Cost Reduction of Permanent Magnet Synchronous Machines

Electrical machine drives are the most electrical energy-consuming systems worldwide. The largest proportion of drives is found in industrial applications. There are, however many other applications that are also based on the use of electrical machines, because they have a relatively high efficiency, a low noise level, and do not produce local pollution. Electrical machines can be classified into several categories. One of the most commonly used electrical machine types (especially in the industry) is induction motors, also known as asynchronous machines. They have a mature production process and a robust rotor construction. However, in the world pursuing higher energy efficiency with reasonable investments not every application receives the advantage of using this type of motor drives. The main drawback of induction motors is the fact that they need slipcaused and thus loss-generating current in the rotor, and additional stator current for magnetic field production along with the torque-producing current. This can reduce the electric motor drive efficiency, especially in low-speed, low-power applications. Often, when high torque density is required together with low losses, it is desirable to apply permanent magnet technology, because in this case there is no need to use current to produce the basic excitation of the machine. This promotes the effectiveness of copper use in the stator, and further, there is no rotor current in these machines. Again, if permanent magnets with a high remanent flux density are used, the air gap flux density can be higher than in conventional induction motors. These advantages have raised the popularity of PMSMs in some challenging applications, such as hybrid electric vehicles (HEV), wind turbines, and home appliances. Usually, a correctly designed PMSM has a higher efficiency and consequently lower losses than its induction machine counterparts. Therefore, the use of these electrical machines reduces the energy consumption of the whole system to some extent, which can provide good motivation to apply permanent magnet technology to electrical machines. However, the cost of high performance rare earth permanent magnets in these machines may not be affordable in many industrial applications, because the tight competition between the manufacturers dictates the rules of low-cost and highly robust solutions, where asynchronous machines seem to be more feasible at the moment. Two main electromagnetic components of an electrical machine are the stator and the rotor. In the case of a conventional radial flux PMSM, the stator contains magnetic circuit lamination and stator winding, and the rotor consists of rotor steel (laminated or solid) and permanent magnets. The lamination itself does not significantly influence the total cost of the machine, even though it can considerably increase the construction complexity, as it requires a special assembly arrangement. However, thin metal sheet processing methods are very effective and economically feasible. Therefore, the cost of the machine is mainly affected by the stator winding and the permanent magnets. The work proposed in this doctoral dissertation comprises a description and analysis of two approaches of PMSM cost reduction: one on the rotor side and the other on the stator side. The first approach on the rotor side includes the use of low-cost and abundant ferrite magnets together with a tooth-coil winding topology and an outer rotor construction. The second approach on the stator side exploits the use of a modular stator structure instead of a monolithic one. PMSMs with the proposed structures were thoroughly analysed by finite element method based tools (FEM). It was found out that by implementing the described principles, some favourable characteristics of the machine (mainly concerning the machine size) will inevitable be compromised. However, the main target of the proposed approaches is not to compete with conventional rare earth PMSMs, but to reduce the price at which they can be implemented in industrial applications, keeping their dimensions at the same level or lower than those of a typical electrical machine used in the industry at the moment. The measurement results of the prototypes show that the main performance characteristics of these machines are at an acceptable level. It is shown that with certain specific actions it is possible to achieve a desirable efficiency level of the machine with the proposed cost reduction methods.

Proteoliposomes as matrix vesicles' biomimetics to study the initiation of skeletal mineralization

During the process of endochondral bone formation, chondrocytes and osteoblasts mineralize their extracellular matrix by promoting the formation of hydroxyapatite (HA) seed crystals in the sheltered interior of membrane-limited matrix vesicles (MVs). Ion transporters control the availability of phosphate and calcium needed for HA deposition. The lipidic microenvironment in which MV-associated enzymes and transporters function plays a crucial physiological role and must be taken into account when attempting to elucidate their interplay during the initiation of biomineralization. In this short mini-review, we discuss the potential use of proteoliposome systems as chondrocyte- and osteoblast-derived MVs biomimetics, as a means of reconstituting a phospholipid microenvironment in a manner that recapitulates the native functional MV microenvironment. Such a system can be used to elucidate the interplay of MV enzymes during catalysis of biomineralization substrates and in modulating in vitro calcification. As such, the enzymatic defects associated with disease-causing mutations in MV enzymes could be studied in an artificial vesicular environment that better mimics their in vivo biological milieu. These artificial systems could also be used for the screening of small molecule compounds able to modulate the activity of MV enzymes for potential therapeutic uses. Such a nanovesicular system could also prove useful for the repair/treatment of craniofacial and other skeletal defects and to facilitate the mineralization of titanium-based tooth implants.

