974 resultados para Driving performance
Resumo:
Better management of knowledge assets has the potential to improve business processes and increase productivity. This fact has led to considerable interest in recent years in the knowledge management (KM) phenomenon, and in the main dimensions that can impact on its application in construction. However, a lack of a systematic way of assessing KM initia-tives’ contribution towards achieving organisational business objectives is evident. This paper describes the first stage of a research project intended to develop, and empirically test, a KM input-process-output framework comprising unique and well-defined theoretical constructs representing the KM process and its internal and external determinants in the context of con-struction. The paper presents the underlying principles used in operationally defining each construct through the use of extant KM literature. The KM process itself is explicitly mod-elled via a number of clearly articulated phases that ultimately lead to knowledge utilisation and capitalisation, which in turn adds value or otherwise to meeting defined business objec-tives. The main objective of the model is to reduce the impact of subjectivity in assessing the contribution made by KM practices and initiatives toward achieving performance improvements.
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Cooperative Systems provide, through the multiplication of information sources over the road, a lot of potential to improve the assessment of the road risk describing a particular driving situation. In this paper, we compare the performance of a cooperative risk assessment approach against a non-cooperative approach; we used an advanced simulation framework, allowing for accurate and detailed, close-to-reality simulations. Risk is estimated, in both cases, with combinations of indicators based on the TTC. For the non-cooperative approach, vehicles are equipped only with an AAC-like forward-facing ranging sensor. On the other hand, for the cooperative approach, vehicles share information through 802.11p IVC and create an augmented map representing their environment; risk indicators are then extracted from this map. Our system shows that the cooperative risk assessment provides a systematic increase of forward warning to most of the vehicles involved in a freeway emergency braking scenario, compared to a non-cooperative system.
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As the world’s population is growing, so is the demand for agricultural products. However, natural nitrogen (N) fixation and phosphorus (P) availability cannot sustain the rising agricultural production, thus, the application of N and P fertilisers as additional nutrient sources is common. It is those anthropogenic activities that can contribute high amounts of organic and inorganic nutrients to both surface and groundwaters resulting in degradation of water quality and a possible reduction of aquatic life. In addition, runoff and sewage from urban and residential areas can contain high amounts of inorganic and organic nutrients which may also affect water quality. For example, blooms of the cyanobacterium Lyngbya majuscula along the coastline of southeast Queensland are an indicator of at least short term decreases of water quality. Although Australian catchments, including those with intensive forms of land use, show in general a low export of nutrients compared to North American and European catchments, certain land use practices may still have a detrimental effect on the coastal environment. Numerous studies are reported on nutrient cycling and associated processes on a catchment scale in the Northern Hemisphere. Comparable studies in Australia, in particular in subtropical regions are, however, limited and there is a paucity in the data, in particular for inorganic and organic forms of nitrogen and phosphorus; these nutrients are important limiting factors in surface waters to promote algal blooms. Therefore, the monitoring of N and P and understanding the sources and pathways of these nutrients within a catchment is important in coastal zone management. Although Australia is the driest continent, in subtropical regions such as southeast Queensland, rainfall patterns have a significant effect on runoff and thus the nutrient cycle at a catchment scale. Increasingly, these rainfall patterns are becoming variable. The monitoring of these climatic conditions and the hydrological response of agricultural catchments is therefore also important to reduce the anthropogenic effects on surface and groundwater quality. This study consists of an integrated hydrological–hydrochemical approach that assesses N and P in an environment with multiple land uses. The main aim is to determine the nutrient cycle within a representative coastal catchment in southeast Queensland, the Elimbah Creek catchment. In particular, the investigation confirms the influence associated with forestry and agriculture on N and P forms, sources, distribution and fate in the surface and groundwaters of this subtropical setting. In addition, the study determines whether N and P are subject to transport into the adjacent estuary and thus into the marine environment; also considered is the effect of local topography, soils and geology on N and P sources and distribution. The thesis is structured on four components individually reported. The first paper determines the controls of catchment settings and processes on stream water, riverbank sediment, and shallow groundwater N and P concentrations, in particular during the extended dry conditions that were encountered during the study. Temporal and spatial factors such as seasonal