PHASE DIAGRAM OF Nd-Fe-B TERNARY SYSTEM——Ⅱ.Two Vertical Sections with Constant Nd and B Respectively,Passing Through Nd_2Fe_(14) B Point

According to the experimental data of phase transition taken from DTA, metallography, SEM and microzone composition, two vertical sections of the ternary phase diagram (B=5.88 at.-%, Nd≤45.41 at.-% andNd_2Fe_(14)BNd_(1.1)Fe_4B_4 , B≤44.56 at.-%) have been drawn in detail. It is verified that the crystallization of both Nd_2Fe_(14)B and Nd_(1.1)Fe_4B_4 phase, during cooling from melt, would take peritectic reaction instead of solid-liquid congruent precipita- tion.

Vertical sections of Tb_(0.15)Ho_(0.85)Fe_y-Tb_(0.3)Dy_(0.7)Fe_y(y=1.85, 1.9, 2.0) in Tb-Dy-Ho-Fe system

The x（Tb0.15Ho0.85Fey）＋（1–x）（Tb0.3Dy0.7Fey）（x=0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9; y=1.85, 1.9, 2.0） samples were prepared by a vacuum arc furnace, and annealed at 1000 oC for 1 d and at 950 oC for a week. Three vertical sections of Tb0.15Ho0.85Fey-Tb0.3Dy0.7Fey（y=1.85, 1.9, 2.0） in the Tb-Dy-Ho-Fe system were determined using optical microscopy, scanning electron microscopy, energy dispersion X-ray spectroscopy, X-ray diffraction, and differential thermal analysis. These vertical sections consisted of two single-phase regions： L and（Tb,Dy,Ho）Fe2; four two-phase regions： L＋（Tb,Dy,Ho）Fe3, L＋（Tb,Dy,Ho）Fe2,（Tb,Dy,Ho）Fe2＋（Tb,Dy,Ho）Fe3, and（Tb,Dy,Ho）Fe2＋（Tb,Dy,Ho）. The high Ho content of（Tb,Dy,Ho）Fey alloys led to the elevation of the peritectic temperature of L＋（Tb,Dy,Ho）Fe3→（Tb,Dy,Ho）Fe2. The region of（Tb,Dy,Ho）Fe2 phase was shifted towards the side of rich-Ho with the Fe content increasing. It meant that the substitution of Ho for Dy or Tb had a marked effect on the solidification process of（Tb,Dy,Ho）Fe2 compounds.

Vertical section phase diagrams of La−Fe−B ternary system

The vertical sections of the La−Fe−B system were investigated using electron probe microanalysis and differential thermal analysis.Based on the microstructures and phase compositions of the as-cast and equilibrium alloys,together with their heat flow−temperature curves,phase diagrams for three vertical sections were drawn:La_(x)Fe_(82)B_(y)(x+y=18),La_(x)Fe_(70)B_(y)(x+y=30)and La_(x)Fe_(53)B_(y)(x+y=47),where x and y represent mass fraction of La and B,respectively,%.Additionally,according to the phase diagrams,the compound La2Fe14B was identified as a stable phase at high temperatures.It was found to be stable between 926.2 and 792.6℃;at low temperatures,however,it decomposed into α-La,α-Fe and LaFe_(4)B_(4),according to the reaction La_(2)Fe_(14)B→α-Fe+α-La+LaFe_(4)B_(4).

Characteristics of wheel-rail vibration of the vertical section in high-speed railways

In order to analyze the characteristics of wheel-rail vibration of the vertical section in a high-speed railway, a vehicle-line dynamics model is established using the dynamics software SIMPACK. Through this model, the paper analyzes the influence of vertical section parameters, including vertical section slope and vertical curve radius, on wheel-rail dynamics interaction and the acting region of wheel-rail vibration. In addition, the characteristics of wheel- rail vibration of the vertical section under different velocities are investigated. The results show that the variation of wheel load is not sensitive to the vertical section slope but is greatly affected by the vertical curve radius. It was also observed that the smaller the vertical curve radius is, the more severe the interaction between the wheel and rail be- comes. Furthermore, the acting region of wheel-rail vibration expands with the vertical curve radius increasing. On another note, it is necessary to match the slope and vertical curve radius reasonably, on account of the influence of operation speed on the characteristics of wheel-rail vibration. This is especially important at the design stage of vertical sec- tions for lines of different grades.