Overexpression of hsa-miR-125b during osteoblastic differentiation does not influence levels of Runx2, osteopontin, and ALPL gene expression

Multipotent mesenchymal stromal cells (MSCs) were first isolated from bone marrow and then from various adult tissues including placenta, cord blood, deciduous teeth, and amniotic fluid. MSCs are defined or characterized by their ability to adhere to plastic, to express specific surface antigens, and to differentiate into osteogenic, chondrogenic, adipogenic, and myogenic lineages. Although the molecular mechanisms that control MSC proliferation and differentiation are not well understood, the involvement of microRNAs has been reported. In the present study, we investigated the role of miR-125b during osteoblastic differentiation in humans. We found that miR-125b increased during osteoblastic differentiation, as well as Runx2 and ALPL genes. To study whether the gain or loss of miR-125b function influenced osteoblastic differentiation, we transfected MSCs with pre-miR-125b or anti-miR-125b and cultured the transfected cells in an osteoblastic differentiation medium. After transfection, no change was observed in osteoblastic differentiation, and Runx2, OPN, and ALPL gene expression were not changed. These results suggest that the gain or loss of miR-125b function does not influence levels of Runx2, OPN, and ALPL during osteoblastic differentiation.

Evaluation of cardiovascular toxicity of carbon nanotubes functionalized with sodium hyaluronate in oral regenerative medicine

It has been demonstrated that carbon nanotubes (CNTs) associated with sodium hyaluronate (HY-CNTs) accelerate bone repair in the tooth sockets of rats. Before clinical application of HY-CNTs, it is important to assess their biocompatibility. Moreover, cardiac toxicity may be caused by the translocation of these particles to the blood stream. The aim of this study was to evaluate possible changes in cardiovascular function in male Wistar rats whose tooth sockets were treated with either CNTs or HY-CNTs (100 μg/mL, 0.1 mL). Blood pressure and heart rate were monitored in conscious rats 7 days after treatment. Cardiac function was evaluated using the Langendorff perfusion technique. The data showed no changes in blood pressure or heart rate in rats treated with either CNTs or HY-CNTs, and no significant changes in cardiac function were found in any of the groups. To confirm these findings, experiments were conducted in rats injected intraperitoneally with a high concentration of either CNTs or HY-CNTs (0.75 mg/kg). The same parameters were analyzed and similar results were observed. The results obtained 7 days following injection indicate that the administration of low concentrations of CNTs or HY-CNTs directly into tooth sockets did not cause any significant change in cardiovascular function in the rats. The present findings support the possibility of using these biocomposites in humans.

Permanent magnet synchronous generator design solution for large directdrive wind turbines: Thermal behavior of the LC DD-PMSG

Wind is one of the most compelling forms of indirect solar energy. Available now, the conversion of wind power into electricity is and will continue to be an important element of energy self-sufficiency planning. This paper is one in a series intended to report on the development of a new type of generator for wind energy; a compact, high-power, direct-drive permanent magnet synchronous generator (DD-PMSG) that uses direct liquid cooling (LC) of the stator windings to manage Joule heating losses. The main param-eters of the subject LC DD-PMSG are 8 MW, 3.3 kV, and 11 Hz. The stator winding is cooled directly by deionized water, which flows through the continuous hollow conductor of each stator tooth-coil winding. The design of the machine is to a large degree subordinate to the use of these solid-copper tooth-coils. Both steady-state and timedependent temperature distributions for LC DD-PMSG were examined with calculations based on a lumpedparameter thermal model, which makes it possible to account for uneven heat loss distribution in the stator conductors and the conductor cooling system. Transient calculations reveal the copper winding temperature distribution for an example duty cycle during variable-speed wind turbine operation. The cooling performance of the liquid cooled tooth-coil design was predicted via finite element analysis. An instrumented cooling loop featuring a pair of LC tooth-coils embedded in a lamination stack was built and laboratory tested to verify the analytical model. Predicted and measured results were in agreement, confirming the predicted satisfactory operation of the LC DD-PMSG cooling technology approach as a whole.