changes, soil character, land use and catchment morphology are considered as well as their effect on controls over distributions of N and P in surface waters and associated groundwater. A total number of 30 surface and 13 shallow groundwater sampling sites were established throughout the catchment to represent dominant soil types and the land use upstream of each sampling location. Sampling comprises five rounds and was conducted over one year between October 2008 and November 2009. Surface water and groundwater samples were analysed for all major dissolved inorganic forms of N and for total N. Phosphorus was determined in the form of dissolved reactive P (predominantly orthophosphate) and total P. In addition, extracts of stream bank sediments and soil grab samples were analysed for these N and P species. Findings show that major storm events, in particular after long periods of drought conditions, are the driving force of N cycling. This is expressed by higher inorganic N concentrations in the agricultural subcatchment compared to the forested subcatchment. Nitrate N is the dominant inorganic form of N in both the surface and groundwaters and values are significantly higher in the groundwaters. Concentrations in the surface water range from 0.03 to 0.34 mg N L..1; organic N concentrations are considerably higher (average range: 0.33 to 0.85 mg N L..1), in particular in the forested subcatchment. Average NO3-N in the groundwater has a range of 0.39 to 2.08 mg N L..1, and organic N averages between 0.07 and 0.3 mg N L..1. The stream bank sediments are dominated by organic N (range: 0.53 to 0.65 mg N L..1), and the dominant inorganic form of N is NH4-N with values ranging between 0.38 and 0.41 mg N L..1. Topography and soils, however, were not to have a significant effect on N and P concentrations in waters. Detectable phosphorus in the surface and groundwaters of the catchment is limited to several locations typically in the proximity of areas with intensive animal use; in soil and sediments, P is negligible. In the second paper, the stable isotopes of N (14N/15N) and H2O (16O/18O and 2H/H) in surface and groundwaters are used to identify sources of dissolved inorganic and organic N in these waters, and to determine their pathways within the catchment; specific emphasis is placed on the relation of forestry and agriculture. Forestry is predominantly concentrated in the northern subcatchment (Beerburrum Creek) while agriculture is mainly found in the southern subcatchment (Six Mile Creek). Results show that agriculture (horticulture, crops, grazing) is the main source of inorganic N in the surface waters of the agricultural subcatchment, and their isotopic signature shows a close link to evaporation processes that may occur during water storage in farm dams that are used for irrigation. Groundwaters are subject to denitrification processes that may result in reduced dissolved inorganic N concentrations. Soil organic matter delivers most of the inorganic N to the surface water in the forested subcatchment. Here, precipitation and subsequently runoff is the main source of the surface waters. Groundwater in this area is affected by agricultural processes. The findings also show that the catchment can attenuate the effects of anthropogenic land use on surface water quality. Riparian strips of natural remnant vegetation, commonly 50 to 100 m in width, act as buffer zones along the drainage lines in the catchment and remove inorganic N from the soil water before it enters the creek. These riparian buffer zones are common in most agricultural catchments of southeast Queensland and are indicated to reduce the impact of agriculture on stream water quality and subsequently on the estuary and marine environments. This reduction is expressed by a significant decrease in DIN concentrations from 1.6 mg N L..1 to 0.09 mg N L..1, and a decrease in the �15N signatures from upstream surface water locations downstream to the outlet of the agricultural subcatchment. Further testing is, however, necessary to confirm these processes. Most importantly, the amount of N that is transported to the adjacent estuary is shown to be negligible. The third and fourth components of the thesis use a hydrological catchment model approach to determine the water balance of the Elimbah Creek catchment. The model is then used to simulate the effects of land use on the water balance and nutrient loads of the study area. The tool that is used is the internationally widely applied Soil and Water Assessment Tool (SWAT). Knowledge about the water cycle of a catchment is imperative in nutrient studies as processes such as rainfall, surface runoff, soil infiltration and routing of water through the drainage system are the driving forces of the catchment nutrient cycle. Long-term information about discharge volumes of the creeks and rivers do, however, not exist for a number of agricultural catchments in southeast Queensland, and such information is necessary to calibrate and validate numerical models. Therefore, a two-step modelling approach was used to calibrate and validate parameters values from a near-by gauged reference catchment as starting values for the ungauged Elimbah Creek catchment. Transposing monthly calibrated and validated parameter values from the reference catchment to the ungauged catchment significantly improved model performance showing that the hydrological model of the catchment of interest is a strong predictor of the water water balance. The model efficiency coefficient EF shows that 94% of the simulated discharge matches the observed flow whereas only 54% of the observed streamflow was simulated by the SWAT model prior to using the validated values from