Case study: A comparison of error sources in high-speed milling

This paper describes a case study devised to quantify the relative contributions of geometric, thermal, contouring, and cutting force errors to machined part dimensional errors. Measurements were performed to independently evaluate the: (1) quasi-static geometric errors using the laser ball bar; (2) variations in geometric errors due to thermal effects; (3) spindle thermal growth errors using a capacitance gage nest; (4) two-dimensional contouring errors using a grid plate encoder; and (5) surface location error due to (stable) forced vibrations during cutting. The effects of the first three error components were related to part dimensions using a homogeneous transformation matrix approach integrated into a Monte Carlo simulation. A comparison of the individual influences of these error sources showed that the cutting force error was dominant for the high-speed machining center/tool-holder combination selected for this study.     

Measurements and simulations of thermal comfort: a synagogue in Tel Aviv,Israel

This study illustrates the utility of empirical and digital methodologies in examining the question to which degree an architect who lives and builds in one distinctive geographic and climatic region adapts his sacred architecture design to a different climatic region. Specifically, we analysed the thermal comfort in a Synagogue in Tel Aviv, Israel, designed by a renowned Swiss architect in 1996. The morphological analyses, actual measurements, and computerized energy simulations show that the synagogue exhibits high thermal discomfort during the hot-humid summers in Tel Aviv. The results of morphological analyses and simulations also show thermal discomfort in the synagogue during Tel Aviv's mild winters. When simulating the synagogue as if built in Switzerland, the results also show high thermal discomfort. Thus, the design of this synagogue did not necessarily consider climate conditions. However, the design does exhibit attentiveness and sensitivity to symbols and faith requirements.     

School nature reserves in South Yorkshire

GARDENS OF PARADISE: THE HISTORY AND DESIGN OF THE GREAT ISLAMIC GARDENS, John Brookes, London: Weidenfeld &; Nicolson, 1987, 239 pp, £20.00

THE LANDSCAPE OF MAN, Geoffrey and Susan Jellicoe, Revised and enlarged edition, Thames and Hudson, 1987, £12.95 (P/B).

Hugh Prince, Department of Geography, University College, London.

THE MODERN URBAN LANDSCAPE, Edward Relph, London, Croom Helm, 1987, 279 pp, 0–7099–4270–2.

PLANNING PARKS FOR PEOPLE by John Hultsman, Richard A. Cottrell, and Wendy Zales‐Hultsman. Venture Publishing Inc., State College, PA. 16803, USA, 1987 and by Spon, £32.50, 310 pp, 0–419–14400–5.

THE COUNTRY PARISH, Anthony Russell, SPCK, London, 1986, 296 pp, 0–281–04214–4, £9.50 (P/B).     

To bridge or to bond? Diverse social connections in an IS project team

Although research has shown that knowledge sharing among project team members is crucial for project performance, achieving knowledge sharing is still challenging. This problem is especially salient in IS project teams. Such teams are temporary organizations that may not progress through the necessary team formation cycle, yet are expected to produce intangible outcomes in a limited time. In this paper, we investigate how bonding and bridging social capital influence knowledge sharing and project performance. Bonding could facilitate cohesiveness within a team and lead a team to achieve project goals. Bridging could facilitate access to various beneficial resources beyond the boundary of a project team, increasing creativity and innovation. However, bridging is costly and can obstruct project performance. Our findings suggest that team members with high bonding social capital are more likely to share their knowledge with their team. Bonding and intention to share knowledge also positively affect project performance. Conversely, bridging social capital can contribute to project performance only through the mediating effect of bonding. This research contributes to theory by empirically examining the two types of social capital and their interdependence, as predictors of knowledge sharing and subsequently project performance. Project managers should form teams composed of members with diverse social connections and consider the balance between bonding and bridging within a team to control the potential disadvantageous effects of bridging social capital.     

