Failure detection and repair of threads in CTAS

Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 73).Reliable, error-free software is hard to come by, and this is especially true for newer, larger, or more complex programs. CTAS, an air traffic control tool, falls into this category, making it a good candidate for research on error compensation. Specifically, this thesis addresses the issue of thread crashes in one portion of CTAS. We reimplement the thread structure in question around a simpler problem, and develop a failure detector and an accompanying repair mechanism to monitor it. These add-on components provide the application with thread consistency by swiftly and transparently recovering from crashes, thereby yielding a more stable, self-sufficient, and generally more reliable operating environment.by Farid Jahanmir.M.Eng.and S.B

Three essays on entrepreneurship and innovation: the role of late adopers

This dissertation presents novel topics in entrepreneurship and innovation. In today’ markets, companies, especially those competing in red oceans, should look for new opportunities to remain competitive. To explore such opportunities, they need to come up with breakthrough ideas, which provide them with new market spaces and allow them to surpass competitors. One way of creating blue oceans is to explore what the competitors are ignoring. One rich source of novel ideas, which has been ignored by both researchers and practitioners, is late adopters. Late adopters are the last group of users who adopt a new product, service or technology. In this thesis, we explore this category of users and examine their potential as a source of innovative ideas and entrepreneurial opportunities. Chapter 1 of this thesis provides a brief introduction to the topics of entrepreneurship and diffusion of innovation. In chapter 2, we conduct an exploratory study in the entrepreneurial eco system of Cambridge. We aim at understanding the choices entrepreneurs make while making decisions, such as listening to early vs late adopters. In the third chapter, we present a measurement scale to access characteristics of late adopters, which facilitates the process of identifying them. Once we identify them, we need a customized new product development method to involve this category of users in idea generation. In chapter 4, we present the Lag-User Method. Through this method, we can benefit from the insights of late adopters. Among others, our studies reveal that late adopters can be among any demographic or social group. Their needs are different from those of other user categories. We find that unlike lead-user, late adopters do not create prototypes and need coaching to come up with incremental, really new or radical innovations. Insights from late adopters and laggards can help firms explore weaknesses of their products/services and target common needs across different markets, (e.g. the need for sophisticated technology that is simple to use). This will enable firms to cut costs and benefit from economies of scale while satisfying local needs and thereby increase their performance

The late adopter scale: A measure of late adopters of technological innovations

Diffusion of Innovation is a topic of interest for researchers and practitioners. Although substantial research is conducted on user categories, researchers often focus on the first half of the curve, ignoring the late adopters. We conduct two studies to measure the attributes of late adopters. In our first study of mobile phone users, we develop the Late-Adopter Scale. We then test it on a sample of laptop users. This scale is multi-dimensional, presents nomological and discriminant validity and has three dimensions: 1) rate of adoption, 2) resistance to innovation, and 3) skepticism. Findings reveal that all three Late Adopter Scale dimensions are significantly associated with low price preference. Moreover, in both samples skepticism is associated with high preference for simple products, lower leading edge status, and lower product involvement. Discussion focuses on implications of this new scale to theory and practice of new product development and diffusion of innovation.Fundação para a Ciência e a Tecnologia, Nova Forum

Lag-user method: Using laggards to leverage user innovation

Laggards are the last users to adopt a product. Prior literature on user-led innovation ignores laggards’ impact on innovation. In this paper, we develop the Lag-User Method, through which laggards can generate new ideas. Through six studies with 62 teams in three countries, we apply the method to different technologies and services and present our findings to executives to get managerial insights. Findings reveal that laggards who generate new ideas (lag-users) have different perceptions of user-friendly products and different unfulfilled needs. They prefer simple products. We propose that by involving lag-users in NPD, firms can improve the effectiveness of NPD.Fundação para a Ciência e a Tecnologia (Portugal), Nova Forum

A fundamental study on the delamination theory of wear.

Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.Vita.Includes bibliographical references.Ph.D

The Scanning Probe Microscope

Scanning probe microscopy bas evolved into a powerful tool since its inception in 1982. The scanning probe microscope bas found applications in metrology, spectroscopy, and lithography. We will review the background of the technology, discuss the different types of scanning probe microscopes including the scanning tunneling microscope and the scanning force microscope, and present many of the applications for the instrument

Determinants of users’ continuance intention toward digital innovations: Are late adopters different?

This study examines the users of digital innovations with covariance-based structural equation modeling (CBSEM) and a fuzzy-set qualitative comparative analysis (fsQCA) to understand the factors that drive their continuance intention. We examine the interplay between the perceptual factors related to the user experience with a digital product and personal factors that characterize late adoption. The findings highlight that perceived radicalness is a core condition to achieve the users’ continuance intention in a digital context. The findings contribute to theory by providing a better understanding of how personal factors in adoption interact with other determinants of the continuance intention. The study also presents practical implications. The results show that in the case of late adopters, firms should invest in both the radicalness and high system quality of their digital innovations.This work was supported by FCT, I.P.info:eu-repo/semantics/publishedVersio

COATINGS FOR HIGH TEMPERATURE FOIL BEARINGS

ABSTRACT High operating speeds and temperatures required for advanced turbomachinery necessitate the development of bearings capable of continuous operation between 3 to 4 million DN at temperatures up to 820°C. Non-contact oil-free bearings such as compliant foil bearings, active magnetic bearings and hybrid foil and magnetic bearings are alternate solutions to the current liquid-lubricated hydrodynamic and rolling element bearings, which have limited life under these extreme conditions. A critical component in these oil-free bearings is the tribological coating system that must be used on the journal and the foil pads to ensure reliable operation during transient periods and start-stop cycles. The purpose of the present investigation was to assess the reliability of tribological coatings being implemented for a large (150 mm diameter) hybrid foil/magnetic bearing. In order to be suitable for use in large turbine engine type applications, the journal coating must accommodate the thermal and centrifugal growth experienced as well as providing the wear life and friction coefficient. Based upon the limitations identified in PS304, this coating is not yet suitable for demanding high temperature and high-speed applications. On the other hand an alternative nickel-chrome based coating applied to the foils versus a shaft with thin dense chrome or a nickel-chrome based coating a has shown excellent characteristics under conditions up to 820°C

Nanoscale study of the as-grown hydrogenated amorphous silicon surface

A scanning tunneling microscope has been used to study the topography of the as-grown surface of device-quality, intrinsic, hydrogenated amorphous silicon deposited by rf discharge from silane. The substrates were atomically flat, oxide-free, single-crystal silicon or gallium arsenide. No evidence for island formation or nanoscale irregularities was seen in studies of 100-Å-thick films on either silicon or gallium arsenide. The topography of 1000- and 4000-Å-thick films has much variation; many regions can be characterized as rolling hills, but atomically flat areas have also been observed nearby. Generally, it appears that surface diffusion plays a role in smoothing the film topography. In most regions, the observed slopes were 10% or less from horizontal, but some steep-sided valleys, indicating incipient voids, were observed. The effect of the finite size of the scanning tunneling microscope probe tip is considered; this has an effect on the observed images in some cases