First-principles rational design of M-doped LiBH4(010) surface for hydrogen release: Role of strain and dopants (M=Na,K, Al,F, or Cl)

To overcome the important challenges of facilitating dehydrogenation in the complex metal hydride, LiBH₄, the structural and chemical effects were considered using the strain (−3% − +3%) and five dopants (M = Na, K, Al, F, or Cl). The desorption energies of a hydrogen molecule decreased with increasing tensile strain on the LiBH₄(010) surface. The tensile strain was useful for promoting the dehydrogenation process by weakening the B-H interactions. Among the dopants examined, the most favorable dopant to enhance dehydrogenation was Al. The ranking of dopants for hydrogen release was Al > Cl > F > Na > K. Remarkably, codoping of Al and Cl was more effective for hydrogen release than the single doping of Al or Cl with the lowest hydrogen desorption energy. These methods that destabilize metal hydrides are practical for tuning the hydrogen release of LiBH₄ hydrides. These studies will provide efficient means for designing excellent hydrides for hydrogen release.     

基于微磨削方法的微织构刀具制备与切削性能研究

目的研究表面微织构对硬质合金刀具切削性能的影响。方法采用微磨削方法在硬质合金刀具前刀面加工出具有不同结构参数的横向、纵向和交叉微织构,通过AL6061切削试验和有限元切削仿真,研究表面微织构对硬质合金刀具的切削温度及刀具磨损的影响。结果采用V形金刚石砂轮微磨削方法能够加工出几何形状规则且表面质量良好的表面微织构。与无织构刀具相比,微织构刀具的切削温度明显降低,高温区域明显减少,其中横向织构刀具降温效果最为显著。微织构刀具的切削温度随沟槽间距的增大而升高,沟槽间距为150μm时,切削温度最低。表面微织构能够有效减轻刀具前刀面的粘结磨损,横向织构刀具减摩抗粘效果最好,且采用较小的沟槽间距更利于减轻刀具的粘结磨损。随着切削速度的增加,表面微织构的抗粘结作用更加明显,当切削速度为150 m/min时,沟槽间距为150μm的横向织构刀具的切屑粘结面积最小。结论在横向、纵向和交叉织构刀具中,沟槽间距为150μm的横向织构刀具切削性能最好,即降温效果、抗粘结性能最为显著。     

The CUSB-II detector

The properties and design philosophy of the first bismuth germanate electromagnetic calorimeter used in high energy physics are discussed. Presented also the first results on the energy resolution obtainable under different background conditions.     

Fabrication of ZrO2 and ATZ materials via UV-LCM-DLP additive manufacturing technology

The development of photosensitive slurries for additive manufacturing is attracting high interest due to their correlation with the final properties of the fabricated parts. Lithography-based ceramics manufacturing (LCM), i.e. digital light processing (DLP), is one of the techniques that is receiving high attention. Within the different ceramic materials, ZrO₂ and ATZ are the most studied due to their potential applications including in the dental field. In this work, the fabrication of ZrO₂ and ATZ materials via LCM-DLP is shown. A comparison between one- and two-step procedures to develop UV-curable ZrO₂ and Al₂O₃-ZrO₂ slurries was performed. The printed parts with a relative density of ∼99% for both ZrO₂ and ATZ were subjected to 4-point bending measurements, obtaining flexural strength values around 800 MPa for both ZrO₂ and ATZ materials prepared by using the one-step slurry.     

A review on application of laser tracker in precision positioning metrology of particle accelerators

The discoveries made in the twentieth-century include attempts to understand the origin of the universe, constituents of matter, enigmas of biological reactions, etc. could be possible mainly due to the extensive development in the field of particle accelerators. All the particle accelerators, irrespective of their scientific application, need precise alignment of various components for proper functioning. Survey and alignment activities in particle accelerators comprise precise positioning of various components, mainly magnets within micrometric tolerances over a length of hundreds of meters relative to the reference position as defined by the beam physicists in an arbitrary plane. The practice of specialized techniques and instruments are compulsory to meet these requirements. Due to the advancement in optical technology, low-cost computation, and fast data acquisition, laser trackers are commonly used in the field of large-scale dimensional metrology (LSDM). The area of LSDM also includes survey and alignment of the components at their nominal value with a precision of better than ±100 μm over a distance ranging from hundreds of meters to a few kilometres in particle accelerators. In the present study, the use and applicability of laser trackers in various precision positioning activities applicable to particle accelerators are presented in detail.