Influence of plasma-assisted ignition on flame propagation and performance in a spark-ignition engine

Lean-burn is an attractive concept for reasons of high thermal efficiency and low nitrogen oxide (NOx) emissions, however, successful implementation in spark-ignition (SI) engines turned out to be challenging because of misfire or partial burn caused by attenuated flame propagation. In order to overcome this issue, microwave-assisted plasma ignition system (MAPIS) has been applied in combustion systems. The MAPIS consists of a conventional ignition coil, a non-resistor spark plug, a mixing unit, a waveguide, and a magnetron (2.45GHz, 3kW). A series of experiments was carried out to understand discharge characteristics and to validate its performance in a constant volume vessel as well as in a single-cylinder spark-ignition engine. The fundamental investigation based on optical emission spectroscopy and flame imaging showed that the ejection of the microwave was beneficial to produce more reactive species such as OH and O radicals thanks to higher electron temperature than conventional spark ignition. The lean limit was able to be extended up to an equivalence ratio of 0.5 based on a larger initial flame kernel size with MAPIS in the vessel test. Meanwhile, in the engine test, combustion stability was noticeably improved showing smaller cycle-to-cycle fluctuations in in-cylinder pressure. Improvement in fuel efficiency up to 6% could be achieved by stable operation under fuel-lean conditions. In terms of emissions, MAPIS was advantageous to reduce carbon monoxide (CO) emissions by promoting more complete combustion

Spatio-temporally Resolved Emission Spectroscopy of Inductive Spark Ignition in Atmospheric Air Condition

Current transistorized coil ignition (TCI) system consists of ignition coil and spark plug, whose electrical properties, structure and gas composition determine entire discharge processes and therefore the early stage of combustion. In this work, a new measurement and diagnostic technique were developed and tested to investigate the early phases of spark ignition process. The spark discharge of commercial TCI system was analyzed by using spatio-temporally resolved optical emission spectroscopy to find out the Interrelation of the characteristic evolution of discharge with the formation of reactive species inside the activated volume. The emission spectra of inductive spark discharge in atmospheric air were measured at the range of wavelength from 300 to 800 nm, while the secondary voltage and current of spark ignition system were acquired simultaneously. An optical probe with linearly arranged glass fiber bundle was used to achieve spatial distribution of emission intensity vertically along the electrode gap of spark plug. At the same time, the time series of emission spectra were illustrated by using the precise gate shift operation of intensified CCD camera mounted on the spectrograph. The emission of electronically excited species such as molecular nitrogen, atomic oxygen and electrode material were effectively measured with the spectral resolution of 0.2 nm. During the abrupt increase of current in breakdown phase, only molecular nitrogen emission was exclusively detected. It was followed by the atomic oxygen and electrode material, which are closely related to the flame initiation and electrode wear respectively. The activated volume of spark discharge near cathode showed higher emission intensity for all the aforementioned species in comparison with the region near anode. The electronic, vibrational and rotational temperatures of the discharge were calculated by using additional spectra measurement at selective wavelength range with spectral resolution of 0.1 nm. Alongside the calorimetric measurement, the temperature profile over position and time allowed the quantitative evaluation of energy-transfer efficiency of spark discharge into the gas mixture

Influence of the Electrical Parameters of the Ignition System on the Phases of Spark Ignition

Untersucht wurde der Einfluss der Kapazität auf das Spektrum der Funkenzündung. Im Mittelpunkt der Untersuchung standen die Spektren von N2 bei 337nm, N2+ bei 391nm, N bei 500nm und O bei 777nm. Dabei wurde ein Zündfunken mit verschiedenen, unmittelbar vor der Zündkerze, montierten Kapazitäten zeitlich abgetastet. Dabei konnte vor allem eine starke Erhöhung der kapazitiv gespeisten Bogenentladung beobachtet werden. Diese resultiert in eine Erhöhung der Nickelemission im Gas. Die 2. pos. Gruppe von Stickstoff bei 337nm weist in dem kapazitiven Bogen eine höhere Intensität auf sobald die Kapazität wächst. Zusätzlich zeigt das Spektrum der 1. neg. Gruppe von Stickstoff bei 391nm erst zum Einsetzen der Glimmentladung eine hohe Leuchterscheinung welche sich auf die Kathode beschränkt. Des Weiteren konnte atomarer Stickstoff nur im Bereich des Durchbruchs und der kapazitiven Bogenentladung gefunden werden. Bei atomarem Sauerstoff konnte eine Reduktion der Emission beobachtet werden

Nondestructive discrimination of Bell states between distant parties

Identifying Bell state without destroying it is frequently dealt with in nowadays quantum technologies such as quantum communication and quantum computing. In practice, quantum entangled states are often distributed among distant parties, and it might be required to determine them separately at each location, without inline communication between parties. We present a scheme for discriminating an arbitrary Bell state distributed to two distant parties without destroying it. The scheme requires two entangled states that are pre-shared between the parties, and we show that without these ancillary resources, the probability of non-destructively discriminating the Bell state is bounded by 1/4, which is the same as random guessing. Furthermore, we demonstrate a proof-of-principle experiment through an IonQ quantum computer that our scheme can surpass classical bounds when applied to practical quantum processor.Comment: 9 pages including Appendix, 7 figures and 2 table

Quantum secure learning with classical samples

Studies addressing the question “Can a learner complete the learning securely?” have recently been spurred from the standpoints of fundamental theory and potential applications. In the relevant context of this question, we present a classical-quantum hybrid sampling protocol and define a security condition that allows only legitimate learners to prepare a finite set of samples that guarantees the success of the learning; the security condition excludes intruders. We do this by combining our security concept with the bound of the so-called probably approximately correct (PAC) learning. We show that while the lower bound on the learning samples guarantees PAC learning, an upper bound can be derived to rule out adversarial learners. Such a secure learning condition is appealing, because it is defined only by the size of samples required for the successful learning and is independent of the algorithm employed. Notably, the security stems from the fundamental quantum no-broadcasting principle. No such condition can thus occur in any classical regime, where learning samples can be copied. Owing to the hybrid architecture, our scheme also offers a practical advantage for implementation in noisy intermediate-scale quantum devices