesel exhaust fluid (DEF) is dosed in accord with a target NH3 loading, is widely used with CuZ catalysts to achieve very high efficiency. The NH3 loading actually achieved on the catalyst is currently estimated through a stoichiometric calculation. With future high-capacity CuZ catalyst designs, it is likely that the accuracy of this NH3 loading estimate will become limiting for NOx conversion efficiency. Therefore, a direct measurement of NH3 loading is needed; RF sensing enables this. Relative to RF sensing of soot in a DPF (which is in commercial production), RF sensing of NH3 adsorbed on CuZ is more challenging. Therefore, more attention must be paid to the “microwave resonance cavity” created within the SCR assembly. The objective of this study was to develop design guidelines to enable and enhance RF sensing.
Journal Article

Study on Energy Loss due to Cornering Resistance in Over-Actuated Vehicles using Optimal Control

2017-03-28
2017-01-1568
As vehicles become electrified and more intelligent in terms of sensing, actuation and processing; a number of interesting possibilities arise in controlling vehicle dynamics and driving behavior. Over-actuation with in- wheel motors, all wheel steering and active camber is one such possibility, which facilitate the control strategies that push boundaries in energy consumption and safety. Optimal control can be used to investigate the best combinations of control inputs to an over-actuated system. This paper shows how an optimal control problem can be formulated and solved for an over-actuated vehicle case, and highlights the translation of this optimal solution to a real-world scenario, enabling intelligent means to improve vehicle efficiency. This paper gives an insight into Dynamic Programming (DP) as an offline optimal control method that guarantees the global optimum.
Technical Paper

A Novel Design for Cruiser Type Motorcycle Silencer Based on Micro-Perforated Elements

2012-10-23
2012-32-0109
Regulations stipulating the design of motorcycle silencers are strict, especially when the unit incorporates fibrous absorbing materials. Therefore, innovative designs substituting such materials while still preserving acceptable level of characteristic sound are currently of interest. Micro perforated elements are innovative acoustic solutions, which silencing effect is based on the dissipation of the acoustic wave energy in a pattern of sub-millimeter apertures. Similarly to fibrous materials the micro-perforated materials have been proved to provide effective sound absorption in a wide frequency range. Additionally, the silencer is designed as a two-stage system that provides an optimal solution for a variety of exploitation conditions. In this paper a novel design for a cruiser type motorcycle silencer, based on micro-perforated elements, is presented.
Technical Paper

Optimization-Based Robust Architecture Design for Autonomous Driving System

2019-04-02
2019-01-0473
With the recent advancement in sensing and controller technologies architecture design of an autonomous driving system becomes an important issue. Researchers have been developing different sensors and data processing technologies to solve the issues associated with fast processing, diverse weather, reliability, long distance recognition performance, etc. Necessary considerations of diverse traffic situations and safety factors of autonomous driving have also increased the complexity of embedded software as well as architecture of autonomous driving. In these circumstances, there are almost countless numbers of possible architecture designs. However, these design considerations have significant impacts on cost, controllability, and system reliability. Thus, it is crucial for the designers to make a challenging and critical design decision under several uncertainties during the conceptual design phase.
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