三峡库区滑坡涌浪作用下桥墩波压特性研究

由于三峡库区的非开敞性,滑坡引起的涌浪衰减较慢,传播过程中可能对沿程桥墩产生巨大破坏。以涪陵长江二桥为依托,构建了比例尺为1∶70的库区河道水槽,试验模拟了滑坡涌浪对桥墩的作用。结果表明:桥墩上涌浪波压分为共振波压(P_(re))和脉动波压(P_(pu)),共振波压为涌浪冲击桥墩瞬间桥墩共振产生的高频振动波,频率为300.0~400.0 Hz;脉动波压为波浪作用过程产生的压力,频率为0.2~0.5 Hz;脉动波压在对岸桥墩上沿水深的分布近似为垂直分布,在同岸桥墩沿水深锯齿状减小,最大脉动波压分布在水面附近;共振波压沿水深分为单峰值、多峰值和无峰值3种,10万m^(3)以上大方量滑坡产生的共振波压为单峰值和多峰值分布,单峰值的峰值波压是水面波压的5.0倍,多峰值的峰值波压为水面波压的2.5倍~4.0倍,10万m^(3)以下滑坡产生的共振波压呈现无峰值分布;共振波压沿水深呈先增大后减小的“侧V”形;P_(re)/P_(pu)最大位置在距水面1/3水深位置,第二大位置在距水面1/5水深位置。该文提出了桥墩迎波面涌浪压力荷载计算模型,并针对三峡库区不同运行水位给出了相应水位条件下最大涌浪波压的计算公式。

Multi-target range and velocity measurements of a digital phased array radar system

As the core of a digital phased array radar system,a radar signal processing environment is created to measure multitarget range and velocity information. The radar echo signal is achieved by superposing target echo, noise, clutter and jamming signals linearly. Considering that these signals have many types,two typical combinations are selected to construct the multi-target echo signal and the simulated echo signal is used as the input of the signal processing environment. This environment mainly adopts pulse compression,moving target indication and detection technologies to process the echo signal.It is found that the frequency domain method is more desirable for the pulse compression effect than the time domain method,and multi-target range information can be measured from the moving target indication result after using a double delay canceller. A new moving target detecting method is proposed,which can present the positive and negative velocity accurately with the multi-target range and velocity measured simultaneously. Simulation results indicate that the potential targets are detected from the chaotic radar echo signals successfully,and their range and velocity can be figured out correctly in the built radar signal processing environment.

Modulation by anti-oketsu formulations in Kampo medicine of human arterial stiffness

Objective:In traditional herbal medicine(Kampo medicine in Japan),'sho'is diagnosed by the traditional assessments of clinical conditions.Among a variety of the shos,there is an'oketsu'syndrome,which is a stagnation and disturbance of microcirculation.The prompt effects of four anti-oketsu formulations in Kampo medicine on cardiovascular functions were compared in oketsu and non-oketsu persons.Methods:The arterial pulse wave from radial artery is formed by the combination with ejection and reflection pulses.An augmentation index(AI),a ration of the ejection and reflection pulses,indicates a degree of arteriosclerosis.For both seventy-six students with oketsu and thirty-seven students with non-oketsu,Kampo formulations overcoming oketsu of Tokishakuyakusan(TS,Dang-Gui-Shao-Yao-San),Kamishoyosan(KS,Jia-Wei-Xiao-Yao-San),Keisibukuryogan(KB,Gui-Zhi-Fu-Ling-Wan)and Tokakujokito(TJ,Tao-He-Cheng-Qi-Tang)were taken once,and then,the cardiovascular functions including blood pressure,heart rate,central arterial blood pressure(CBP)and AI were examined for 60 min.Results:At 40-60 min after an intake,these formulations decreased the AI almost by 6-18%(n=76),by 18.3±3.1%(P<0.01,n=15)with TJ.Simultaneously,the CBP was reduced by 9.0±1.8%(P<0.05,n=23)with KS and by 9.1±2.0%(P<0.05,n=15)with TJ.On the other hands,non-oketsu group had less or no effect by any kinds of the formulations.Conclusion:The anti-oketsu formulations can exert the ameliorative action for oketsu persons via decreasing AI and CBP.

