Acoustic emission from plastic deformation of a pure single crystal

Acoustic emission (AE) during plastic deformation is analyzed for a pure single crystal neglecting the effects of grain boundaries, impurities, and second‐phase particles. Acceleration of a moving dislocation is considered to be the principal AE source. There are two major mechanisms of dislocation motion related to acceleration, initial, and continuous oscillatory motion. Initial motion induced by the creation of mobile dislocations is modeled as a step function of velocity. Continuous oscillatory motion produced by interactions with neighboring dislocations is modeled as a harmonic function. These mechanisms vary with strain and strain rate due to dislocation multiplication. AE can thus be described in terms of strain and strain rate. Annihilation at a free surface is also regarded as an AE source in addition to the initial and oscillatory motions. The kinetic and strain energies stored around a moving dislocation are dissipated during annihilation, and can be related to AE. The frequency spectrum of AE is also determined. A shift of the spectrum to higher frequencies with increasing strain is explained by an increase in the interaction force between dislocations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70245/2/JAPIAU-72-5-1812-1.pd

Mapping the relationship between the subjective response of jurors to fan blade parameters

Thesis (MEng)--Stellenbosch University, 2020.ENGLISH ABSTRACT: The noise generated by computer cooling fans is known to be a factor which may cause discomfort in the workplace. Aerodynamic noise caused by fan blades has been identified to be a significant factor which contributes largely to noise emission by fans. Fan parameters used in the design of fan blades are known to affect noise emission levels significantly. Considerations made for fan noise are known to be centred around taking unweighted and A-weighted sound pressure readings, with fan designs often being designed to limit sound pressure levels. The analysis made towards the unweighted and A-weighted sound pressure levels in the temporal and frequency domain alone is known to sufficiently define objective measures for fan noise. It is of interest to consider whether the subjective evaluation of noise made by jurors can also be accounted for. The presented work is focused on identifying the feasibility of mapping the relationship between fan blade parameters to the subjective response of jurors, using the interim step of psychoacoustic analysis to make predictions for an expected level of annoyance towards fan noise emissions. Three blade parameters were selected for investigation, consisting out of blade chord, blade angle and sweep; these are considered to have significant effects on noise emissions produced by fan blades. Fifteen prototype models with varied blade parameters were created to investigate the effect which blade parameters have on the subjective evaluation of noise. Prototype models were created by 3D scanning and recreating a reference commercial fan, altering its blade parameters by using mesh morphing techniques. Jury evaluation tests were used to collect data towards the perceived annoyance for fan noise using a forced pairwise comparison test, and a bipolar semantic differential test. The jury tests were used to obtain a ranking for prototype models, giving a relative measure of perceived preference, and also a description for noise, as experienced by jurors. Statistical analysis methods were used to fit simple, well-defined regression models, which were used to learn about the interaction effects present. One model, deemed adequate for making predictions on jury preferences, was selected and used for optimisation purposes. This model was optimised to determine the best expected performance, for a specific set of blade parameters. A final model using optimised blade parameters was 3D printed and used as a validation set to evaluate for the model. The