Design and Material Selection of High-Speed Rotating Electrical Machines

The increasing emphasis on energy efficiency is starting to yield results in the reduction in greenhouse gas emissions; however, the effort is still far from sufficient. Therefore, new technical solutions that will enhance the efficiency of power generation systems are required to maintain the sustainable growth rate, without spoiling the environment. A reduction in greenhouse gas emissions is only possible with new low-carbon technologies, which enable high efficiencies. The role of the rotating electrical machine development is significant in the reduction of global emissions. A high proportion of the produced and consumed electrical energy is related to electrical machines. One of the technical solutions that enables high system efficiency on both the energy production and consumption sides is high-speed electrical machines. This type of electrical machines has a high system overall efficiency, a small footprint, and a high power density compared with conventional machines. Therefore, high-speed electrical machines are favoured by the manufacturers producing, for example, microturbines, compressors, gas compression applications, and air blowers. High-speed machine technology is challenging from the design point of view, and a lot of research is in progress both in academia and industry regarding the solution development. The solid technical basis is of importance in order to make an impact in the industry considering the climate change. This work describes the multidisciplinary design principles and material development in high-speed electrical machines. First, high-speed permanent magnet synchronous machines with six slots, two poles, and tooth-coil windings are discussed in this doctoral dissertation. These machines have unique features, which help in solving rotordynamic problems and reducing the manufacturing costs. Second, the materials for the high-speed machines are discussed in this work. The materials are among the key limiting factors in electrical machines, and to overcome this limit, an in-depth analysis of the material properties and behavior is required. Moreover, high-speed machines are sometimes operating in a harsh environment because they need to be as close as possible to the rotating tool and fully exploit their advantages. This sets extra requirements for the materials applied.

Postglacial paleoecology and effects of European settlement on the environment of Lake Hunger and Lake Lisgar, Southwestern Ontario /

This investigation has three purposes I to make a comparative chemical study on sediment cores collected for Lake Lisgar (man-made lake in an urban center) and Lake Hunger (natural basin in a rural community) encompassing the time since European settlement I to determine the postglacial chemical history of Lake Hunger, and to determine the vegetational history of the Lake Hunger area from postglacial time to the present. The minus 80 mesh fraction of 108 soil samples and 18 stream sediment samples collected in the vicinity of Lakes' Lisgar and Hunger were analyzed for cold hydrochloric acid soluble lead, zinc, nickel, cobalt, copper, aluminum, sodium, potassium, calcium, magnesium, iron and manganese. Lacustrine sediments from 5 boreholes in the Lake Lisgar basin were collected. Boreholes 1, 2, 3, and 4 were analyzed for palynological and chemical information and Borehole 5 was subjected to pollen and ostracode analysis. Lacustrine sediments from 6 boreholes in the Lake Hunger basin were collected. Palyno- -logical and chemical analysis were performed on Boreholes 1, 2, 3, 4, and 6 and Borehole 5 was analyzed for pollen. In addition, radiocarbon dates were obtained on sediment samples from Boreholes 4 and 5. A total of 8 surface samples were collected from the margins of the Lake Hunger basin and these were chemically analyzed in the laboratory. All of the lacustrine sediments were ashed and analyzed for cold hydrochloric acid soluble lead, zinc, nickel, cobalt, copper, aluminum, sodium, potassium, calcium, magnesium, iron and manganese using a Perkin Elmer 40) Atomic Absorption spectrophotometer. The results . obtained for the 12 elements were expressed as parts per million in dry sediments. It was found that man's influence on the element distribution patterns in the sediments of Lake Lisgar appeared to be related to his urbanizing developments within the lake vicinity, whereas, the rural developments in the vicinity of lake Hunger appeared to have had little effect on the element distribution patterns in the lake sediments. The distribution patterns of lead, zinc, nickel, cobalt, aluminum, magnesium, sodium and potassium are similar to the % ash curve throughout postglacial time indicating that the rate of erosion in the drainage basin is the main factor which controls the concentration of these elements in the sediments of Lake Hunger. The vegetational history, from palynological analysis, of Lake Hunger from postglacial time to the present includes the following stages: tundra, open spruce forest, closed boreal forest, deciduous forest and the trend towards the re-establishment of pine following the clearing of land and the subsequent settlement of the Lake Hunger area by European settlers. The concentrations of some elements (cobalt, nickel, iron, manganese, calcium, magnesium, sodium and potassium) in the sediments of Lake Hunger appears to be higher during pre-cultural compared to post-cultural times. At least one complete postglacial record of the chemical history within a lake basin is necessary in order to accurately assess man's effects on his environment.

