Analysis of factors affecting wireless communication systems in underground coal mines

Since recent disasters in the mining industry in 2006 the push for a reliable communication system has became a high priority. This thesis will discuss each wireless communication system available and/or being developed for underground mines as well as the frequencies that will be used for each system\u27s operation.;The second part of the investigation will be on the factors affecting these frequencies as well as possible ways to model these factors analytically. It is important to understand these factors in order to make intelligent conclusions as to what communication systems will perform adequately in an underground mining environment.;The third area discussed will be an analysis of empirical studies completed by various agencies, companies, and schools (including West Virginia University). These studies were completed to judge the practicality and performance of each system. Practicality is important to the mining industry. The industry tends not to accept new technology quickly, so proof of performance is a key component to introducing the products into the market

Succession management practices in Australian organizations

In order to assess the current usage of succession management programs in Australian-based organizations, and gain information on the characteristics and perceived effectiveness of such programs, a national research study was undertaken. A total of 711 human resource management professionals from a range of organizations across the country answered the questionnaire, a response rate of 59 percent. Succession management programs were present in less than half of the respondent's organizations. Furthermore, these programs were generally less than five years old. The prime imperatives for introducing succession management programs were reported as the desire to improve business results, and the need for new skill requirements in the business. A relationship between organization size, industry and type and the likelihood to use succession management was found. Common perceptions concerning the characteristics of effective succession management programs were also identified and are described in the paper. In brief, these are: high level involvement by the chief executive officer; senior management support; line management involvement in identifying candidates; developmental assignments as part of the process; and succession management linked to business strategies

Exploring Human Resource Management Practices in Nonprofit Sport Organisations

Contemporary business challenges and globalisation pressures have had a significant impact on the human resource management (HRM) practices of many organisations. Whilst the adoption of more sophisticated, complex and strategic management systems is well documented in the general HR literature, organisations that operate with both paid and volunteer human resources have been virtually ignored by scholars. In this paper we report on a study on the adoption of HRM practices by state sport organisations in New.South Wales, Australia. Our results indicate that despite pressures to become more strategic in their people management, only a minority of these sport organisations have formal HRM systems. We also found differences between the HRM practices used with paid employees and volunteers particularly in organisations with formal HR policies. Research and practical implications for HRM in sport organisations are discussed as well as future challenges. © 2006 Sport Management Association of Australia and New Zealand

Ternary nucleation of H_2SO_4, NH_3 and H_2O

A classical theory of the ternary homogeneous nucleation of sulfuric acid—ammonia—water is presented. For NH3 mixing ratios exceeding 1 ppt, the presence of ammonia enhances the binary (sulfuric acid—water) nucleation rate by several orders of magnitude. However, the limiting component for ternary nucleation—as for binary nucleation—is sulfuric acid. The sulfuric acid concentration needed for significant ternary nucleation is several orders of magnitude below that required in binary case

Theoretical approaches and practical strategies for change management

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Bistable Gradient Networks II: Storage Capacity and Behaviour Near Saturation

We examine numerically the storage capacity and the behaviour near saturation of an attractor neural network consisting of bistable elements with an adjustable coupling strength, the Bistable Gradient Network (BGN). For strong coupling, we find evidence of a first-order "memory blackout" phase transition as in the Hopfield network. For weak coupling, on the other hand, there is no evidence of such a transition and memorized patterns can be stable even at high levels of loading. The enhanced storage capacity comes, however, at the cost of imperfect retrieval of the patterns from corrupted versions.Comment: 15 pages, 12 eps figures. Submitted to Phys. Rev. E. Sequel to cond-mat/020356

Variability of Low-ionization Broad Absorption Line Quasars Based on Multi-epoch Spectra from The Sloan Digital Sky Survey

We present absorption variability results for 134 bona fide \mgii\ broad absorption line (BAL) quasars at 0.46~$\lesssim z \lesssim$~2.3 covering days to $\sim$ 10 yr in the rest frame. We use multiple-epoch spectra from the Sloan Digital Sky Survey, which has delivered the largest such BAL-variability sample ever studied. \mgii-BAL identifications and related measurements are compiled and presented in a catalog. We find a remarkable time-dependent asymmetry in EW variation from the sample, such that weakening troughs outnumber strengthening troughs, the first report of such a phenomenon in BAL variability. Our investigations of the sample further reveal that (i) the frequency of BAL variability is significantly lower (typically by a factor of 2) than that from high-ionization BALQSO samples; (ii) \mgii\ BAL absorbers tend to have relatively high optical depths and small covering factors along our line of sight; (iii) there is no significant EW-variability correlation between \mgii\ troughs at different velocities in the same quasar; and (iv) the EW-variability correlation between \mgii\ and \aliii\ BALs is significantly stronger than that between \mgii\ and \civ\ BALs at the same velocities. These observational results can be explained by a combined transverse-motion/ionization-change scenario, where transverse motions likely dominate the strengthening BALs while ionization changes and/or other mechanisms dominate the weakening BALs.Comment: 24 pages, accepted for publication in ApJ

Flow distributed oscillation, flow velocity modulation and resonance

We examine the effects of a periodically varying flow velocity on the standing and travelling wave patterns formed by the flow-distributed oscillation (FDO) mechanism. In the kinematic (or diffusionless) limit, the phase fronts undergo a simple, spatiotemporally periodic longitudinal displacement. On the other hand, when the diffusion is significant, periodic modulation of the velocity can disrupt the wave pattern, giving rise in the downstream region to travelling waves whose frequency is a rational multiple of the velocity perturbation frequency. We observe frequency locking at ratios of 1:1, 2:1 and 3:1, depending on the amplitude and frequency of the velocity modulation. This phenomenon can be viewed as a novel, rather subtle type of resonant forcing.Comment: submitted to Phys. Rev.