A review of construction work sampling methods and an investigation into their use in South Africa

Work sampling had its origin in industrial engineering; however, its use in construction has increased greatly during the 1970's and 1980's. Research would suggest that most of the innovation in this field is taking place in the United States. The basic methods of Work Sampling have been developed to suit the peculiarities of the construction site as opposed to the production line or factory where it was first used. The objectives of this report are as follows: 1. To review the existing methods of Construction Work Sampling as well as discuss further aspects and problems which should be considered when undertaking a Work Sampling study. 2. To compare Construction Work Sampling with other methods of measuring productivity. 3. To evaluate by means of a case study the ease of applicability of the sampling methods to a South African construction site, and at the same time to identify differences between the description of the methods in theory and their use in practice. 4. To establish by means of a questionnaire the extent to which Construction Work Sampling methods are already in use in South Africa as well as other related information. Information for this report was obtained from journals, manuals, text books, interviews, and the case study and questionnaires mentioned

HEMODYNAMIC DESIGN OPTIMIZATION OF A VENTRICULAR CANNULA:EVALUATION AND IMPLEMENTATION OF OBJECTIVE FUNCTIONS

Shape optimization has been used for decades to improve the aerodynamic performance of automobiles and aircraft. The application of this technology to blood-wetted medical devices have been limited, in part, due to the ambiguity of hemodynamic variables associated with biocompatibility - specifically hemolysis, platelet activation, and thrombus formation. This study undertook a systematic evaluation of several objective functions derived directly from the flow field. We specifically focused on the optimization of a two-dimensional blood conduit (cannula) by allowing free variation of the centerline and cross-sectional area. The flow was simulated using computational fluid dynamics (CFD) at a nominal flow rate of 6 lpm and boundary conditions consistent with an abdominally positioned left-ventricular-assist device (LVAD). The objectives were evaluated both locally and globally. The results demonstrated similarities between four of the functions: vorticity, viscous dissipation, principal shear stress, and power-law (PL) blood damage models based on shear history. Of the functions analyzed, those found to be most indicative of flow separation and clearance were flow deviation index and the Peclet Number. The conclusions from these studies will be applied to ongoing development of algorithms for optimizing the flow path of rotary blood pumps, cannula, and other blood contacting devices

Genetic structure and history of Swiss maize ( Zea mays L. ssp. mays ) landraces

Between 1930 and 2003 with emphasis on the 1940s maize landraces (Zea mays L. ssp. mays) from all over Switzerland were collected for maintenance and further use in a new Swiss breeding program. The genetic relationship and diversity among these accessions stored in the Swiss gene bank is largely unknown. Our hypothesis was that due to the unique geographic, climatic, and cultural diversity in Switzerland a diverse population of maize landraces had developed over the past three centuries. The aims were to characterize the genetic diversity of the Swiss landraces and their genetic relationship with accessions from neighbouring regions as well as reviewing their history, collection, and maintenance. The characterization and grouping was based on analyses with ten microsatellite markers. Geographic, cultural, and climatic conditions explained a division in two distinct groups of accessions. One group consisted of landraces collected in the southern parts of Switzerland. This group was related to the Italian Orange Flints. The other group contained accessions from northern Switzerland which were related to Northern European Flints in particular German Flints. Historic evidence was found for a frequent exchange of landraces within the country resulting in a lack of region-specific or landrace-specific genetic groups. The relatively large separation between the accessions, indicated by high F ST (0.42), might be explained partly by a bottleneck during the collection and maintenance phase as well as by geographical and cultural separation of north and south of the country. Due to the high genetic diversity, the accessions here are a potential resource for broadening the European flint poo

Learning from the Past, Looking to the Future: Modeling Social Unrest in Karachi, Pakistan

Social unrest represents a major challenge for policy makers around the globe, as it can quickly escalate from small scale disturbances to highly public protests, riots and even civil war. This research was motivated by a need to understand social instability and to unpack the comments made during a spring 2013 conference hosted by Pacific Northwest National Laboratory’s Center for Global Security and the U.S. Institute for Peace, where policymakers noted that models considering social instability are often not suitable for decision-making. This analysis shows that existing state level models of instability could be improved in spatial scale to the city level, even without significantly improved data access. Better data would make this analysis more complete and likely improve the quality of the model. Another challenge with incorporating modeling into decision-making is the need to understand uncertainty in a model. Policy makers are frequently tasked with making decisions without a clear outcome, so characterization of uncertainty is critical. This report describes the work and findings of the project. It took place in three phases: a literature review of social stability research, a “hindsight scan” that looked at historical data, and a “foresight scan” looking at future scenarios

