Hydrological Prediction in a Tropical Watershed Dominated by Oxisols Using a Distributed Hydrological Model

Hydrological models have been used in many places of the world in order to support practitioners with respect to watershed management actions. The goal of this research was to apply the Lavras Simulation of Hydrology (LASH model) to a Brazilian tropical watershed dominated by Oxisols, to estimate maximum, minimum and mean stream flows for both current land-use (“scenario 1”) and other regional trend land-use scenarios (“scenario 2”—pasture into eucalyptus; and “scenario 3”—eucalyptus into pasture). This model is a continuous, distributed and semi-conceptual model for simulation of different hydrological components on a daily basis. The model had a good performance with respect to the “scenario 1”, resulting in Nash-Sutcliffe coefficients equal to 0.81, 0.82 and 0.98 for minimum, maximum and mean discharges, respectively. When “scenario 2” was simulated, it was found that minimum, mean and maximum stream flows had their values reduced in average by 7.39 %, 13.84 % and 20.38 %, respectively. On the contrary, it was observed in “scenario 3” an increase in average by 0.23 %, 0.44 % and 1.19 % for minimum, mean and maximum stream flows, respectively. With respect to water yield, scenario 2 resulted in a mean reduction of 119 mm, whereas for scenario 3 the difference was not so pronounced in relation to the current land use. Results obtained in scenario 2 are troublesome since this watershed drains into an important regional Hydroelectric Power Plant Reservoir and this approach needs to be considered by the Minas Gerais State electric energy company for its planning strategies for the future.     

Temperature Measurements during Microwave Processing: The Significance of Thermocouple Effects

Reliable and accurate temperature measurement during microwave processing of ceramic bodies is controversial. Although thermocouples are routinely used in conventional thermal furnaces, their presence in microwave furnaces can locally distort the electromagnetic field, conduct heat away from the sample, induce thermal instabilities and microwave breakdown, and lead to serious measurement errors. These thermocouple effects have been studied and found to be more pronounced in low- and medium-loss ceramic materials. To decrease the thermocouple effects during the processing of advanced ceramic materials, an optical, noncontact temperature sensing system has been developed, calibrated, and incorporated into a computer-controlled microwave furnace.     

Algorithmic Aspects of Topology Control Problems for Ad Hoc Networks

Topology control problems are concerned with the assignment of power values to the nodes of an ad hoc network so that the power assignment leads to a graph topology satisfying some specified properties. This paper considers such problems under several optimization objectives, including minimizing the maximum power and minimizing the total power. A general approach leading to a polynomial algorithm is presented for minimizing maximum power for a class of graph properties called monotone properties. The difficulty of generalizing the approach to properties that are not monotone is discussed. Problems involving the minimization of total power are known to be NP-complete even for simple graph properties. A general approach that leads to an approximation algorithm for minimizing the total power for some monotone properties is presented. Using this approach, a new approximation algorithm for the problem of minimizing the total power for obtaining a 2-node-connected graph is developed. It is shown that this algorithm provides a constant performance guarantee. Experimental results from an implementation of the approximation algorithm are also presented.     

Association of sex of fetus, sire, month of conception, or year of foaling with duration of gestation in standardbred mares

OBJECTIVE: To determine whether sex of fetus, sire, month of conception, or year of foaling was associated with duration of gestation in mares. DESIGN: Epidemiologic retrospective cohort study. ANIMALS: 500 foalings for 296 Standardbred mares. PROCEDURE: Data for reproductive events from 1986 to 1992 were analyzed. Analyses were conducted to determine whether duration of gestation was associated with sex of fetus, sire, month of conception, or year of foaling. RESULTS: Mean duration of gestation was 343.3 days and was significantly greater for colt fetuses (344.4 days) than for filly fetuses (342.2 days). Sire was associated with duration of gestation; gestation after mating with certain sires was consistently less than 340 days in duration, whereas duration after mating with other sires was consistently more than 350 days. Duration of gestation was associated with month of conception, decreasing by about 2.5 d/mo for mares conceiving later during the breeding season. CLINICAL IMPLICATIONS: Duration of gestation is affected by mating to specific sires and by month of conception. Stallions associated with exceptionally prolonged gestations might be used to breed mares early in the breeding season, whereas stallions associated with shorter gestations might be desirable for mares bred later in the breeding season. Preparations for impending parturition should be more effective and efficient with improved information on expected date of parturition.     

“EDGE TOUGHNESS” AND MATERIAL PROPERTIES RELATED TO THE MACHINING OF DENTAL CERAMICS

Abstract

Seven dental ceramic compositions, including zirconia, glass-infused alumina, polycrystalline alumina, porcelain and three different machinable glass ceramics (MGC's) were tested for edge flaking. The chosen load range encompassed the forces typically associated with machining operations for these materials. The results were examined with regard to material properties and the applicability of a parameter defined as “edge toughness” to machin-ability. It was determined that a non-linear low-load chipping relationship may be more relevant to machinability than the “edge toughness” parameter calculated from the high-load linear region.     

Mechanical Characteristics of Coated Fabrics

When fabrics are coated, their deformation behaviour changes considerably. The tensile, shear, and bending properties of four typical coated fabrics have been measured using the FAST system and an Instron tensile machine. The fabrics were measured before coating, after coating and after subsequent stretching or shearing treatment. Empirical polynomial functions were fitted to the experimental load–extension curves to allow the calculation of strain energies for comparison purposes. Mechanical treatment in the form of stretching or shearing partly restored the original fabric properties and so might be beneficial in apparel applications.     

Management Issues in Engineer Supply

ABSTRACT

This article presents the authors' research on quantifying trends in the future supply of professional engineers in Australia. Predictions are made concerning the effects of demographic change in the Australian population and within the Australian professional engineering work force. Similar trends are identified in other countries, which lead to further predictions of future drastic reductions in immigration of engineers to Australia. The overall conclusion is a rapidly developing scarcity of professional engineers in Australia and a very significant reduction in the growth rate of the professional engineering labor force. Similar trends are indicated in other countries including the United States. Some remedial human resource management strategies for Australia are identified.