Showing papers on "Spark (mathematics) published in 2009"

A critical review of established methods of structural topology optimization

Abstract: The aim of this article is to evaluate and compare established numerical methods of structural topology optimization that have reached the stage of application in industrial software. It is hoped that our text will spark off a fruitful and constructive debate on this important topic.

Optimizing the operation of a spark ignition engine: Simulation and theoretical tools

Abstract: By performing quasidimensional computer simulations and finite-time thermodynamic analysis we study the effect of spark advance, fuel ratio, and cylinder internal wall temperature in spark ignition engines. We analyze the effect of these parameters on the power output and efficiency of the engine at any rotational speed, ω. Moreover, we propose the optimal dependence on ω of the spark advance angle and the fuel ratio with the objective to get maximum efficiency for any fixed power requirement. The importance of engine power-efficiency curves in order to perform this optimization procedure and also of the evaluation of macroscopic work losses in order to understand the physical basis of the optimization process is stressed. Taking as reference results from simulations with constant standard values of spark advance, fuel ratio, and cylinder internal wall temperature, the optimized parameters yield to substantial increases in engine performance parameters.

Finite element prediction of material removal rate due to traveling wire electrochemical spark machining

Abstract: Manufacturing engineers are facing new challenges during machining of electrically nonconducting or partially conducting materials such as glass, quartz, ceramics, and composites. Traveling wire electrochemical spark machining (TW-ECSM), a largely unknown technology, has been applied successfully for cutting these types of materials. However, hardly any theoretical work has been reported related to machining performance of TW-ECSM process. The present work is an attempt in this direction. In the present work, a 3-D finite element transient thermal model has been developed to estimate the temperature field and material removal rate (MRR) due to Gaussian distributed input heat flux of a spark during TW-ECSM. First, the developed code calculates the temperature field in the workpiece and then MRR is calculated using this temperature field. The calculated MRR has been compared with the experimental MRR for verifying the approach. Computational experiments have been performed for the determination of energy partition and spark radius of a single spark. The effects of various process parameters such as energy partition, duty factor, spark radius, and ejection efficiency on MRR have been reported. It has been found that MRR increases with increase in energy partition, duty factor, and ejection efficiency but decreases with increase in spark radius.

Explosion proof communications relay and communications system

Abstract: A wireless communication system for use in an explosive environment includes at least a pair of explosion-proof communication relay modules which relay communication to mobile communication devices in locations beyond the reach of normal wireless communications with base station antennas. The explosion-proof communication relay modules include features to preclude the generation of a spark or heat source which could ignite any explosive gas or vapor. Similarly, explosion-proof mobile devices include design features which also preclude the generation of a spark or heat source.

Spark voltage limiting system for active fuel management

Abstract: An engine control system for a vehicle includes a variable displacement module that deactivates N of M cylinders of an engine during a fuel management mode. N is an integer and M is an integer greater than 1. A spark control module generates a spark timing signal for the N cylinders based on a pre-dwell time and a fuel management dwell modifier during the fuel management mode. The spark control module reduces dwell time of the N cylinders during the fuel management mode based on the fuel management dwell modifier.

Spark plug and manufacturing method therefor

Abstract: Provided are a spark plug in which the occurrence of spark blowout or the like is restrained for improvement of ignition performance, and a method of manufacturing the spark plug. A ground electrode 27 of the spark plug has a protrusion 28 which faces a center electrode 5. The distal end surface of the protrusion 28 has a noble metal tip 32 provided at the center thereof and includes an annular fusion portion 33 adjacent to the periphery of the noble metal tip 32, and an annular electrode base metal surface located externally of the annular fusion portion 33. A spark discharge gap 35 is formed between the center electrode 5 and the distal end of the protrusion 28 including the noble metal tip 32.

Spark ignition of turbulent non-premixed flames: experiments and simulations

Abstract: Spark ignition of turbulent non-premixed gaseous and spray flames is of fundamental and technological importance, but has been very little studied compared to spark ignition of premixed combustion. In addition to the spark parameters, the value of the mixture fraction and its gradient at the spark location and instant and the local fluid velocities can affect the success of generating a kernel. These phenomena are briefly discussed through recent laminar and turbulent flame simulations and experiments and pointers to the recent literature are given.

