The cost of noise reduction for departure and arrival operations of commercial tilt rotor aircraft

February 1976Includes bibliographical references (p. 50-51)The relationship between direct operating cost (DOC) and noise annoyance due to a departure and an arrival operation was developed for commercial tilt rotor aircraft. This was accomplished by generating a series of tilt rotor aircraft designs to meet various noise goals at minimum DOC. These vehicles ranged across the spectrum of possible noise levels from completely unconstrained to the quietest vehicles that could be designed within the study ground rules. Optimization parameters were varied to find the minimum DOC. This basic variation was then extended to different aircraft sizes and technology time frames. It was concluded that reducing noise annoyance by designing for lower rotor tip speeds is a very promising avenue for future research and development. It appears that the cost of halving the annoyance compared to an unconstrained design is insignificant and the cost of halving the annoyance again is small.Prepared under contract for Ames Research Center, National Aeronautics and Space Administratio

A systems analysis of scheduled air transportation networks

Originally presented as the author's Ph. D. thesis, M.I.T. Dept. of Aeronautics and Astronautics, 1979June 1979Includes bibliographical references (p. 231-234)This work establishes the conditions for airline system design building from submodels of smaller aspects of air transportation. The first three sections develop submodels which then are combined in extensive numerical studies of singles market services. The final section discusses the changes to this problem that occur due to network effects. The first section develops a simple model of the cost of providing scheduled transportation on a link. The cost of aircraft of various capacities are divided into a per-frequency cost and a per-capacity cost for conventional subsonic turbojet designs. This cost structure implies that the more capacity provided in conjunction with a fixed schedule of departures the lower the average cost per seat. It is suggested that such aircraft scale economies create a trend toward monopoly or at least oligopoly services. The second section develops a model for demand. The market for transportation is argued to be the city pair. Demand for scheduled service is expressed in terms of fare, frequency and load factor. Fare, frequency, and load factor are combined into total perceived price for the service. This price depends on the consumer's personal value of time. With only a few competitors in such a market, only a few of the technically possible qualities of service will be offered. The services available will be suited better to some tastes than to others. Distributional effects influence the politics of regulation and have been neglected in the past. In this light it is shown that competitive firms are likely to design their services for the same value of time. Product matching increases costs without improving the distribution of benefits. Chapter 4 develops in detail the statistical model used to estimate denied boarding rates from long run design load factors. The development raises doubts about the viability of competition in this dimension. Chapter 5 develops the optimal service for a single carrier on a single city pair market. Optima defined by maximum traffic at zero loss show the importance of the flexibility in aircraft capacity for long run system design. Both algebraic solutions and extensive numerical studies suggest that optimal designs depend on traffic and distance. Changes in frequency and capacity are large; load factor and fare are more stable. Optima are shallow for U.S. domestic cost structures. The final section brings to the discussion issues associated with networks of services. Most U.S. domestic city pairs have amounts of traffic of only modest size compared to the efficient aircraft capacities. Networks overcome these limitations by sharing vehicles among markets. This is done at the expense of extra departure costs. The network design tradeoff in its simplest form is shown to be between larger aircraft capacities and longer stage lengths. The corresponding routing patterns emphasize stops and connections or direct flights. Network design adds another degree of flexibility to the design of transport services: the number of intermediate stops per passenger trip. This affects both cost and service quality

Optimisation of water treatment works using Monte-Carlo methods and genetic algorithms

Hand movements reveal the temporal characteristics of visual attention Optimisation of potable water treatment could result in substantial cost savings for water companies and their customers. To address this issue, computational modelling of water treatment works using static and dynamic models was examined alongside the application of optimisation techniques including genetic algorithms and operational zone identification. These methods were explored with the assistance of case study data from an operational works. It was found that dynamic models were more accurate than static models at predicting the water quality of an operational site but that the root mean square error of the models was within 5% of each other for key performance criteria. Using these models, a range of abstraction rates, for which a water treatment works was predicted to operate sufficiently, were identified, dependent on raw water temperature and total organic carbon concentration. Genetic algorithms were also applied to the water treatment works models to identify near optimal design and operating regimes. Static models were identified as being more suitable for whole works optimisation than dynamic models based on their relative accuracy, simplicity and computational demands