Synoptic Characteristics Related to Warm-Sector Torrential Rainfall Events in South China During the Annually First Rainy Season

Warm-sector torrential rainfall(WSTR)events that occur in the annually first rainy season in south China are characterized by high rainfall intensity and low radar echo centroids.To understand the synoptic characteristics related to these features,16 WSTR events that occurred in 2013-2017 were examined with another 16 squall line(SL)events occurred during the same period as references.Composite analysis derived from ERA-Interim reanalysis data indicated the importance of the deep layer of warm and moist air for WSTR events.The most significant difference between WSTR and SL events lies in their low-level convergence and lifting;for WSTR events,the low-level convergence and lifting is much shallower with comparable or stronger intensity.The trumpet-shaped topography to the north of the WSTR centers is favorable for the development of such shallow convergences in WSTR events.Results in this study will provide references for future studies to improve the predictability of WSTR.

Graphlike Manifolds with Contraction ×

In this paper I calculate the homeomorphic class of graphlike manifold with contraction.

Study on Injection-Production System Adjustment of Fault Block Reservoir Based on Equilibrium Displacement

This paper proposed a method of injection-production system adjustment to solve the problem that the water flooding effect was restricted because of the horizontal and vertical contradictions during the development process of fault block reservoirs. Considering the heterogeneity of reservoir, the Buckley-Leverett water flooding theory was applied to establish the relationship between the recovery and cumulative water injection. In order to achieve the goal of vertically balanced recovery of each section, the calculation method of vertical sectional injection allocation was proposed. The planar triangular seepage unit was assumed and sweep coefficients of different oil-water distribution patterns were characterized using multi-flow tube method. In order to balance and maximize the plane sweep coefficient, the calculation method of plane production system optimization was obtained. Then the injection-production system stereoscopic adjustment method based on equilibrium displacement was proposed with vertical sectional injection allocation and plane production system optimization. This method was applied to injection and production adjustment of BZ oilfield in southern Bohai. The effect of water control and oil increase was obvious. This method can greatly improve the effect of water flooding of offshore fault block reservoirs with the adjustment of injection-production system.

Effect of delivery mode on maternal-infant transmission of hepatitis B virus by immunoprophylaxis

To study the effect of different delivery modes on immunoprophylaxis efficacy so as to clarify whether or not cesarean section reduces immunoprophylaxis failure Methods Mothers with positive hepatitis B surface antigen (HBsAg) were selected in the third trimester of pregnancy Their babies were inoculated with hepatitis B immunoglobulin at birth and hepatitis B vaccine at 1, 2 and 7 months of age HBsAg and its antibodies (anti HBs) were tested at 1, 4, 7, and 12 months of age, then followed up yearly Results A total of 301 babies entered the study, including 144 born by normal spontaneous vaginal delivery, 40 by obstetric forceps or vacuum extraction, and 117 by cesarean section The incidence of mother’s HBeAg positivity or baby’s gender constitution was comparable between the three groups There were no significant differences in the positive rate of anti HBs or HBsAg at follow up periods among the three groups At 12 months of age, anti HBs could be detected in 78 9% of the babies born by normal vaginal delivery, 84 6% of the babies by forceps or vacuum extraction, and 86 4% of the babies by cesarean section The positive rate of HBsAg was 8 1%, 7 7%, 9 7%, and chronic HBV infection incidence was 7 3%, 7 7%, 6 8% respectively Conclusions There are no significant effects of delivery mode on the interruption of HBV maternal baby transmission by immunoprophylaxis Cesarean section does not reduce the incidence of immunoprophylaxis failure