Target tracking has emerged as an important application of sensor networks. There are two subproblems inherent to target tracking. The first is the initial location of the target as it enters the region being covered. The second is following its track once it has been discovered. In this work, we outline an approach to target tracking. We present an energy-aware tracking algorithm that predicts the target track and activates nodes based on that prediction. We then discuss different energy management schemes that resolve tradeoffs between energy savings and track quality for a specified mission lifetime. Our energy management schemes perform better in terms of track quality and have an energy consumption similar to other schemes. We also consider energy harvesting in this energy management. We present a multitarget tracking algorithm; in connection with that, we present a filtering algorithm that improves the quality of tracking. We also study adaptive approaches to manage the tracking process to the observed mobility characteristics of the target. Such adaptive approaches are shown to have noticeable performance advantages.

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The dependence on coal ores for energy supply has led to the considerable increase in coal discards (CD) and fine waste (FW) arising from mining and processing operations. These wastes typically contain sulphide minerals, which when oxidised may lead to the generation of acidic and toxic discharge. A deficit of naturally occurring neutralising minerals to counteract this acidic discharge results in acid rock drainage (ARD). Far reaching consequences on water systems, vegetation, people and wildlife ensue as a result. To minimise the environmental burden, the acidic water resulting from the oxidation of sulphide minerals present in wastes from both active and abandoned mines is often treated with alkaline materials and is further processed to remove metals. Indefinite maintenance and operational activities emanate from these treatment processes. Further, accumulating sludge from processing streams presents post-closure liabilities. To reduce the environmental footprint, mine waste management strategies have been developed to minimise the risk of ARD formation and proliferation. In this study, the co-disposal of CD and FW was investigated as a means to prevent the initiation of oxidation reactions at source. The CD fraction is sulphide rich with high acid producing potential but can be effectively utilised to construct structurally stable beds. In these beds, large voids are formed between the particles that facilitate the transport of oxygen and water to the sulphide mineral surfaces. Co-packing FW with sulphide-rich CD provides a sustainable approach to ARD prevention. The FW has a high-water retention capacity and can be used to encapsulate, seal or cap the sulphide bearing mineral surfaces. Apart from providing a physical barrier and decreasing voids, FW typically have low sulphide content and high specific surface area that result in increased release rates of any acid neutralising minerals present in these waste materials. Co-disposal techniques thereby provide a longterm end-of-pipe approach to ARD mitigation that may offset indefinite, resource intensive, treatment options. The co-disposal of CD with FW, however, is challenging particularly at large bed cross-sectional areas, as the incidence of high percolation rates increases. This is attributed to decreased inter-particle contact that emerge in packed beds with high void ratios, decreased packing density and increased susceptibility to deformation. This undesirable packing behaviour impacts negatively on bed stability culminating in particle displacement and increased likelihood for sulphide mineral oxidation. Fine wastes conceal these sulphide minerals by either filling voids between coarse particles or forming covers with capillary barriers and acid-neutralising effects. Consequently, the generation of ARD is inhibited. At increased scale, however, the ARD prevention efficiency of covers is enhanced by increasing the CD to FW proportion to result in a structure with high load and acid buffering capacity. The approach adopted in this study entails developing packing arrangements of co-mingled CD and FW in dry-mass ratios of 3:2 and 2:3, respectively, to improve bed stability and hence prevent ARD formation with scale up. In addition to mixture ratios, improved co-packing of CD and FW is contingent on the material geochemical properties and geotechnical parameters of the resulting packed structure. As such, geochemical analyses were performed to determine the acid producing and neutralising potential of the CD and FW through acid base accounting, net acid generating and biokinetic tests followed by geotechnical assessments. The static test results indicated that the high sulphur CD (2.16% S) was potentially acid forming and the low-sulphur FW (0.84% S) was non-acid forming with high acid neutralising capacity. The co-mingled CD and FW samples (ca. 1.5% S) were deemed uncertain as the net acid producing potential was near zero and the NAG pH was less than 4.5. Accordingly, biokinetic tests were conducted over 120 days to fully understand the acid generating and neutralising rates of the