Direct solution of the EFIE with half the computation

When using the electric field integral equation (EFIE) with the same basis and testing functions, a complex symmetric (non-Hermitian) moment method matrix results. Stable methods that directly solved this matrix with roughly half the storage and execution time required for the nonsymmetric case exist. Apparently these methods are relatively unknown among moment method practitioners. Furthermore, the resulting advantage in storage and execution time of the EFIE (when a direct solution is used) over other methods (such as the MFIE and CFIE) seems not to be widely appreciated     

Numbers or apologies? Customer reactions to telephone waiting time fillers.

The authors examined the effect of time perception and sense of progress in telephone queues on caller reactions to 3 telephone waiting time fillers: music, apologies, and information about location in the queue. In Study 1, conducted on 123 real calls, call abandonment was lowest, and call evaluations were most positive with information about location in the queue as the time filler. In Study 2, conducted with 83 participants who experienced a simulated telephone wait experience, sense of progress in the queue rather than perceived waiting time mediated the relationship between telephone waiting time filler and caller reactions. The findings provide insight for the management and design of telephone queues, as well as theoretical insight into critical cognitive processes that underlie telephone waiting, opening up an important new research agenda. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Post-hydrogen-loaded draw tower fiber Bragg gratings and their thermal regeneration

The idea of Bragg gratings generated during the drawing process of a fiber dates back almost 20 years. The technical improvement of the draw tower grating (DTG) process today results in highly reliable and cost-effective Bragg gratings for versatile application in the optical fiber sensor market. Because of the single-pulse exposure of the fiber, the gratings behave typically like type I gratings with respect to their temperature stability. This means that such gratings only work up to temperatures of about 300?°C. To increase temperature stability, we combined DTG arrays with hydrogen postloading and a thermal regeneration process that enables their use in high-temperature environments. The regenerated draw tower gratings are demonstrated to be suitable for temperatures of more than 800?°C.     

Fast direct solution of standard moment-method matrices

All of the matrices which arise in the method-of-moments solution of scattering and antenna problems have a hidden structure. This structure is due to the physics of electromagnetic interactions. Matrix-algebra routines are used to uncover this structure in moment-method matrices, after they have been calculated. This structure is used to create a sparse representation of the matrix. Although this step involves an approximation, the error involved can be nearly as small as the precision of the calculation. Then, without further approximation, a sparse representation of the LU factorization of this matrix is computed. A significant speed improvement is realized over that of the standard LU factorization of this matrix. The resulting method can be added to any of a variety of moment-method programs to solve the matrix problem more quickly, and with less computer memory. For large problems this is the time-critical operation, so this allows larger problems to be solved. The computer program we have written can be used immediately with most moment-method programs, since it amounts to simply a better matrix-inversion package. The method presented is referred to as the LU sparse integral factored representation (LUSIFER)     

Position and orientation features and the development of spatial concepts.

Tested the speed with which spatial information is classified into categories by asking 34 6-yr-olds, 35 10-yr-olds, 30 14-yr-olds, and 30 undergraduates to sort 6 decks of cards, each requiring a spatial judgment. Results indicate that (1) oblique discriminations required more processing time than did vertical–horizontal discriminations; (2) stimuli along the vertical axis were not processed significantly more quickly than stimuli along the horizontal axis; and (3) position variations slowed orientation discriminations, especially if the lines were of oblique orientation. The effect of position variations was particularly marked for the 6-yr-olds. The role of positional cues in spatial organization, as well as aspects of developmental changes in spatial concepts and strategies, are discussed. (French abstract) (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using Scenarios to Understand the Frontiers of IS

As we arrive at the millenium, the literature is filled with predictions and forecasts of the state of affairs in the 21st century. Most of these forecasts are single point prognoses. This paper uses scenario-building ideas to describe a richer set of possible states of Information Systems in the year 2010. The scenarios are integrative and consider a set of possible events and their impacts. Two major driving forces: (1) telecommunications development and (2) social acceptance of information systems (IS) are assumed to define the scenario space. Based on these driving forces, four scenarios are created: Utopian, Dystopian, Status Quo, and Technology. The Utopian (ubiquitous telecommunications, high social acceptance of IS) and Dystopian (limited gains in telecommunications, low social acceptance of IS) scenarios are described in detail. The scenarios provide a basis for assessing the frontiers of information systems.