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In the first part of this thesis, the stimulated Raman scattering (SRS) effect in optical time domain reflectometry (OTDR) on-line monitoring fiber transmission systems are investigated. We have investigated the distortion of baseband video picture arising from the 1.65 £gm OTDR-induced SRS effect in 1.55 £gm amplitude modulation with vestigial sideband (AM-VSB) cable television (CATV) transmission system. The baseband video-picture distortion in appearance with ¡§faintly white horizontal thins lines¡¨ on the TV picture is observed. The baseband video-picture distortion disappearing is demonstrated in the 1.31 £gm OTDR on-line monitoring 1.55

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2005. / Härtill 6 uppsatser.

Växjö kommuns mål är att minska sin miljöpåverkan från fossila bränslen och ett steg i detta är den samordnade varudistributionen. Rapportens fokus är inriktat på returhanteringen av SRS-backar som ingår i den samordnade varudistributionen.  Rapporten redogör för hur processen för returhanteringen av SRS-backar ser ut vid en samordnad varudistribution i Växjö kommun. Underlag för en processkartläggning insamlades genom semi-strukturerade intervjuer och kartläggningen genomfördes i analysen.  I en samordnad varudistribution där flera olika aktörer ingår och vill få sin röster hörda uppstår det problem. Rapporten ämnar utöver att beskriva processens utseende, även att redogöra för dessa problem. Problemen som upplevs i nuläget för respektive aktör är säkerhetsrisker på grund av kvarlämnade SRS-backar på de kommunala enheternas lastkajar enligt logistikhandläggaren vid Växjö kommun, extra transport samt lagerhållningskostnader för Växjö Partiaffär, identifikationssvårigheter för Scandinavian Supply Chain. För att skapa en problembild utfördes semi-strukturerade intervjuer samt mejlintervjuer.  Rapporten avslutas med att behandla olika förbättringsmöjligheter för att lösa aktörernas upplevda problemen genom analys av litteraturstudier samt empirisk insamlat underlag. De förbättringsmöjligheter som analyserats är RFID, olika metoder inom ruttplanering samt nyckeltal för uppföljning.

Space equipment is often subjected to mechanical shocks. Some devices like electronics are sensitive to shocks, and they can easily be damaged. To protect these devices, it is important to study shock penetrations in space structures. The Finite Element Method is an effective tool to simulate response to transient excitations. Unlike Statistical Energy Analysis (SEA) which can ensure sufficient accuracy in high frequency range, Finite Element Analysis (FEA) is limited to low frequency range, but has no spatial restrictions. In this thesis, Tuma’s digital filter method and Irvine’s recursive digital method were combined to calculate the Shock Response Spectrum (SRS). FEA models based on a given experimental system, i.e., shock table were used to predict the structural response to Haversine shaped forces. The modal transient structural analysis in ANSYS Workbench was used as the solver. Transient analysis based on modal results neglects material and structural non-linearities, so it uses less memory and computation time. FEA and the Bernoulli beam equation were employed to simulate the shock response of cantilever beams and fixed-pinned beams to validate the FEA models. SRS calculated from FEA results were compared with those from the beam equation results. Almost no difference between Bernoulli beam equation results and FEA results for thin beams reveals that the FEA models were validated. The SRS of two beam models calculated from FEA using solid elements were compared with those using beam elements. The results from two different element types are almost consistent with each other. Response at different positions on the shock table were measured to predict the shock attenuation. The attenuation was described in the way of remaining percentage from shock source, and the curve from FEA simulation roughly agreed with the attenuation rule from the ESTEC database. / Rymdutrustning utsätts ofta för mekaniska stötar, s.k. mekanisk chock. Vissa enheter, som elektronik, är känsliga för stötar och de kan lätt skadas. För att skydda dessa enheter är det viktigt att studera chockdämpningen i rymdstrukturer. Finita elementmetoden är ett effektivt verktyg för att simulera responsen vid transienta excitationer. Till skillnad från statistisk energianalys (SEA) som kan säkerställa tillräcklig noggrannhet i högfrekvensintervall, är finit elementanalys (FEA) begränsad till lågt frekvensområde, men har inga rumsliga begränsningar. I detta examensarbete kombinerades Tumas digitala filtermetod och Irvines rekursiva digitala metod för att beräkna Chockresponsspektrum (SRS). FEA-modeller baserade på ett givet experimentellt system, d.v.s. chockbord, användes för att förutsäga den strukturella responsen på Haversine-formade krafter. Den modala transienta strukturanalysen genomfördes med ANSYS Workbench. Den transienta analysen baserad på modala resultat försummar icke-linjäriteter i material och struktur för att använda mindre minne och förkorta beräkningstiden. FEA och Bernoulli-balkekvationen användes för att simulera chockresponsen av konsolbalkar och balkar med fast inspänning i ena änden och fri uppläggning i den andra änden, för att validera FEA-modellerna. SRS beräknat från FEA-resultaten jämfördes med resultat från balkekvationen. Ingen avgörande skillnad noteras mellan Bernoullis balkekvationsresultat och FEA-resultat för tunna balkar, vilket validerar FEA-modellerna. SRS för två balkmodeller beräknade från FEA med solida element jämfördes med de som använde balkelement. Resultaten från de två olika elementtyperna överensstämmer mycket bra. Responsen vid olika positioner på chockbordet mättes för att förutsäga chockdämpningen. Chockdämpningen beskrivs som kvarvarande procent av responsen vid chockkällan och kurvan från FEA-simulering överensstämde ganska bra med tumregeln för chockdämpning från ESTEC-databasen.