Numerical Evaluation by Models of Load and Spark Timing Effects on the In-Cylinder Heat Transfer of a SI Engine

Abstract: The aim of this study is to examine numerically the effects of spark timing and load parameters on the in-cylinder heat transfer of a SI engine by using experimental engine test data. For the investigation, a four-stroke, air-cooled, single-cylinder SI engine was tested at different spark timings and loads at a single engine speed of 2000 rpm. Woschni, Hohenberg, and Han models were employed to estimate the in-cylinder heat transfer coefficient in the case of different test conditions because of being favorable models on the SI engine operations. The evaluations show that the in-cylinder heat transfer characteristics of the air-cooled SI engine strongly depend on the load while they slightly depend on the spark timing.

Pre-ignition in highly charged spark ignition engines — visualisation and analysis

Abstract: Highly boosted spark ignition engines must confront violent forms of pre-ignition limiting the maximal low-end torque. French research institute IFP presents here an innovative tool allowing a better understanding of this phenomenon and a structured reasoning considering all its potential causes of this phenomenon. Advanced statistical analyses of the combustion process and direct visualisations inside the combustion chamber are successfully combined to accurately assess the development of pre-ignition. This coupled approach provides an efficient tool for analysis and development of new engines and new control concepts on IFP test beds.

Objective Determination of Minimum Engine Mapping Requirements for Optimal SI DIVCP Engine Calibration

Abstract: In response to marketplace demand for increased engine performance and economy, spark-ignition (SI) engine applications with dual-independent variable camphaser actuators (DIVCP) are now commonplace. In this paper, the minimum number of test measurements required to optimally calibrate the steady-state spark advance and cam-phaser settings of a SI DIVCP engine was determined, using a high-fidelity model of a 2.2L SI DIVCP engine with predictive combustion capability as a basis. A calibration development process was designed to objectively determine the minimum number of torque vs. spark advance sweeps required for the SI DIVCP engine.

Control method and spark plug for spark -ignited internal combustion engine

Abstract: A control method for a spark-ignited internal combustion engine includes generating plasma by interacting an electric field generated in a combustion chamber by electric field generation means with spark discharge caused by a spark plug, and igniting an air-fuel mixture, wherein the electric field generated by the electric field generation means is set to an intensity weaker than that of an electric field generated by the spark plug when the spark discharge is caused, and set to an intensity at which discharge into the combustion chamber is disabled, and the air-fuel mixture can be securely ignited and combusted at an intended ignition timing and at a position of the spark plug.

Power supply control for spark plug of internal combustion engine

Abstract: A method for controlling the power supply of a radiofrequency spark plug in an internal combustion engine up to an electric voltage sufficient for generating a highly branched spark. To this end, the electric voltage for powering the spark plug is increased step by step up to an adequate voltage adapted for ignition.

Spark gaps for EMP and SREMP pulsers

Abstract: The breakdown of almost uniform field spark gaps is described. An extrapolation of published uniform field spark breakdown of SF6 and air is presented.

Method and apparatus for reducing spark plug fouling

Abstract: A control module and method for controlling an engine operation includes a runtime module that determines a previous run period, a fuel mass module that determines a fuel mass during the previous run period, a spark fouling condition estimation module that determines a spark fouling condition based on the fuel mass during the previous run period and an engine operation module that controls the engine in response to the spark fouling condition.

Cold start engine control diagnostic systems and methods

Abstract: An engine control module includes a spark control module, an engine speed module, a residual determination module, and a metric determination module. The spark control module actuates spark plugs based on a commanded spark timing. The engine speed module determines a desired engine speed based on an engine temperature and a period of time an engine is in operation after a cold start. The residual determination module determines a desired spark timing based on the desired engine speed, and determines a residual spark timing based on a difference between the commanded spark timing and the desired spark timing. The metric determination module detects a spark timing fault based on the residual spark timing and a predetermined spark timing range.

A study of nano-scale electrical discharge characteristics for automotive sensor applications

Abstract: To study the relationship between spark ignition and the gap in the nano-scale region, the electric potential was applied to between a Pt-Ir tip and a gold substrate. The tip was sharpened by electro-chemical etching process in the solution of CaCl₂, H₂O and acetone. The radius of tip was measured to be around 200㎚ and attached to the scanning probe microscope to control the gap between the tip and the substrate. The electric potential of 10V to 80V was applied to initialize the spark. The gaps and the current profile were measured to analyze the characteristics of spark ignition. A spark sustaining time was measured to be between 50㎱ and 200㎱ depending on the applied electric potential and the gap between the electrodes. The continuous electric discharge was successfully sustained up to 1 second of spark or arc time. The developed process can be applicable to the micro-scale fabrication of automotive sensors as a similar concept of GTAW.