Palynology of late-glacial and postglacial sediments in Georgian Bay, Ontario, Canada, as related to the Great Lakes history /

This investigation comprises three parts: (1) the source, mechanism of transport, and distribution of pollen, spores and other palynomorphs in Georgian Bay bottom sediments and a comparison of these data with the contemporary vegetation, (2) the relative significance of fluvial transportation of pollen and spores, and (3) the late- and postglacial history of vegetational and climatic changes in the Georgicin Bay region. Modem pollen and spore assemblages in Georgian Bay do reflect the surrovinding vegetation when preservation and pollen production by the different species are considered and accounted for. Relative pollen percentage and concentration isopoll patterns indicate that rivers contribute large quantities of pollen and spores to Georgian Bay. This is further substantiated by large amounts of pollen and spores which were caught in traps in the Moon, Muskoka, and Nottawasaga Rivers which flow into Georgian Bay. The majority of pollen and spores caught in these traps were washed into the rivers by surface water runoff and so reflect the vegetation of the watershed in a regional sense. In a 12.9 metre long sediment core from northeastern Georgian Bay the relative percentage and absolute pollen concentrations allow correlation of Georgian Bay Lake phases with climatic and forest history. Four distinct pollen zones are distinguished: zone GB IV which is the oldest, reflects the succession from open spruce woodland to boreal forest; zone GB III represents a period of pine-mixed hardwoods forests from about 10,000 to 7,500 years ago. A pine-maplehemlock association dominated in zone GB II, although during the culmination of postglacial warming about 4,000 to 5,000 years ago the Georgian Bay forests had a more deciduous character. Zone GB I clearly shows European man's disturbance of the forest by logging activities.

Paleolimnology of selected Precambrian Shield lakes /

The analysis of fossil diatoms and Mallomonas assemblages in a 2.85 m sediment core revealed that a series of distinct floristic changes have occurred in the development of Found Lake, a small Shield lake in southern Ontario. Climatic and vegetational changes in the lake's watershed were closely associated with successional changes in the lake's biota. Nutrients released by the deciduous component of the Found Lake watershed appeared to be especially important in determining diatom and Mallomonas standing crop. The top 20 cm of sediment of 3 ,Shield lakes was then investigated using close interval (1 cm) analyses of diatoms, Mallomonas scales, pollen grains and sedimentary phosphorus. Found and Jake Lake are adjacent to Highway 60, whereas Delano Lake has been undisturbed and was used as a control. Dramatic changes in the diatom and Mallomonas communities were recorded in the Found and Jake Lake stratigraphies and could be closely associated with known historical events. Increased turbidity and nutrient enrichment were believed responsible for these successional changes. In addition, diatom and Mallomonas standing crop increased substantially following road construction in Found Lake's drainage basin. Meanwhile, no. sharp changes in diatom or Mallomonas communities were recorded in the recent sediments of the control (Delano) lake. The use£ulness o£ Synuracean scales as paleoindicators, as well as the importance o£ sectioning cores at close intervals during transition periods in a laker's development, was stressed.

