Reconstruction Beyond Proto-Languages In the Middle Andes

The perception that the numerous similarities in lexicon, phonology and structure which unite the Quechuan and Aymaran language families in the Middle Andes region are due to intensive language contact prior to the stage of their proto-languages, rather than to a common genetic source as was previously assumed, has made it possible to visualize some of the originally inherited characteristics of each of the two linguistic lineages. This new perspective opens up multiple fields of further investigation, for instance, (a) determining the directionality of loan words (mainly from Quechuan to Aymaran, and rarely the other way around); (b) reconstructing the the structural profile of each of the two lineages prior to the beginning of their contact relation; and (c) creating the conditions for a separate external comparison of each lineage with other language families and isolates in the wider surroundings. In more general terms, it now appears possible to access earlier stages in the historical development of the Quechuan and Aymaran than that of the two proto-languages, to locate the original homeland of each lineage in relation to the newly established chronology, and to speculate on the societal context of the initial contact.

A Two-Step Composite Time Integration Scheme for Vehicle-Track Interaction Analysis considering Contact Separation

The two-step composite time integration scheme is combined with the linear contact relation between the wheel and rail (termed the two-step method) to solve coupled vehicle-track dynamic problems. First, two coupled vehicle-track models with different degrees-of-freedom are constructed, in which a vehicle-track system is modeled as two subsystems and the interaction between the two subsystems is implemented via kinematic constraints. Then, the two-step method is applied in the models to simulate several cases, and the accuracy and efficiency of this method are discussed in comparison with additional methods of the Newmark family. Contact separation can also be simulated using the same scheme without causing spurious oscillations for large integration steps. The results indicate that track irregularities can cause wheels to momentarily lose contact with the track, causing large impacts between the wheels and rail. Additionally, with the increase of the running velocity, contact separation will occur more frequently. The adoption of the two-step integration method can ensure the accuracy of solutions and significantly increase the computational efficiency; moreover, the matrixes representing the model information will not change during the calculation process, so the substructure data exported from commercial finite element software can be directly adopted.

Comparison of non-Hertzian modeling approaches for wheel–rail rolling contact mechanics in the switch panel of a railway turnout

Due to the complicated wheel–rail contact relation of railway turnouts, it is necessary to select a reasonable rolling contact model to simulate the vehicle–turnout dynamics and wheel–rail damages. This paper mainly aims to evaluate the calculation accuracy and efficiency of different non-Hertzian modeling approaches in solving normal and tangential wheel–rail contact problems of railway turnouts. Four different non-Hertzian approaches, namely CONTACT, Kik–Piotrowski, Ayasse–Chollet, and Sichani methods are compared and analyzed. The above four models are built considering the relative motion of stock/switch rails. A wheel profile called LMA contacting with stock/switch rails (head width 35 mm) of CN60-1100-1:18 turnouts is selected as the object of analysis. The normal contact problems are evaluated by the wheel–rail contact areas, shapes, and normal contact pressures. The assessment of tangential contact problems is based on the creep curves, tangential contact stresses, and distribution of the stick/slip region. In addition, a contrast analysis is performed on the calculation efficiencies of the four approaches. It is found that the normal and tangential contact results calculated based on the Sichani method coincide well with those obtained according to CONTACT, and the calculation efficiency is about 262 times that of CONTACT. The conclusions can provide some guidance to the selection of wheel–rail rolling contact approach in the simulation of vehicle–turnout dynamics and wheel–rail damages.

The Lattice Structure of L-Contact Relations

From the point of view of graded truth approach, we define the notion of a contact relation on the collection of allL-sets, discuss the connection to the set of all close, reflexive, and symmetric relations on allL-ultrafilters onX, and investigate the algebraic structure of allL-contact relations.

New Analysis Theory and Method for Drag and Torque Based on Full-Hole System Dynamics in Highly Deviated Well

The research on calculation of torque and drag in highly deviated wells has demonstrated a significant gap against oil exploration and development; with the increasingly rigorous situation, the drill string dynamics and the contact or friction of drill pipe with borehole wall under the drill string action of dynamic need more attention and urgent research work. Based on full-hole system dynamics, three-dimensional nonlinear dynamic model and dynamic torque and drag model were established in highly deviated well by using the finite element method. An application of analyzing typical torque and drag problems presented here provides a means to more accurate description of the contact relation between drill string and wellbore. The results show that those models established in this paper have complete adaptability for a complex three-dimensional borehole trajectory. For the actual well application, it will help to evaluate security performance of drill string in complex working conditions.

Analysis of Sedimentary Characteristics of Deep-Water Fan

Deep-water fan systems have become the main body of international oil production and reserves growth. It has important significance of science and production to study the sedimentary characteristics of deep-water fans. On the basis of a large number of literature research, this paper summarizes the research history and current situation of the deep-water fan. For several kinds of sedimentary microfacies in the fan, typical sedimentary characteristics and seismic combination structures are identified, including the composition, sedimentary structure, granularity, contact relation, seismic reflection and so on. These results are hoped to be helpful for sedimentary microfacies discrimination and research of deep-water fan.