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Most of the previous research on flame ionization in spark ignition engines applied positive polarity on the spark plug center electrode, referred to as positively biased probe. In this paper an investigation is made to determine the characteristics of the ion current signal with negatively biased probe. The factors that contribute to the second ion current peak, reported to be missing with negative polarity, are investigated. Experiments were conducted on a research single-cylinder, spark ignition engine and the negative polarity is applied by a SmartFire Plasma Ignition system. The effect of different spark plug designs and engine operating parameters on the amplitude and timing of each of the two ion current peaks is determined. The results indicated that, with negative polarity, the cathode area is one of the main factors that contribute to the amplitude of the ion current signal, particularly the second peak.

As the durations of manned space missions increase, so will the need for compact and reliable water recycling systems. Optimization of such water-recycling systems involves computer simulation of process elements and subsystems. The operations of water recycling systems are simulated at the Ames Research Center using commercial software called ASPEN-PLUS. Ion exchange is a part of the multifiltration subsystem, used for final polishing of recycled water and in some cases as a complete water treatment. Ion-exchange resins remove hazardous ions from solution by exchanging them with innocuous ions according to selection parameters. The ion-exchange operation is not provided in the ASPEN-PLUS multiprocess simulator package, but FORTRAN-callable modules may be added. Therefore we have adapted a FORTRAN program simulating multicomponent adsorption by ion-exchange resins, for use both as an ASPEN-callable module and as a free-standing simulator of the ion-exchange bed.

A mathematical model is presented for analysis and optimization of the ion exchange beds in the International Space Station (ISS) Water Processor. The model consists of a physical properties database, an equilibrium description for binary and multicomponent ion exchange, and a kinetic description for ion exchange beds in the Water Processor. The ion exchange model will be verified for an Ersatz water designed to mimic the ISS shower/handwash waste stream.

Chromic acid losses through dragout, bath dumps, and fume scrubber blowdown result in waste treatment expense, bath replacement, and environmental liabilities. Purification of the bath can eliminate bath dumping and improve performance by removing contaminates which are detrimental to the finishing operation. Closed loop recovery of rinsewaters (tied to scrubbers) can eliminate environmental liabilities and provide considerable savings. Ion exchange techniques are especially well suited to purification and recovery of chromic acid. In particular, a system which employs short resin columns and rapid operating cycles has been developed specifically for such applications.

Honeywell has developed a new approach to Solid Free-form Fabrication called Ion Fusion Formation (IFF), a Direct Metal Deposition (DMD) process. This is a near-net-shape hardware manufacturing process that uses a very hot ionized gas to deposit metal in small discreet amounts and ultimately build a complete part. Components can be used as-deposited or post-deposition processed to gain some improvement in properties and then final machined. The process has low initial capital, maintenance and operating cost and is user friendly. Other forms of SFF use expensive lasers or electron beam for their heat source. IFF uses inexpensive electrical energy to generate power for fusion.

Ion plating is a high-energy or plasma deposition method which essentially consists of sputtering and ion implantation (thermal evaporation with ionization). During ion plating, deposition is by ions as opposed to atoms. Ion plating has the two distinct characteristics of high throwing power and high kinetic energy. The high throwing power is responsible for coating complex geometrical surfaces with a uniform film without rotation. The high kinetic energy of the ion flux forms a graded interface; as a result a very adherent film is formed. Mechanical tests (tensile, fatigue, and friction) show a very strong adherence of the film and even an increase in mechanical properties such as tensile strength and fatigue life.

During the combustion of an air-fuel mixture ions are produced by thermo, photo, and chemical ionization. The process of ion neutralization in heavy hydrocarbons and particles is considerably slower than in gas molecules. Only exhaust gas particles and atoms are expected to carry an electric charge. The ions flowing in the exhaust manifold can be detected by an ion probe. The induced charge at the ion probe can measure up to 50 pC and can be directly recorded on an oscillograph. The signals from two diesel engines (DI and IDI) and as a double check also a spark-ignition engine were picked up by an ion probe. In the case of the diesel engine the signals increased with the smoke emission. Signals from the spark-ignition engine have a different shape to those of a diesel engine.

DRS. Werner Von Braun and Ernst Stuhlinger have advocated a rather interesting concept for travel to Mars. The trip would involve transport in three separate vehicles. The first, a conventional liquid or solid fueled 3-stage vehicle, escapes from the Earth's atmosphere and terminates at an orbiting space station 1000 miles from the Earth's surface. The second vehicle, the space cruiser, leaves the satellite orbit and enters an orbit 600 miles above Mars. The third vehicle, the landing vehicle, would be detached from the space cruiser, reduce its orbiting speed by rocket power and enter a downward trajectory thru the Martian atmosphere. To return, the landing vehicle would leave from Mars to the orbiting cruiser, the crew transfer to it, and begin the return flight to the Earth's satellite. Return to the Earth is made in the crew-cargo portion of the third stage rocket that made the trip from Earth to its satellite.

The combustion stability of a direct injected spark ignited engine depends on the injection timing and it is desirable to have controller that minimizes the combustion variability. A novel approach for determining combustion stability in stratified mode is presented that rely on the ionization current and enables closed loop control of the injection timing. The co-efficient of variation for IMEP is used as a measure of combustion stability and a connection between maximum torque and low combustion variability is pointed out. The coefficient of variation of the ion current integral is well correlated with the coefficient of variation for IMEP. Furthermore, it is shown how the integral of the ion current together with COV(ion integral) can be used to determine the combustion stability and to distinguish high combustion stability from misfire.

