The effects of shaft misalignment on efficiency and bearing load of electric motors

This thesis examines the characteristics of misalignment of rotating machinery. The first phase of this research determined the effects of motor shaft misalignment on power consumption, and the second phase determined the relationships between motor shaft alignment, roller bearing load, and predicted life. U.S. industry invests significant resources performing precision alignment of rotating machinery. The basis for this expenditure is two assumptions: misalignment causes a decrease in motor efficiency, and misaligned machinery is more prone to failure due to increased loads on bearings, seals, and couplings. To determine the effects of rotating machinery misalignment on power consumption, controlled experiments were performed at The University of Tennessee and at the Oak Ridge Center for Electrical Machinery System Testing. The testing was performed using a 50 HP and a 60 HP AC induction motor with four different types of flexible couplings. Approximately 15 different alignment conditions were examined for each coupling. To determine the effects of misalignment on bearing load, sensors were designed, fabricated, and installed into a working motor. These sensors could measure transverse bearing loads in both the vertical and horizontal directions at both the inboard and outboard bearings. The testing was performed using a 60 HP induction motor and four different types of flexible couplings. Testing was performed while the motor was static and while the motor was in operation at full speed and maximum torque. The results of alignment versus efficiency tests show no significant correlation between misalignment and efficiency when the couplings were operated within the manufacturer\u27s recommended range. Power consumption and power output remained constant regardless of the alignment condition. The results of bearing load tests show that relatively small amounts of shaft misalignments can have a significant impact on the operational life of a bearing. The magnitude of the bearing life reduction varies with the coupling type, bearing load capacity, and dimensions of the motor. The results from this research show that, in some cases, up to 50% percent of the expected bearing life can be lost with as small as a 5 mil offset misalignment

Effect of alachlor and 1, 8-naphthalic anhydride on the growth and development of grain sorghum and corn seedlings

Morphological, physiological, and biochemical parameters were measured to determine the site of action of alachlor [2-chloro-2\u27,6’ diethyl-N-(methoxymethyl) acetanilide] and the protective effect of 1,8-naphthalic anhydride (hereafter referred to as NA) in grain sorghum (Sorghum bicolor (L.) Moench, \u27AKS 614’) and com (Zea mays L. \u27Tn 5009\u27) seedlings. Time of coleorhiza emergence through the pericarp of grain sorghum was not affected by 1, 5, or 25 ppmw alachlor, by 2 percent w/w NA, or their combinations. Coleoptile emergence was delayed slightly by NA alone and in combination with alachlor, but not by alachlor alone. Emergence of the primary leaf from the coleoptile was inhibited by alachlor treatments in the presence of NA and even more so in its absence. Various degrees of leaf distortion resulted when grain sorghum seedlings not exhibiting leaf emergence were placed in light. Severity of distortion was less with 1 ppmw alachlor than with 5 ppmw and the alachlor-induced distortion was less when in combination with 150 ppmw NA. After four weeks, the primary leaves were still distorted but subsequent emerging leaves were normal in all treatments. More complete emergence and unrolling of the primary leaf was observed when terminal segments (3.5 cm long, including the coleoptile and part of the first internode) of grain sorghum grown in the presence of 150 ppmw NA were vacuum infiltrated with 15, 25, and 50 ppmw alachlor than in the controls. Fifty ppmw gibberellic acid (GA) was as effective as 150 ppmw NA in counteracting alachlor-induced leaf retention in the coleoptiles of com. The GA was also effective in nullifying the height reduction observed in com coleoptiles grown in the presence of 25 ppmw alachlor and ISO ppmw NA, while 150 ppmw NA applied in combination with the alachlor further reduced coleoptile length. One-cm coleoptile segments from com grown in the presence of 25 ppmw alachlor, 150 ppmw NA and their combination responded more to indoleacetic acid (lAA)- induced elongation than did the controls. More force was required to induce leaf slippage in coleoptiles from com grown in the presence of 25 ppmw alachlor than in the controls, or in coleoptiles from plants grown in the presence of 25 ppmw alachlor in combination with 150 ppmw NA. The NA alone reduced the force required to induce leaf slippage below that of all treatments compared. Incubation for 16 hours in 10 ppmw lAA did not lower the amount of force required to induce leaf slippage in coleoptiles from com grown in the presence of 25 ppmw alachlor even though the length of the coleoptiles increased 30 percent more than coleoptiles not receiving lAA treatment. Percent dry matter, dry matter per 100 plants, and percent protein increased in coleoptiles from alachlor treated com, while percent cellulose and lignin decreased. The extent of variation in these parameters was reduced when NA was applied in combination with alachlor, with the exception of percent lignin which was further decreased by the combination treatment. Percent hemicellulose was not affected by alachlor, NA, or their combinations. The RNA-DNA ratio of corn coleoptiles was decreased by the alachlor-NA combination treatment, but not by either chemical alone

The City Too Busy to Hate

This is the novel-in-stories I have been working on here at UMD. Some of the stories are not included in this thesis. The stories that are included are intended to be representative of the larger work. A young man named Franklin Mitchem comes from the small town of Marthasville, Georgia, to live in Atlanta in late 1999. He is an anxious young man, and his social anxiety is exacerbated by an event that takes place during his freshman year of high school back in Marthasville. To cope with his anxiety, and as a way of healing from what happened to him in Marthasville, Franklin creates narratives about the people he encounters in Atlanta. Some of these stories are Franklin's imaginations, others are his "real" life

The Band Excitation Method in Scanning Probe Microscopy for Rapid Mapping of Energy Dissipation on the Nanoscale