The purpose of this dissertation is to advance the understanding of SrS-based a. c. thin film electroluminescent (ACTFEL) devices. The role of traps in the bulk phosphor layer in the light emission mechanism from ACTFEL devices is studied, characterized and modeled. Experiments were performed to observe the response of the ACTFEL devices to tailored voltage excitations. A physical model was developed to describe the optoelectronic processes taking place in the phosphor; analytical equations were written and numerically simulated to plot the flux and luminance responses of the device to similarly tailored voltage excitations. The voltage excitation parameters such as amplitude, rise times and fall times were varied both experimentally and in simulations and their effect on the opto-electronic response of the device was studied. Thermally stimulated luminance studies were performed to determine critical device parameters. Theoretical predictions matched the experimental data in a qualitative manner. A much improved quantitative accuracy is obtained when the role of dipoles in the EL mechanisms is incorporated into the model.

The a. c. thin film electroluminescent (ACTFEL) devices are of scientific interest due to their applications in large area, flat panel displays. Of particular interest to the research community is the mechanism of electron transport and luminance in these devices. Toward this end, a physical model and a mathematical model for SrS:Cu ACTFEL Devices were developed and published earlier by our group. The purpose of this thesis is to obtain a qualitative and quantitative match between experiment and theory. A brief summary of the model can be found here [1]. Effects of variation in drive parameters in experimental steady state measurements, and analysis of VIL (Voltage-Current-Luminance) plots for different simulated device and drive parameters are performed. The effects of voltage amplitude, activator concentration, interface energy levels, and critical field for dipole collapse were studied. The plots matched qualitatively in that all major experimental features were produced in the simulated waveforms. The measured and the simulated peak currents are 72.5 mA/cm2 and 66.42 mA/cm2 for VA = 123 V. Experimental and theoretical charge transferred per pulse were 2.75 C/cm2 and 2.26 C/cm2. Peak experimental and simulated luminance values for VA = 123 V were 531 cd/m2 and 49150 cd/m2. Total experimental and simulated luminance values for VA = 123 V case were 6.2 cd/m2 and 561.2 cd/m2 respectively. The large difference is attributed to the loss factors such as optical losses (due to total internal reflection), scattering of electrons by impurities in the bulk phosphor layer, and concentration quenching; these have not been incorporated in the model yet.

The purpose of this thesis is to contribute to the understanding of SrS based ACTFEL devices. Better understanding of the processes in the host phosphor will give us the possibility to design more efficient blue emitting ACTFEL devices. Towards this aim, a physical model, that describes the optoelectronic processes taking place in the phosphor, was developed and analytical equations were written. The analytical model was numerically simulated and the plots of flux flowing through the device and luminance output by the device were obtained. Experiments were performed to obtain the plots of current flowing through the device and luminance output by the device. These plots were then qualitatively compared and the results of comparisons are presented. The numerical simulations qualitatively verify the accuracy of the model. The drive parameters were varied in order to study its effect on the VIL characteristics of the device. On varying the voltage applied to the device and its rise and fall times, a good insight was obtained into device behavior. Simulations were also performed to obtain responses to qualitatively match the experimentally obtained responses. Various What-If scenarios have been studied by varying the device parameters. These studies have indicated the importance of these parameters in determining device performance.

Presently in ground vehicle industries, conducting durability tests with a high acceleration factor have become increasingly demanding for the less time and cost involvement. In the previous work, to accelerate the field test, the standard ‘test tailoring’ approach has been modified due to the requirement of high acceleration factors and the limitations of testing implementation. In this study, a computer-aided testing method is developed for the validation of this modified approach. Hence, a new test-piece has been designed by a conjugative approach involving the finite element technique and fatigue analysis. Afterwards, the accelerated durability loading profiles synthesized via the modified approach have been applied on the designed test-piece and the fatigue life has been simulated to verify the effectiveness of those loading profiles. Simulation results show that loading profiles with an acceleration factor up to 330 can be successfully generated with an accuracy of 95% by this modified approach.

Presently in ground vehicle industries, conducting durability tests with a high acceleration factor have become increasingly demanding for the less time and cost involvement. In the previous work, to accelerate the field test, the standard ‘test tailoring’ approach has been modified due to the requirement of high acceleration factors and the limitations of testing implementation. In this study, a computer-aided testing method is developed for the validation of this modified approach. Hence, a new test-piece has been designed by a conjugative approach involving the finite element technique and fatigue analysis. Afterwards, the accelerated durability loading profiles synthesized via the modified approach have been applied on the designed test-piece and the fatigue life has been simulated to verify the effectiveness of those loading profiles. Simulation results show that loading profiles with an acceleration factor up to 330 can be successfully generated with an accuracy of 95% by this modified approach.