An alternative control structure for telerobotics

A new teletobotic control concept which couples human supervisory commands with computer reasoning is presented. The control system is responsive and accomplishes an operator's commands while providing obstacle avoidance and stable controlled interactions with the environment in the presence of communication time delays. This provides a system which not only assists the operator in accomplishing tasks but modifies inappropriate operator commands which can result in safety hazards and/or equipment damage

Nindestructive Evaluation of Metal Matrix Composite Products with Implanted Defects

The Westinghouse Science and Technology Center has undertaken a program to develop nondestructive evaluation (NDE) techniques for characterizing the internal structure of SiC particle-reinforced aluminum matrix composites at critical stages during fabrication [1–5]. Because of the large number of processing variables in the manufacture of metal matrix composites (MMC), the likelihood of having detrimental discontinuities is high. The detection of potential defects early in the processing cycle would increase the overall system yield, lower costs, and enhance final product quality [4]. The aim of this investigation was to develop and conduct NDE at various stages of MMC fabrication, correlate the results with microstructural characterization, and establish qualified product quality assurance processes. A large-scale billet was fabricated specially using powder metallurgy techniques to facilitate this objective. The billet contained implanted silicon-carbide particle and aluminum powder clusters as inspection targets. The billet was subsequently extruded into a primary cylindrical extrusion, and finally into a flat plate. The NDE objectives included evaluating the detectability and mapping the implanted defects through each of the processing steps. Comprehensive evaluation of MMC structures requires the use of multiple NDE techniques, including ultrasonic, eddy current, and radiographic testing. This paper concentrates on the results of the ultrasonic investigations. Our experimental approach was: (1) fabricate a MMC billet with intentionally placed inhomogeneities; (2) develop and implement NDE techniques to characterize the MMC internal structure; (3) extend the NDE techniques to intermediate processing and final product forms; and (4) correlate the NDE data with microstructural characterization and mechanical testing results

Strategic system design and development using collaborative tools

Thesis (S.M.)--Massachusetts Institute of Technology, System Design & Management Program, 2001.Includes bibliographical references (p. 77-80).This thesis focuses on the fields of technology and business in order to enhance and optimize system design solutions. The intent of this thesis is to apply the theoretical concepts identified in core System Design and Management (SDM) classes in a professional business environment, with consideration given to strategic design and development aspects for an enterprise-wide system. Over the past decade, business enterprises have been forced to downsize, outsource, and/or merge in order to stay competitive. This holds true for the United States Navy as well. As a result of the end of the Cold War and the fall of Communism, new requirements have resulted in a substantial decrease in defense funding and have forced the Navy to reduce its number of personnel. This, in turn, has led to a number of programs and products being outsourced. The combination of new requirements. outsourcing, and the increased complexities of new and existing technologies have resulted in a lack of system understanding, thus creating interoperability issues. Given this scenario, the requirement for a holistic understanding of system and subsystem interactions in a dynamic environment has become paramount. The objective is to enable an enterprise to be adaptive, so that when changes are required, the ability exists to have an architecture that allows rapid understanding of the system and its surroundings. This thesis examines engineering and management tools that assist an organization in understanding a system and in the rapid development of strategic designs that exhibit the desired integrated system-level characteristics. Specifically, three product and process tools will be examined: the Distributive Object-based Modeling Environment (DOME) application, the Design Structure Matrix (DSM), and Set-Based Concurrent Engineering (SBCE) principles. It is believed that the application of DOME can significantly reduce costs for product and process design by allowing engineers to access existing models/tools in a distributive fashion to improve system design quality. Likewise, methodologies such as DSM and SBCE provide an improved process to effectively perform system level engineering. This thesis considers two Navy programs that the author has participated in while in the SDM program. These programs, the Torpedo Silencing Initiative and the Warfighting Concepts to Future Weapon System Designs (WARCON) project, are used as case studies to show that DOME, DSM, and SBCE principles can provide a distributed, integrated framework for enterprise-wide predictive design simulation.by Peter A.M. Harrigan.S.M

A global streamflow reanalysis for 1980–2018

Global and continental scale hydrological reanalysis datasets receive growing attention due to their increasing number of applications, ranging from water resources management, climate change studies, water related hazards and policy support. Until recently, their use was mostly limited to qualitative assessments, due to their coarse spatial and temporal resolution, large uncertainty and bias in the model output, and limited extent of the dataset in space and time. This research reports on the setup of a gridded hydrological model with quasi-global coverage, able to reproduce a seamless 39-year streamflow simulation in all world’s medium to large river basins. The model was calibrated at 1226 river sections with a total drainage area of 51 million km2 within 66 countries, using ECMWF’s latest atmospheric reanalysis ERA5. A performance assessment revealed large improvements in reproducing past discharge observations, in comparison to the calibration used in the current operational setup of the hydrological model as part of the Copernicus – Global Flood Awareness System (GloFAS, www.globalfloods.eu), with median scores of Kling-Gupta Efficiency KGE = 0.67 and correlation r = 0.8. The simulation bias was also dramatically reduced and narrowed around zero, with more than 60% of stations showing percent bias within ±20%. Pronounced regional differences in the simulation results remain, pointing out the need for detailed investigation of the hydrological processes in specific regions, including parts of Africa and South Asia. In addition, observed discharges with high data quality is key to achieving skillful model output. The new calibrated model will become part of the operational runs of GloFAS in the next system release foreseen for Spring 2020, together with a near real time extension of the streamflow reanalysis

