Numerical Simulation and Experimental Examination of an Oldham Coupling

In scroll compressors, the Oldham couplings have typically been formed of aluminum alloy and have often broken issues due to the higher force that transmitted to Oldham coupling by the orbiting scroll. This problem was especially pronounced in scroll compressors and in particular during flooded start or slug conditions.  So, to enhance Oldham coupling’s strength performance in above conditions becomes an important work to Engineers. In this paper, about 30 pcs failed Oldham couplings which were broken in by flood start or slug conditions were investigated. Meanwhile, Oldham coupling’s stress distribution and deformation were simulated in ANSYS software. High stress zones and weak positions were got; potential failure risks were also reappeared in the simulation. After simulation, two optimized proposals were stated and simulated. And then, corresponding prototypes were made and sent to test together with mass production parts in lab. Tests results indicate new design’s strength performances were improved and highly aligned with numerical simulation results. But, some test errors were also found between mass production parts and prototypes. The factors which can impact errors and their weight were analyzed and calculated. In the end, a prediction model of using numerical model to estimate mass production part performance is given in this paper.

Sympathy and Punishment: Evolution of Cooperation in Public Goods Game

An important way to maintain human cooperation is punishing defection. However, since punishment is costly, how can it arise and evolve given that individuals who contribute but do not punish fare better than the punishers? This leads to a violation of causality, since the evolution of punishment is prior to the one of cooperation behaviour in evolutionary dynamics. Our public goods game computer simulations based on generalized Moran Process, show that, if there exists a \'behaviour-based sympathy\' that compensates those who punish at a personal cost, the way for the emergence and establishment of punishing behaviour is paved. In this way, the causality violation dissipates. Among humans sympathy can be expressed in many ways such as care, praise, solace, ethical support, admiration, and sometimes even adoration; in our computer simulations, we use a small amount of transfer payment to express \'behaviour-based sympathy\'. Our conclusions indicate that, there exists co-evolution of sympathy, punishment and cooperation. According to classical philosophy literature, sympathy is a key factor in morality and justice is embodied by punishment; in modern societies, both the moral norms and the judicial system, the representations of sympathy and punishment, play an essential role in stable social cooperation.Public Goods Game, Cooperation, Social Dilemma, Co-Evolution, Sympathy, Punishment

Tooth Surface Reconstruction and Tooth Profile Geometric Analysis of Circular Arc Tooth Trace Cylindrical Gears

To reconstruct the tooth surface of a circular arc tooth trace cylindrical gear (CATT gear), one needs to create an accurate 3D model and investigate geometric features of the tooth profile. According to the processing principle of the rotating knife dish milling, and using the space meshing theory and differential geometry, the tooth surface equation and the tooth profile of CATT gears have been deduced. Then, the tooth surface reconstruction of CATT gears was done and a 3D model was created. Next, based on theoretical deduction, it was proven that the profile of the middle section was involute, and the other section was hyperbolic. Finally, the influences of the design parameters on the tooth profile were investigated. The general tendency is that the gear tooth thickness becomes thinner as the gear width increases and the tooth line radius decreases, and the tooth profiles of the concave and the convex tooth surface may intersect. The influences of the module need to be discussed separately. The tooth thickness deviation increases as the module increases. But the relative tooth thickness deviation is opposite. Therefore, it is suggested that RT>= (3-4)b and the module should be large to improve the bearing capacity. The results of the investigation provide a reference for the design, profile modification, lubrication, and measuring of CATT gears

Are Advice Takers Bayesian? Preference Similarity Effects on Advice Seeking and Taking

Consumers increasingly depend on online reviews to inform purchase decisions. We show that they make two systematic errors that are in offsetting directions in utilizing advice to make a "probabilistic affective forecasting". People underestimate the degree of "preference matching" with reviewers, whereas overweigh their advice compared to a Bayesian criterion

DEVELOPING MULTI-LAYERED, FLOWERING MEDITERRANEAN PLANT COMMUNITIES USING SOUTH AFRICAN FLORA

Abstract The aim of this study was to create sown multi-layered communities of Mediterranean South African plants based on Fynbos and Renosterveld species. These communities were designed to test naturalistic design principles as to achieve long flowering designed plantings involving three canopy heights (tall, medium and low). Competition between shrubs/forbs/succulents and geophytes by using microcosm experiments mirrors the form of actual designed vegetation in practice. The experiments prior to the competition experiment provided the understanding of germination, winter cold and summer wetness tolerance of a large number of SA species (over 300 species) from Western Cape. All winter growing and summer dormant geophyte species had the capacity to emerge from autumn sowings, and some were able to do the same from spring sowing. Smoke treatment prior to sowing is effective on many forb and small shrub species from Fynbos and Renosterveld, but much less useful (or necessary) on geophyte species. Species such as Gladiolus carneus, Gladiolus tristis and Ixia curvata tolerated -8°C in winter 2010/11, and many more species survived -5°C in winter 2011/12. Bulbinella elata, Bulbinella elegans, Bulbinella nutans, Moraea tripetala, Kniphofia uvaria, Romulea atrandra and Romulea sabulosa suffered no loss at -5°C and no loss over summer 2012 (historically the wettest summer in the UK since 1910). Altitude and the resulting number frost days which individuals experience at the collection locations were critical factors influencing their winter mortality in Northern England. Habitat soil conditions and other environment factors are important in relation to their summer mortality. Species naturally occuring in Renosterveld and seasonally wet habitats are typically more wet tolerant response in Uk summers (i.e. many Bulbinella, Kniphofia, Gazania and Romulea species). Specific geographical provenances were explored to find more useful genotypes that can survive well in the UK. Species collected from the inland Roggeveld region, including the provenances Sutherland, Rooiwal, Groot Swartberg mountains, and the Komsberg, were the most successful species in response to winter cold in Sheffield. Fifteen plant community types were designed to access competition amongst 30 selected species in terms of mortality and biomass production within the studies main microcosm experiment. The most successful communities were generally those composed of tall canopy layer geophytes and forbs/shrubs. Geophytes suffered less mortality than shrub/forb/succulent species but contributed less biomass in the first two years, particularly in low height geophytes. Medium height geophytes formed a more extensive canopy and had higher competition capacity to increase their coverage and biomass in communities from the third year on. Species that did this included Watsonia ‘Tresco Dwarf Pink’, Gladiolus cardinalis and Watsonia schlechteri. Some small Fynbos and Renosterveld geophytes tested in the combinations demonstrated a degree of shade tolerance, as in Romulea komsbergensis, Ixia and Hesperantha species. These communities were managed by annual cutting in late summer-early autumn

(E)-2-[2-(2-Thien­yl)vin­yl]-1H-1,3-benzimidazole

In the title compound, C13H10N2S, the dihedral angle between the imidazole and thio­phene rings is 16.89 (19)°, and the double bond adopts an E configuration. In the crystal structure, N—H⋯N hydrogen bonds link the mol­ecules into rows along b. There is also evidence of weak C—H⋯S inter­actions

2-{4-[(Quinolin-8-yl­oxy)meth­yl]phen­yl}benzonitrile

In the title compound, C23H16N2O, the bond angle at the O atom that connects the benzene ring and the quinoline ring system is 116.0 (2)°. The quinoline ring system make a dihedral angle of 16.5 (2)° with the adjacent benzene ring. The dihedral angle between the biphenyl benzene rings is 70.8 (2)°