Research on Shifting Control Method of Positive Independent Mechanical Split Path Transmission for the Starting Gear

To realize a smooth and quick shift of the positive independent mechanical split path transmission (PIMSPT) equipped with automatic shifting control system (ASCS), the research on the feasibility of improving shift quality by dynamic and cooperative controlling engine, steering clutches, and brakes has been conducted. The shifting control method suited to starting gear of PIMSPT has been proposed. The control method is based on control parameters, such as the driving shaft speed and its derivative. The control laws of steering clutches and brakes are presented during each gear and stage of shifting. Bench and road test results show that the proposed shifting control method can not only shorten the shift time, but also decrease the jerk of shifting effectively

Trajectory of systolic blood pressure fluctuation and its influencing factors in community-dwelling patients with hypertension

Objective To analyze and construct systolic blood pressure (SBP) fluctuation trajectory in a community population with hypertension and to analyze the factors influencing different trajectories. Methods This is a community-based retrospective cohort study. A latent class trajectory model was used to identify and construct longitudinal trajectories of blood pressure change. Multinomial logistic regression analysis was performed to identify the associated factors of blood pressure trajectories by adjusting for different confounders. Potential confounding factors were identified using a directed acyclic graph based on a priori knowledge. Results A total of 793 patients with hypertension were enrolled in the analysis. They were divided into 3 groups by LCTM-fitted systolic blood pressure trajectories, namely stable low-level group (n=561, 70.74%), declining group (n=170, 21.44%) and rising group (n=62, 7.82%). Significant differences were observed among the 3 trajectories groups in terms of age, frequency of exercise, ways of follow-up, salt intake, compliance behavior, and referral (P<0.05). Compared to the stable low-level group and adjusting for corresponding confounding factors, the male patients and the patients with "outpatient follow-up" were more likely to be classified into "declining group", with OR and 95% CI of 1.436 (1.016~2.030) and 1.702 (1.202~2.410), respectively. The participants aged ≥65 years, who did not exercise or occasionally exercised, and had moderate and severe salt intake, were more likely to be classified into the "rising group"(OR=1.949, 2.284, 2.433, 4.540, 95%CI: 1.145~3.317, 1.305~3.998, 1.272~4.654, 1.291~15.963). Conclusion SBP trajectories in community-dwelling hypertensive population can be divided into stable low-level, declining and rising groups. Gender, age, salt intake, exercise frequency, and follow-up methods may be influencing factors for SBP blood pressure trajectory

Trajectory and influencing factors of fasting blood glucose fluctuations in patients with type 2 diabetes mellitus in community

Objective To construct trajectory models of fasting blood glucose fluctuations in type 2 diabetes mellitus (T2DM) patients in community, and analyze the influencing factors of the trajectory of glucose fluctuation in different categories. Methods A retrospective cohort study was carried out on 769 T2DM patients who had health records and been involved in the diabetic management in Shuangbei Community Health Service Center of Shapingba District, Chongqing from 2012 to 2019. Group-based trajectory modelling (GBTM) was employed to identify and construct the fluctuation trajectory of fasting blood glucose in the patients. BIC, AvePP and other evaluation indicators were used to select the optimum subgroup number model. Then the differences in demographic characteristics, health status, medical history, lifestyle, medication compliance, etc were compared among different categories. Multinomial logistic regression model was constructed to explore the influencing factors of different fluctuation trajectories. Results The 769 T2DM subjects were divided into 3 groups of different fluctuation trajectories by GBTM, that is, low-level steady, high-level falling, and medium-level rising groups. Multinomial logistic regression analysis indicated that the patients with a history of hypertension and not taking medication were less likely to be assigned into the high-level falling group than into the low-level steady group, indicating that their high glucose level was not predisposed to a progressive decline (OR=0.50, 95%CI: 0.28~0.90, P=0.021; OR=0.13, 95%CI: 0.03~0.56, P=0.006). However, the subjects who occasionally or not exercised, consumed alcohol or abstained from alcohol were more likely to be assigned into the high-level falling group (OR=2.02, 95%CI: 1.15~3.55, P=0.014; OR=2.32, 95%CI: 1.16~4.63, P=0.017). When compared with the patients with regular medication, those with intermittent medication were more likely to be assigned into the medium-level rising group (OR=6.02, 95%CI: 2.86~12.66, P < 0.001). Conclusion There are different trajectories of dynamic changes in fasting glucose for T2DM patients. History of hypertension, medication adherence, frequency of exercise, and alcohol consumption may be associated with different trajectories of blood glucose fluctuations

