Showing papers on "Spark (mathematics) published in 2003"

Scaling Java points-to analysis using SPARK

Abstract: Most points-to analysis research has been done on different systems by different groups, making it difficult to compare results, and to understand interactions between individual factors each group studied. Furthermore, points-to analysis for Java has been studied much less thoroughly than for C, and the tradeoffs appear very different. We introduce SPARK, a flexible framework for experimenting with points-to analyses for Java. SPARK supports equality- and subset-based analyses, variations in field sensitivity, respect for declared types, variations in call graph construction, off-line simplification, and several solving algorithms. SPARK is composed of building blocks on which new analyses can be based. We demonstrate SPARK in a substantial study of factors affecting precision and efficiency of subset-based points-to analyses, including interactions between these factors. Our results show that SPARK is not only flexible and modular, but also offers superior time/space performance when compared to other points-to analysis implementations.

SPARK: a high-level synthesis framework for applying parallelizing compiler transformations

Abstract: This paper presents a modular and extensible high-level synthesis research system, called SPARK, that takes a behavioral description in ANSI-C as input and produces synthesizable register-transfer level VHDL. SPARK uses parallelizing compiler technology, developed previously, to enhance instruction-level parallelism and re-instruments it for high-level synthesis by incorporating ideas of mutual exclusivity of operations, resource sharing and hardware cost models. In this paper, we present the design flow through the SPARK system, a set of transformations that include speculative code motions and dynamic transformations and show how these transformations and other optimizing synthesis and compiler techniques are employed by a scheduling heuristic. Experiments are performed on two moderately complex industrial applications, namely MPEG-1 and the GIMP image processing tool. The results show that the various code transformations lead to up to 70 % improvements in performance without any increase in the overall area and critical path of the final synthesized design.

An Improved Friction Model for Spark-Ignition Engines

Abstract: Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.

Closed loop cold start retard spark control using ionization feedback

Abstract: This feature of the present invention comprises a method and apparatus to retard the spark time. As a result, the catalyst heats up quickly during the cold start. The retard spark control method of the present invention uses a closed loop to adjust the engine retard limit during an engine cold start to retard the engine spark as much as possible without engine misfire and with minimum partial burn. The increased exhaust temperature heats up the catalyst more quickly than conventional open loop approaches, which as a result, reduces hydrocarbon emissions. The closed loop retard spark control using ionization current feedback consists of four major components or functions, an error and gain generator, a proportional and integration control processing block, a default spark timing processor, and an adaptive learning apparatus.

Chaotic Combustion in Spark Ignition Engines

Abstract: We analyse the combustion process in a spark ignition engine using the experimental data of an internal pressure during the combustion process and show that the system can be driven to chaotic behaviour. Our conclusion is based on the observation of unperiodicity in the time series, suitable stroboscopic maps and a complex structure of a reconstructed strange attractor. This analysis can explain that in some circumstances the level of noise in spark ignition engines increases considerably due to nonlinear dynamics of a combustion process.

Local fuel concentration, ignition and combustion in a stratified charge spark combustion in a stratified charge spark ignited direct injection engine: Spectroscopic, imaging and pressure-based measurements

Abstract: A recently developed spark emission spec-troscopy technique has been used to measure the effects of fuel injection timing, spark timing and intake swirl level on the individual-cycle fuel concentration at the spark gap in a wall-guided spark ignited direct injection (SIDI) engine The fuel-concentration measurements were made simultaneously with measurements of individual-cycle spark discharge energy and cylinder pressure Endoscopic imaging of the fuel spray and high-speed imaging of combustion (both broadband and spectrally resolved) augment these quantitative data For optimum engine operation, the fuel-air equivalence ratio at the spark gap just after spark breakdown is rich on average (〈φ〉 ≈14–15) and varies widely from cycle to cycle (∼25 per cent) The evolution with crank angle of the mean equivalence ratio and its cycle-to-cycle fluctuations are correlated with the cylinder pressure, heat release and imaging data to provide insights into fuel transport and mixture preparation that are i

Nonperiodic Oscillations of Pressure in a Spark Ignition Engine

Abstract: We report our results on non-periodic experimental time series of pressure in a spark ignition engine. The experiments were performed for a low rotational velocity of a crankshaft and a relatively large spark advance angle. We show that the combustion process has many chaotic features. Surprisingly, the reconstructed attractor has a characteristic butterfly shape similar to a chaotic attractor of Lorentz type. The suitable recurrence plot shows that the dynamics of the combustion is a nonlinear multidimensional process mediated by stochastic noise.

