Flow Characteristics of Gerotor Motors with Pin and Nonpin Designs

The geometric design of a gerotor motor has a significant impact on its function, performance, quality, reliability and cost. When designing a gerotor motor all these features must be considered. A gerotor motor can be classified into two types based on the geometric design; gerolor (pin design) and gerotor (nonpin design). In this article geometric parameters of the two design types are discussed briefly and the operation of the gerotor motor is described as well. A numerical analysis is carried out by using computational fluid dynamics (CFD) tool (PumpLinx) to analyze the fluid flow and predict the performance of both types of gerotor designs. Various characteristics of the two designs of the gerotor motor are investigated and compared which include the gerotor design, fluid flow rate, velocity, pressure and output torque. Comparison of the results found out that using pin design gerotor motor, the flow rate, flow velocity, pressure and torque will vary greatly. Nonpin design can significantly reduce variations in all the flow characteristics thereby enhancing the stability and reduction in the leakage risk.

Burial of a Hunnic Period Noblewoman at Karakabak, Mangystau, Kazakhstan

This study continues a series of publications describing the fi ndings of excavations at the Karakabak cemetery on the Mangyshlak Peninsula, dating to the Hunnic period. Burial 11 was that of a girl dressed in an outfi t imitating a royal vestment. The reconstructed headdress consisted of a cape decorated with round, gold plaques and a diadem-type headband of red cloth with mask-shaped plaques. The central forehead plaque is a replica of Hellenistic gorgoneia. Similar masks were found in the Volga basin and the Northern Black Sea region. Temporal mask-plaques, carved of wood and covered with gold foil, have no parallels but follow the archaic Scythian tradition. Belt and shoe buckles were not attached to belts and were not used in everyday life. In terms of style and technique, the gold casing with an embossed geometric design on a wooden base belongs to a series of artifacts of the so-called Shipovo horizon. The buckle frames are shaped as stylized birds of prey with spread wings. The forehead plaque and details of the shoe straps are paralleled by those from Altynkazgan. The Karakabak artifacts are unique for the Aral-Caspian region, providing yet another indication of close cultural ties with the Hunnic world. All details of the outfi t were likely manufactured at a nearby workshop (the Karakabak settlement) in the second half of the 5th or fi rst half of the 6th century for the burial of a nomadic noblewoman.

The Compatibility between the Takeover Process in Conditional Automated Driving and the Current Geometric Design of the Deceleration Lane in Highway

In recent years, the takeover process of conditional automated driving has attached a great deal of attention. However, most of the existing research has focused on the effects of human-machine interactions or driver-related features (e.g., non-driving-related tasks), while there is little knowledge about the compatibility between the takeover process and existing road geometric design. As there is a high possibility that drivers must take over the vehicle before they diverge from the mainline of the highway, this explanatory study aimed to examine the compatibility between the takeover process and the current deceleration lane geometric design. The distribution range of existing deceleration lanes’ lengths were obtained through a geo-based survey. Nine scenarios were recreated in the driving simulator which were designed with various deceleration lane lengths and driving modes (different takeover time budgets and manual driving as the baseline group). A total of 31 participants were recruited to take part in the experiment, their gaze behaviors were recorded simultaneously. Results showed that, compared with manual driving, both drivers’ horizontal and vertical gaze dispersion increased, while drivers adopted higher deceleration in the mainline and merged into the deceleration lane later under takeover conditions. Moreover, a longer deceleration lane could benefit vehicle control. However, its marginal effect was reduced with the increase of deceleration lane length. These findings can help automated vehicle manufacturers design dedicated takeover schemes for different deceleration lane lengths.

Femoral Stems With Porous Lattice Structures: A Review

Cementless femoral stems are prone to stress shielding of the femoral bone, which is caused by a mismatch in stiffness between the femoral stem and femur. This can cause bone resorption and resultant loosening of the implant. It is possible to reduce the stress shielding by using a femoral stem with porous structures and lower stiffness. A porous structure also provides a secondary function of allowing bone ingrowth, thus improving the long-term stability of the prosthesis. Furthermore, due to the advent of additive manufacturing (AM) technology, it is possible to fabricate femoral stems with internal porous lattices. Several review articles have discussed porous structures, mainly focusing on the geometric design, mechanical properties and influence on bone ingrowth. However, the safety and effectiveness of porous femoral stems depend not only on the characteristic of porous structure but also on the macro design of the femoral stem; for example, the distribution of the porous structure, the stem geometric shape, the material, and the manufacturing process. This review focuses on porous femoral stems, including the porous structure, macro geometric design of the stem, performance evaluation, research methods used for designing and evaluating the femoral stems, materials and manufacturing techniques. In addition, this review will evaluate whether porous femoral stems can reduce stress shielding and increase bone ingrowth, in addition to analyzing their shortcomings and related risks and providing ideas for potential design improvements.