The Imperial Japanese Consulate in Songkhla, Thailand : Prelude to the Invasion of 8 December 1941

departmental bulletin pape

Coprescription of Isotretinoin and Systemic Corticosteroids for Acne: An Analysis of the National Ambulatory Medical Care Survey

Introduction: Isotretinoin treatment has been linked to flares of severe acne, which can be managed by the coadministration of systemic corticosteroids or prevented by beginning with a low dose of isotretinoin. To our knowledge, there are no estimates in the literature on the frequency of coprescription of isotretinoin and systemic corticosteroids. Objectives: We sought to quantify the estimated frequency of coprescription of isotretinoin and systemic corticosteroids and assess trends of the use of isotretinoin with systemic corticosteroids for acne as they relate to age, sex, race, insurance, and provider specialty. Methods: Data from the National Ambulatory Medical Care Survey (NAMCS) from 2003 to 2015, National Hospital Ambulatory Medical Care Survey Hospital Outpatient Departments (NHAMCS-OPD) from 2003 to 2011, and National Hospital Ambulatory Medical Care Survey Hospital Emergency Departments (NHAMCS-ED) from 2003 to 2014 were aggregated for this analysis. The number of prescriptions for isotretinoin and/or systemic corticosteroids was estimated by specialty (for NAMCS) and by survey type (for NHAMCS-OPD and NHAMCS-ED). Results: Among all first visits to a physician for acne (n=18,914,096), approximately 3.9 percent prescribed isotretinoin, 0.24 percent prescribed corticosteroids, and the remaining 96 percent prescribed neither drug. This was comparable to estimates for first visits to a dermatologist for acne (n=13,920,913), where approximately 4.2 percent prescribed isotretinoin, 0.32 percent prescribed corticosteroids, and the remaining 95 percent prescribed neither medication. Conclusion: Currently, isotretinoin and systemic corticosteroids are rarely prescribed together

Retrofit assessment: Getting it right from the start

The UK has some of the oldest buildings in Europe. They are also some of the worst performing in terms of energy performance. In tandem with these issues the UK has committed to making a substantial reduction in CO2 emissions. UK homes are currently responsible for almost 20 per cent of CO2 emissions. This leaves little option other than to make considerable progress with the retrofitting of homes to improve their energy performance. This is a technical process, however, and can introduce risks to building and their occupants. Examples exist of homes being retrofitted with disastrous consequences. Some of these issues can be due to the lack of thorough examination of a home before it undergoes a retrofit. This paper proposes a method that provides a detailed pre-retrofit assessment of a home, to fall in line with PAS 2035, a standard that provides guidance around publicly funded retrofit in the UK

An overview of decentralized autonomous organizations on the blockchain

Blockchain technology has emerged as a new paradigm to build decentralized systems which do not require a central authority. It is most popular for enabling Bitcoin and other crypto-currencies. However, blockchain applications span beyond Finance, and recently it has been applied to decentralized governance. Blockchainenabled "Decentralized Autonomous Organizations" (DAOs) have emerged as a new form of collective governance, in which communities may organize themselves relying on decentralized infrastructure. In this article, we introduce the concept of DAO and review the main software platforms that offer DAO creation as a service, which simplifies the use of DAOs to non-blockchain experts; namely: Aragon, DAOstack, DAOhaus and Colony. These platforms will be compared by showing their key features. Finally, we will review the available visualisation tools for DAOs, and we will introduce our open-source tool to plot DAOs activity, DAOAnalyzer. We will illustrate its potential with the case of the DAO Genesis Alpha, which is the main DAO of the DAOstack project

A Practitioner Study into the Variability of Domestic Energy Assessments

This paper focuses on the assessment of a domestic property’s energy performance status by a Domestic Energy Assessor (DEA), to ascertain the possible underlying reasons for variability in the results of Energy Performance Certificates (EPCs). By variability we mean discrepancies in assessment between different DEAs on similar properties. This is important because the uses for the EPC have been extended beyond their original function as an asset rating system, to include a wider range of themes encompassing issues such as building policy decisions, building performance, and the distribution of incentives and grants. As a consequence, inaccuracies in EPC reporting will have a greater impact than may have been the case at their outset