Application of variation risk management processes in commercial aircraft design and manufacture

Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2004.Includes bibliographical references (p. 95-96).Companies and academics have known for many years that reducing variation in production processes can decrease production cost, increase product quality, and have substantial impact on overall profitability. Tools to help companies track, assess, and improve variation are numerous and readily available, but gradually an understanding has emerged from implementing these tools that significant amounts of variation cannot be removed from the factory, and the only way to continue to improve cost and quality beyond diminishing returns is to move upstream in the process and design parts and assemblies that are more variation resistant, or maintain quality functionality over a broader range of variation. One methodology emerging to help companies with this task is Variation Risk Management (VRM). The problem with VRM and other methodologies is that they are often treated as side processes that do not get well integrated into the overall product development process. This results in training and improvement activities that optimize VRM on its own rather than maximizing the effect VRM has on the product. In order to do this the initiative failure cycle must be understood, and attention must be focused on information management, management and organizational support, and process like communication and integration.by Michael A. Parkins.S.M.M.B.A

Development of a low-power wireless acoustic emission sensor node for aerospace applications

Acoustic emission (AE) is the spontaneous release of energy caused by the growth of damage, the monitoring of which gives an indication of the presence of damage within a structure. The current standard for AE localisation is difficult to apply in a low‐power system as sensors must either be wired together or Node's time synchronised, which is power intensive. This paper proposes the use of a method of bonding three piezoelectric sensors in a small triangular array, which has previously been shown by Aljets et al. to be capable of locating sources in simple structures. In this prior work the wave's A0 mode was used to predict the angle of arrival and the distance the wave has travelled through single sensor modal analysis. This paper presents the development of hardware to apply this technique and testing that showed artificial sources could be located in simple plates to a good level of accuracy. The addition of complexity to structures significantly reduced accuracy. This prompted hardware modifications to use the S0 mode for angle prediction. Testing showed that this significantly improved performance in a complex composite structure. The power consumption of the device is very low, consuming 0.33 mW in sleep mode, 17.44 mW whilst waiting for an event and 38 mW to record, process and transmit an event. This level of consumption has the potential to be self‐powered via energy harvesting

Factors influencing accuracy of referral and the likelihood of false positive referral by optometrists in Bradford, United Kingdom

YesAims: Levels of false positive referral to ophthalmology departments can be high. This study aimed to evaluate commonality between false positive referrals in order to find the factors which may influence referral accuracy. Methods: In 2007/08, a sample of 431 new Ophthalmology referrals from the catchment area of Bradford Royal Infirmary were retrospectively analysed. Results: The proportion of false positive referrals generated by optometrists decreases with experience at a rate of 6.2% per year since registration (p < 0.0001). Community services which involved further investigation done by the optometrist before directly referring to the hospital were 2.7 times less likely to refer false positively than other referral formats (p = 0.007). Male optometrists were about half as likely to generate a false positive referral than females (OR = 0.51, p = 0.008) and as multiple/corporate practices in the Bradford area employ less experienced and more female staff, independent practices generate about half the number of false positive referrals (OR = 0.52, p = 0.005). Conclusions: Clinician experience has the greatest effect on referral accuracy although there is also a significant effect of gender with women tending to refer more false positives. This may be due to a different approach to patient care and possibly a greater sensitivity to litigation. The improved accuracy of community services (which often refer directly after further investigation) supports further growth of these schemes.This study was funded by the University of Bradford

A simulation model to investigate interactions between first season grazing calves and Ostertagia ostertagi

