327 research outputs found
The Family History of Arin A. Pitcher
No full textThe Family History of
Arin A. Pitcher
30 April 2023
Arin Alicejean Pitcher authored this family history as part of the course requirements for HIST 550/700 Your Family in History offered online in Spring 2023 and was submitted to the Pittsburg State University Digital Commons. Please contact the author directly with any questions or comments: [email protected]
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License
Numerical modelling of particle distribution effects on fatigue in Al-SiCp composites
No full textVarious reports in the literature have highlighted the effects of particle distribution on the fatigue behaviour of particulate reinforced metal matrix composites (PMMCs), although few attempts have been made at modelling such effects. A micromechanical understanding of the effects of clustering on short crack growth behaviour in Al–SiCp composites has been achieved via finite element modelling. Comparison of preliminary models with the literature has shown that shielding/anti-shielding effects were significantly affected by the relative sizes of the particle and the overall model such that, when edge effects were removed, a crack was predicted to be accelerated rather than decelerated as it propagated through closely spaced pairs of particles. Consistent differences were identified between models with homogeneous versus clustered particle arrangements in terms of crack path morphologies and local crack–tip stress intensity fluctuations. Furthermore, predicted influences of clustering on growth rates in the numerical models were found to be consistent with previous experimental results (i.e. growth rates rose with increased clustering), demonstrating that load transfer effects associated with changes in particle distribution may play a direct role in controlling the growth of short cracks in these materials
Relations between microstructure, precipitation, age-formability and damage tolerance of Al-Cu-Mg-Li (Mn,Zr,Sc) alloys for age forming
No full textAge forming of Al based alloys for damage tolerant applications requires an alloy with good age formability and good post-forming mechanical properties. To investigate optimisation of this balance, several newly designed Al–Cu–Mg–Li (Mn, Zr, Sc) alloys were subjected to artificial ageing representative of age forming. It was seen that combinations of yield strength and fatigue crack growth resistance could be achieved that are at least comparable to the incumbent damage tolerant material for such applications, whilst creep rates at the ageing temperatures applied were better than those achieved in commercially applied age forming processes of heat treatable Al based alloys. Coarse grain structure and high Li content are associated with good fatigue crack growth resistance but reduce age formability. The underlying physical aspects responsible for the balance between creep rates and resulting properties are discussed. The metallurgical and micromechanical mechanisms analysed and discussed provide a framework for optimisation of composition and forming conditions for age forming of damage tolerant parts
Development of Al-Cu-Mg-Li (Mn,Zr,Sc) alloys for age-forming
No full textAge forming of lower wing skin structures for civil airframes requires an alloy with good age formability and mechanical properties (yield strength, ultimate tensile strength, fatigue resistance, toughness). Using property modelling and general metallurgical understanding, a series of Al-Cu-Mg-Li (Mn, Zr, Sc) alloys have been designed. After artificial ageing representative of age-forming several of the newly designed alloys have yield strength, fatigue crack growth resistance and toughness that are at least comparable to the incumbent damage tolerant material for such applications, viz. 2024-T351. Coarse grain structure and high Li content are seen to be associated with good fatigue resistance but reduced formability, and an optimum balance needs to be sought
Development of new damage tolerant alloys for age-forming
No full textThe applicability of age forming for the forming of damage tolerant structures is investigated by formulating and testing new alloy-age forming combinations. The alloy formulation process is driven initially by modelling of strength and semi-quantitative understanding of other microstructure-property relations. Using this a range of Al-Cu-Mg-Li-(Zr-Mn) based alloys that are predicted to provide yield strengths in aged condition comparable with incumbent the 2024-T351 alloy for lower wing skins are selected. It is shown that several of these new alloys after artificial aging representative of age-forming have proof strengths (PS), fatigue crack growth resistance (FCGR) and toughness that are comparable or better than incumbent 2024-T351. UTS to PS ratios of the new alloys are lower than incumbent 2024-T351
Establishing the elbow load and the within-pitcher load variability during a baseball pitch in relation to the ball speed
No full textUlnar collateral ligament (UCL) injuries are common in baseball pitching. The elbow external valgus torque is assumed to be indicative for the applied load on the UCL. This study investigated the maximum external valgus and extension torque and their corresponding load variability during a baseball pitch and the relationship between the magnitude and the within-pitcher load variability of these elbow torques. Furthermore, this study investigated to what extend the elbow torques and the ball speed are related. Eleven Dutch AAA pitchers each threw 25 fastballs. The motion was captured with an optical motion capture system. The ball speed was measured with a radar gun. The data of the upper body, in particular the elbow torques, were analysed using a custom-made 3D inverse dynamics model. The results show that the within-pitcher load variability differs among pitchers. A higher applied elbow torque compared to other pitchers indicates a higher within-pitcher variability. From these results, both a higher valgus torque and a higher within-pitcher load variability are expected to lead to higher injury risk. It is advised not to take one pitch per pitcher into account since it cannot represent all the pitches, especially if only the fastest is selected. Among the pitchers, ball speed is found not to be a good indicator for the elbow torques. Within a pitcher, the ball speed serves better as an indicator. This study emphasises the importance of analysing each pitcher’s results individually instead of comparing them to the whole group.Biomedical Engineerin