Report on the State of Available Data for the Study of International Trade and Foreign Direct Investment

This report, prepared for the Committee on Economic Statistics of the American Economic Association, examines the state of available data for the study of international trade and foreign direct investment. Data on values of imports and exports of goods are of high quality and coverage, but price data suffer from insufficient detail. It would be desirable to have more data measuring value-added in trade as well as prices of comparable domestic and imported inputs. Value data for imports and exports of services are too aggregated and valuations are questionable, while price data for service exports and imports are almost non-existent. Foreign direct investment data are of high quality but quality has suffered from budget cuts. Data on trade in intellectual property are fragmentary. The intangibility of the trade makes measurement difficult, but budget cuts have added to the difficulties. Modest funding increases would result in data more useful for research and policy analysis.

Population genomic analysis of North American eastern wolves (Canic lycaon) support their conservation priority status

The threatened eastern wolf is found predominantly in protected areas of central Ontario and has an evolutionary history obscured by interbreeding with coyotes and gray wolves, which challenges its conservation status and subsequent management. Here, we used a population genomics approach to uncover spatial patterns of variation in 281 canids in central Ontario and the Great Lakes region. This represents the first genome-wide single nucleotide polymorphism (SNP) dataset with substantial sample sizes of representative populations. Although they comprise their own genetic cluster, we found evidence of eastern wolf dispersal outside of the boundaries of protected areas, in that the frequency of eastern wolf genetic variation decreases with increasing distance from provincial parks. We detected eastern wolf alleles in admixed coyotes along the northeastern regions of Lake Huron and Lake Ontario. Our analyses confirm the unique genomic composition of eastern wolves, which are mostly restricted to small fragmented patches of protected habitat in central Ontario. We hope this work will encourage an innovative discussion regarding a plan for managed introgression, which could conserve eastern wolf genetic material in any genome regardless of their potential mosaic ancestry composition and the habitats that promote them

Daily ensemble river discharge reforecasts and real-time forecasts from the operational Global Flood Awareness System

Operational global-scale hydrological forecasting systems are used to help manage hydrological extremes such as floods and droughts. The vast amounts of raw data that underpin forecast systems and the ability to generate information on forecast skill have, until now, not been publicly available. As part of the Global Flood Awareness System (GloFAS; https://www.globalfloods.eu/, last access: 3 December 2022) service evolution, in this paper daily ensemble river discharge reforecasts and real-time forecast datasets are made free and openly available through the Copernicus Climate Change Service (C3S) Climate Data Store (CDS). They include real-time forecast data starting on 1 January 2020 updated operationally every day and a 20-year set of reforecasts and associated metadata. This paper describes the model components and configuration used to generate the real-time river discharge forecasts and the reforecasts. An evaluation of ensemble forecast skill using the continuous ranked probability skill score (CRPSS) was also undertaken for river points around the globe. Results show that GloFAS is skilful in over 93 % of catchments in the short (1 to 3 d) and medium range (5 to 15 d) against a persistence benchmark forecast and skilful in over 80 % of catchments out to the extended range (16 to 30 d) against a climatological benchmark forecast. However, the strength of skill varies considerably by location with GloFAS found to have no or negative skill at longer lead times in broad hydroclimatic regions in tropical Africa, western coast of South America, and catchments dominated by snow and ice in high northern latitudes. Forecast skill is summarised as a new headline skill score available as a new layer on the GloFAS forecast Web Map Viewer to aid user interpretation and understanding of forecast quality

The British economy [June 1988]

The rate of growth of output in the British economy appears to be slowing down in line with earlier expectations for 1988. The rate of growth of domestic demand remains strong. Manufacturing investment is forecast to rise to record levels during 1988 and there is little evidence that the growth in consumer demand is slackening. The slow-down in the rate of growth is therefore largely a reflection of decline in the external demand for exports and buoyant import growth. The progressive upward movement of sterling in recent months and the evidence of increasing inflationary pressure, has placed the Government in a significant policy dilemma. Recent events are a clear illustration that interest rate policy cannot be used both to target the exchange rate and to regulate the expansion of domestic money and credit

Outlook and appraisal [June 1988]

The growth of the Scottish economy is now moving into line with the rest of the UK. Industrial production is buoyant. The growth of demand is becoming more broadly based between domestic and external sectors. Yet, construction output still remains relatively depressed, and in a significant number of other industries the ratio of Scottish to UK output remains below that of 1980. As yet there is little indication of the favourable changes in unemployment and vacancies during 1987 being reflected in the most recent employment data. But short-term prospects are more favourable than for several years, while growth forecasts for the medium term compare favourably with those for the UK as a whole

The world economy [June 1988]

Growth in the world economy appears to be continuing at a brisk rate. Recent forecasts suggest that output should expand by about 3% this year compared with 3.IX in 1987. The outlook therefore appears to be more favourable than when we last reported; a reflection of the limited impact to date of the October stock market crash. Some progress has been made in adjusting the key trade imbalances but progress remains slow