This report documents an MSc Thesis work of sub-transmission reliability study using PSS/Eperformed at Vattenfall. The network that is examined in this thesis is a sub-transmission network.Vattenfall Distribution Sweden is going to invest and rebuild the network in their 70 and 130 kVmeshed sub transmission network. To invest and rebuild in a network is very expensive. The gridowners want a reliable system that has a high reliability at a low cost.The main focus in this thesis is to examine different substation layouts. Calculating the failureintensities and unavailability for the different substation layouts gives the opportunity to do a life cyclecosts (LCC) on the different substations. With help of LCC calculations it is possible to find thesubstation that gives the lowest cost during a life time. Choosing right equipment in the grid will helpthe Vattenfall network company lower their equipment costs.The thesis work consists of mainly three parts as follows. Network modeling in PSS/EA subset of the existing sub transmission network was used in the project. This subset was taken outfrom the complete network model and modeled in PSS/E. Validation of PSS/E reliability modulesPSS/E reliability modules were new and have not been used earlier by the Vattenfall networkcompany. To be sure that the program calculates correctly a validation was performed. The main focusof the validation has been in looking if the program calculates the interrupted power correctly. Reliability analysis of different substation layoutsFor each of the substation layout the reliability was calculated. On component level (e.g. breaker,disconnector) different types of configuration were studied. To find out the best layout from aneconomical point of view a LCC calculation was also performed.The LCC calculation on the different substation layouts showed that the investment costs affect theresult very much. When the active power through the substation is low it is preferred to use asubstation that has low investment costs. At active power that is 30 MW or higher it is preferred to usethe substation with higher reliability (having higher investment cost). The result shows that using acombined breaker and disconnector instead of circuit breaker could lower the failure intensity andunavailability of substations.

An investigation has been carried out to determine the fundamental reliability unit of copper dual-damascene metallization. Electromigration experiments have been carried out on straight via-to-via interconnects in the lower metal (M1) and the upper metal (M2), and in a simple interconnect tree structure consisting of straight via-to-via line with an extra via in the middle of the line (a "dotted-I"). Multiple failure mechanisms have been observed during electromigration testing of via-to-via Cu interconnects. The failure times of the M2 test structures are significantly longer than that of identical M1 structures. It is proposed that this asymmetry is the result of a difference in the location of void formation and growth, which is believed to be related to the ease of electromigration-induced void nucleation and growth at the Cu/Si₃N₄ interface. However, voids were also detected in the vias instead of in the Cu lines for some cases of early failure of the test lines. These early failures are suspected to be related to the integrity and reliability of the Cu via. Different magnitudes and directions of electrical current were applied independently in two segments of the interconnect tree structure. As with Al-based interconnects, the reliability of a segment in this tree strongly depends on the stress conditions of the connected segment. Beyond this, there are important differences in the results obtained under similar test conditions for Al-based and Cu-based interconnect trees. These differences are thought to be associated with variations in the architectural schemes of the two metallizations. The absence of a conducting electromigration-resistant overlayer in Cu technology allows smaller voids to cause failure in Cu compared to Al. Moreover, the Si₃N₄ overlayer that serves as an interlevel diffusion barrier provides sites for easy nucleation of voids and also provides a high diffusivity path for electromigration. The results reported here suggest that while segments are not the fundamental reliability unit for circuit-level reliability assessments for Al or Cu, vias, rather than trees, might be the appropriate fundamental units for the assessment of Cu reliability. / Singapore-MIT Alliance (SMA)

In many manufacturing companies, large databases containing data on failures and repairs of products are maintained. This paper reports on a case where information from such a database is extracted. Such information extracted could be useful for identifying opportunities for reliability improvements in the products. The database was obtained from a manufacturer of inkjet printers and contains both fixed-format and free-form text fields. At present, techniques developed in data mining and information retrieval are mainly designed to handle either fixed-format or free-form text fields, but not a combination of both. The approach taken in this paper is to first transform the free-form text fields into a number of fixed-format fields through analysis of the frequency of key words. Association analysis was then carried out on the resulting fixed-format fields. Results obtained from the analysis produced a number of associations that could contribute to improving product reliability. / Singapore-MIT Alliance (SMA)

Howard J. Chizeck, Alan S. Willsky. / Bibliography: leaf 2. / Caption title. / Supported in part by the Office of Naval Research under Contract no. N00014-77-C-0224 NASA Ames Research Center Grant NGL-22-009-124

Thesis (Ph.D. (Marketing))--North-West University, Vaal Triangle Campus, 2004.