Method and apparatus for detection of brush sparking and spark erosion on electrical machines

Abstract: The invention relates to a method and device for detecting spark activity in an electric machine The shaft voltage (Us(t)) and/or the shaft current (Is(t)) are measured and characteristic components are analyzed in order to detect spark activity The inventive method, which utilizes respective shaft currents which are mainly considered to be harmful, is precise and suitable for long-term monitoring of spark activities such as sparking, spark erosion, and spark discharges between parts of shaft bearings Said method can be carried out in a constructively simple and reliable manner using available earthing devices

Effects of the compression ratio on nitric oxide emissions for a spark ignition engine: Results from a thermodynamic cycle simulation:

Abstract: Past experimental work has not provided consistent results for the effects of the compression ratio on nitric oxide emissions. A thermodynamic cycle simulation for spark ignition engines, w...

Development of a low-cost piezo film-based knock sensor

Abstract: It is well known that spark advance is a key parameter in spark ignition engine manage- ment. Increasing fuel cost and emission regulation strictness require a higher engine eA ciency, which can be improved by an accurate regulation of the spark advance. Under high load conditions, an optimal spark advance choice leads the engine to run next to the knock limit, so the management and control system needs to be equipped with a knock sensor in order to preserve the engine from damage. The authors developed a low-cost knock sensor whose sensing element is a thin washer of polyvinylidine e uoride (PVDF), a e uoropolymer characterized by a great piezoelectric eA ect if polar- ized. The sensor has been tested on a spark ignition CFR engine (the standard single-cylinder test engine used by ASTM for octane number determination of spark ignition engine fuel) and compared with a commercial accelerometer and a pressure sensor, in terms of knocking detection capability, measured knock intensity (KI) and signal-to-noise ratio (SNR). Knocking tests have also been carried out on a Renault series production engine. The collected data show that PVDF ensures a reliable detection of knock, a precise measurement of knock energy and accurate information about the frequency content of the perceived vibration. The sensor worked for several hours without depolariz- ing and, above all, owing to the great piezoelectric eA ect of PVDF, the use of a charge amplie er was unnecessary. PVDF proved to have great potential as a knock detector in spark ignition engines at a very low cost.

Method and device for detecting sparking and spark erosion in electric machines

Abstract: The invention relates to a method and device for detecting spark activity in an electric machine. The shaft voltage (Us(t)) and/or the shaft current (Is(t)) are measured and characteristic components are analyzed in order to detect spark activity. The inventive method, which utilizes respective shaft currents which are mainly considered to be harmful, is precise and suitable for long-term monitoring of spark activities such as sparking, spark erosion, and spark discharges between parts of shaft bearings. Said method can be carried out in a constructively simple and reliable manner using available earthing devices.

The spark of Enlightenment

Abstract: of direction.” Our Own Devices is even more insightful and provocative than Tenner’s earlier book in illuminating how contemporary technology changes us as much as we change it. Tenner has become a worthy successor to such luminaries as business philosopher Peter Drucker, social critic Lewis Mumford and historian Lynn White in connecting technology’s past, present and future. ■ Howard P. Segal is in the Department of History, University of Maine, Orono, Maine 04469-5774, USA.

Material transport in a low-inductance vacuum spark

Abstract: The transport processes and the parameters of material flows in a low-inductance vacuum spark excited in a medium produced by erosion of the electrodes are investigated.

Cylinder pressure for control purposes of spark ignition engines

Abstract: From the very beginning of .intcmal combustion engines, the measurement and analysis of the cylinder pressure has been reported. However, the use of this information was limited to research and development for several reasons, namely the insufficient reliability, the price of the sensors and the computational cost of the calculations required for an analysis of the measured cylinder pressure. In contrast, recently developed cylinder pressure sensors are rugged, and the price of the sensors has become such that their use within production type engines seems to be viable at reasonable costs. Additionally, due to the increased computing power now available, applications of the cylinder pressure information for control of combustion engines are currently getting more attention. The main result of this thesis is the development of a method for the estimation of the air mass in the cylinder of a spark ignited combustion engine. The method developed considers the application needs. Apart from the cylinder pressure information, only the engine speed and the temperature in the inlet manifold is required. To allow for an easy applicability to different engines, the method developed is strictly model-based. Since the calculations required are relatively simple, a real time application is considered feasible. The error of the air mass estimation described in this work is less than ±5%. Thus, the accuracy of this method is quite comparable to the accuracy achievable with production type air mass flow meters. Due to the model-based character of the algorithm developed, a cylinder individual estimation of the air/fuel ratio and of the external exhaust gas recirculation ratio is possible as weIl.