Prediction of pulmonary arterial wedge pressure from arterial pressure or pulse oximetry plethysmographic waveform

Objective To assess the possibility of using arterial pressure waveform or pulse oximetry plethysmographic waveform variation to estimate the pulmonary arterial wedge pressure (PAWP) Methods Fourteen American Society of Anesthesiologists grade Ⅰ-Ⅱ patients aged 33-69 years and weighing 62 0±9 5 kg scheduled for elective abdominal tumor surgery were studied Their hemoglobin exceeded 120 g/L and hematocrit exceeded 35% Pre operative acute hypervolemic hemodilution was applied immediately after general anesthestic induction and tracheal intubation PAWP, systolic pressure variation (SPV), delta down (dDown), SPV plet , dDown plet and other hemodynamic parameters were measured and recorded when total fluid volume (crystalloid and colloid) infused reached 10 ml/kg and 20 ml/kg and again at the end of the operation Central venous pressure was maintained at 10-12 mm Hg during operation Systolic blood pressure at the end of Valsalva maneuver (airway pressure was kept at 22 mm Hg) and the systolic pressure before the Valsalva manoeuvre during apnea were used to calculate arterial pressure ratio (APR) Results APR, SPV, dDown, SPV plet and dDown plet all correlated well with PAWP ( r =0 717, -0 695, -0 680, -0 522 and -0 624 respectively, P <0 01) There was a closer linear correlation between APR and PAWP than between the other parameters The regression equation was PAWP (mm Hg)=0 207×APR (%)-0 382 Conclusion During positive pressure mechanical ventilation, APR, SPV, dDown, SPV plet and dDown plet can be used to estimate PAWP effectively

Pressure fluctuation propagation of a pump turbine at pump mode under low head condition

Pressure fluctuation at the vaneless space and vanes passages is one of the most important problems for the stable operation of a pump turbine. The fluctuation appears in any operating condition. Much research has been done on the pressure fluctuation of hydraulic machinery. However, the details of pressure fluctuation propagation of the pump turbine at the pump mode have not been revealed. The modem pump turbine with high water head requires the runner to be ＂flat＂, which would induce pressure fluctuation more easily than the low head pump turbine. In this article, a high head pump turbine model is used as the re- search object. As the pressure fluctuation at off-design point is more serious than at the design point, the low head condition is chosen as the research condition. Pressure fluctuation at the vaneless space and vanes passages is predicted by the computa- tional fluid dynamics method based on k-co shear stress transport model. The experiment conducted on the test rig of the Har- bin Institute of Large Electrical Machinery is used to verify the simulation method. It proves that the numerical method is a feasible way to research the fluctuation under this operating condition. The pressure fluctuation along the passage direction is analyzed at time and frequency domains. It is affected mainly by the interaction between the runner and vanes. In the circumferential direction, the influence of the special stay vane on the pressure fluctuation is got. The amplitude in the high-pressure side passage of that vane is lower than that in the other side. The study provides a basic understanding of the pressure fluctua- tion of a pump turbine and could be used as a reference to improve the operation stability of it.

Determination of delay time in individual transfer function for central aortic pressure reconstruction

In previous research, time-delay （△t） was a more important parameter than the reflection coefficient in the individual transfer function of central aortic pressure reconstruction. The At can be obtained by electrocardiography （ECG） or phonocardiography （PCG）. Because the pre-ejection period remains an uncertain factor, the present study used ECG and PCG to define the delay time and analyzed the accuracy of the reconstruction results. The △tpre is the actual delay time derived from the aorta to the carotid pressure wave, △tpco is the time delay between the aortic valve component of the second heart sound and the dicrotic incisura of the carotid pressure wave, and AtEcc represents the delay from the interval of the ECG R-peak to the foot of the carotid pressure wave. Compared with the measured aortic pressure, the reconstruction result obtained by △t=△tpcslightly differed from the best result estimated by △t=△tpre. However, the differences between the result obtained by △t=△tEco and the best result were significant in terms of the diastolic blood pressure, and pulse pressure, and especially in terms of the augmentation index and root-mean-square-error. Thus, the At should be determined by PCG for central aortic pressure reconstruction in practice.

External iliac artery injury secondary to indirect pressure wave effect from gunshot wound

In patients presenting with gunshot wounds, a high clinical suspicion of injury to vasculature and viscera remote from the projectile track is paramount. We present a case of a 17 year old male who sustained a gunshot wound to his abdomen and subsequently developed a right external iliac artery contusion recluiring surgery as an indirect effect of the oressure wave from the bullet.