inoculated and uninoculated co-mingled samples. Near-neutral conditions were sustained for prolonged periods (> 90 days) in FW dominant samples (2CD:3FW) after which a transition to acidic conditions ensued. This highlighted the limited role of acid neutralising minerals in sustaining near neutral conditions. As ARD mitigation is contingent on preventing the rapid percolation of water and exclusion of oxygen from sulphide mineral surfaces, means to prevent the rapid depletion of neutralising minerals by either dilution or washout are essential in flow through systems. This can be achieved by decreasing voids to result in increased packing density and improved bed stability. Bed stability was shown to be dependent on several interrelated factors that included the degree of saturation of the particles (water to solid ratio, W/S), CD to FW ratio, packing configuration (layers or blends), and the extent of material compaction (assisted versus unassisted packing approach). These factors were integrated to produce 16 packing arrangements. The efficiency of these configurations was compared using packing density, slump and compressibility tests. Packing densities of ca. 0.8 m3solids. m-3mould coupled with low slump spread values (< 0.391 m) were obtained for wet, unassisted packings of CD-dominant layered and blended arrangements. Comparable packing densities and slump results were obtained for assisted packings of CD-dominant layered and blend configurations under dry conditions. Dry assisted packings of either CD or FW dominant layered systems resulted in ore beds with low compressive strain (< 7%), while in wetted structures, extensions of up to 30% over extended periods (>600 s) were noted. The large compressive extensions and the delay to achieving maximum compressive strains signalled the low particle consolidation and decreased bed stability of unassisted wet packings. As engineered co-disposal approaches are associated with long-term bed stability and hence prolonged ARD prevention, select packings were further analysed to validate their efficacy using kinetic column tests of increasing scale. An acidic feed of pH 2 was continuously introduced to the test columns at a flow rate of 3.5 L.m-2.h-1 to expedite the oxidation process and to assess the efficiency of the packing arrangements for ARD mitigation. Segregated disposal of CD in small scale columns (D = 0.19 m, H/D = 1.12) with inherent large voids allowed unrestricted access of the aqueous oxidants to the exposed sulphide minerals leading to rapid discharge of highly acidic effluent (ca. pH 2). For the wet, unassisted co-packed systems, structural instability was observed with the wash out of FW and subsequent fast effluent discharge rates. With the loss of the neutralising and reactive barrier due to migration, acidic conditions presented earlier in these wet packed beds (after 30 days) than in dry packed beds (after 90 days). The loss in geotechnical stability was more prevalent in blended systems than in layered configurations, with a rapid loss of geochemical stability following soon thereafter, despite similar neutralising characteristics in both packing configurations. In these blended arrangements, non-functional migration of the fine waste particles transpired to result in unhindered access of the oxidants with the acid generating minerals. With dilution and wash out of the neutralising components, acidic reactions dominated. In multi-layered systems, a cascading effect prevailed despite breakthrough in some layers such that a fail-safe condition resulted. Consequently, near-neutral effluent discharge at low flow rates transpired. This further emphasised the importance in preventing the displacement of particles to maintain bed stability in co-disposal prevention strategies. Assisted dry packings of blends and layers were anticipated to result in improved bed stability at large scale. As such, CD dominant blends (3CD:2FW) and FW dominant blend and layered (2CD:3FW) systems were investigated in large scale columns (D = 0.32 m, H/D = 1.12). These columns were similarly exposed to aggressive leach conditions over 120 days. As with the smaller scale columns, the packing efficiency in multi-layered arrangements were higher than for the blends. In the blended systems, evolving geochemical and geotechnical conditions were similar regardless of the CD:FW ratio demonstrating the complexity in achieving homogenously packed matrices at large scale. In multi-layered configuration, bed structural stability was sustained for extended periods as the stress imposed on the packed bed was uniformly distributed across the moisture retaining FW layers and dissipated within the matrix. Correspondingly, particle displacement was minimised, and with the cascading phenomena, ARD was successfully prevented over extended periods. A dry cover system composed of multi-layers of CD and FW is therefore recommended for pilot scale studies. Dry cover systems can be easily constructed and present a cost-effective approach to sustainable mine waste management. Further evaluation of the structural stability of multi-layers at large scale is required as changes in bed geometry, particle size and environmental conditions can alter the dump geotechnical properties and hence geochemical stability.