optimised model was ranked 3rd in the final, forced pairwise comparison test, where 20 jurors were asked to partake in the test. The presented work determined the relationship between blade parameters, psychoacoustic metrics and data obtained from subjective jury test results to determine the feasibility of determining jury preference from the parameters of a fan blade alone.AFRIKAANSE OPSOMMING: Die geraas wat 'n rekenaar se waaier genereer, is 'n faktor wat ongemak in die werkplek kan veroorsaak. En hoe harder die waaier werk, hoe groter is die ongewenste geraasvlakke dikwels ook. Aërodinamiese geraas, wat deur waaierlemme veroorsaak word, is geïdentifiseer as 'n belangrike faktor wat grootliks bydra tot die geraas wat 'n waaier vrystel. Die waaierparameters wat in die ontwerp van waaierlemme gebruik word, is bekend daarvoor dat dit 'n beduidende invloed het op die vlak van geraas wat gemaak word. Dit is bekend dat die oorwegings vir waaiergeraas, op die neem van ongeweegde en A-geweegde klankdruklesings berus, met waaiers wat dikwels ontwerp word om klankdrukvlakke te beperk. Die ontleding wat van die ongeweegde en Ageweegde klankdrukvlak gemaak word, in die tydelike en frekwensie-domein alleen, is bekend daarvoor dat dit op voldoende wyse objektiewe maatstawwe vir waaiergeraas omskryf. 'n Vraag van belang is egter of die subjektiewe evaluering van geraas deur 'n persoon wat dit beoordeel, ook verantwoord kan word. Die werk wat hier aangebied word, fokus daarop om te bepaal hoe haalbaar dit is om die verband tussen die parameters van waaierlemme en die subjektiewe respons van beoordelaars te karteer, deur middel van psigo-akoestiese analise as tussenstap te gebruik om voorspellings te maak oor die irritasievlak wat 'n waaier se geraas na verwagting sal veroorsaak. Vir die ondersoek is drie parameters van 'n waaierlem geselekteer: naamlik die koord, die hoek en die swiep van die lem, wat geïdentifiseer is as elemente wat 'n aansienlike invloed het op die geraas wat waaierlemme maak. Vyftien prototipiese modelle, met verskillende lemparameters, is geskep om die effek te ondersoek wat lemparameters het op die subjektiewe evaluering van geraasuitset, soos waargeneem deur die beoordelaars. Die prototipiese modelle is geskep deur 3D-skandering en die herskepping van 'n kommersiële waaier as verwysing deur sy lemparameters, deur middel van sogenaamde mesh morphing-tegnieke te verander. Tweeledige beoordelaarsevalueringstoetse is gebruik om data te versamel oor die werklik waargenome ergernis weens waaiergeraas: naamlik, 'n gedwonge paargewys-vergelykende toets en 'n bipolere semantiese differensiaaltoets. Die beoordelaarstoetse is gebruik om 'n rangorde vir die prototipiese modelle te bepaal, deur 'n relatiewe maatstaf van waargenome voorkeur te gee, asook 'n beskrywing van die geraas, soos deur die beoordelaars ervaar. Statistiese ontledingsmetodes is daarna gebruik om 'n eenvoudige, goed gede niëerde regressiemodel op die data toe te pas, en die model is gebruik om meer te wete te kom oor die wisselwerking tussen lemparameters, psigo-akoestiese maatstawwe en die subjektiewe reaksie van beoordelaars. Die sensitiwiteit vir modelle is bepaal en 'n model, wat met behulp van lemparameters, voorspellings oor beoordelaarsvoorkeur kon maak, is geselekteer en geoptimaliseer vir 'n stel lemparameters wat na verwagting die beste prestasie sou gee. 'n Finale model met lemparameters wat uit die optimalisering voortgespruit het, is 3D gedruk en as 'n valideringstel gebruik om die model te evalueer. In die finale, gedwonge paargewys-vergelykende toets, waarin 20 beoordelaars gevra is om aan die toets deel te neem, is die optimeerde model derde geplaas. Die werk wat hier aangebied word, het die verband bepaal tussen lemparameters, psigoakoestiese maatstawwe en data, wat uit subjektiewe beoordelaarstoetse verkry is, om te bepaal hoe haalbaar dit is om beoordelaarsvoorkeur op grond van die parameters van 'n waaierlem alleenlik, te bepaal.Master