Method for manufacturing spark plug and apparatus for manufacturing spark plug

Abstract: A method and apparatus for manufacturing a spark plug which avoids depth insufficiency of the weld metal portion or thickness insufficiency of the spark portion and which thus enhances the weld strength and service life of the spark portion. According to the method, a noble metal chip is attached to a chip joint face formed on a distal end of a center electrode of a spark plug workpiece, along the direction of the longitudinal axis of the workpiece, so as to form a chip-attached assembly. The chip-attached assembly is irradiated with a laser beam LB so as to form a laser-beam weld metal portion intruding into the noble metal chip and into the chip joint face, thereby forming a noble-metal spark portion having a discharge face. The position of the chip joint face of the center electrode as viewed along the direction of the longitudinal axis is detected, and on the basis of the detected position, the position of irradiation with the laser beam on the chip-attached assembly along the direction of the longitudinal axis is adjusted.

Power supply device and method having a spark prevention function

Abstract: Disclosed is power supply device and method having a spark prevention function. The power supply device having a spark prevention function includes output connectors to which an external device is coupled to be supplied with electric power; and an output controller for controlling a level of a voltage outputted to the output connectors depending upon whether the external device is coupled to the output connectors. Accordingly, damages to parts and malfunctions due to spark occurrences can be prevented, so an external device can be coupled to a power supply device in operation without any damage.

Densification rate of Cu-Al2O3 composite in the spark sintering process

Abstract: The densification rate of CuAl2O3 composite was measured and analyzed to investigate the influences of the alumina particles addition on the densification process in the spark sintering process. The consolidation of Cu10~50 volAl2O3 composites proceeds due to the plastic flow of copper powder compact matrix. The effect of the alumina particles on the spark sintering of composites was analyzed based on the following equation, including the increase of relative density of composite compact, D-D0, that of copper (Dcc-D0) and alumina (Dalal-D0) and the particle contact probability of ``coppercopper'' ((1-Vp)), ``copperalumina''(2Vp(1-Vp)) and ``aluminaalumina'' (Vp). (D-D0)={(1-Vp)+2hVp(1-Vp)}(Dcc-D0)+Vp(Dalal-D0) where h is a ratio of the relative density increase at ``copperalumina'' particle contacts to that at ``coppercopper'' particles contacts, and h≦1. Moreover, D, Dcc and Dalal are the relative density of composite compact, copper and alumina at a given temperature and pressure, respectively, and Vp is the volume fraction of added alumina particles.

Control method for internal combustion engine

Abstract: PROBLEM TO BE SOLVED: To improve the transient responsiveness of an engine as an internal combustion engine with a turbo charger during acceleration while controlling an intake valve to be closed with a delay to achieve a higher expansion ratio. SOLUTION: In the engine 1 as the internal combustion engine with the turbo charger 8, the intake valve 41 is controlled to be closed with a delay to achieve a higher expansion ratio. When a transient condition is found out, a target spark advance amount of the intake valve 41 at a closing timing is determined corresponding to the transient condition, a spark timing is delayed by a preset spark delay amount, and the spark advance amount of the intake valve 41 at the closing timing is controlled to be set as a preset spark advance amount AA greater than a target spark advance amount A and as the target spark advance amount A thereafter. COPYRIGHT: (C)2005,JPO&NCIPI

Cylinder event based spark

Abstract: A method to deliver spark during a start for an internal combustion engine is described. The method provides individual cylinder spark angle control based on the number of fueled cylinder events. The method offers improved engine emissions while maintaining engine speed run-up performance.

Investigation of the effect of double ignition on the combustion processes in a 2-valves gasoline engine through 3D simulation

Abstract: In this study, the ability of 3D engine computation to take into account the effects of double spark ignition in a small size 2-valves gasoline engine has been investigated. The KIVA-II GSM code has been used, in combination with the AKTIM spark ignition model and the ECFM premixed combustion model. Comparisons of the combustion processes using one or two spark plugs have been made at partial load, using different EGR concentrations and spark timings. A careful post-processing of the flame surface fields leads to a complete understanding of the balance between gain and losses relative to the double ignition strategy. For a low EGR concentration, IMEP gains expected for the double ignition appear to be rather weak, partly due to an early merging of the two flame fronts. Thus, despite radically different instantaneous combustion scenarios, the resulting motoring work remains close to the single spark case. Thermal losses analysis brings further insight into this gains and losses balance. However, at higher EGR concentration and earlier corresponding spark timings, gains linked with double ignition become higher, because the presence of a second spark plug corrects a weakness in the development of the flame front issued from the serial spark plug, keeping the global combustion speed to an acceptable level. NOx formation for the different strategies has also been analyzed and linked to the local flame propagation processes and burnt gases temperatures.

Reason Analysis for Continuous Spark in Current Collection of Catenary-pantograph System

Abstract: This paper describes the analysis of continuous spark in current collection of catenary-pantograph system based on the data measured on some test lines. The reasons caused this phenomena are non-matching in the fluctuation and vibration of catenary-pantograph system, irregularity of contact wire, uneven rigidness of contact wire, unequal height of contact wire at droppers. In order to reduce spark between contact wire and pantograph, some methods are put forward.