Aquatic insect populations in transplanted and natural populations of the purple pitcher plant, Sarracenia purpurea, on Prince Edward Island, Canada
No full textIn early July 1991, 234 pitcher plants (Sarracenia pulpurea) were transplanted from a Prince Edward Island bog being mined for peat into three bogs that varied with respect to previous pitcher plant abundance. One bog had a thriving natural pitcher plant population prior to transplant, while the other two had fewer than three pitcher plants. Between mid-June and late August 1993, abundances of the pitcher plant inquilines Wyeomyia smithii (Diptera: Culicidae), Metriocnemus knabi (Diptera: Chironomidae) and an unidentified sarcophagid fly (Diptera: Sarcophagidae) from transplant bogs were compared with remaining populations in die source bog and with other natural populations. Of the three inquilines, W. smithii was the most severely affected by transplant; it was extremely rare or absent in transplanted pitchers, although it was found in all other bogs investigated on Prince Edward Island. Metriocnemus knabi larvae were common in ail bogs investigated, except for those transplant bogs where pitcher plants were rare prior to transplant. Sarcophagid larvae were found in all of the bogs sampled, and were apparently unaffected by transplant. Desiccation during the transplant process, as well as the time of the transplant, may play a role in the success of recolonization of the pitcher plants after transplanting.PT: J; CR: ADDICOTT JF, 1974, ECOLOGY, V55, P475 BRADSHAW WE, 1984, AM MIDL NAT, V112, P294 CAMERON CJ, 1977, CAN J ZOOL, V55, P2018 ELLIOTT JM, 1977, FRESHWATER BIOL ASS, V25 FAIRCHILD WL, 1987, CAN ENTOMOL, V119, P647 FARKAS MJ, 1986, CAN ENTOMOL, V118, P1307 FARKAS MJ, 1986, CAN J ZOOL, V64, P285 FISH D, 1978, AM MIDL NAT, V99, P172 FORSYTH AB, 1975, CAN J ZOOL, V53, P174 GIVNISH TJ, 1989, PLANT ANIMAL INTERAC, P243 HEARD SB, 1994, ECOLOGY, V75, P1647 HEARD SB, 1994, ENVIRON ENTOMOL, V23, P1250 ISTOCK CA, 1975, EVOLUTION, V29, P296 ISTOCK CA, 1983, PHYTOTELMATA TERREST, P191 JUNIPER BE, 1989, CARNIVOROUS PLANTS MOGI M, 1980, TROPICAL MED, V22, P1 MOORE PD, 1974, PEATLANDS NASTASE AJ, 1991, AM MIDL NAT, V125, P356 NASTASE AJ, 1995, AM MIDL NAT, V133, P44 PATERSON CG, 1982, CAN J ZOOL, V60, P3075 SCHNELL DE, 1976, CARNIVOROUS PLANTS U WALLIS RC, 1967, MOSQ NEWS, V27, P9; NR: 22; TC: 5; J9: CAN J ZOOL; PG: 8; GA: VQ081Source type: Electronic(1
A Training and Conditioning Program for the High School Baseball Pitcher
No full textThe purpose of this study is to present in a clear and concise form the rudimentary mechanics of the game and an adaptable conditioning program for the high school baseball pitcher. While organizing the paper, the author hoped to gain further insight into the complexities of improving the young pitcher during the high school\u27s short spring season
Population Growth of the Pitcher Plant, Sarracenia Purprea L., at Cranberry Bog, Licking County, Ohio
No full textAuthor Institution: Department of Botany, University of IllinoisA population of the pitcher plant, Sarracenia purpurea L., at Cranberry Bog Nature Preserve, Licking County, Ohio, was founded by a single individual transplanted to the bog in 1912. From an observation of the population in 1921, the intrinsic rate of increase for this population was estimated to be between .0016 and .0023 per day. A recent survey of the present size of the population revealed approximately 157,000 pitcher plants. These observations suggest that the population has not only reached the carrying capacity of Cranberry Bog, but that it did so as early as 1942. Comparisons between the intrinsic rate of increase for S. purpurea and the few other plant species that have been studied suggest that pitcher plants have a relatively slow rate of population increase for an herbaceous species
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A Markov Approach to Modeling Baseball At-Bats and Evaluating Pitcher Decision-Making and Performance
No full textThe author models baseball at-bats using absorbing Markov chains, formed based on pitch-by-pitch data for 90 pitchers from the 2015 season. These matrices are used to reverse-predict performance statistics that compare closely to actual values for these pitchers. The author finds that Markov chains are well-suited to model at-bats because they illuminate differences in pitching style and effectiveness and explain performance changes over time. After showing that Markov matrices provide a reasonable model, the author uses this model to examine the effectiveness of two traditional baseball strategies — a batter taking, or not swinging at, the first pitch of an at-bat, and a pitcher intentionally throwing a ball on an (0,2) count — and, more generally, to examine how pitchers could optimize their performance by making better decisions. The results show that taking the first pitch is significantly more effective against weaker pitchers, while the (0,2) waste pitch is generally more effective for strikeout pitchers than contact pitchers, but the difference is not significant. In addition, this thesis highlights the importance of “the count” in baseball and finds that pitcher performance is largely predictable based on the manner in which the count progresses in an average at-bat against him
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