The Cavitation-Induced Pressure Fluctuations in a Mixed-Flow Pump under Impeller Inflow Distortion

To reduce cavitation-induced pressure fluctuations in a mixed-flow pump under impeller inflow distortion, the dynamic pressure signal at different monitoring points of a mixed-flow pump with a dustpan-shaped inlet conduit under normal and critical cavitation conditions was collected using high-precision digital pressure sensors. Firstly, the nonuniformity of the impeller inflow caused by inlet conduit shape was characterized by the time&ndash;frequency-domain spectra and statistical characteristics of pressure fluctuation at four monitoring points (P4&ndash;P7) circumferentially distributed at the outlet of the inlet conduit. Then, the cavity distribution on the blade surface was captured by a stroboscope. Lastly, the characteristics of cavitation-induced pressure fluctuation were obtained by analyzing the time&ndash;frequency-domain spectra and statistical characteristic values of dynamic pressure signals at the impeller inlet (P1), guide vanes inlet (P2), and guide vanes outlet (P3). The results show that the flow distribution of impeller inflow is asymmetric. The pav values at P4 and P6 were the smallest and largest, respectively. Compared with normal conditions, the impeller inlet pressure is lower under critical cavitation conditions, which leads to low pav, pp-p and a main frequency amplitude at P1. In addition, the cavity covered the whole suction side under H = 13.6 m and 15.5 m, which led the pp-p and dominant frequency amplitude of pressure fluctuation at P2 and P3 under critical cavitation to be higher than that under normal conditions

The Cavitation-Induced Pressure Fluctuations in a Mixed-Flow Pump under Impeller Inflow Distortion

To reduce cavitation-induced pressure fluctuations in a mixed-flow pump under impeller inflow distortion, the dynamic pressure signal at different monitoring points of a mixed-flow pump with a dustpan-shaped inlet conduit under normal and critical cavitation conditions was collected using high-precision digital pressure sensors. Firstly, the nonuniformity of the impeller inflow caused by inlet conduit shape was characterized by the time–frequency-domain spectra and statistical characteristics of pressure fluctuation at four monitoring points (P4–P7) circumferentially distributed at the outlet of the inlet conduit. Then, the cavity distribution on the blade surface was captured by a stroboscope. Lastly, the characteristics of cavitation-induced pressure fluctuation were obtained by analyzing the time–frequency-domain spectra and statistical characteristic values of dynamic pressure signals at the impeller inlet (P1), guide vanes inlet (P2), and guide vanes outlet (P3). The results show that the flow distribution of impeller inflow is asymmetric. The pav values at P4 and P6 were the smallest and largest, respectively. Compared with normal conditions, the impeller inlet pressure is lower under critical cavitation conditions, which leads to low pav, pp-p and a main frequency amplitude at P1. In addition, the cavity covered the whole suction side under H = 13.6 m and 15.5 m, which led the pp-p and dominant frequency amplitude of pressure fluctuation at P2 and P3 under critical cavitation to be higher than that under normal conditions

Upper Mantle beneath the Myanmar and Surrounding Tomography: New Insight into Plate Subduction and Volcanism

Myanmar and its surrounding areas have complex topography and strong tectonic movement, which has always been a challenge to most geoscientists. We used teleseismic tomography to study the subsurface velocity structure in this area. We present a new P-wave tomographic model beneath Myanmar and the surrounding areas by inverting 129,788 arrival-time data recorded by 372 stations. We found an inclined high-velocity subducting plate beneath central Myanmar, where the dip angle becomes smaller near 25&deg;~26&deg;N, and the seismic depth is limited below 200 km. The Indian oceanic lithosphere is being detached from the Indian continental lithosphere, which limits the depth of the earthquake. The active Tengchong volcano is underlain by a prominent low-velocity (low-V) anomaly in the shallow mantle, which may be caused by the subduction and dehydration of the Burma microplate (or Indian plate). The formation of the Singu volcano is related to the mantle flow of the Qinghai&ndash;Tibet plateau and the tearing of the Indian plate. The Yangtze craton (beneath the Sichuan Basin) shows a high-velocity anomaly, and both the shallow and deep parts have been destroyed, which may be related to the upwelling of deep heat flow

