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The single-cone bit has become the first choice for slim hole sidetracking and deep well drilling with its unique rock breaking method and high ROP (Rate Of Penetration), with its main failure mode being of early excessive wear of the cutting teeth. In order to improve the adaptability of single-cone bits to hard and highly abrasive formations, a spherical single-cone Polycrystalline Diamond Compact (PDC) compound bit is designed. According to the characteristics of the tooth profile, the way of tooth arrangement and the way of contact between the cutting teeth and the rock, the acceleration equation to the cutting teeth of the spherical single-cone PDC compound bit is established. The acceleration of the single-cone bit is verified by numerical simulation experiment of rock-breaking. The shaft inclination angle of the cone, the position and height of the PDC teeth, the radius of the PDC teeth, the lateral rotation angle and the front inclination angle on the acceleration are studied. The results show that as the shaft inclination angle increases, the bit transmission ratio gradually increases, and the harder the rock formation, the larger the transmission ratio of the single-cone bit; the shaft inclination angle and the position of the PDC tooth have a greater influence on the acceleration of the PDC tooth, and the radius, lateral rotation angle and front inclination angle of the PDC tooth have a small influence on the acceleration of the PDC tooth; rock properties have an impact on the acceleration of the cutting teeth, with the acceleration of the cutting teeth in hard rock formations being higher than that in soft rock formations; near the top of the cone, the absolute acceleration of the cutting teeth will fluctuate sharply and cause severe wear of the cutting teeth, so the tooth distribution in this area should be strengthened; on the premise that the bearing life of the single-cone bit is allowed, the value of the shaft inclination angle β can be approached to 70°. The relative error between the theoretical analysis results of the acceleration of the PDC cutter and the rock-breaking simulation experiment results is between −0.95% and −2.24%. This research lays a theoretical foundation for the dynamic research of spherical single-cone PDC compound bit.

In the dual casing sidetracking,the oil casing wall,cement ring,technical casing wall and rock formations’ hardness are different,furthermore,in the process of dual casing sidetracking the bit in contact with the oil casing wall,cement ring,technical casing wall and rock formations are different,bit bending moment certainly exist. Considered the situation of that the sidetracking bit in actual contact with the oil casing wall,cement ring,technical casing wall and rock formations,established the bending moment mathematical model of the dual casing sidetracking drill bit,and combined with examples using MATLAB software solved the relationship between the drill bit bending moment and the drill bit horizontal moving distance under that Three different working conditions was given. Further reference the theory of metal cutting mechanics,researched cutting force and cutting torque of the drill bit in sidetracking the process,checked the sidetracking bit strength,provided technical advice to prevent the drill bit holded in and stuck fracture accident occurred in the dual casing sidetracking process. The analysis and calculation could provide the reference to designing the sidetracking bit and determinating construction parameters in the dual casing sidetracking process.

Adhesive is the key component and factor for the manufacture of glulam, affected both the properties and cost of glulam product. Bio-based resorcinol-phenol-formaldehyde (BRPF) resin was developed by partly replacing the expensive resorcinol and phenol with the cheap biomass derived pyrolysis oil. The press process parameters and the dosage of adhesive and corresponding curing agent were selected as the factors and extensively studied. BRPF resin was successfully used to bond the laminas to produce glulam, and the optimized process parameters for the cold-pressing adhesion of BRPF resin with pine wood were obtained as follows: the cold-pressing pressure 1.4 MPa, the cold-pressing time 9 h, the amount of adhesive coating 320 g/m2, and the proportion of curing agent (poly-formaldehyde) 17%. The mechanical performances of laminated wood bonding with BRPF resin under the optimal condition were further verified. It is believed that the results obtained here will promote the use of bio-based resin in the bonding of laminated wood, and then contribute to the green manufacturing of glulam with lower cost.

The single‐cone bit has become the first choice for slim hole sidetracking and deep well drilling with its unique rock breaking method and high ROP (rate of penetration). The single‐cone bits currently used in the oil field all use cemented carbide inserts, with its main failure mode being of early excessive wear of the cutting teeth. In order to improve the adaptability of single‐cone bits to hard and highly abrasive formations, a single‐cone PDC composite bit is designed. According to the characteristics of the tooth profile, the way of tooth arrangement and the way of contact between the cutting teeth and the rock, the acceleration equation to the cutting teeth of the single‐cone PDC composite bit is established. The shaft inclination angle of the cone, the position and height of the PDC teeth, the radius of the PDC teeth, the lateral rotation angle, and the front inclination angle on the acceleration are studied. The acceleration of the single‐cone bit is verified by numerical simulation and drilling experiment of rock‐breaking. Rock formation properties have an impact on the acceleration of the cutting teeth, with the acceleration of the cutting teeth in hard rock formations being higher than that in soft rock formations. On the premise that the bearing life of the single‐cone bit is allowed, the value of the shaft inclination angle β can be approached to 70°. This research lays a theoretical foundation for the dynamic research and wear analysis of single‐cone PDC composite bit. [ABSTRACT FROM AUTHOR]

Post‐partum ovarian cycle arrest is the main factor affecting yak reproductive efficiency. There are few reports regarding the molecular regulatory mechanism of post‐partum oestrus at transcriptome and proteome levels in yaks. Our previous studies focussed on the ovaries of yaks with post‐partum ovarian cycle arrest and post‐partum oestrus yaks. In this study, RNA sequencing transcriptomic study was combined with quantitative proteomic analyses to identify post‐partum ovarian cycle‐related genes and proteins. Consequently, 1,149 genes and 24 proteins were found to be up‐ or downregulated during post‐partum oestrus. The analysis of differentially regulated genes identified three gene or protein pairs that were synchronously upregulated and no gene or protein pairs that were synchronously downregulated, suggesting that these upregulated genes may regulate the post‐partum ovarian cycle. The functional classification of these differentially expressed genes and proteins indicated their connection with the oocyte meiosis, the oestrogen signalling pathway, the progesterone‐mediated oocyte maturation and the gonadotrophin‐releasing hormone (GnRH) signalling pathway. In this study, a total of six genes and two proteins involved in the oocyte meiosis, the oestrogen signalling pathway, the progesterone‐mediated oocyte maturation and the GnRH signalling pathway were identified. The CSNK1A1, M91_09723, M91_11326, M91_21439, M91_19073, SHC2, Atf6b, M91_03062, HSPCA and calmodulin could regulate oestrus, respectively, in the post‐partum so as to control the anoestrus status. [ABSTRACT FROM AUTHOR]