Impregnated drill bits strengthened by nanoparticles for mineral exploration drilling

In order to improve the drilling efficiency and service life of impregnated diamond drill bit, WC and ZrO2 nanoparticles were introduced into traditional drill bit matrix. The matrix formula and fabrication process were optimized to utilize the dispersion strengthening effect of WC and ZrO2 nanoparticles, improving physical and mechanical performance of working layer. Indoor drilling experiment was carried out to compare reinforced drill bits and traditional bit. Results showed that drill bits with 2.5 wt% nano-WC and 1 wt% nano-ZrO2 shows better performance than traditional bits. WC nanoparticles have better dispersion strengthening effect on diamond drill bit than ZrO2 nanoparticles

Bacterial Communities of the Coronal Sulcus and Distal Urethra of Adolescent Males

Lactobacillus-dominated vaginal microbiotas are associated with reproductive health and STI resistance in women, whereas altered microbiotas are associated with bacterial vaginosis (BV), STI risk and poor reproductive outcomes. Putative vaginal taxa have been observed in male first-catch urine, urethral swab and coronal sulcus (CS) specimens but the significance of these observations is unclear. We used 16 S rRNA sequencing to characterize the microbiota of the CS and urine collected from 18 adolescent men over three consecutive months. CS microbiotas of most participants were more stable than their urine microbiotas and the composition of CS microbiotas were strongly influenced by circumcision. BV-associated taxa, including Atopobium, Megasphaera, Mobiluncus, Prevotella and Gemella, were detected in CS specimens from sexually experienced and inexperienced participants. In contrast, urine primarily contained taxa that were not abundant in CS specimens. Lactobacilllus and Streptococcus were major urine taxa but their abundance was inversely correlated. In contrast, Sneathia, Mycoplasma and Ureaplasma were only found in urine from sexually active participants. Thus, the CS and urine support stable and distinct bacterial communities. Finally, our results suggest that the penis and the urethra can be colonized by a variety of BV-associated taxa and that some of these colonizations result from partnered sexual activity

Geometric reinforcement learning for path planning of UAVs

We proposed a new learning algorithm, named Geometric Reinforcement Learning (GRL), for path planning of Unmanned Aerial Vehicles (UAVs). The contributions of GRL are as: (1) GRL exploits a specific reward matrix, which is simple and efficient for path planning of multiple UAVs. The candidate points are selected from the region along the Geometric path from the current point to the target point. (2) The convergence of calculating the reward matrix is theoretically proven, and the path in terms of path length and risk measure can be calculated. (3) In GRL, the reward matrix is adaptively updated based on the Geometric distance and risk information shared by other UAVs. Extensive experimental results validate the effectiveness and feasibility of GRL on the navigation of UAVs