Study on Inflow Distortion Mechanism and Energy Characteristics in Bidirectional Axial Flow Pumping Station

In the present work, unsteady flow solved by the Reynolds time-averaged Navier–Stokes equation was investigated to determine the inflow distortion mechanism and the spatial distribution of hydraulic loss in a bidirectional axial flow pumping station (Case 1) based on the entropy production theory. A laboratory-scale performance experiment was also employed for the accuracy verification of the simulation approach, and an axial flow pump with pipe passages (Case 2) accompanying uniform inflow was utilized for analysis comparison. The results show that the non-uniform inflow causes a noticeable reduction in head and efficiency, as high as 27% and 21%, respectively, and the best efficiency point with uniform inflow shifts to the point with a larger flow rate. The axial velocity of the impeller inlet in Case 2 changes more smoothly along the Span compared with that in Case 1, which further indicates a more uniform inflow at the impeller inlet. The total entropy production (TEP) of each domain in Case 1 is always higher than that in Case 2, and the TEP of the whole domain in Case 1 increased by 18.68%, 30.50%, and 29.67% with flow rates of 0.8Qdes, 1.0Qdes, and 1.2Qdes, respectively, compared with that in Case 2. In the inlet passage, the larger TEPR regions in Case 1 are mainly located in the horn passage, which is far away from the inlet side, and are also distributed in the suction side of impeller blades and guide vanes. Therefore, this work may provide an optimal design reference for pumping stations in practical application

Upper Mantle beneath the Myanmar and Surrounding Tomography: New Insight into Plate Subduction and Volcanism

Myanmar and its surrounding areas have complex topography and strong tectonic movement, which has always been a challenge to most geoscientists. We used teleseismic tomography to study the subsurface velocity structure in this area. We present a new P-wave tomographic model beneath Myanmar and the surrounding areas by inverting 129,788 arrival-time data recorded by 372 stations. We found an inclined high-velocity subducting plate beneath central Myanmar, where the dip angle becomes smaller near 25°~26°N, and the seismic depth is limited below 200 km. The Indian oceanic lithosphere is being detached from the Indian continental lithosphere, which limits the depth of the earthquake. The active Tengchong volcano is underlain by a prominent low-velocity (low-V) anomaly in the shallow mantle, which may be caused by the subduction and dehydration of the Burma microplate (or Indian plate). The formation of the Singu volcano is related to the mantle flow of the Qinghai–Tibet plateau and the tearing of the Indian plate. The Yangtze craton (beneath the Sichuan Basin) shows a high-velocity anomaly, and both the shallow and deep parts have been destroyed, which may be related to the upwelling of deep heat flow

The Influence of a Pumping Chamber on Hydraulic Losses in a Mixed-Flow Pump

In this study, entropy generation theory based on computational fluid dynamics (CFD) is used to study the influence of a pumping chamber type (guide vane and volute scheme) on the spatial distribution of hydraulic loss in a mixed-flow pump. The CFD data of the mixed-flow pump with a volute is validated by external characteristic test data under Q = 561.4&ndash;1598.6 m3/h. The results show that the efficiency and the head of the guide vanes scheme are lower under Q = 800&ndash;1200 m3/h, which resulted from a higher total entropy production (TEP) in the pumping chamber and outlet pipe. The high total entropy production rate (TEPR) inside the guide vanes can be found near the leading edge of the hub side and trailing edge of the rim side due to flow separation, which reduces the recovery efficiency of kinetic energy of the guide vanes. The high TEPR inside outlet pipe can be seen near the inlet, caused by back flow. However, the efficiency and head of the volute scheme are lower, under Q = 1200&ndash;1600 m3/h, owing to the fact that the volute cannot effectively convert kinetic energy into pressure energy and thus the high TEPR can be found near outlet of volute and inlet of outlet pipe. These results can provide useful suggestions to the matching optimization of the impeller and pumping chamber in a mixed-flow pump