When shield machine traverses through hard rock mass, disc cutters will be abraded to different degrees. Excessive height difference exists between adjacent cutters, which critically affects the rock-breaking efficiency. Relying on a section of mass in Qingdao, cutter abrasions are measured site, and reason for low construction efficiency is analysed. Subsequently, discrete element method used ...

conclusions in this study, we found that in spite of previous beliefs, discopathies were not common etiologies of lbp. thus, even in patients with proven ldh by imaging studies, the physician should perform a thorough evaluation for other causes of lbp to avoid unnecessary lumbar surgeries. results in our study, among 1250 patients with proven ldh by mri, 500 patients (40%) had chronic lbp and ...

ABSTRACT The black hole candidate MAXI J1348-630 was discovered in 2019 January 26, with the Gas Slit Camera (GSC) on-board MAXI. We report a detailed spectral analysis of this source by using archived data NuSTAR. A total nine observations covered complete outburst evolution from hard state to soft and finally back state. Additionally, intermediate is found transition use state-of-the-art refl...

This paper presents a disc-type ultrasonic piezoelectric motor, which is designed for micro flying vehicles. It provides high output rotation speed under low operating voltage, compared with common devices, by employing “contact teeth” wave transmission structure. The motor (USM) consists of trimorph disc stator, triple internal contact teeth, shaft and two hemispheric hard-wearing rotors. prin...

In the course of its evolution, a black hole (BH) accretes gas from wide range directions. Given random accretion event, typical angular momentum an disc would be tilted by ∼60∘ relative to BH spin. Misalignment causes precess at rate that increases with spin and depends on morphology. We present general-relativistic magnetohydrodynamic (GRMHD) simulations spanning full precession period highly...

ABSTRACT We extend the relativistic time-dependent thin-disc TDE model to describe non-thermal (2−10 keV) X-ray emission produced by Compton up-scattering of thermal disc photons a compact electron corona, developing analytical and numerical models evolving light curves. In simplest cases, these curves follow power-law profiles in time. suggest that discs act many respects as scaled-up versions...

This paper presents a robust, discrete, near time-optimal control algorithm for hard disk drives. Building on the continuous-time control law of Newman [Trans. Automatic Control 35 (7) (1990) 841] and Newman and Souccar [J. Dynamic Syst. Measure. Control 113 (1991) 363], the chattering phenomenon for continuous-time systems is first examined, and it is shown how additional chattering can occur ...

We provide a stochastic analysis of hard disk performance, including a closed form solution for the average access time of a memory request. The model we use covers a wide range of types and applications of disks, and in particular it captures modern innovations like zone bit recording. The derivation is based on an analytical technique we call “shuffling”, which greatly simplifies the analysis...

ABSTRACT We studied the transient Galactic black hole candidate MAXI J0637−430 with data from Insight-HXMT, Swift, and XMM–Newton. The broad-band X-ray observations Insight-HXMT help us constrain power-law component. J0637–430 is located at unusually high latitude; if it belongs to thick disc, we suggest a most likely distance ≲7 kpc. Compared other transients, also unusual for reasons: fast tr...