Investigation into precision engineering design and development of the next-generation brake discs using Al/SiC metal matrix composites

Substantially lightweight brake discs with high wear resistance are highly desirable in the automotive industry.This paper presents an investigation of the precision-engineering design and development of automotive brake discs using nonhomogeneous Al/SiC metal-matrixcomposite materials.The design and development are based on modeling and analysis following stringent precision-engineering principles,i.e.,brake-disc systems that operate repeatably and stably over time as enabled by precision-engineering design.The design and development are further supported by tribological experimental testing and finite-element simulations.The results show the industrial feasibility of the innovative design approach and the application merits of using advanced metal-matrix-composite materials for next-generation automotive and electric vehicles.

Nanotechnology and Precision Engineering

http://www.keaipublishing.com/en/journals/nanotechnology-and-precision-engineering/Nanotechnology and Precision Engineering (NPE) is a peer-reviewed, interdisciplinary research journal that covers all areas related to nanotechnology and precision engineering, which provides a forum for researchers of the related fi eld all over the world.

NANO-BEARING:THE DESIGN OF A NEW TYPE OF AIR BEARING WITH FLEXURE STRUCTURE

A new type of air bearing with flexure structure is introduced. The new bearing is designed for precision mechanical engineering devices such as mechanical watch movement. The new design uses the flexure structure to provide 3D damping to absorb shocks from all directions. Two designs are presented： one has 12 T-shape slots in the radian direction while the other has 8 spiral slots in the radian direction. Both designs have flexure mountings on the axial directions. Based on the finite element analysis （FEA）, the new bearing can reduce the vibration （displacement） by as much as 8.37% and hence, can better protect the shafts.

Genes and genetics in eye diseases: a genomic medicine approach for investigating hereditary and inflammatory ocular disorders

Past 25 y have witnessed an exponential increase in knowledge and understanding of ocular diseases and their respective genetic underpinnings. As a result, scientists have mapped many genes and their variants that can influence vision and health of our eyes. Based on these findings, it is becoming clear that an early diagnosis employing genetic testing can help evaluate patients＇ conditions for instituting treatment plan（s） and follow-up care to avoid vision complications later. For example, knowing family history becomes crucial for inherited eye diseases as it can benefit members in family who may have similar eye diseases or predispositions. Therefore, gathering information from an elaborate examination along with complete assessment of past medical illness by ophthalmologists followed by consultation with geneticists can help create a roadmap for making diagnosis and treatment precise and beneficial. In this review, we present an update on ocular genomic medicine that we believe has tremendous potential towards unraveling genetic implications in ocular diseases and patients＇ susceptibilities. We also discuss translational aspects of genetic ophthalmology and genome engineering that may help advance molecular diagnostics and therapeutics.

光催化CO_(2)还原多原子催化剂的设计与制备进展

光催化CO_(2)还原合成太阳能燃料对缓解CO_(2)排放引起的全球变暖和降低化石燃料消耗具有重要意义.然而,目前的光催化剂仍然存在反应动力学缓慢和选择性不理想的问题,特别是对于C_(2+)产物的生成,极大地限制了光催化的工业化进程.过去几十年中,关于太阳能驱动的CO_(2)还原的研究展示出鼓舞人心的结果,包括活性位点的构建.本综述重点介绍了通过构建活性位点制备原子级分散催化剂在光催化CO_(2)还原中的最新进展,包括两个独立的活性位点、成对双活性位点和基于活性位点构型的纳米团簇.此外,详细讨论了CO_(2)在活性位点上的活化机制和表征方法.特别是考虑到实验研究与实际应用之间的差距,整合实验和理论的结果,以实现潜在的结构-活性关系和高目标产物选择性发展.最后,概述了该领域存在的挑战,并展望了活性位点的合理设计和机理研究.

Defect and interface control on graphitic carbon nitrides/upconversion nanocrystals for enhanced solar hydrogen production

The effective utilization of solar energy for hydrogen production requires an abundant supply of thermodynamically active photo-electrons;however,the photocatalysts are generally impeded by insufficient light absorption and fast photocarrier recombination.Here,we report a multiple-regulated strategy to capture photons and boost photocarrier dynamics by devel-oping a broadband photocatalyst composed of defect engineered g-C_(3)N_(4)(DCN)and upconversion NaYF4:Yb^(3+),Tm^(3+)(NYF)nanocrystals.Through a precise defect engineering,the S dopants and C vacancies jointly render DCN with defect states to effectively extend the visible light absorption to 590 nm and boost photocarrier separation via a moderate electron-trapping ability,thus facilitating the subsequent re-absorption and utilization of upconverted photons/electrons.Importantly,we found a promoted interfacial charge polarization between DCN and NYF has also been achieved mainly due to Y-N interaction,which further favors the upconverted excited energy transfer from NYF onto DCN as verified both theoretically and experimentally.With a 3D architecture,the NYF@DCN catalyst exhibits a superior solar H2 evolution rate among the reported upconversion-based system,which is 19.3 and 1.5 fold higher than bulk material and DCN,respectively.This work provides an innovative strategy to boost solar utilization by using defect engineering and building up interaction between hetero-materials.

Rapid Manufacturing of Non-Assembly Complex Micro-Devices by Microstereolithography

This paper introduces a non-assembly manufacturing case with microstereolithography technology. The design and manufacturing process of a pneumatic thrust bearing is described, and a special tessellation method is developed to further improve the capability of the manufacturing system thus bigger products can also be easily manufactured. Implemented in a layer-by-layer fashion, stereolithography has been used for the rapid manufacturing of complex devices, and it avoids the expensive assembly process in the traditional manufacturing. This paper presents that microstereolithography can produce high-resolution products with intricate details, small openings, and smooth surfaces. The potential of the microstereolithograhy technique is explored for the rapid manufacturing of small and complex objects.

New development of atmospheric pressure plasma polishing

Atmospheric pressure plasma polishing （APPP） high quMity optical surfaces. The changes of is a precision machining technology used for manufacturing surface modulus and hardness after machining prove the distinct improvement of surface mechanical properties. The demonstrated decrease of surface residual stresses testifies the removal of the former deformation layer. And the surface topographies under atomic force microscope （AFM） and scanning electron microscope （SEM） indicate obvious amelioration of the surface status, showing that the 0.926-nm average surface roughness has been achieved.

Semi-analytical assessment of the relative accuracy of the GNSS/INS in railway track irregularity measurements

An aided Inertial Navigation System(INS)is increasingly exploited in precise engineering surveying,such as railway track irregularity measurement,where a high relative measurement accuracy rather than absolute accuracy is emphasized.However,how to evaluate the relative measurement accuracy of the aided INS has rarely been studied.We address this problem with a semi-analytical method to analyze the relative measurement error propagation of the Global Navigation Satellite System(GNSS)and INS integrated system,specifically for the railway track irregularity measurement application.The GNSS/INS integration in this application is simplified as a linear time-invariant stochastic system driven only by white Gaussian noise,and an analytical solution for the navigation errors in the Laplace domain is obtained by analyzing the resulting steady-state Kalman filter.Then,a time series of the error is obtained through a subsequent Monte Carlo simulation based on the derived error propagation model.The proposed analysis method is then validated through data simulation and field tests.The results indicate that a 1 mm accuracy in measuring the track irregularity is achievable for the GNSS/INS integrated system.Meanwhile,the influences of the dominant inertial sensor errors on the final measurement accuracy are analyzed quantitatively and discussed comprehensively.