An investigation of sugar feeding by black flies (Diptera: Simuliidae)

Although much research has been conducted on blood-meal acquisition in adult female black flies (Diptera: Simuliidae), the same cannot be said for sugarmeals. Both sexes feed on sugar which provides energy for flight and it has been commonly held that nectar is the major carbohydrate source. This thesis addresses the question of whether a non-floral carbohydrate source, specifically homopteran honeydew, is ingested by male and female black flies. Black flies reared in the laboratory have been observed to readily ingest freshly excreted and older (dry) honeydew when presented with honeydew coated tamarack branches. Field work was conducted in Algonquin Park, Ontario in the spring and summer of 1993. Three separate studies were designed to test whether homopteran honeydew is an important carbohydrate source for black flies and whether flies from different habitats utilize different sugar sources. The sugars melezitose and / or stachyose are known to occur in a variety of homopteran honeydews and therefore were used as indicators of honeydew feeding by black flies. In the first study, black flies were collected with insect nets from a stand of Larix larcina heavily infested with honeydew - producing homopterans (Adelges lariciatus). Six black fly species were captured: Simulium venustum, S. rostra tum, S. vittatum, Stegopterna mutata, S. aureum and S. quebecense. Samples of honeydew and individual black flies were tested using thin layer chromatography (T. L. C.) with fructose, glucose, sucrose, turanose, melezitose, raffinose and stachyose as standards. All sugars except turanose and melezitose were found in the adelgid honeydew samples. Since the sugar melezitose was absent from ~ honeydew samples, stachyose was used to indicate that black flies were feeding from this particular honeydew source. Of the 201 black flies tested, 194 contained sugars which occurred in 16 combinations. Stachyose combinations excluding melezitose, present in 45.9 % of flies, were used to indicate that black flies had been feeding on the adelgid honeydew. In the second study, black flies were collected in the morning and evening on 8 collection dates, using a vehicle mounted insect net. The crops and midguts of 10 male and 10 female Simulium venustum were dissected on each sample date. In total the gut contents of 320 individual flies were analysed by T. L. C. The sugars identified from these flies were present in the following proportions: fructose (100.0%), glucose (100.0%), sucrose/turanose (50.4%), melezitose (30.3%), raffinose (18.8%) and stachyose (8.7%). These sugars occurred in fourteen different combinations. It is argued that the presence of melezitose and / or stachyose indicates that black flies had fed on homopteran honeydew. Significantly more female flies (40.0%) than male flies (27.5%) had fed on honeydew. In the third study, adult black flies were sampled by sweep netting vegetation in four habitats in the morning and evening on 8 collection dates. The habitats are as follows: (1) Davies Bog, (2) Abandoned Air Field (dominated by blueberries, Vaccinium spp.), (3) Deciduous Habitat and (4) Coniferous Habitat. Sugars in the crops and midguts of female flies were tested by T. L. C. and, for S. venustum, it was found that significantly fewer flies (18.8%) from the Air Field contained honeydew than from the other three sites (Davies Bog, 34.4%; Deciduous Habitat, 36.2%; Coniferous Habitat, 25.0%). Of the 1287 black flies tested individually by T. L. C. 441 (34.3%) contained melezitose and / or stachyose sugars indicating that this proportion of the population were feeding from Homopteran honeydew. It is therefore clear that floral (nectar) sugars are not the only source of carbohydrates available to black flies.

Paragenetic history of the Ordovician Trenton Group carbonates, Southwestern Ontario