The cyclic changes of the cylinder pressure are mainly influenced by the primary inflammation phase, which in turn depends on the local air/fuel ratio and the residual-gas fraction at the spark plug. The ion-current measurement technique is based on the conductivity of the mixture during the internal combustion. It is therefore possible to use the signal for combustion diagnostics when using the spark plug as a sensor. This article demonstrates the potential of ion sensing at the spark plug and in the combustion chamber to detect sources of interference which prevent an optimal combustion process. Comparing the ion signals of consecutive combustion cycles delivers explanations of phenomena that could not yet be sufficiently characterized by cylinder-pressure indication. The results allow new fundamental approaches to the optimization of the combustion process.

This paper will discuss the views and studies that are currently being conducted by the ASTM (American Society for Testing and Materials), D15 Engine Coolants Committee members regarding coolant and cooling system degradation products and their effects. It will include what has been involved in the process of establishing coolant recycling guidelines and several recycling views by heavy-duty manufacturers. This paper will also overview the process of recycling used coolant by a dual-resin, ion-exchange process and indicate how proper maintenance of cooling systems will lower operation costs and eliminate unscheduled downtime. Purification and performance test data will be shown in regards to TDS (Total Dissolved Solids) removal and reinhibition with proper additive levels not requiring the initial SCA (Supplemental Coolant Additive) addition.

The combustion of fuel inside an engine cylinder produces ions. By applying a small DC voltage across the spark gap after ignition, ion current is produced. The ion current wave form contains combustion information and is called Ion-Gap sense. Ion-Gap sense is described and can be used to detect misfire, control knock, obtain cam phasing, and detect pre-ignition. In the future, it will provide air/fuel information. Test results on nine different engine types are summarized for misfire detection. Knock testing is reviewed for eight engines. Engine tests associated with engine control techniques have been included.

The cycle-to-cycle and cylinder-to-cylinder variations that occur in a spark ignited engine create the opportunity for monitoring combustion in real time to provide useful benefits for engine control. Reduction of variation and operation of the engine at closer-to-optimum conditions is possible if real time feedback of the combustion process is available. An in-cylinder pressure sensor with pressure-based control algorithms is one method of monitoring the combustion process. However, such a solution presents new challenges of an additional cylinder penetration location, sensor packaging and added cost. A substitute for the in-cylinder pressure sensor is a device which measures the flame conductivity, commonly known as an ionization current sensor. It can be integrated with the spark plug in the case of SI engines, or with the glow plug in the case of compression ignition engines.

Homogenous Charge Compression Ignition (HCCI) combustion phasing and stability provides a challenging control problem over conventional combustion technologies of Spark Ignition (SI) and Compression Ignition (CI). Due to the auto ignition nature of the HCCI combustion there are no direct methods for actuation, the combustion and the phasing relies on indirect methods. This in itself creates a nonlinear dynamic problem between the relationships of control actuators and the combustion behavior. In order to control the process, an accurate feedback signal is necessary to determine the state of the actual combustion process. Ideally to ensure that combustion remains stable and phased correctly an in-cylinder feedback of each cylinder for multi cylinder engines would be preferable. Feedback has been seen in studies using piezoelectric pressure sensors for visually monitoring the pressure in the combustion chamber. This is expensive and requires redesign of the combustion chamber.

In-cylinder ion sensing is a subject of interest due to its application in spark-ignited (SI) engines for feedback control and diagnostics including: combustion knock detection, rate and phasing of combustion, and mis-fire On Board Diagnostics (OBD). Further advancement and application is likely to continue as the result of the availability of ignition coils with integrated ion sensing circuitry making ion sensing more versatile and cost effective. In SI engines, combustion knock is controlled through closed loop feedback from sensor metrics to maintain knock near the borderline, below engine damage and NVH thresholds. Combustion knock is one of the critical applications for ion sensing in SI engines and improvement in knock detection offers the potential for increased thermal efficiency. This work analyzes and characterizes the ionization signal in reference to the cylinder pressure signal under knocking and non-knocking conditions.

Traditionally radiation protection is left for evaluation after the completion of other engineering design processes followed by design changes to improve protection leading to off-optimum solutions of design problems. This project is a first attempt to develop optimization procedures with radiation constraint components from the beginning of the design process allowing performance optimization at reduced costs. The traditional limitation of radiation constraint analysis has been the slow computation time and the main focus thus far has been to apply high-performance computing to shielding analysis in preparation for MDO processes. We will describe the problem formulation, the framework for optimization, and progress towards developing highspeed computational procedures.

Battery cell operating characteristics were determined for a unique load profile planned for the Motorola Iridium™ spacecraft. The Iridium™ mission requires that the battery be on line at all times and operated for extended periods with a short duration, high rate, charge/discharge duty cycle. The effort reported here reflects a repetitive duty cycle of 1.3 milliseconds discharge and 2.9 milliseconds charge, with discharge rates in the range 2.0 C to 3.0 C and charge rates in the range 0.9 C to 1.4 C. Cell transient characteristics were determined for candidate cell types including nickel-hydrogen individual pressure vessel (IPV), nickel-hydrogen common pressure vessel (CPV), Super nickel-cadmium, and fiber nickel-cadmium (FNC). Experimental approach, cell performance data, derived transient characteristics, and cell electrical models are presented.

IRON-aluminum base alloys have shown great resistance to high-temperature oxidation, the authors report. These alloys can be made to exceed the resistance of any stainless steel. Several problems exist in connection with the alloys: room-temperature brittleness, only moderate high-temperature strength, and susceptibility to grain growth. However, the authors think these problems will probably be solved with further experimentation. The principal advantages of the alloys are their low cost and availability, factors in case a chromium shortage affects the availability of straight-chromium stainless steels.