Luxury Fashion Consumption: The Interplay of Guilt and Pleasure

We draw on the Affect Balance Theory to (a) explore whether two distinct modes of luxury consumption (i.e., conspicuous consumption and style consumption) are related to pleasure (i.e., positive affect) and guilt (i.e., negative affect); and (b) determine whether pleasure and guilt interplay to make interactive impacts, as well as independent impacts, on consumers’ repurchase intention

Pattern Visual Evoked Potential as a Predictor of Occlusion Therapy for Amblyopia

PURPOSE: This study was conducted to investigate the role of the pattern visual evoked potential (pVEP) as a predictor of occlusion therapy for patients with strabismic, anisometropic, and isometropic amblyopia. The secondary aim was to compare the characteristics of pVEP between strabismic and anisometropic amblyopia. METHODS: This retrospective comparative case series included 120 patients who had received occlusion therapy or a glasses prescription for correction of strabismic, anisometropic, and isometropic amblyopia (20 patients had strabismic amblyopia, 41 patients had anisometropic amblyopia, and 59 patients had isometropic amblyopia). For each patient, the value of the P100 latency on pVEP at the time of the initial diagnosis of amblyopia was collected. Subsequently, the P100 latency was compared according to types of amblyopia. Fifty of 120 patients (7 patients with strabismic amblyopia, 21 patients with anisometropic amblyopia, and 22 patients with isometropic amblyopia) who were followed-up for longer than 6 months were divided into two groups based on the value of their P100 latency (Group 1, P100 latency 120 msec or less; Group 2, P100 latency longer than 120 msec.) The amount of visual improvement after occlusion therapy or glasses was compared between two study groups. RESULTS: The mean P100 latency was 119.7+/-25.2 msec in eyes with strabismic amblyopia and 111.9+/-17.8 msec in eyes with non-strabismic (anisometropic or isometropic) amblyopia (p=0.213). In Group 1, the mean visual improvement after occlusion therapy or glasses was 3.69+/-2.14 lines on Dr. Hahn's standard test chart; in Group 2, the mean improvement was 2.27+/-2.21 lines (p=0.023). CONCLUSIONS: The P100 latency on pVEP at the time of initial diagnosis was significantly related to the visual improvement after occlusion therapy or glasses in patients with strabismic, anisometropic, and isometropic amblyopia. Therefore, it was presumed that patients with a delayed P100 latency might have less visual improvement after occlusion therapy or glasses. In addition, there was no apparent difference in P100 latency between patients with strabismic and non-strabismic (anisometropic or isometropic) amblyopia.ope

Parent-Reported Symptoms of Attention Deficit Hyperactivity Disorder in Children with Intermittent Exotropia before and after Strabismus Surgery

∙ The authors have no financial conflicts of interest. © Copyright: Yonsei University College of Medicine 2012 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licens

Two Cases of Mirror-Image Eye Anomalies in Monozygotic Twins

We report two cases of mirror image anomalies in two different pairs of monozygotic twins. In case 1, the twins exhibited mirroring of strabismus and refractive errors. Twin 1 had 35 prism diopters (PD) right intermittent exotropia at distant fixation and myopic anisometropia that was spherical 2.00 diopters more myopic in the right eye. Twin 2 had 35 PD left intermittent exotropia at distant fixation and her left eye was more myopic by - spherical 1.00 diopters. In case 2, the twins were diagnosed with infantile nystagmus with upbeat jerk. Twin 1 exhibited a habitual head turn of 30° to the left with dampening of her nystagmus in dextroversion. Twin 2 also exhibited abnormal head position, but in his case the habitual turn was 30° to the right. We believe that this is the first report describing mirror imaged intermittent exotropia with anisometropia and infantile nystagmus with opposite abnormal head positions in pairs of monozygotic twins

MMP-3 Contributes to Nigrostriatal Dopaminergic Neuronal Loss, BBB Damage, and Neuroinflammation in an MPTP Mouse Model of Parkinson\u27s Disease

The present study examined whether matrix metalloproteinase-3 (MMP-3) participates in the loss of dopaminergic (DA) neurons in the nigrostriatal pathway in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson\u27s disease with blood brain barrier (BBB) damage and infiltration of peripheral immune cells. Tyrosine hydroxylase (TH) immunostaining of brain sections from MPTP-treated mice showed that MPTP induced significant degeneration of nigrostriatal DA neurons. Moreover, FITC-labeled albumin detection and immunostaining revealed that MPTP caused damage to the BBB and increased the number of ED-1- and CD-3-immunopositive cells in the substantia nigra (SN). Genetic ablation of MMP-3 reduced the nigrostriatal DA neuron loss and improved motor function. This neuroprotective effect afforded by MMP-3 deletion was associated with the suppression of BBB disruption and a decrease in the number of ED-1- and CD-3-immunopositive cells in the SN. These data suggest that MMP-3 could play a crucial role in neurodegenerative diseases such as PD in which BBB damage and neuroinflammation are implicated

Recurred pneumocephalus in a head trauma patient following positive pressure mask ventilation during induction of anesthesia -A case report-

Pneumocephalus is a condition which usually results from head trauma. It has been known that iatrogenic pneumocephalus can occur as a complication of positive pressure mask ventilation during induction of anesthesia or ventilatory care for head trauma patients. We report a case of mask ventilation during anesthesia induction in a 50-year-old male patient with head trauma. Initial pneumocephalus associated with cerebrospinal fluid leakage was diagnosed immediate following head injury involving facial sinuses. He was managed with emergent lumbar drainage and supportive care. Pneumocephalus recurred following positive pressure mask ventilation (PPMV) during anesthesia induction for surgery on the right arm. Recurred pneumocephalus was managed with high flow oxygen and supportive care. Anesthesiologists should be aware of pneumocephalus as a potential complication of PPMV in head trauma patients, even after resolution of previous pneumocephalus