Quantum Dot Potentials: Symanzik Scaling, Resurgent Expansions and Quantum Dynamics

This article is concerned with a special class of the ``double-well-like'' potentials that occur naturally in the analysis of finite quantum systems. Special attention is paid, in particular, to the so-called Fokker-Planck potential, which has a particular property: the perturbation series for the ground-state energy vanishes to all orders in the coupling parameter, but the actual ground-state energy is positive and dominated by instanton configurations of the form exp(-a/g), where a is the instanton action. The instanton effects are most naturally taken into account within the modified Bohr-Sommerfeld quantization conditions whose expansion leads to the generalized perturbative expansions (so-called resurgent expansions) for the energy values of the Fokker-Planck potential. Until now, these resurgent expansions have been mainly applied for small values of coupling parameter g, while much less attention has been paid to the strong-coupling regime. In this contribution, we compare the energy values, obtained by directly resumming generalized Bohr-Sommerfeld quantization conditions, to the strong-coupling expansion, for which we determine the first few expansion coefficients in powers of g^(-2/3). Detailed calculations are performed for a wide range of coupling parameters g and indicate a considerable overlap between the regions of validity of the weak-coupling resurgent series and of the strong-coupling expansion. Apart from the analysis of the energy spectrum of the Fokker-Planck Hamiltonian, we also briefly discuss the computation of its eigenfunctions. These eigenfunctions may be utilized for the numerical integration of the (single-particle) time-dependent Schroedinger equation and, hence, for studying the dynamical evolution of the wavepackets in the double-well-like potentials.Comment: 13 pages; RevTe

Complex spatial language improves from 3 to 5 years: The role of prompting and overhearing in facilitating direction giving using between and middle.

The primary goal of this study was to specify age-related improvements in young children’s use of the complex spatial terms between and middle in response to prompting and overhearing supports. Three- to 5-year-old children described the location of a mouse hidden between two furniture items in a dollhouse. Three prompting conditions (Between Directive, Middle Directive, Nondirective) were compared with two overhearing conditions (Overhearing Between, Overhearing Middle). Children’s use of between and middle was much more frequent in response to directive prompting than in response to nondirective prompting or overhearing. Only 4-5-year-old children showed some evidence of using middle in response to nondirective prompting and overhearing, demonstrating developmental gains in sensitivity to subtle cues. The secondary goal was to assess young children’s production and comprehension of between and middle using tasks suitable for young children and parent report checklists. As expected, children’s spatial language showed strong developmental improvement and was related to direction-giving performance

Effect of Haptic Feedback on Static Standing Sway

Study Goal: To explore the use of proprioceptive input as a means of attenuating postural sway through the development and implementation of a hands-free device, with the ultimate goal of providing sway-reference haptic input located at the upper trunk and shoulders to determine: Does sway-referenced haptic input improve static standing stability

Characteristic Potentials for Mesoscopic Rings Threaded by an Aharonov-Bohm Flux

Electro-static potentials for samples with the topology of a ring and penetrated by an Aharonov-Bohm flux are discussed. The sensitivity of the electron-density distribution to small variations in the flux generates an effective electro-static potential which is itself a periodic function of flux. We investigate a simple model in which the flux sensitive potential leads to a persistent current which is enhanced compared to that of a loop of non-interacting electrons. For sample geometries with contacts the sensitivity of the electro-static potential to flux leads to a flux-induced capacitance. This capacitance gives the variation in charge due to an increment in flux. The flux-induced capacitance is contrasted with the electro-chemical capacitance which gives the variation in charge due to an increment in an electro-chemical potential. The discussion is formulated in terms of characteristic functions which give the variation of the electro-static potential in the interior of the conductor due to an increment in the external control parameters (flux, electro-chemical potentials). Paper submitted to the 16th Nordic Semiconductor Meeting, Laugarvatan, Iceland, June 12-15, 1994. The proceedings will be published in Physica Scripta.Comment: 23 pages + 4 figures, revtex, IBM-RC1955