This research develops yield and reliability models for fault-tolerant semiconductor integrated circuits and develops optimization algorithms that can be directly applied to these models. Since defects cause failures in microelectronics systems, accurate yield and reliability models considering these defects as well as optimization techniques determining efficient defect-tolerant schemes are essential in semiconductor manufacturing and nanomanufacturing to ensure manufacturability and productivity. The defect-based yield model considers various types of failures, fault-tolerant schemes such as hierarchical redundancy and error correcting code, and burn-in effects, simultaneously. The reliability model counts on carry-over single-cell failures accompanied by the failure rate of the semiconductor integrated circuits under the assumption of an error correcting code policy. The redundancy allocation problem, which seeks to find an optimal allocation of redundancy that maximizes system reliability, is one of the representative problems in reliability optimization. The problem is typically formulated as a nonconvex integer nonlinear programming problem that is nonseparable and coherent. Two iterative heuristics, tree and scanning heuristics, and variants are studied to obtain local optima and a branch-and-bound algorithm is proposed to find the global optimum for redundancy allocation problems. The proposed algorithms engage a multiple-search paths strategy to accelerate efficiency. Experimental results of these algorithms indicate that they are superior to the existing algorithms in terms of computation time and solution quality. An example of memory semiconductor integrated circuits is presented to show the applicability of both the yield and reliability models and the optimization algorithms to fault-tolerant semiconductor integrated circuits.