the reference catchment. In addition, the hydrological model confirmed that total surface runoff contributes the majority of flow to the surface water in the catchment (65%). Only a small proportion of the water in the creek is contributed by total base-flow (35%). This finding supports the results of the stable isotopes 16O/18O and 2H/H, which show the main source of water in the creeks is either from local precipitation or irrigation waters delivered by surface runoff; a contribution from the groundwater (baseflow) to the creeks could not be identified using 16O/18O and 2H/H. In addition, the SWAT model calculated that around 68% of the rainfall occurring in the catchment is lost through evapotranspiration reflecting the prevailing long-term drought conditions that were observed prior and during the study. Stream discharge from the forested subcatchment was an order of magnitude lower than discharge from the agricultural Six Mile Creek subcatchment. A change in land use from forestry to agriculture did not significantly change the catchment water balance, however, nutrient loads increased considerably. Conversely, a simulated change from agriculture to forestry resulted in a significant decrease of nitrogen loads. The findings of the thesis and the approach used are shown to be of value to catchment water quality monitoring on a wider scale, in particular the implications of mixed land use on nutrient forms, distributions and concentrations. The study confirms that in the tropics and subtropics the water balance is affected by extended dry periods and seasonal rainfall with intensive storm events. In particular, the comprehensive data set of inorganic and organic N and P forms in the surface and groundwaters of this subtropical setting acquired during the one year sampling program may be used in similar catchment hydrological studies where these detailed information is missing. Also, the study concludes that riparian buffer zones along the catchment drainage system attenuate the transport of nitrogen from agricultural sources in the surface water. Concentrations of N decreased from upstream to downstream locations and were negligible at the outlet of the catchment.
Resumo:
The global economy experienced continuous growth from 2002 to 2007 until the U.S. subprime mortgage crisis caused instability in worldwide stock markets. Simultaneously, global CEO turnover continued to fall to 13.8 percent in 2007. In contrast, the CEO turnover rate in Australia increased to 18 percent in 2007. The purpose of this paper is to determine under what conditions a change in a CEO is associated with firm performance. Succinctly, does the firm’s decision to replace the CEO depend on the CEO’s human capital or firm performance? The empirical study of Australian listed firms (2005 – 2008) shows that firm performance is not a determinant of CEO turnover, rather a CEO with less valuable human capital is more likely to be replaced. The study also finds that merely changing the CEO is not associated firm performance. Rather, there is a positive association between firm performance and the successor’s general human capital for firms that replace the CEO. Specifically, it is the internal successor’s general human capital that is an important determinant of increasing firm performance. These results are important because they imply that CEO turnover is a result of a more active market for CEOs and contributes to explaining why firms retain CEOs despite poor firm performance.
"I drove after drinking alcohol" and other risky driving behaviours reported by young novice drivers
Resumo:
Background Volitional risky driving behaviours including drink- and drug-driving and speeding contribute to the overrepresentation of young novice drivers in road crash fatalities, and crash risk is greatest during the first year of independent driving in particular. Aims To compare: 1) the self-reported compliance of drivers with road rules relating to substance-impaired driving and other risky driving behaviours including speeding and driving tired, one year after progression from a Learner to a Provisional (intermediate) licence; and 2) the interrelationships between substance-impaired driving and other risky driving behaviours (crashes, offences, and Police avoidance). Methods 1268 drivers (373 males) aged 17-26 years were surveyed regarding their sociodemographics (age, gender) and self-reported driving behaviours including crashes, offences, Police-avoidance, and driving intentions. Results A relatively small proportion of participants reported driving after taking drugs (5.9% males, 1.3% females) and drinking alcohol (19.3% males, 11.6% females). In comparison, a considerable proportion of participants reported at least occasionally exceeding speed limits (85.7% novices) and driving when tired (82.7% novices). Substance-impaired driving was associated with avoiding Police, speeding, risky driving intentions, and self reported crashes and offences. Forty-four percent of illicit-drug drivers also reported alcohol-impaired driving. Discussion and conclusions The low self-reported prevalence of substance-impaired driving suggests official enforcement measures play a role in promoting compliance, in addition to social influences such as the broader community and the young novice drivers’ social networks including friends and family. Conversely, the prevalence of speeding appears to reflect the pervasive cultural acceptance of this behaviour. Given the interrelationships between the risky driving behaviours, a deeper understanding of influential factors is required to inform targeted and general countermeasure implementation and evaluation during this critical driving period.
