Academic literature on the topic 'Back-of-the-envelope calculation'

This concluding chapter reviews the basic goods approach, its intellectual sources, and its practical importance. It emphasizes the role of basic goods as basic rights and connects these basic subsistence rights to the tradition of moral minimalism in political philosophy. It questions the claims of technological optimists and calls for a “rational pessimism” in the setting of global policy priorities. It also proposes a set of ten basic development goals to replace the current and often criticized sustainable development goals. It considers the feasibility of basic goods provision using back-of-the-envelope calculations, concluding that the goal of universal basic goods provision is indeed feasible.

These notes are restricted to those geochemical methods which have been used to quantify rates of groundwater recharge. There have been two main approaches. The first involves the use of mass balances and mixing cell models, mainly using conservative (non-reacting) dissolved species. The methods range in complexity from simple back-of-the-envelope calculations (zero-dimensional chloride mass balance), to complex three-dimensional computer models. The second approach seeks to estimate the age or residence time of the groundwater by measuring compounds which are radioactive, or whose input to the aquifer has been changing over time (chlorofluorocarbons).
 In this report, the methodology and case examples are described. References to further information on the techniques are also provided.

This chapter looks at the conflict between the exponents of two different and incompatible ways of conducting financial research by Fischer Black and Eugene Fama. It contrasts the trajectory of the efficient-market hypothesis with that of the Capital Asset Pricing Model (CAPM). Financial economists ultimately relegated CAPM to the status of one among many competing methods of portfolio selection, while market practitioners continue using it to make quick, back-of-the-envelope calculations. The chapter discusses how CAPM is recognized as the “centerpiece of modern financial economics” and how it is mainly explained in terms of historical significance, practical implications, and empirical shortcomings. The heart of the matter is that CAPM could be framed as one of the auxiliary assumptions that tests of the joint hypothesis of market efficiency relied on.

In recent years, a number of prototypical demonstrators have shown that augmented reality has the potential to improve manual work processes as much as desktop computers and office tools have improved administrative work (Azuma et al., 2001; Ong & Nee, 2004). Yet, it seems that the “classical concept” of augmented reality is not enough (see also http://www.ismar05.org/IAR). Stakeholders in industry and medicine are reluctant to adopt it wholeheartedly due to current limitations of head-mounted display technology and due to the overall dangers involved in overwhelming a user’s view of the real world with virtual information. It is more likely that moderate amounts of augmented reality will be integrated into a more general interaction environment with many displays and devices, involving tangible, immersive, wearable, and hybrid concepts of ubiquitous and wearable computing. We call this emerging paradigm ubiquitous augmented reality (UAR) (MacWilliams, 2005; Sandor, 2005; Sandor & Klinker, 2005). It is not yet clear which UAR-based humancomputer interaction techniques will be most suitable for users to simultaneously work within an environment that combines real and virtual elements. Their success is influenced by a large number of design parameters. The overall design space is vast and difficult to understand. In Munich, we have worked on a number of applications for manufacturing, medicine, architecture, exterior construction, sports, and entertainment (a complete list of projects can be found at http://ar.in.tum.de/Chair/ProjectsOverview). Although many of these projects were designed in the short-term context of one semester student courses or theses, they provided insight into different aspects of design options, illustrating trade-offs for a number of design parameters. In this chapter, we propose a systematic approach toward identifying, exploring, and selecting design parameters at the example of three of our projects, PAARTI (Echtler et al., 2003), FataMorgana (Klinker et al., 2002), and a monitoring tool (Kulas, Sandor, & Klinker, 2004). Using a systematic approach of enumerating and exploring a defined space of design options is useful, yet not always feasible. In many cases, the dimensionality of the design space is not known a-priori but rather has to be determined as part of the design process. To cover the variety of aspects involved in finding an acceptable solution for a given application scenario, experts with diverse backgrounds (computer science, sensing and display technologies, human factors, psychology, and the application domain) have to collaborate. Due to the highly immersive nature of UAR-based user interfaces, it is difficult for these experts to evaluate the impact of various design options without trying them. Authoring tools and an interactively configurable framework are needed to help experts quickly set up approximate demonstrators of novel concepts, similar to “back-of-the-envelope” calculations and sketches. We have explored how to provide such first-step support to teams of user interface designers (Sandor, 2005). In this chapter, we report on lessons learned on generating authoring tools and a framework for immersive user interfaces for UAR scenarios. By reading this chapter, readers should understand the rationale and the concepts for defining a scheme of different classes of design considerations that need to be taken into account when designing UAR-based interfaces. Readers should see how, for classes with finite numbers of design considerations, systematic approaches can be used to analyze such design options. For less well-defined application scenarios, the chapter presents authoring tools and a framework for exploring interaction concepts. Finally, a report on lessons learned from implementing such tools and from discussing them within expert teams of user interface designers is intended to provide an indication of progress made thus far and next steps to be taken.

Although Micro-Electro-Mechanical Systems (MEMS) are forming the basis for a rapidly growing industry and fields of research, many MEMS designers still rely on back-of-the-envelope calculations due to a lack of efficient computer-aided design (CAD) tools that can assist with the initial stages of design exploration. This paper introduces case-based reasoning (CBR) techniques to the design of MEMS, as part of a larger MEMS synthesis framework currently under development at UC Berkeley. Having the ability to draw upon past design knowledge is advantageous to the MEMS designer, allowing reuse and modification of previous successful designs to help deal with the complexities of a new design problem. CBR utilizes past successful MEMS designs and sub-assemblies as building blocks stored in an indexed library. Reasoning tools find cases in the library with solved problems similar to the current design problem in order to propose promising conceptual designs. This paper discusses case representation and case library design as well as the results of case retrieval studies, focusing on MEMS resonant structures. The paper recommends strategies for integrating the MEMS case library with evolutionary computation when parameter optimization over the retrieved conceptual designs is not sufficient or there are gaps of knowledge in the case library.

Creep calculations indicate a crude furnace radiant section carbon steel tubes exceeding their life fraction due to flame impingement reaching up to 700°C for a year. The ambiguity of the temperature and material data means the life fraction of creep calculations were based on limited inspection data and infra-red scanning giving a conservative indication of end of life. Due to unavailable tubes in stock, a planned pit stop cannot be arranged due to economic and safety reasons as the furnace may not be started back up safely. To safeguard the integrity of the furnace until the planned outage, the temperature on the furnace tube was stabilized to a current limit of 540°C through improvements in burner operations. The crude diet was also maintained within the crude acceptance envelope. Visual checks at every shift were done to ensure no observation from tube bulging or uneven flame pattern. A decision tree was created to facilitate quick decision making using a go/no go criteria of which tubes to replace during the August 2015 planned turnaround. The criteria set for the decision tree required tube wall thickness, surface hardness test, tube outer diameter ring gauge to be examined. Failing any of the criteria will require the tube to be replaced. The replaced tubes (one worst and one representative) will also be lab tested through destructive examination to identify the degradation mechanism and high temperature properties of the worst tubes to quantitatively define the high temperature properties and life fraction of the tubes that are left in the furnace. The lab test will provide results after a year of creep testing and can give assurance of continued furnace operation for 4 more years until the next outage. The final decision after the examination based on the decision tree was made required 17 tubes to be replaced in this turnaround. The worst degraded tubes were found to be at the vicinity of the initial observed location around the flame impingement zone.