Specializations of the mandibular anatomy and dentition ofSegnosaurus galbinensis(Theropoda: Therizinosauria)

Definitive therizinosaurid cranial materials are exceptionally rare, represented solely by an isolated braincase and tooth in the North American taxonNothronychus mckinleyi, the remarkably complete skull of the Asian taxonErlikosaurus andrewsi, and the lower hemimandibles ofSegnosaurus galbinensis. To date, comprehensive descriptions of the former taxa are published; however, the mandibular materials ofS. galbinensishave remained largely understudied since their initial description in 1979. Here we provide a comprehensive description of the well-preserved hemimandibles and dentition ofS. galbinensis(MPC-D 100/80), from the Upper Cretaceous Bayanshiree Formation, Gobi Desert, Mongolia. The subrectangular and ventrally displaced caudal hemimandible, extreme ventral deflection of the rostral dentary, and edentulism of the caudal dentary ofS. galbinensisare currently apomorphic among therizinosaurians. Unique, unreported dental traits including lingually folded mesial carinae, development of a denticulated triangular facet on the distal carinae near the cervix, and extracarinal accessory denticles, suggest a highly specialized feeding strategy inS. galbinensis. The presence of triple carinae on the distalmost lateral tooth crowns is also unique, although may represent an abnormality. Contrasted with the simplistic dentition of the contemporaneous therizinosauridE. andrewsi, the dentition ofS. galbinensisis indicative of niche partitioning in food acquisition, processing, or resources among known therizinosaurids inhabiting Asian ecosystems in the Late Cretaceous. Although not quantitatively correlated with diet, this suite of specializations is otherwise unique among theropod dinosaurs and supports derived inferences of facultative or obligate herbivory in therizinosaurids, ultimately adding novel information to our understanding of ecomorphology in theropods.

Variations of Gerdy's tubercle, proposal of a morphological classification: Anatomical study and its clinical importance

Introduction: Gerdy's tubercle is described as a triangular facet in standard textbooks of human anatomy. The present study addresses the prevalence and shape of the anterolateral tubercle, which has been named as Gerdy's tubercle in adult human tibia. Examination of tibia revealed in excess of usual variations in the shape and texture of tubercle present at the anterior surface of lateral condyle of tibia. Material and Methods: The study was conducted on 103 (52 right and 51 left) of either sex dry Indian tibia bone to study the shape and texture of Gerdy's tubercle. The shape and texture of tubercle were very inconsistent and varied from a small circular smooth facet to very irregular rough facet. Results: Gerdy's tubercle was triangular & smooth in 44.6%, circular & smooth in 17.4%, vertically oval & smooth in 2.9%, transversely oval & smooth in 3.8%, irregular & rough in18.4% and triangular & rough in 6.7%. In 5.8% of tibia, it was unobtrusive. Conclusion: The different shapes of Gerdy's tubercle demonstrated in the present study may contribute to produce significant effect on surgical interventions and some shapes may be more prone to traumatic injuries on it.

Modeling Cutter Engagement Region for Triangular Mesh

Cutter Engagement Region (CER) is the part of tool that contacts with stock, where a series of energy exchange and material transportation take place. A full understanding of its shape and area is indispensible for cutting force calibration, chatter analysis, and tool wear prevention. It can provide a criterion for efficient tool-path planning as well. In literature, however, there is no available modeling of CER. We hereby propose a modeling method for ball-end tool with design surface represented in triangular mesh. First, design surface is offset to form a stock surface. Next, compute the intersection between every triangular facet and the tool. Then, connect all the intersecting arcs to form the boundary of CER. Finally, compute the area of CER. Experimental validation for the proposed method is still needed.

Studies on the Algorithm for Five-Axis NC Machining with Triangular Facet Model

Using five-axis equipment for NC machining of free-form surface is an effective way to improve machining quality and machining efficiency, the surface shape and the five coordinate of the complexity of the machine tool movement led to its tool path planning technology is difficult. The paper aimed at the five coordinate NC machining of free-form surface and puts forward a five-axis NC machining method based on triangular facet model. The research based on triangular facet model, using constant scallop height method to calculate the step distance and improve the cutting efficiency to a great extent. In the process, tool path is generated, combining with the method of configuration space interference free.

Research on the Rapid Slicing Algorithm Based on STL Topology Construction

Constructing the topology of STL file efficiently is a key factor to improve the efficiency of slicing algorithm. In this paper a topology construction algorithm based on Standard Template Library set containers and a rapid slicing algorithm are developed. The algorithm developed removes a large number of redundant vertices, and only calculates intersection per triangular facet with slice plane once, and attains another point of intersection directly from the adjacent relations. In addition, the algorithm can reduce the times of traversing and sorting for the triangular facets, and also the times of calculation of intersection in the slicing processes, which results in the simplification of the process of constructing the slice contour, consequently the efficiency of the slicing algorithm is improved.