The general aim was to examine the Swedish version of the Philadelphia Geriatric Center Multilevel Assessment Instrument, PGCMAI, in a population of old people with locomotor disability in Sweden. Specific aims were to examine whether the Swedish version of the PGCMAI meets the criteria of reliability and validity when assessing the life situation of Swedish old people with locomotor disability and to explore the pattern of the Swedish version of the instrument in respect of age and gender. Home visits were made to 199 people aged 60 years and older in two counties in Sweden. They were interviewed using the Swedish version of the PGCMAI and tested with the Standardized Practical Equipment test, SPE. The data collected were tested for reliability and validity. Cronbach’s alpha varied from 0.27 to 0.86 among the eight domains of the PGCMAI, which concurred with other studies in the field. Validity was analyzed by explorative factor analysis. The eight new factors showed construct validity with a logical relation to the eight original domain distributions. There were also significant relationships between both the original domains of the PGCMAI and the SPE and the new factors of the PGCMAI and the SPE. Both the original Mobility domain index and the new factor correlated well with the ‘Balance and mobility’ factor in the SPE. The Cognitive domain index and the corresponding new factor show a high correlation with the ‘Cognitive functions’ factor in the SPE. The Swedish version of the PGCMAI and SPE presented a functional pattern among old men and women whereby women had deteriorated most with age, which is in agreement with other studies. In conclusion the reliability and validity testing of the Swedish version of the PGCMAI has given satisfactory results when used with old people with locomotor disability. The Swedish version of the PGCMAI can be considered a valuable tool for measuring function in old people with locomotor disability. / Befolkningen åldras mer och mer, både i Europa och Sverige, som en följd av längre livslängd och låga födelsetal. Det ställer krav på samhällets resurser i form av vård och omsorg för äldre. I en tid när resurserna inte ökar blir det allt viktigare att samhällets stöd fördelas efter behov. I den här studien utvecklades och prövades den svenska versionen av the Philadelphia Geriatric Center Multilevel Assessment Instrument, PGCMAI, på personer 60 år och äldre med rörelsehinder. Instrumentet omfattar åtta huvudsakliga funktionsområden eller domäner, Activities of Daily Living, ADL, Personal Adjustment, PADI, Physical Health, PHDI, Social, SDI, Environmental, EDSI, Time Use, Mobility, MOBI and Cognitive, CDI. Varje område består av frågor som ställs till den enskilde vid en intervju. Originalversionen av instrumentet, på amerikanska, finns i tre varianter eller längder, ’short-length’, ’mid-length’ och ’full-length’. Den svenska versionen av PGCMAI är en översättning och bearbetning av ’mid-length’ varianten. Studiens målgrupp har varit äldre med rörelsehinder. Den har genomförts i tre steg. I det första steget skickades ett frågeformulär till 3469 personer, 60 år och äldre i två geografiska områden i Jönköpings och Värmlands län, där de tillfrågades om de hade något rörelsehinder. Det andra steget innebar att de som rapporterat rörelsehinder, 566 personer, erhöll ett nytt frågeformulär där de bl.a. tillfrågades om svårigheter att förflytta sig och ADL. Det tredje steget innebar att de som besvarade det andra frågeformuläret och accepterade besök i det egna hemmet, 199 personer, intervjuades med PGCMAI och testades med det praktiska testet, Standardized Practical Equipment test, SPE. Det första delarbetet syftade till att utreda om den svenska versionen av PGCMAI fyllde kriterierna för reliabilitet och validitet vid bedömning av livssituationen hos äldre med rörelsehinder i Sverige. Reliabilitet testades med Cronbach’s alpha och visade högre värde för det ursprungliga PGCMAI än för den svenska versionen, med undantag av domänerna EDSI och Time Use. Jämförelse av Cronbach´s alpha mellan äldre med rörelsehinder i den egna studien (n=199) och studie från 1982 av Lawton et al (n=590) visade likheter med högst värde för ursprungsinstrumentets domäner ADL, PADI och CDI, och lägst värde för domän SDI. Den svenska versionen av PGCMAI testades på validitet med exploratorisk faktoranalys av de 40 variabler i PGCMAI som ingick i de ursprungliga domänerna. Faktoranalysen identifierade åtta faktorer som förklarade 47% av variansen. Dessa åtta faktorer visade betydande överensstämmelse med det ursprungliga instrumentets åtta domäner. Högst korrelation med de nya faktorerna visade domänerna EDSI, SDI och ADL. MOBI i originalversionen och motsvarande faktor i den nya versionen visade högst korrelation med ’Balance and mobility’ i SPE, på motsvarande sätt erhölls samband mellan CDI och ’Cognitive functions’ i SPE. Det andra delarbetet hade syftet att undersöka mönstret i den svenska versionen av PGCMAI utifrån ålder och kön samt i jämförelse med andra studier inom området. Materialet analyserades i två och fyra åldersgrupper och indelat i män (n=67) och kvinnor (n=132). Analysen visade att rörelsehinder ökar med ålder både för män och kvinnor. Jämförelse mellan åldersgrupperna 60-79 år, 80-99 år, visa att rörligheten försämrades med ålder enligt domänen MOBI. För kvinnor försämrades förmågan enligt domänerna ADL, Time Use, MOBI, SDI och i alla SPE faktorerna, med ålder. Slutsatsen är att PGCMAI kunde särskilja ett funktionellt mönster bland äldre män och kvinnor med rörelsehinder och en försämring med ålder. SPE visade ett motsvarande resultat. Slutsatsen av studien är att testningen av validitet och reliabilitet på den svenska versionen av PGCMAI har givit tillfredställande resultat när det används på gruppen 60 år och äldre med rörelsehinder. PGCMAI kunde särskilja funktionella mönster hos äldre män och kvinnor och visade att kvinnor med rörelsehinder hade försämrats mest med ålder. SPE visade liknande resultat. Den svenska versionen av PGCMAI bedöms vara ett värdefullt instrument för att mäta funktionen hos äldre med rörelsehinder och kan bli ett viktigt hjälpmedel för att ge rätt insats och i rätt omfattning.

