Managing Well Integrity using Reliability Based Models

Imperial Users onl

Assessing the number of users who are excluded by domestic heating controls

This is the pre-print version of the Article. This Article is also referred to as: "Assessing the 'Design Exclusion' of Heating Controls at a Low-Cost, Low-Carbon Housing Development". - Copyright @ 2011 Taylor & FrancisSpace heating accounts for almost 60% of the energy delivered to housing which in turn accounts for nearly 27% of the total UK's carbon emissions. This study was conducted to investigate the influence of heating control design on the degree of ‘user exclusion’. This was calculated using the Design Exclusion Calculator, developed by the Engineering Design Centre at the University of Cambridge. To elucidate the capability requirements of the system, a detailed hierarchical task analysis was produced, due to the complexity of the overall task. The Exclusion Calculation found that the current design placed excessive demands upon the capabilities of at least 9.5% of the UK population over 16 years old, particularly in terms of ‘vision’, ‘thinking’ and ‘dexterity’ requirements. This increased to 20.7% for users over 60 years old. The method does not account for the level of numeracy and literacy and so the true exclusion may be higher. Usability testing was conducted to help validate the results which indicated that 66% of users at a low-carbon housing development could not programme their controls as desired. Therefore, more detailed analysis of the cognitive demands placed upon the users is required to understand where problems within the programming process occur. Further research focusing on this cognitive interaction will work towards a solution that may allow users to behave easily in a more sustainable manner

Orbit determination and control for the European Student Moon Orbiter

Scheduled for launch in 2014-2015 the European Student Moon Orbiter (ESMO) will be the first lunar microsatellite designed entirely by the student population. ESMO is being developed through the extensive use of flight spared and commercial of the shelf units. As such ESMO is significantly constrained by the available mission delta-V. This provides a considerable challenge in designing a viable transfer and stable orbit around the Moon. Coupled with an all-day piggy-back launch opportunity, where ESMO has little or no control over the launch date, ESMO is considered to be an ambitious design. To overcome these inherent challenges, the use of a Weak Stability Boundary (WSB) transfer into a highly eccentric orbit is proposed. However to ensure accurate insertion around the Moon, ESMO must use a complex navigation strategy. This includes mitigation approaches and correction strategies. This paper will therefore present results from the ongoing orbit determination analysis and navigation scenarios to ensure capture around the Moon. While minimising the total delta-V, analysis includes planning for orbital control, scheduling and the introduction of Trajectory Correction Manoeuvres (TCMs). Analysis was performed for different transfer options, final lunar orbit selection and available ground stations

Integrated reliability centred maintenance approach in public sector facilities management.

Reliability Centred Maintenance (RCM) is focused on ensuring an asset continues to provide its designed function in its present operating context. Through a number of stages, RCM allows for thorough and constant monitoring of assets to maintain their level of performance, expand life cycle and improve efficiency. A conceptual holistic framework was developed embedding RCM approach and assessing the impact of maintenance strategies in four dimensions: business, functional, legal and context requirements to ensure optimum level of maintenance. A prototype spread-sheet model was developed encapsulating the concept and the model was evaluated using a case study. The preliminary evaluation has shown the potential of the model to realise benefits and improve reliability of the services of the assets to the clients/users. Further research and development is essential in order to calibrate model parameters to specific company requirements as well as to develop a database of assets with failure patterns and monitoring methods

Precise time dissemination via portable atomic clocks

The most precise operational method of time dissemination over long distances presently available to the Precise Time and Time Interval (PTTI) community of users is by means of portable atomic clocks. The Global Positioning System (GPS), the latest system showing promise of replacing portable clocks for global PTTI dissemination, was evaluated. Although GPS has the technical capability of providing superior world-wide dissemination, the question of present cost and future accessibility may require a continued reliance on portable clocks for a number of years. For these reasons a study of portable clock operations as they are carried out today was made. The portable clock system that was utilized by the U.S. Naval Observatory (NAVOBSY) in the global synchronization of clocks over the past 17 years is described and the concepts on which it is based are explained. Some of its capabilities and limitations are also discussed

Dynamic Pricing, Advanced Metering, and Demand Response in Electricity Markets

Presents an overview and analysis of the possible approaches to bringing an active demand side into electricity markets. Part of a series of research reports that examines energy issues facing California

Temporary Assistance for Needy Families: Update on Families Served and Work Participation

[Excerpt] The Temporary Assistance for Needy Families (TANF) program, created in 1996, is one of the key federal funding streams provided to states to assist low-income families. A critical aspect of TANF has been its focus on employment and self-sufficiency, and the primary means to measure state efforts in this area has been TANF’s work participation requirements. When the Deficit Reduction Act of 2005 (DRA) reauthorized TANF, it also made changes that were generally expected to strengthen these work requirements. Given the impending extension or reauthorization of TANF, this testimony primarily draws on previous GAO work to focus on (1) how the welfare caseload and related spending have changed since TANF was created and (2) how states have met work participation rates since DRA. To address these issues, in work conducted from August 2009 to May 2010, GAO analyzed state data reported to the Department of Healthand Human Services (HHS); surveyed state TANF administrators in 50 states and the District of Columbia; conducted site visits to Florida, Ohio, and Oregon, selected to provide geographic diversity and variation in TANF program characteristics; and reviewed relevant federal laws, regulations, and research. In July 2011, GAO updated this work by analyzing state data reported to HHS since that time. In addition, GAO gathered information on caseload changes through its forthcoming work on TANF child-only cases

Value of thermostatic loads in future low-carbon Great Britain system

This paper quantifies the value of a large population of heterogeneous thermostatically controlled loads (TCLs). The TCL dynamics are regulated by means of an advanced demand side response model (DSRM). It optimally determines the flexible energy/power consumption and simultaneously allocates multiple ancillary services. This model explicitly incorporates the control of dynamics of the TCL recovery pattern after the provision of the selected services. The proposed framework is integrated in a mixed integer linear programming formulation for a multi-stage stochastic unit commitment. The scheduling routine considers inertia-dependent frequency response requirements to deal with the drastic reduction of system inertia under future low-carbon scenarios. Case studies focus on the system operation cost and CO2 emissions reductions for individual TCLs for a) different future network scenarios, b) different frequency requirements, c) changes of TCL parameters (e.g. coefficient of performance, thermal insulation etc.)