The effect of air humidity and velocity, tray surface and ring thickness, on the drying rates of apple rings, is reported. Drying rates for different apple slice thicknesses are correlated with the total moisture content of the fruit and the air relative humidity. Also reported are results on the simulation, both experimental and computational, for the parallel-flow industrial dehydrator drying process.

A finite element computer program which uses the conical, frustrum element is presented for the Linear elastic, static analysis of variable thickness, branched, thin shells of revolution, composed of straight sections and subject to general, axisymmetric mechanical, 1,oading. The thin she1,1, theory and finite element theory forming the basis of the analysis are described, with particular attention being given to the closing of the she l, 1, at the axis of symmetry, and shell branching. Numerous problems embodying al,1, relevant features of the program are analysed, and their solutions are discussed. A user's manual, for the program is appended, and guidelines for the efficient use of the program are given.

An ejector (jet pump) is a continuous flow pump which utilises the kinetic energy in a high velocity fluid stream, to entrain end extract a second fluid from a given location.

Energy inefficiencies are at present a characteristic of the Heavy Clay Industry throughout the world. In the Western Cape there has been a marked trend towards the use of unsophisticated plant for the manufacture of non-face plaster bricks since the nineteen sixties. At present all non-face plaster bricks are fired in clamps and only a few factories use dryers. Hollow ware rather than solid bricks find favour in South America, Asia and Europe, with the exceptions of the United Kingdom and the Netherlands, (the Netherlands use the soft mud process which does not lend itself to hollow ware production). However, in South Africa, in spite of potential energy and clay saving, the number of hollow block factories, has shrunk in the past 30 years. The only move towards hollow ware, has been the perforation, of face bricks. In the Western Cape no factories perforate their non-face bricks. The reduced production and cartage costs, could be passed on to the builder. Other advantages for low-cost housing are easier bricklaying, as well the aesthetic appeal of clay for semi-face finishes. Of considerable concern, to the Heavy Clay Industry is the fact that the energy and clay saving, as well as the reduced cartage cost, allows the clay hollow block to be competitive against cement, it's major rival in the field of "affordable housing". The hollow block, although larger, can be lighter than the solid brick, and has the further advantages of less units per square metre "in the wall", as well as good insulating properties. To produce hollow ware in the Western Cape, without major plant changes, it was necessary to test the possibility of firing hollow ware in clamps. This was achieved for the conventional non-face brick size and the maxi brick, both made with transverse holes. The purpose of this study was to provide an efficient method of drying bricks, particularly for factories which were drying in the open air. The hollow ware possibility widened the scope of the study, and a dryer was designed to dry both hollow ware and solid bricks. A constraint on the dryer design was the basic premise that the dryer would ultimately form part of an integrated dryer/kiln system. Open air drying in the Western Cape, while requiring no additional heat or electrical energy, does use forklifts, which use diesel and are expensive. The open air drying process has a high waste component and is weather dependent. Heavy losses have been experienced, not only during the autumn and spring, but often even in the middle of summer, due to unseasonal downpours. Arguably the main area of concern, to the producer, is the inefficient use of plant and labour during the winter months. The costs, to the producer, of the open air drying process were established. The literature survey dealt with the basic principles and problems of drying heavy clay products, as well as innovations and engineering problems in the field of drying. Initial tests were done on a test unit, large enough to simulate plant conditions. From the results of these tests, the work covered in the literature, as well as past practical plant experience, sufficient information was available to build a prototype plant dryer. The prototype dryer was constructed to dry units standing "one-high, soldier". With this setting, and the proposed airflow, it is possible to treat each unit in exactly the same manner as its neighbour. In this way it is possible to obtain results comparable to those obtained under laboratory conditions and achieve fast drying times. Fast drying implies a relatively small dryer with minimum heat losses, as well as having good control. The "One-high" configuration lends itself to simple setting and off-loading mechanisms. An objective of this study was to minimise the capital investment. The value of the waste saving, on open air drying, over two years, was regarded as an arbitrary amount to aim for, as the cost of the dryer. In fact, the dryer was built at below the capital cost of the forklifts which were eliminated by changing the drying method. Pallets were eliminated, as was the need for setting labour. Fast drying of the order of 1-3 hours implies that the dryer is, in a sense, an extension of the extrusion process. The dryer can be switched on and off with the extruder, but what is more important is the fact that a plant which normally operates only on day shift, can be operated on a 24 hour basis without the need to build extra drying facilities. This latter point is of considerable importance in building boom periods. Clamps do not generate recoverable waste heat for drying. Phase two of this project will be to design the kiln, which is compatible, in concept, with the dryer. The proposed kiln will operate with less specific energy than clamps and generate the heat required to dry the bricks. In conclusion, the study leaves the fine tuning of the dryer for energy efficiency, still to be completed. In spite of this the dryer satisfies all the proposed conceptual criteria. It will be able to operate on the waste hot air from the kiln. If the kiln can operate at the level of the best commercial kilns at present available, and yet be built for a capital amount of the same order as the dryer, then an attractive alternative to clamp firing will have been found. Because the recoverable heat from the kiln is available, irrespective of the drying process, there will be no specific energy drying cost, the same situation that applies with open air drying, but, with none of its attendant problems.