This thesis deals with the reliability and life-time ofelectronic components and ways to determine these factors.Plastic encapsulated and open test circuits were assessed atdifferent humidity and temperature conditions. From the resultsan acceleration factor could be derived using the Arrheniusrelation. This factor is used to determine failure rates atdifferent drift conditions under accelerated test conditions. Aformula for the factor containing both relative humidity andtemperature could be established and was found to hold also formeasurements published by others. Electrostatic discharge (ESD) transients were studiedexperimentally and by simulation with good agreement. A verysensitive method to detect latent failures of two kinds wasintroduced by nonlinearity measurements utilizing the thirdharmonic of a test signal. The ESD-susceptibility dependence ondesign and technology is shown and can be used to improvebuilt-in reliability. Influences in the performance of semiconductor devices fromdefects like fixed charges and ions were interpreted for thefirst time by simulation using a 2D- finite element componentprogram. Significant results gave an application to a MOSFETdevice showing parameter derating, especially the change of thethreshold value. A short description of later development insimulation methods with new, more powerful tools improvingcomponent performance and reliability is given. Charged thin films of Teflon, so calledelectrets, are used as microphone membranes. Theelectret voltage is a suitable reliability factor. Fromexperimental results a mathematical relation including thetemperature was established for the rate of decay of theelectret voltage with time. A method to charge the electretswith radioactive sources is outlined and described in apatent. Finally an attempt was done to analyze the reliability ofthin film circuits by mathematical methods. Bell LabsintroducedRC-feedback filters realized in tantalum thin filmtechnology. The phase shift of the filter is about π or180°. A mathematical apparatus was developed to calculatethe change in frequency and attenuation from small componentvariations in resistors and capacitors. First and higher ordercorrections were derived, using expansion by the Taylor seriesfor the higher order. <b>Keywords:</b>reliability, failure mechanism, accelerationtests, ESD, latent failure, plastic encapsulation, electret,thin film

The Texas Commission on Environmental Quality (TCEQ) uses a Water Availability Modeling System (WAM) to support long-term regional and statewide water resources planning and management. The water availability studies are based on the modeling capabilities of the Water Rights Analysis Package (WRAP). This research improves the understanding of decision support tools for short-term river basin management. Current reservoir storage levels must be considered to assess short-term frequencies and reliabilities. Conditional reliability modeling (CRM) is used to assess the likelihood of meeting targets for instream flow, reservoir storage, water supply diversion and hydroelectric power generation in the near future (next month to next several years), conditioned upon preceding storage. This study uses data for the Brazos River Basin from the TCEQ WAM System to assess key complexities of water supply reliability analysis in general and conditional reliability modeling in particular. These complexities include uncertainties associated with river basin hydrology, estimating yield-reliability relationships for individual reservoirs and multiple reservoir systems, conventional long-term planning versus short-term adaptive management and other modeling and analysis issues. The modeling capabilities of WRAP were expanded to support near real-time operation of dams under various stream flow conditions. The sensitivity to changes in modeling options is assessed for short and long-term simulations. Traditional and newly developed methodologies for estimating firm yields and water supply reliabilities are evaluated. Guidelines are developed regarding the practical application of firm yield analyses and conditional reliability modeling. Important applications of this research include real-time decision support during drought and routinely recurring operational planning activities. A case study of the drought of 2009 uses the CRM features of WRAP for these applications.

The performance of low latency Network on Chip (NoC) architectures, which incorporate fast bypass paths to reduce communication latency, is limited by crosstalk induced skewing of signal transitions on link wires. As a result of crosstalk interactions between wires, signal transitions belonging to the same flit or bit vector arrive at the destination at different times and are likely to violate setup and hold time constraints for the design. This thesis proposes a two-step technique: TransSync- RecSync, to dynamically eliminate packet errors resulting from inter-bit-line transition skew. The proposed approach adds minimally to router complexity and involves no wire overhead. The actual throughput of NoC designs with asynchronous bypass designs is evaluated and the benefits of augmenting such schemes with the proposed design are studied. The TransSync, TransSync-2-lines and RecSync schemes described here are found to improve the average communication latency by 26%, 20% and 38% respectively in a 7X7 mesh NoC with asynchronous bypass channel. This work also evaluates the bit-error ratio (BER) performance of several existing crosstalk avoidance and error correcting schemes and compares them to that of the proposed schemes. Both TransSync and RecSync scheme are dynamic in nature and can be switched on and off on-the-fly. The proposed schemes can therefore be employed to impart unequal error protection (UEP) against intra-flit skewing on NoC links. In the UEP, a larger fraction of the energy budget is spent in providing protection to those parts of the data being transmitted on the link which have a higher priority, while expending smaller effort in protecting relatively less important parts of the data. This allows us to achieve the prescribed level of performance with lower levels of power. The benefits of the presented technique are illustrated using an H.264 video decoder system-on-chip (SoC) employing NoC architecture. We show that for Akyio test streams transmitted over 3mm long link wires, the power consumption can be reduced by as much as 20% at the cost of an acceptable degradation in average peak signal to noise ratio (PSNR) with UEP.