Improving the new product/service introduction process by the application of system dynamics

The development and marketing of new products and services are amongst the most powerful weapons that organisations can'use in order to survive and prosper under turbulent global market conditions. The successful introduction of a new product or service can assist an organisation to remain competitive by being able to sufficiently address the continuously changing market requirements. Therefore, the process of New Product / Service Introduction (NP/SI) constitutes a crucial activity for every organisation. In an environment of ever shortening product life cycles, increased customer expectation, technology advancements and increased market competition, the only factor that remains constant within a modem manufacturing operation is change. Such changes are ultimately reflected in the products and the manufacturing processes. One particular type of change apparent within a manufacturing or assembly environment is engineering change (EQ. The changes or modifications in forms, fits, materials, dimensions, functions, etc. of a product or component are usually referred to as ECs. The aims of this thesis were fulfilled by using the technique of System Dynamics (SD) in order to model and simulate the generic structure of the NP/Sl process and to identify ways to improve it. The results of the simulation were also used for developing an Engineering Change Management System which was then modelled by using the same technique of SD. In this attempt, two Greek organisations collaborated by providing data and information in order to investigate the existence of a cost-time-quality relationship throughout the NP/SI process

Localised vibrational mode spectroscopy studies of self-interstitial clusters in neutron irradiated silicon

The evolution of self-interstitial clusters in silicon (Si), produced by fast neutron irradiation of silicon crystals followed by anneals up to 750 degrees C, is investigated using localised vibrational mode spectroscopy. A band at 582 cm(-1) appears after irradiation and is stable up to 550 degrees C was attributed to small self-interstitial clusters (I-n, n <= 4), with the most probable candidate the I-4 structure. Two bands at 713 and 758 cm(-1) arising in the spectra upon annealing of the 582 cm(-1) band and surviving up to similar to 750 degrees C were correlated with larger interstitial clusters (I-n, 5 <= n <= 8), with the most probable candidate the I-8 structure or/and with chainlike defects which are precursors of the 311 extended defects. The results illustrate the presence of different interstitial clusters I-n, at the various temperature intervals of the material, in the course of an isochronal anneal sequence. As the annealing temperature increases, they evolve from first-order structures with a small number of self-interstitials (I-n, n <= 4) for the temperatures 50 < T < 550 degrees C, to second order structures (I-n, 5 <= n <= 8) with a larger number of interstitials, for the temperatures 550 < T < 750 degrees C. (C) 2013 AIP Publishing LLC

The influence of thermal treatments under hydrostatic pressure prior to irradiation on the annealing characteristics of the VO defect in Si

Cz-Si samples, initially subjected to thermal treatments under high hydrostatic pressure, were subsequently irradiated by fast neutrons. This paper describes a series of infrared spectroscopy measurements that enabled us to determine the effect of the pre-treatments on the annealing characteristics of the VO defect in Si. We found that the activation energies of the two main annealing reactions: VO + Oi → VO2 and VO + SiI → Oi that the defect participates, are comparatively smaller than those of initially untreated samples, correspondingly. We argue that the pre-treatments reduce the potential barrier for the migration of the VO defect (VO + Oi → VO2) and also reduces the binding energy of the SiI's, bound at large defect clusters (VO + SiI → Oi). © 2008 Elsevier B.V. All rights reserved

Di-interstitial defect in silicon revisited

Infrared spectroscopy was used to study the defect spectrum of Cz-Si samples following fast neutron irradiation. We mainly focus on the band at 533 cm-1, which disappears from the spectra at ∼170 °C, exhibiting similar thermal stability with the Si-P6 electron paramagnetic resonance (EPR) spectrum previously correlated with the di-interstitial defect. The suggested structural model of this defect comprises of two self-interstitial atoms located symmetrically around a lattice site Si atom. The band anneals out following a first-order kinetics with an activation energy of 0.88 ± 0.3 eV. This value does not deviate considerably from previously quoted experimental and theoretical values for the di-interstitial defect. The present results indicate that the 533 cm-1 IR band originates from the same structure as that of the Si-P6 EPR spectrum. © 2013 AIP Publishing LLC

Infrared signals correlated with self-interstitial clusters in neutron-irradiated silicon

Using infrared spectroscopy we have investigated the defect spectrum of neutron-irradiated Czochralski-silicon (Cz-Si). The study was focused on three weak signals, mainly on a band at 533 cm-1, as well as on two other bands at 582 and 592 cm-1. The band at 533 cm-1 disappears from the spectra at ~170 C exhibiting similar thermal stability with the Si-P6 electron paramagnetic resonance spectrum, previously correlated with a di-interstitial defect. The suggested model for the latter defect, comprising two self-interstitials placed symmetrically a lattice site Si atom, is very similar with that of the allene molecule. This allowed the calculation of the vibrational frequency of the suggested di-interstitial structure giving a value close to the 533 cm-1, in further support of the above assignment. The band at 582 cm-1 is stable up to 550 C. The possible correlation of its origin to large self-interstitial clusters is examined. Also, the origin of the 592 cm-1 band, which is stable up to 200 C is discussed, with indications tentatively pointing to a CV pair. © 2013 Springer Science+Business Media New York

