| 1. |
- Thaduri, Adithya, et al.
(författare)
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Failure modeling of constant fraction discriminator using physics of failure approach
- 2013
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Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 20:3
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Tidskriftsartikel (refereegranskat)abstract
- Due to several advancements in the technology trends in electronics, the reliability prediction by the constant failure methods and standards no longer provide accurate time to failure. The physics of failure methodology provides a detailed insight on the operation, failure point location and causes of failure for old, existing and newly developed components with consideration of failure mechanisms. Since safety is a major criteria for the nuclear industries, the failure modeling of advanced custom made critical components that exists on signal conditioning module are need to be studied with higher confidence. One of the components, constant fraction discriminator, is the critical part at which the failure phenomenon and modeling by regression is studied in this paper using physics of failure methodology.
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| 2. |
- Thaduri, Adithya, et al.
(författare)
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Reliability prediction of semiconductor devices using modified physics of failure approach
- 2013
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Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer Science and Business Media LLC. - 0975-6809 .- 0976-4348. ; 4:1, s. 33-47
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Tidskriftsartikel (refereegranskat)abstract
- Traditional approaches like MIL-HDBK, Telcordia, and PRISM etc. have limitation in accurately predicting the reliability due to advancement in technology, process, materials etc. As predicting the reliability is the major concern in the field of electronics, physics of failure approach gained considerable importance as it involves investigating the root-cause which further helps in reliability growth by redesigning the structure, changing the parameters at manufacturer level and modifying the items at circuit level. On the other hand, probability and statistics methods provide quantitative data with reliability indices from testing by experimentation and by simulations. In this paper, qualitative data from PoF approach and quantitative data from the statistical analysis is combined to form a modified physics of failure approach. This methodology overcomes some of the challenges faced by PoF approach as it involves detailed analysis of stress factors, data modeling and prediction. A decision support system is added to this approach to choose the best option from different failure data models, failure mechanisms, failure criteria and other factors.
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| 3. |
- Thaduri, Adithya, et al.
(författare)
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Stress factor and failure analysis of constant fraction discriminator using design of experiments
- 2013
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Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 20:3
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Tidskriftsartikel (refereegranskat)abstract
- Reliability prediction using traditional approaches were implemented at earlier stages of electronics. But due to advancements in science and technology, the above models are outdated. The alternative approach, physics of failure provides exhaustive information on basic failure phenomenon with failure mechanisms, failure modes and failure analysis becomes prominent because this method depends on factors like materials, processes, technology, etc., of the component. Constant fraction discriminators which is important component in NFMS needs to study failure characteristics and this paper provides this information on failure characteristics using physics of failure approach. Apart from that, the combined physics of failure approach with the statistical methods such as design of experiments, accelerated testing and failure distribution models to quantify time to failure of this electronic component by radiation and temperature as stress parameters. The SEM analysis of the component is carried out by decapsulating the samples and studied the impact of stress parameters on the device layout.
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| 4. |
- Thaduri, Adithya, et al.
(författare)
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Study of reliability aspects in constant fraction discriminator
- 2011
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Ingår i: 5th International Conference on Quality, Reliability and Information Technology (ICQRIT). - Kathmandu. ; , s. 1-7
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Konferensbidrag (refereegranskat)abstract
- Reliability prediction using conventional constant failure models by standard books in early phases of electronics dominates wide acceptance. But after 1980s, there was wide variation in electronic technology which made above models obsolete. Physics of Failure approach provides information on basic failure phenomenon with failure mechanisms and failure modes becomes prominent as it entirely depends on materials, processes, technology etc. Constant fraction discriminators which are failing frequently in the field need to be studied and this paper provides information on failure characteristics using physics of failure approach. Apart from that, we combined statistical methods such as Design of Experiments, Accelerated testing and failure distribution models to quantify time to failure of this electronic component by radiation and temperature as stress parameters.
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| 5. |
- Kumar, Ranjeet, et al.
(författare)
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Comparative analysis of malate synthase G from Mycobacterium tuberculosis and E. coli : Role of ionic interaction in modulation of structural and functional properties
- 2011
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 49:5, s. 917-922
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Tidskriftsartikel (refereegranskat)abstract
- Metabolic plasticity of Mycobacterium renders high degree of adaptive advantages in the persistence through the upregulation of glyoxylate shunt. The malate synthase (MS), an important enzyme of the shunt belongs to the G isoform and expressed predominantly as monomer. Here we did a comparative unfolding studies of two homologous MS from Mycobacterium tuberculosis (MtbMS) and Escherichia coil (ecMS) using various biophysical techniques. Despite having high sequence identities, they show different structural, stability and functional properties. The study suggests that the differences in the stability and unfolding of the two enzymes are by virtue of differential electrostatic modulation unique to their respective molecular assembly.
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| 6. |
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| 7. |
- Romanos, Jihane, et al.
