Precedence relationship representations of mechanical assembly sequences

Two types of precedence relationship representations for mechanical assembly sequences are presented: precedence relationships between the establishment of one connection between two parts and the establishment of another connection, and precedence relationships between the establishment of one connection and states of the assembly process. Precedence relationship representations have the advantage of being very compact. The problem with these representations was how to guarantee their correctness and completeness. Two theorems are presented each of which leads to the generation of one type of precedence relationship representation guaranteeing its correctness and completeness for a class of assemblies

The effect of flight line spacing on radioactivity inventory and spatial feature characteristics of airborne gamma-ray spectrometry data

Airborne Gamma Spectrometry (AGS) is well suited to the mapping of radioactivity in the environment. Flight parameters (e.g. speed and line spacing) directly affect the rate of area coverage, cost, and data quality of any survey. The influences of line spacing have been investigated for data from inter‐tidal, coastal and upland environments with a range of <sup>137</sup>Cs activity concentrations and depositional histories. Estimates of the integrated <sup>137</sup>Cs activity (‘inventory’) within specified areas and the shapes of depositional features were calculated for subsets of the data at different line spacings. Features with dimensions greater than the line spacing show variations in inventory and area of less than 3%, and features with dimensions less than the line spacing show larger variations and a decreased probability of detection. The choice of line spacing for a task is dependent on the dimensions of the features of interest and required edge definition. Options for line spacing for different tasks are suggested. It is noted that for regional mapping, even 5–10 km line spacing can produce useful data

Occupier Satisfaction and Investment Returns from UK Commercial Real Estate

Purpose The purpose of this paper is to investigate the relationship between occupiers’ satisfaction with the property management service they receive and the financial performance of commercial real estate. Design/methodology/approach The study uses occupier satisfaction data for 240 UK commercial properties collected over a 12-year period and the annual total returns achieved by those properties. Various statistical techniques are employed to assess whether increasing occupier satisfaction leads to greater returns for investors. These include comparing excess returns and risk-adjusted returns with occupier satisfaction at each property to assess whether superior property management generates outperformance (“positive alpha”). The study also investigates whether the relationship between occupier satisfaction and returns is the same across all sectors and whether it is affected by market conditions. Findings A positive correspondence is found between benchmark outperformance and occupier satisfaction. The relationship is similar for all sectors of commercial property and is particularly strong during the Global Financial Crisis, indicating that paying attention to satisfying the needs of occupiers has particular benefits during periods when the supply of commercial real estate exceeds demand. Research limitations/implications The sample of properties was restricted to those for which occupier satisfaction data had been collected by RealService Ltd and whose owners permitted access to the financial performance results. This meant that the properties belong to only three landlords, all UK REITs that care sufficiently about occupier satisfaction to commission studies. Thus the findings might not apply to all commercial properties. The mechanism by which the positive relationship between satisfaction and financial performance occurs is not tested, but the conventional mechanisms of reputation and customer loyalty (the “service-profit chain”) are discussed. Practical implications The findings suggest that it is worthwhile for landlords, or property managers acting on their behalf, to understand the needs of their occupiers in order to deliver the level of service that those occupiers desire. Leases in the UK are generally “triple net” and the total returns used for this analysis are net of property management costs, so the positive relationship between satisfaction and performance is not the result of economising on service delivery. A further implication is that valuers should take more account of occupier satisfaction when assessing the capital value of a property, from which total returns are assessed. Originality/value Demonstrating the links between customer service, customer satisfaction and business profitability is rarely attempted because of the many confounding factors that affect profitability. UK listed real estate companies are typically reluctant to reveal the financial performance of individual properties, and information about occupiers’ satisfaction is not generally available. The authors were fortunate to be granted access to a time series of such data, and to be able to demonstrate that attention to delivering a property management service that satisfies occupiers is likely to bring financial rewards to the owners of the property

Task planning and control synthesis for robotic manipulation in space applications

Space-based robotic systems for diagnosis, repair and assembly of systems will require new techniques of planning and manipulation to accomplish these complex tasks. Results of work in assembly task representation, discrete task planning, and control synthesis which provide a design environment for flexible assembly systems in manufacturing applications, and which extend to planning of manipulatiuon operations in unstructured environments are summarized. Assembly planning is carried out using the AND/OR graph representation which encompasses all possible partial orders of operations and may be used to plan assembly sequences. Discrete task planning uses the configuration map which facilitates search over a space of discrete operations parameters in sequential operations in order to achieve required goals in the space of bounded configuration sets

Meeting of the MINDS: an information retrieval research agenda

Since its inception in the late 1950s, the field of Information Retrieval (IR) has developed tools that help people find, organize, and analyze information. The key early influences on the field are well-known. Among them are H. P. Luhn's pioneering work, the development of the vector space retrieval model by Salton and his students, Cleverdon's development of the Cranfield experimental methodology, Spärck Jones' development of idf, and a series of probabilistic retrieval models by Robertson and Croft. Until the development of the WorldWideWeb (Web), IR was of greatest interest to professional information analysts such as librarians, intelligence analysts, the legal community, and the pharmaceutical industry

Particle retention in suspension-feeding fish after removal of filtration structures

The suspension-feeding cichlids Oreochromis aureus (blue tilapia) and Oreochromis esculentus (ngege tilapia) are able to selectively retain small food particles. The gill rakers and microbranchiospines of these species have been assumed to function as filters. However, surgical removal of these oral structures, which also removed associated mucus, did not significantly affect the total number of 11–200 μm particles ingested by the fish. This result supports the hypothesis that the branchial arch surfaces themselves play an important role in crossflow filtration. Both species selectively retained microspheres greater than 50 μm with gill rakers and microbranchiospines intact as well as removed, demonstrating that neither these structures nor mucus are necessary for size selectivity to occur during biological crossflow filtration. After removal of the gill rakers and microbranchiospines, O. esculentusretained significantly more microspheres 51–70 μm in diameter and fewer 91–130 μm microspheres compared to retention with intact structures, but the particle size selectivity of O. aureus was not affected significantly. These results support conclusions from previous computational fluid dynamics simulations indicating that particle size can have marked effects on particle trajectory and retention inside the fish oropharyngeal cavity during crossflow filtration. The substantial inter-individual variability in particle retention by suspension-feeding fish is an unexplored area of research with the potential to increase our understanding of the factors influencing particle retention during biological filtration

Ecosystem Management in Pasture Communities: Tools from Restoration Ecology

Pasture systems have the potential to improve both economic and environmental sustainability in agricultural communities worldwide. To achieve maximum benefits, pasture plant communities must be tailored to the climate, the site type and the goals of the producer. Little is known about how to accomplish this, beyond very broad recommendations. We approached the problem by adapting a three-step conceptual framework from restoration ecology for use in managed pasture communities of the northeastern United States. The three steps, inventory, assessment and remediation, were designed for managers interested in restoring degraded native ecosystems, but can be applied equally well in managed ecosystems

UK utility data integration: overcoming schematic heterogeneity

In this paper we discuss syntactic, semantic and schematic issues which inhibit the integration of utility data in the UK. We then focus on the techniques employed within the VISTA project to overcome schematic heterogeneity. A Global Schema based architecture is employed. Although automated approaches to Global Schema definition were attempted the heterogeneities of the sector were too great. A manual approach to Global Schema definition was employed. The techniques used to define and subsequently map source utility data models to this schema are discussed in detail. In order to ensure a coherent integrated model, sub and cross domain validation issues are then highlighted. Finally the proposed framework and data flow for schematic integration is introduced