AbstractA dynamic, deterministic model was developed to investigate the consequences of parasitism with Ostertagia ostertagi, the most prevalent and economically important gastrointestinal parasite of cattle in temperate regions. Interactions between host and parasite were considered to predict the level of parasitism and performance of an infected calf. Key model inputs included calf intrinsic growth rate, feed quality and mode and level of infection. The effects of these varied inputs were simulated on a daily basis for key parasitological (worm burden, total egg output and faecal egg count) and performance outputs (feed intake and bodyweight) over a 6 month grazing period. Data from published literature were used to parameterise the model and its sensitivity was tested for uncertain parameters by a Latin hypercube sensitivity design. For the latter each parameter tested was subject to a 20% coefficient of variation. The model parasitological outputs were most sensitive to the immune rate parameters that affected overall worm burdens. The model predicted the expected larger worm burdens along with disproportionately greater body weight losses with increasing daily infection levels. The model was validated against published literature using graphical and statistical comparisons. Its predictions were quantitatively consistent with the parasitological outputs of published experiments in which calves were subjected to different infection levels. The consequences of model weaknesses are discussed and point towards model improvements. Future work should focus on developing a stochastic model to account for calf variation in performance and immune response; this will ultimately be used to test the effectiveness of different parasite control strategies in naturally infected calf populations

Connecting Quantum Mechanics to Molecular Dynamics: Generating a Ligand Topology

A topology file provides the physical parameters necessary for Molecular Dynamic (MD) simulations. A topology file needs to be generated from a set of coordinates from Quantum Mechanical (QM) calculations. We used Gaussian to optimize and generate the classical charges for the ligand LDN, which is the first time the topology for this molecule has been calculated. After calculations are finished, rotations around non-chiral atoms can be made to possibly find more stable conformations that could be different than the given structure. Once a minimum is found a force-field topology file can then be constructed. This will be released for use by other scientists as part of the large dictionary of topology files for the CHARMM force-field. This means that other users will be able to use different sections of LDN’s topology for other molecules that have a similar structure. By having a ligand’s topology, we are able to better understand the factor that it’s charge plays into binding. The ability to run a MD simulation also gives us the ability to understand how the ligand possibly binds to the site and how we could improve the manufactured ligand. Having a large library of ligand topologies is very helpful in the field of drug discovery

Connecting Quantum Mechanics to Molecular Dynamics: Generating a Ligand Topology

A topology file provides the physical parameters necessary for Molecular Dynamic (MD) simulations. A topology file needs to be generated from a set of coordinates from Quantum Mechanical (QM) calculations. We used Gaussian to optimize and generate the classical charges for the ligand LDN, which is the first time the topology for this molecule has been calculated. After calculations are finished, rotations around non-chiral atoms can be made to possibly find more stable conformations that could be different than the given structure. Once a minimum is found a force-field topology file can then be constructed. This will be released for use by other scientists as part of the large dictionary of topology files for the CHARMM force-field. This means that other users will be able to use different sections of LDN’s topology for other molecules that have a similar structure. By having a ligand’s topology, we are able to better understand the factor that it’s charge plays into binding. The ability to run a MD simulation also gives us the ability to understand how the ligand possibly binds to the site and how we could improve the manufactured ligand. Having a large library of ligand topologies is very helpful in the field of drug discovery

Science in the News - Using CRISPR/Cas9 to Remove the HIV-1 Genome from T-Cells

Kaminski, R.; Chen, Y.; Fischer, T.; Tedaldi, E.; Napoli, A.; Zhang, Y.; Karn, J.; Hu, W.; Khalili, K. Elimination of HIV-1 Genomes from Human T-lymphoid Cells by CRISPR/Cas9 Gene Editing. https://www.nature.com/articles/srep22555#ref11 (accessed Dec 14, 2018)

Science in the News - Using CRISPR/Cas9 to Remove the HIV-1 Genome from T-Cells

Kaminski, R.; Chen, Y.; Fischer, T.; Tedaldi, E.; Napoli, A.; Zhang, Y.; Karn, J.; Hu, W.; Khalili, K. Elimination of HIV-1 Genomes from Human T-lymphoid Cells by CRISPR/Cas9 Gene Editing. https://www.nature.com/articles/srep22555#ref11 (accessed Dec 14, 2018)