Copper (Cu) nanowire (NW) arrays have potential applications in sensors, batteries, thermal and electrical management, and more. The performance and reliability of these devices depend on the robust bonding between the metal structures and the underlying substrates. Quantitative evaluation of the mechanical properties and bonding strength between the metal structures and substrates can provide guidance for device design, fabrication, and failure analysis. In the first part of the work, Cu NW arrays with different diameters, filling ratios, and spacings were prepared on Cu substrates. The effective Young’s modulus of the Cu NWs and the interfacial bonding strength between NWs and Cu substrates were evaluated using nanoindentation and nanoscratch tests, respectively. Our results showed that the effective Young's modulus of the Cu NW arrays decreased with their length, possibly due to the early buckling of some Cu NWs caused by their non-uniform length distribution and tilted angles. After correcting for full density, the effective Young’s modulus of Cu NWs was comparable to that of bulk Cu. On the other hand, the adhesion force and adhesion energy per unit area of the interface were found to be up to 67.62 mN and 544.87 J m-2, respectively, which are significantly higher compared to other one-dimensional (1D) nanostructure arrays evaluated using the same constant load scratch method. The constantly increasing power density of electronic devices necessitates the development of advanced thermal management solutions. TIMs play a crucial role in efficiently transferring heat from heat sources to heat sinks, ensuring that the device maintains a safe operating temperature and prevents thermal breakdowns. Likewise, electrical interconnects are vital in establishing low-resistance pathways for efficient electrical interconnection, thereby avoiding temperature rises caused by Joule heating. In the second part of the work, double-sided Cu NW arrays on Cu substrate were prepared and used as TIMs and electrical interconnect. The experimental results showed that the double-sided Cu NW arrays greatly reduced the thermal contact resistance (TCR), with reported values less than 5 mm2 K W-1, outperforming or comparable to double-sided nanostructural TIMs reported previously. The prepared double-sided Cu NW arrays were also used as electrical interconnects, resulting in a significant reduction in electrical contact resistance (ECR). Currently, the most widely used and commercially available templates are anodic aluminum oxide (AAO) and polycarbonate track etched (PCTE) templates. However, due to technical difficulties in the fabrication process, the thickness of these templates is limited to a few tens of microns. Some applications, such as advanced seal application, require structures that are longer, up to hundreds of microns. In the third part of the work, a polydimethylsiloxane (PDMS) template with a thickness of 200 to 300 μm was prepared and used for Cu MWs growth. The technical processes demonstrated here can be extended to prepare other 1D metal structures with customized geometries, lengths, diameters, and densities, paving the way for new applications of 1D metal structures. / Mechanical Engineering

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No description available.