Creating signed directed graph models for process plants

The identification of possible hazards in chemical plants is a very important part of the design process. This is because of the potential danger that large chemical installations pose to the public. One possible route for speeding up the identification of hazards in chemical plants is to use computers to identify hazards automatically. This will facilitate safe plant design and will avoid late design changes which can be very costly to implement. Previous research at Loughborough has concentrated on developing a model-based approach and an analysis algorithm for automating hazard identification. The results generated have demonstrated the technical feasibility of the approach. This approach requires a knowledge-base of unit models. This library of models describes how different plant equipment behaves in qualitative terms. The research described in this thesis develops a method for creating and testing the equipment models. The model library was previously achieved by an expert writing the models in a format that could be directly used by the system described above. An engineer unfamililar with the system would find this difficult. An alternative method would have been to use an intermediary (a knowledge engineer) to gather information from the engineer and convert it into the system format. This would be expensive. Both methods would take up a lot of the engineer's time. An engineer should be able to enter information personally in order to maintain efficiency and avoid information loss through the intermediary. A front end interface has been built to the system which enables an expert to enter information directly without needing to understand details of the application system. This interface incorporates ideas from the knowledge acquisition field in order to produce a tool that is simple to use. Unit-based qualitative modelling can lead to incorrect or ambiguous inference. The method developed here identifies situations where ambiguities may arise. A new modular approach is presented to overcome this type of problem. This method also presents a technique to verify that the models created are both complete and correct

Engendering the Scholarship of Problem-based Learning

In this case-based research article, we describe how the implementation an instructional method, problem-based learning, across disciplines at a single institution stimulated scholarship on teaching among the faculty involved in the project. We conducted interviews with 30 participating faculty and administrators and triangulated these data with a document analysis of project documents, course portfolios, meeting minutes, and the project Web site. Our institutional-level analysis focuses on the campus environment and how it supported and/or constricted the scholarship of teaching across campus. At the faculty-level, we describe faculty perceptions about and experiences with producing scholarship on their own teaching

A method to extract pure Raman spectrum of epitaxial graphene on SiC

A method is proposed to extract pure Raman spectrum of epitaxial graphene on SiC by using a Non-negative Matrix Factorization. It overcomes problems of negative spectral intensity and poorly resolved spectra resulting from a simple subtraction of a SiC background from the experimental data. We also show that the method is similar to deconvolution, for spectra composed of multiple sub- micrometer areas, with the advantage that no prior information on the impulse response functions is needed. We have used this property to characterize the Raman laser beam. The method capability in efficient data smoothing is also demonstrated.Comment: 3 figures, regular pape

An automated system for batch hazard and operability studies

A widely used hazard identification technique within the process industry is HAZOP (hazard and operability study). To overcome the repetitive and time-consuming nature of the technique automated systems are being developed. This work considers batch processes, in which material undergoes processing in distinct stages within the plant equipment items according to a set of operating procedures, rather than each equipment item remaining in a “steady state”, as is normal for continuous plants. In batch plants deviations which can lead to hazards can arise both from deviations from operating procedures and process variable deviations. Therefore, the effect of operator actions needs to be considered. CHECKOP is an automated batch HAZOP identification system being developed as a joint project between HAZID Technologies Ltd and Loughborough University. CHECKOP uses a state-based approach to HAZOP analysis. CHECKOP takes a plant description and a set of operating instructions as input and produces a HAZOP report automatically. The overall system architecture and the details of the major components of the systems will be described. Examples of incorrect plant operation along with the resulting output generated by CHECKOP will be shown. The advantages and limitations of CHECKOP will be discussed

SU(4) symmetry breaking revealed by magneto-optical spectroscopy in epitaxial graphene

Refined infrared magnetotransmission experiments have been performed in magnetic fields B up to 35 T on a series of multilayer epitaxial graphene samples. Following the main optical transition involving the n=0 Landau level (LL), we observe a new absorption transition increasing in intensity with magnetic fields B>26 T. Our analysis shows that this is a signature of the breaking of the SU(4) symmetry of the n=0 LL. Using a quantitative model, we show that the only symmetry-breaking scheme consistent with our experiments is a charge density wave (CDW)

Exploring the early experiences of parents who adopt older children: “A happy ending, but an ongoing struggle”?