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In the modern built environment, building construction and demolition consume a large amount of energy and emits greenhouse gasses due to widely used conventional construction materials such as reinforced and composite concrete. These materials consume high amount of natural resources and possess high embodied energy. More energy is required to recycle or reuse such materials at the cessation of use. Therefore, it is very important to use recyclable or reusable new materials in building construction in order to conserve natural resources and reduce the energy and emissions associated with conventional materials. Advancements in materials technology have resulted in the introduction of new composite and hybrid materials in infrastructure construction as alternatives to the conventional materials. This research project has developed a lightweight and prefabricatable Hybrid Composite Floor Plate System (HCFPS) as an alternative to conventional floor system, with desirable properties, easy to construct, economical, demountable, recyclable and reusable. Component materials of HCFPS include a central Polyurethane (PU) core, outer layers of Glass-fiber Reinforced Cement (GRC) and steel laminates at tensile regions. This research work explored the structural adequacy and performance characteristics of hybridised GRC, PU and steel laminate for the development of HCFPS. Performance characteristics of HCFPS were investigated using Finite Element (FE) method simulations supported by experimental testing. Parametric studies were conducted to develop the HCFPS to satisfy static performance using sectional configurations, spans, loading and material properties as the parameters. Dynamic response of HCFPS floors was investigated by conducting parametric studies using material properties, walking frequency and damping as the parameters. Research findings show that HCFPS can be used in office and residential buildings to provide acceptable static and dynamic performance. Design guidelines were developed for this new floor system. HCFPS is easy to construct and economical compared to conventional floor systems as it is lightweight and prefabricatable floor system. This floor system can also be demounted and reused or recycled at the cessation of use due to its component materials.
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Background: Studies on the relationship between performance and design of the throwing frame have been limited and therefore require further investigation. Objectives: The specific objectives were to provide benchmark information about performance and whole body positioning of male athletes in F30s classes. Study Design: Descriptive analysis. Methods: A total of 48 attempts performed by 12 stationary discus throwers in F33 and F34 classes during seated discus throwing event of 2002 International Paralympic Committee Athletics World Championships were analysed in this study. The whole body positioning included overall throwing posture (i.e. number of points of contact between the thrower and the frame, body position, throwing orientation and throwing side) and lower limb placements (i.e. seating arrangements, points of contact on the both feet, type of attachment of both legs and feet). Results: Three (25%), five (42%), one (8%) and three (25%) athletes used from three to six points of contact, respectively. Seven (58%) and five (42%) athletes threw from a standing or a seated position, respectively. A straddle, a stool or a chair was used by six (50%), four (33%) or two (17%) throwers, respectively. Conclusions: This study provides key information for a better understanding of the interaction between throwing technique of elite seated throwers and their throwing frame.
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The purpose of this article is to examine the role of the alignment between technological innovation effectiveness and operational effectiveness after the implementation of enterprise information systems, and the impact of this alignment on the improvement in operational performance. Confirmatory factor analysis was used to examine structural relationships between the set of observed variables and the set of continuous latent variables. The findings from this research suggest that the dimensions stemming from technological innovation effectiveness such as system quality, information quality, service quality, user satisfaction and the performance objectives stemming from operational effectiveness such as cost, quality, reliability, flexibility and speed are important and significantly well-correlated factors. These factors promote the alignment between technological innovation effectiveness and operational effectiveness and should be the focus for managers in achieving effective implementation of technological innovations. In addition, there is a significant and direct influence of this alignment on the improvement of operational performance. The principal limitation of this study is that the findings are based on investigation of small sample size.
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Boards of directors are key governancemechanisms in organizations and fulfill twomain tasks:monitoringmanagers and firm performance, and providing advice and access to resources. In spite of a wealth of researchmuch remains unknown about how boards attend to the two tasks. This study investigates whether organizational (firm profitability) and environmental factors (industry regulation) affect board task performance. The data combine CEOs' responses to a questionnaire, and archival data from a sample of large Italian firms. Findings show that past firm performance is negatively associatedwith board monitoring and advice tasks; greater industry regulation enhances perceived board task performance; board monitoring and advice tasks tend to reinforce each other, despite their theoretical and practical distinction.