Mapping energy transformation pathways and dissipation on the nanoscale and understanding the role of local structure on dissipative behavior is a challenge for imaging in areas ranging from electronics and information technologies to efficient energy production. Here we develop a novel Scanning Probe Microscopy (SPM) technique in which the cantilever is excited and the response is recorded over a band of frequencies simultaneously rather than at a single frequency as in conventional SPMs. This band excitation (BE) SPM allows very rapid acquisition of the full frequency response at each point (i.e. transfer function) in an image and in particular enables the direct measurement of energy dissipation through the determination of the Q-factor of the cantilever-sample system. The BE method is demonstrated for force-distance and voltage spectroscopies and for magnetic dissipation imaging with sensitivity close to the thermomechanical limit. The applicability of BE for various SPMs is analyzed, and the method is expected to be universally applicable to all ambient and liquid SPMs.Comment: 32 pages, 9 figures, accepted for publication in Nanotechnolog

Relational Approach to Knowledge Engineering for POMDP-based Assistance Systems as a Translation of a Psychological Model

Assistive systems for persons with cognitive disabilities (e.g. dementia) are difficult to build due to the wide range of different approaches people can take to accomplishing the same task, and the significant uncertainties that arise from both the unpredictability of client's behaviours and from noise in sensor readings. Partially observable Markov decision process (POMDP) models have been used successfully as the reasoning engine behind such assistive systems for small multi-step tasks such as hand washing. POMDP models are a powerful, yet flexible framework for modelling assistance that can deal with uncertainty and utility. Unfortunately, POMDPs usually require a very labour intensive, manual procedure for their definition and construction. Our previous work has described a knowledge driven method for automatically generating POMDP activity recognition and context sensitive prompting systems for complex tasks. We call the resulting POMDP a SNAP (SyNdetic Assistance Process). The spreadsheet-like result of the analysis does not correspond to the POMDP model directly and the translation to a formal POMDP representation is required. To date, this translation had to be performed manually by a trained POMDP expert. In this paper, we formalise and automate this translation process using a probabilistic relational model (PRM) encoded in a relational database. We demonstrate the method by eliciting three assistance tasks from non-experts. We validate the resulting POMDP models using case-based simulations to show that they are reasonable for the domains. We also show a complete case study of a designer specifying one database, including an evaluation in a real-life experiment with a human actor

Aboveground Net Primary Productivity in Grazed and Ungrazed pastures: Grazing Optimisation Hypothesis or Local Extinction of Vegetation Species

The controversy that has surrounded herbivory studies in the last few decades prompted our investigation to establish the extent to which herbivore optimisation hypothesis or compensatory growth evidence is real. We used the traditional movable cage method to collect primary productivity data on herbage, functional groups and key individual grass species in various controlled large herbivore treatments in an east African savanna. The herbivore treatments in triplicate blocks included cattle, wild herbivores with and without mega herbivores and combinations of cattle and wild herbivores also with and without mega herbivores. The findings revealed that at herbage level, most grazed treatments (four out of five) had higher productivity than the ungrazed control and three showed grazing optimisation curve at sixth polynomial degree between monthly productivity and grazing intensity (1-g/ng). At functional group level forbs productivity was higher in the ungrazed control than in any of the grazed treatments while at individual grass species level _Themeda triandra_ productivity was higher in all grazed treatments than in ungrazed control. We conclude against presence of herbivore optimisation hypothesis at herbage, functional group and species level because of lack of attributable grazing effect in grazed treatments that matches complex ecological effects in the ungrazed treatment

Persistence and storage of activity patterns in spiking recurrent cortical networks: modulation of sigmoid signals by after-hyperpolarization currents and acetylcholine

Many cortical networks contain recurrent architectures that transform input patterns before storing them in short-term memory (STM). Theorems in the 1970's showed how feedback signal functions in rate-based recurrent on-center off-surround networks control this process. A sigmoid signal function induces a quenching threshold below which inputs are suppressed as noise and above which they are contrast-enhanced before pattern storage. This article describes how changes in feedback signaling, neuromodulation, and recurrent connectivity may alter pattern processing in recurrent on-center off-surround networks of spiking neurons. In spiking neurons, fast, medium, and slow after-hyperpolarization (AHP) currents control sigmoid signal threshold and slope. Modulation of AHP currents by acetylcholine (ACh) can change sigmoid shape and, with it, network dynamics. For example, decreasing signal function threshold and increasing slope can lengthen the persistence of a partially contrast-enhanced pattern, increase the number of active cells stored in STM, or, if connectivity is distance-dependent, cause cell activities to cluster. These results clarify how cholinergic modulation by the basal forebrain may alter the vigilance of category learning circuits, and thus their sensitivity to predictive mismatches, thereby controlling whether learned categories code concrete or abstract features, as predicted by Adaptive Resonance Theory. The analysis includes global, distance-dependent, and interneuron-mediated circuits. With an appropriate degree of recurrent excitation and inhibition, spiking networks maintain a partially contrast-enhanced pattern for 800 ms or longer after stimuli offset, then resolve to no stored pattern, or to winner-take-all (WTA) stored patterns with one or multiple winners. Strengthening inhibition prolongs a partially contrast-enhanced pattern by slowing the transition to stability, while strengthening excitation causes more winners when the network stabilizes

Mass equidistribution for Saito-Kurokawa lifts

Let $F$ be a holomorphic cuspidal Hecke eigenform for $\mathrm{Sp}_4(\mathbb{Z})$ of weight $k$ that is a Saito--Kurokawa lift. Assuming the Generalized Riemann Hypothesis (GRH), we prove that the mass of $F$ equidistributes on the Siegel modular variety as $k\longrightarrow \infty$. As a corollary, we show under GRH that the zero divisors of Saito--Kurokawa lifts equidistribute as their weights tend to infinity.Comment: minor edits; 54 page