Since the 1970s, in UK adoption practice, there has been a shift away from placing relinquished infants towards placing children who were once considered to be ‘unadoptable’. These children included older children, placed from the foster care system. The practice of placing older children for adoption is now well established. This dissertation examines the experiences of early parenthood of parents who adopted older children, defined in this study as children aged four and over at the time of adoptive placement. The data presented in this study are drawn from data collected for a larger study, the Wales Adoption Cohort Study. The study is primarily based on 14 in-depth interviews with new adoptive parents 9-months after an older child or children arrived in their home. The findings from the qualitative data are supplemented by findings from an analysis of quantitative data from a questionnaire issued to 84 new adoptive parents at two time points (four-months and sixteen-months post-placement). Using the quantitative data, the characteristics, support needs and experiences of adjustment to parenthood of parents of older- and younger-placed children are compared. The qualitative data were analysed thematically, using codes organised into categories to manage and organise the data. Several key themes were developed from the data, these include the notion of adoption as a marketplace, ideas of family practices, displays of family, identity work, surveillance, and risk. The approach to analysis allowed for new insights to be made around family formation in adoptive homes. From the analysis of the interview data, this study presents the process of decision-making which caused adoptive parents to adopt older children; parents’ experiences of establishing routines and relationships with older-placed children; how parents began to explore and address issues of identity with their new children; and parents’ experiences of receiving support from, and being scrutinised by, social workers after the arrival of their child. The findings from this study, when taken together, suggest that becoming a parent to an older child represents a challenging and emotionally complex transition to parenthood, as adopters of older children face immediate and non-normative parenting tasks. Adopters of older children often experience a high level of scrutiny in early parenthood, both from professionals and from their new child or children. Social workers have the potential to help or hinder adoptive parents as they negotiate this transition to parenthood, and at times, social work practice appeared to be overly scrutinising rather than being experienced as supportive by the new parents in the study. Within this dissertation, recommendations are made as to how social work practice, and policy relating to this, could shift to better support new adoptive parents of older children

Controlled epitaxial graphene growth within amorphous carbon corrals

Structured growth of high quality graphene is necessary for technological development of carbon based electronics. Specifically, control of the bunching and placement of surface steps under epitaxial graphene on SiC is an important consideration for graphene device production. We demonstrate lithographically patterned evaporated amorphous carbon corrals as a method to pin SiC surface steps. Evaporated amorphous carbon is an ideal step-flow barrier on SiC due to its chemical compatibility with graphene growth and its structural stability at high temperatures, as well as its patternability. The amorphous carbon is deposited in vacuum on SiC prior to graphene growth. In the graphene furnace at temperatures above 1200$^\circ$C, mobile SiC steps accumulate at these amorphous carbon barriers, forming an aligned step free region for graphene growth at temperatures above 1330$^\circ$C. AFM imaging and Raman spectroscopy support the formation of quality step-free graphene sheets grown on SiC with the step morphology aligned to the carbon grid

Wafer bonding solution to epitaxial graphene - silicon integration

The development of graphene electronics requires the integration of graphene devices with Si-CMOS technology. Most strategies involve the transfer of graphene sheets onto silicon, with the inherent difficulties of clean transfer and subsequent graphene nano-patterning that degrades considerably the electronic mobility of nanopatterned graphene. Epitaxial graphene (EG) by contrast is grown on an essentially perfect crystalline (semi-insulating) surface, and graphene nanostructures with exceptional properties have been realized by a selective growth process on tailored SiC surface that requires no graphene patterning. However, the temperatures required in this structured growth process are too high for silicon technology. Here we demonstrate a new graphene to Si integration strategy, with a bonded and interconnected compact double-wafer structure. Using silicon-on-insulator technology (SOI) a thin monocrystalline silicon layer ready for CMOS processing is applied on top of epitaxial graphene on SiC. The parallel Si and graphene platforms are interconnected by metal vias. This method inspired by the industrial development of 3d hyper-integration stacking thin-film electronic devices preserves the advantages of epitaxial graphene and enables the full spectrum of CMOS processing.Comment: 15 pages, 7 figure