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Participant performance is critical to the success of projects. At the same time, enhancing the satisfaction of participants not only helps in problem solving but also improves their motivation and cooperation. However, previous research related to participant satisfaction is primarily concerned with clients and customers and relatively little attention has been paid to contractors. This paper investigates how the performance of project participants affects contractor project satisfaction in terms of the client's clarity of objectives (OC) and promptness of payments (PP), designer carefulness (DC), construction risk management (RM), the effectiveness their contribution (EW) and mutual respect and trust (RT). With 125 valid responses from contractors in Malaysia, a contractor satisfaction model is developed based on structural equation modelling. The results demonstrate the necessity for dividing abstract satisfaction into two dimensions, comprising economic-related satisfaction (ES) and production-related satisfaction (PS), with DC, OC, PP and RM having significant effects on ES, while DC, OC, EW and RM influence PS. In addition, the model tests the indirect effects of these performance variables on ES and PS. In particular, OC indirectly affects ES and PS through mediation of RM and DC respectively. The results also provide opportunities for improving contractor satisfaction and supplementing the contractor selection criteria for clients.
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This paper presents an experimental study on the effect of presoaked lightweight aggregates (LWAs) for internal curing on water permeability, water absorption and resistance of concrete to chloride-ion penetration in comparison with those of a control concrete and a concrete with shrinkage reducing admixture (SRA) of similar water/cement ratios (w/c). In general, the concretes with LWA particles had initial water absorption, sorptivity and water permeability similar to or lower than those of the control concrete and the concrete with SRA. The charges passed, chloride migration coefficient and chloride diffusion coefficient of such concretes were in the same order as those of the control concrete and the concrete with SRA. However, the incorporation of the LWAs for internal curing reduced unit weight, compressive strength and elastic modulus of the concrete. Comparing the LWAs of different sizes for internal curing, finer particles were more efficient in reducing the shrinkage and generally resulted in less reduction in the unit weight, compressive strength, and elastic modulus. However, the increase in the more porous crushed LW particles in concrete seems to increase the penetration of chloride ions in the concrete. The concrete with SRA had initial water absorption, sorptivity, water permeability and resistance to chloride ion penetration comparable with those of the control concrete. The use of SRA in concrete does not affect the elastic modulus of the concrete, except for a minor influence on the compressive strength of the concrete.
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In the last two decades, there are developments that lead to greater understanding on how and why lightweight concretes (LWC) may achieve similar or higher performance than their normal weight counterparts. The present paper reviews some of these aspects beginning with basic properties such as unit weight, compressive strength and specific strength (strength/ unit weight). Stability and workability of LWC is discussed from rheological perspective. The volumetric stability of LWC in terms of shrinkage and creep are presented with some recent published data. Transport properties of the LWC in terms of sorptivity, water permeability and resistance to chloride-ion penetration are reviewed in comparison with normal weight concrete. Fire resistance of LWC and some current measures used to improve the resistance are discussed. With continual research and development, the performance of LWC is being enhanced to provide new opportunities for practical applications.
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Load bearing Light Gauge Steel Frame (LSF) walls made of cold-formed steel studs and tracks are commonly used in residential and commercial buildings. Fire safety of these walls is essential to minimize the damage caused by fire related accidents. Past investigations on the fire performance of load bearing LSF wall systems have been limited to LSF walls made of conventional lipped channel section studs. Although structurally efficient hollow flange steel sections are available in the building industry, they are not used as LSF wall studs due to the lack of fire performance data for such walls. The hollow flange sections have torsionally rigid hollow flanges that eliminate the occurrence of local and distortional buckling to an extent, thereby increasing their structural efficiency. The weaknesses of hollow flange sections such as lower lateral distortional buckling capacity are also eliminated when they are used as studs of LSF walls as the plasterboard restraints will prevent any lateral movement. Therefore hollow flange sections can be considered as structurally more efficient studs for use in LSF wall systems. This paper reports the full scale fire tests of LSF walls made of hollow flange section studs under standard fire conditions. The frames were made of 1.6 mm thick and 150 mm deep hollow flange section studs with two closed rectangular flanges of 45 mm width x 15 mm depth. Dual plasterboards were attached on both sides of the test wall panels. The load ratio was varied and the failure times, the lateral deflections and the axial displacements of the test walls were obtained. The failure behaviour of LSF walls made of hollow flange section studs was found to be different to that of LSF walls made of conventional lipped channel section studs. The results of these fire tests show that hollow flange section studs have a higher potential in being used in load bearing LSF Walls.