(författare)
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Improving coeliac disease risk prediction by testing non-HLA variants additional to HLA variants
- 2014
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Ingår i: Gut. - : BMJ. - 0017-5749 .- 1468-3288. ; 63:3, s. 415-422
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The majority of coeliac disease (CD) patients are not being properly diagnosed and therefore remain untreated, leading to a greater risk of developing CD-associated complications. The major genetic risk heterodimer, HLA-DQ2 and DQ8, is already used clinically to help exclude disease. However, approximately 40% of the population carry these alleles and the majority never develop CD. OBJECTIVE: We explored whether CD risk prediction can be improved by adding non-HLA-susceptible variants to common HLA testing. DESIGN: We developed an average weighted genetic risk score with 10, 26 and 57 single nucleotide polymorphisms (SNP) in 2675 cases and 2815 controls and assessed the improvement in risk prediction provided by the non-HLA SNP. Moreover, we assessed the transferability of the genetic risk model with 26 non-HLA variants to a nested case-control population (n=1709) and a prospective cohort (n=1245) and then tested how well this model predicted CD outcome for 985 independent individuals. RESULTS: Adding 57 non-HLA variants to HLA testing showed a statistically significant improvement compared to scores from models based on HLA only, HLA plus 10 SNP and HLA plus 26 SNP. With 57 non-HLA variants, the area under the receiver operator characteristic curve reached 0.854 compared to 0.823 for HLA only, and 11.1% of individuals were reclassified to a more accurate risk group. We show that the risk model with HLA plus 26 SNP is useful in independent populations. CONCLUSIONS: Predicting risk with 57 additional non-HLA variants improved the identification of potential CD patients. This demonstrates a possible role for combined HLA and non-HLA genetic testing in diagnostic work for CD.
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| 8. |
- Singh, Bhupender L., et al.
(författare)
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Cefuroxime axetil loaded solid lipid nanoparticles for enhanced activity against S. aureus biofilm
- 2014
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 121, s. 92-98
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Tidskriftsartikel (refereegranskat)abstract
- The present research work is focused on the development of solid lipid nanoparticles of cefuroxime axetil (CA-SLN) for its enhanced inhibitory activity against Staphylococcus aureus produced biofilm. CA-SLN was prepared by solvent emulsification/evaporation method using single lipid (stearic acid (SA)) and binary lipids (SA and tristearin (TS)). Process variables such as volume of dispersion medium, concentration of surfactant, homogenization speed and time were optimized. The prepared SLN were characterized for encapsulation efficiency, drug polymer interaction studies (DSC and FT-IR), shape and surface morphology (SEM and AFM), in vitro drug release, stability studies and in vitro anti biofilm activity against S. aureus biofilm. Among the process variables, increased volume of dispersion medium, homogenization speed and time led to increase in particle size whereas increase in surfactant concentration decreased the particle size. SLN prepared using binary lipids exhibited higher entrapment efficiency than the single lipid. DSC and FT-IR studies showed no incompatible interaction between drug and excipients. CA-SLN showed two folds higher anti-biofilm activity in vitro than pristine CA against S. aureus biofilm.
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| 9. |
- Thaduri, Adithya, et al.
(författare)
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Two-stage design of experiments approach for prediction of reliability of optocouplers
- 2012
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Ingår i: International Journal of Reliability, Quality and Safety Engineering (IJRQSE). - 0218-5393. ; 19:2
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Tidskriftsartikel (refereegranskat)abstract
- Conventionally, reliability prediction of electronic components is carried out using standard handbooks such as MIL STD 217 plus, Telcordia, etc. But these methods fail to provide a realistic estimate of reliability for upcoming technologies. Currently, electronic reliability prediction is moving towards applying the Physics of Failure approach which considers information on process, technology, fabrication techniques, materials used, etc. Industries employ different technologies like CMOS, BJT and BICMOS for various applications. The possibility of chance of failure at interdependencies of materials, processes, and characteristics under operating conditions is the major concern which affects the performance of the devices. They are characterized by several failure mechanisms at various stages such as wafer level, interconnection, etc. For this, the dominant failure mechanisms and stress parameters needs to be identified. Optocouplers are used in input protection of several instrumentation systems providing safety under over-stress conditions. Hence, there is a need to study the reliability and safety aspects of optocouplers. Design of experiments is an efficient and prominent methodology for finding the reliability of the item, as the experiment provides a proof for the hypothesis under consideration. One of the important techniques involved is Taguchi method which is employed for finding the prominent failure mechanisms in semiconductor devices. By physics of failure approach, the factors that are affecting the performance on both environmental and electrical parameters with stress levels for optocouplers are identified. By constructing a 2-stage Taguchi array with these parameters where output parameters decides the effect of top two dominant failure mechanisms and their extent of chance of failure can be predicted. This analysis helps us in making the appropriate modifications considering both the failure mechanisms for the reliability growth of these devices. This paper highlights the application of design of experiments for finding the dominant failure mechanisms towards using physics of failure approach in electronic reliability prediction of optocouplers for application of instrumentation
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