Isochronal annealing studies of carbon-related defects in irradiated Si

We report infrared spectroscopy studies of defects in neutron-irradiated, carbon-doped, Cz-grown silicon. At room temperature irradiations, among the main defects formed are the CiCs and CiOi complexes. A peak in the spectra at 544 cm-1 was found to be the contribution of two bands at 543.5 and 545.5 cm-1. From the corresponding annealing behavior of these bands, the 543.5 cm-1 band was correlated with the CiCs defect although the 544.5 cm-1 band with the CiOi defect. At high-irradiation doses, complexes as the Ci(SiI) (953,960cm-1), CiOi(SiI)(934,1018cm-1), CiCs(SiI)(987,993cm-1) and CsCs(527cm-1) form. Isochronal anneals performed in order to study the thermal evolution of these centers, showed that the Ci(SiI) and CiOi(SiI) begin to decay in the spectra around 150 °C. Their disappearance is not accompanied by the emergence of any signal. The CiCs and the CiCs(SiI) centers begin to decay around ∼250°C. Their disappearance is accompanied by the emergence of two pairs of bands at (918,1006cm-1) and (945,964cm-1), respectively. The origin of the centers, giving rise to these bands is discussed. © 2005 Elsevier B.V. All rights reserved

Infrared absorption spectra of defects in carbon doped neutron-irradiated Si

Experimental data of infrared (IR) absorption measurements carried out on fast neutron irradiated carbon rich Cz-Si crystals were studied. Data from similar crystals, subjected prior to irradiation to thermal treatments at 1000 °C [(HT)] and thermal treatments at 1000 °C under high hydrostatic pressure [(HTHP)] of 11Kbar, were also studied. The time duration of both treatments was 5 h. After the irradiation the intensities of most of the observed bands were always stronger in the pre-treated material. Transformation of the defects upon post-irradiation isochronal anneals was investigated. Two out of six IR bands of the C iC s defect in the neutral charge state, at 543.5 and 635 cm -1, were detected at room temperature [(RT)]. It is argued that another two bands at 918 and 1006 cm -1 arising in the spectra upon annealing of the C iC s bands are associated with the same carbon-related structure giving rise to the Si-PT4 electron paramagnetic resonance (EPR) spectrum. A band at 533 cm -1 shows the same thermal evolution with a defect giving rise to the Si-P6 EPR spectrum attributed to a multi-interstitial cluster in silicon. Differences observed in the evolution curves of the C iC s (Si I) defect (987, 993 cm -1) between the as-grown and the pre-treated samples are considered and discussed. © Springer Science+Business Media, LLC 2007

The effect of thermal treatments on the annealing behaviour of oxygen-vacancy complexes in irradiated carbon-doped silicon

Cz-grown, carbon-doped silicon samples were irradiated by fast neutrons. We investigated the annealing behaviour of oxygen-related defects, by infrared spectroscopy. We studied the reaction channels leading to the formation of various VmOn defects and in particular the VOn defects formed by the accumulation of oxygen atoms and vacancies in the initially produced by the irradiation VO defects, as the annealing temperature ramps upwards. We mainly focused on bands appearing in the spectra above 450 degrees C. A band at 1005 cm(-1) is found to be the convolution of two bands at 1004 and 1009 cm(-1). The latter band has the same thermal stability with the 983 cm(-1) of the VO4 defect and therefore is also attributed to this defect. The former band has the same thermal stability with three other bands at 965, 1034 and 1048 cm(-1). These four bands may be attributed to VOn (n=5,6) defects, although other VmOn complexes are also potential candidates. Furthermore, we found that pre-treatments of the samples at 1000 degrees C, with or without the application of high hydrostatic pressure lead to an increase in the concentration of the VO2, VO3 and generally VOn defects in comparison with that of the untreated samples

The effect of thermal treatments on the annealing behaviour of oxygen-vacancy complexes in irradiated carbon-doped silicon

Cz-grown, carbon-doped silicon samples were irradiated by fast neutrons. We investigated the annealing behaviour of oxygen-related defects, by infrared spectroscopy. We studied the reaction channels leading to the formation of various VmOn defects and in particular the VOn defects formed by the accumulation of oxygen atoms and vacancies in the initially produced by the irradiation VO defects, as the annealing temperature ramps upwards. We mainly focused on bands appearing in the spectra above 450°C. A band at 1005 cm-1 is found to be the convolution of two bands at 1004 and 1009 cm-1. The latter band has the same thermal stability with the 983 cm-1 of the VO4 defect and therefore is also attributed to this defect. The former band has the same thermal stability with three other bands at 965, 1034 and 1048 cm-1. These four bands may be attributed to VOn (n=5,6) defects, although other VmOn complexes are also potential candidates. Furthermore, we found that pre-treatments of the samples at 1000°C, with or without the application of high hydrostatic pressure lead to an increase in the concentration of the VO2, VO3 and generally VOn defects in comparison with that of the untreated samples