Geochemical examination of the rock matrix and cements from core material extracted from four oil wells within southwestern Ontario suggest various stages of diagenetic alteration and preservation of the Trenton Group carbonates. The geochemical compositions of Middle Ordovician (LMC) brachiopods reflect the physicochemical water conditions of the ambient depositional environment. The sediments appear to have been altered in the presence of mixed waters during burial in a relatively open diagenetic microenvironment. Conodont CAl determination suggests that the maturation levels of the Trenton Group carbonates are low and proceeded at temperatures of about 30 - 50°C within the shallow burial environment. The Trenton Group carbonates are characterized by two distinct stages of dolomitization which proceeded at elevated temperatures. Preexisting fracture patterns, and block faulting controlled the initial dolomitization of the precursor carbonate matrix. Dolomitization progressed In the presence of warm fluids (60 75°C) with physicochemical conditions characteristic of a progressively depleted basinal water. The matrix is mostly Idiotopic-S and Idiotopic-E dolomite, with Xenotopic-A dolomite dominating the matrix where fractures occur. The second stage of dolomitization involved hydrothermal basinal fluid(s) with temperatures of about 60 - 70°C. These are the postulated source for the saddle dolomite and blocky calcite cements occurring in pore space and fractures. Rock porosity was partly occluded by Idiotopic-E type dolomite. Late stage saddle dolomite, calcite, anhydrite, pyrite, marcasite and minor sphalerite and celestite cements effectively fill any remaining porosity within specific horizons. Based on cathode luminescence, precipitation of the different diagenetic phases probably proceeded in open diagenetic systems from chemically homogeneous fluids. Ultraviolet fluorescence of 11 the matrix and cements demonstrated that hydrocarbons were present during the earliest formation of saddle dolomite. Oxygen isotope values of -7.6 to -8.5 %0 (PDB), and carbon isotope values of - 0.5 and -3.0 %0 (PDB) from the latest stage dog-tooth calcite cement suggest that meteoric water was introduced into the system during their formation. This is estimated to have occurred at temperatures of about 25 - 40°C. Specific facies associations within the Trenton Group carbonates exhibit good hydrocarbon generating potential based on organic carbon preservation (1-3.5%). Thermal maturation and Lopatin burial-history evaluations suggest that hydrocarbons were generated within the Trenton Group carbonates some time after 300 Ma . Progressively depleted vanadium trends measured from hydrocarbon samples within southwestern Ontario suggests its potential use as a hydrocarbon migration indicator on local (within an oilfield) and on regional scales.

Larval habitat associations with human land uses, roads, rivers, and land cover for Anopheles albimanus, A. pseudopunctipennis, and A. punctimacula (Diptera: Culicidae) in coastal and highland Ecuador

Larval habitat for three highland Anopheles species: Anopheles albimanus Wiedemann, Anopheles pseudopunctipennis Theobald, and Anopheles punctimacula Dyar and Knab was related to human land uses, rivers, roads, and remotely sensed land cover classifications in the western Ecuadorian Andes. Of the five commonly observed human land uses, cattle pasture (n = 30) provided potentially suitable habitat for A. punctimacula and A. albimanus in less than 14% of sites, and was related in a principal components analysis (PCA) to the presence of macrophyte vegetation, greater surface area, clarity, and algae cover. Empty lots (n = 30) were related in the PCA to incident sunlight and provided potential habitat for A. pseudopunctipennis and A. albimanus in less than 14% of sites. The other land uses surveyed (banana, sugarcane, and mixed tree plantations; n = 28, 21, 25, respectively) provided very little standing water that could potentially be used for larval habitat. River edges and eddies (n = 41) were associated with greater clarity, depth, temperature, and algae cover, which provide potentially suitable habitat for A. albimanus in 58% of sites and A. pseudopunctipennis in 29% of sites. Road-associated water bodies (n = 38) provided potential habitat for A. punctimacula in 44% of sites and A. albimanus in 26% of sites surveyed. Species collection localities were compared to land cover classifications using Geographic Information Systems software. All three mosquito species were associated more often with the category “closed/open broadleaved evergreen and/or semi-deciduous forests” than expected (P ≤ 0.01 in all cases), given such a habitat’s abundance. This study provides evidence that specific human land uses create habitat for potential malaria vectors in highland regions of the Andes.

We need to have a conversation about OpenURL, a close look at a corpus of error reports from the 2013 academic year. Or, How I learned to stop worrying and give up on clean metadata.

Presented at Access 2014, winner of poster contest.

Letter - E.C. Schmon to Arthur A. Schmon, 25 February 1920

This letter remarks on the arrival of spring and Eleanore Celeste soon reuniting with Arthur. She describes some pain concerning a wisdom tooth cutting and stepping on a tack and then stubbing her foot on her bed. This letter is labelled number 135.

Letter - E.C. Schmon to Arthur A. Schmon, 25 November 1919

The letter begins with discussion about possible improper handling of "the books". She then describes "new plans" for their home. The second letter discusses her mother having five teeth extracted and two abscesses burned off. Her sister also had a wisdom tooth removed. The first letter is labelled number 56 and the second 57.