岩矿扫描录井在碳酸盐岩储层异常高压预测中的应用

做好碳酸盐岩储层异常高压随钻预测,是降低溢流、井漏风险发生概率的关键。针对塔里木盆地富满地区一间房-鹰山组碳酸盐岩储层异常高压预测难题,通过岩矿扫描录井技术,获取与断控缝洞型碳酸盐岩储层异常高压相关的孔隙度、裂缝数两个参数,引入反映裂缝复杂程度的裂缝复杂指数,并建立孔隙度与裂缝复杂指数图板,对塔里木盆地富满地区一间房-鹰山组碳酸盐岩储层异常高压进行识别和预测。以塔里木盆地富满地区FD 1井为例,应用孔隙度与裂缝复杂指数图板能有效表征碳酸盐岩储层异常高压段,为该地区碳酸盐岩储层异常高压研究和预测提供了一个新方法,也为下一步勘探开发提前采取工程措施,降低溢流、井漏风险发生概率提供技术支撑。

基于最小二乘支持向量机的副热带高压预测模型

采用EOF时空分解、小波频率分解和最小二乘支持向量机(LS-SVM)交叉互补方法,建立夏季500 hPa位势高度场的预测模型,用以描绘和表述副热带高压形势场的形态和变化。首先用经验正交函数分解(EOF)方法将NCEP/NCAR再分析资料500 hPa位势高度场序列分解为彼此正交的特征向量及其对应时间系数,随后提取前15个主要特征向量的时间系数(方差贡献96.2%),采用小波分解方法将其分解为相对简单的带通信号,再利用LS- SVM方法建立各分量信号的预测模型,最后通过小波时频分量重构和EOF时空重构,得到500 hPa位势高度场的预测结果以及副热带高压形势场的预测。通过对预测模型的试验情况和分析对比,结果表明:基于上述思想提出的算法模型能较为准确地描述500 hPa位势高度场的形态分布并预测1～7 d的副热带高压活动,对10～15 d的副热带高压活动预测结果也有参考意义。

M701F4改进型燃气-蒸汽联合循环中低压合缸机组冷态快速启动优化

为解决M701F4改进型燃气-蒸汽联合循环中低压合缸机组冷态启动时间长约12 h的问题,通过分析该类型机组在启动前的冷态倒暖、启机过程、机组振动、高压缸膨胀及高压缸胀差等情况,并利用机组检修机会,清理轴封及高压缸内脱落变形残留物,同时采用一些创新方案,从邻机高参数疏水管路接引蒸汽作为冷态倒暖汽源,提高倒暖参数,结合近中压缸启动方式,汽轮机冲转升速至全速后尽快并网,有利于高压缸多进蒸汽带负荷暖缸,开机过程用预测高压缸胀差控制带负荷暖缸速度等办法,将机组冷态开机时间缩短至3 h左右,极大缩短同类型燃气轮机联合循环发电机组冷态启动时间,对中低压合缸机组的优化设计或技术改造有借鉴意义。

Neural network based online hypertension risk evaluation system

Since the previous research works are not synthetic and accurate enough for building a precise hypertension risk evaluation system,by ranking the significances for hypertension factors according to the information gains on 2 231 normotensive and 823 hypertensive samples,totally 42 different neural network models are built and tested.The prediction accuracy of a model whose inputs are 26 factors is found to be much higher than the 81.61% obtained by previous research work. The prediction matching rates of the model for ＂hypertension or not＂,＂systolic blood pressure＂,and ＂diastolic blood pressure＂ are 95.79%,98.22% and 98.41%,respectively.Based on the found model and the object oriented techniques,an online hypertension risk evaluation system is developed,being able to gather new samples,learn the new samples,and improve its prediction accuracy automatically.

Relationship between Rice Planthopper Occurrence Area in China and Atmospheric Circulation Indices

[Objective] This study aimed to establish models based on atmospheric cir- culation indices for forecasting the area attacked by rice planthopper every year, and to provide guide for preventing and controlling planthopper damage. [Method] The data related to rice planthopper occurrence and atmospheric circulation were collected and analyzed with the method of stepwise regression to establish the prediction models. [Result] The factors significantly related to the area attacked by rice plan-thopper were selected. Two types of prediction models were established. One was for Sogatella furcifera （Horvath）, based on Atlantic-Europe circulation pattern W in October in that year, Pacific polar vortex area index in October in that year, North America subtropical high index in August in that year, Atlantic-Europe circulation pattern W in June in that year, northern boundary of North America subtropical high in February in that year, Atlantic-Europe polar vortex intensity index in October in that year and Asia polar vortex intensity index in November in the last year; the other type of prediction models were for Nilaparvata lugens （Stal）, based on the Eastern Pacific subtropical high intensity index in July in that year, northern hemi- sphere polar vortex area index in October in the last year, Asia polar vortex strength index in November in the last year, north boundary of North America-At- lantic subtropical high in September in that year, north boundary of North Africa-At- lantic-North America subtropical high in January in that year, sunspot in September of the last year and eastern Pacific subtropical high area index in September in that year. [Conclusion] With the stepwise regression, the forecasting equations of the rice planthopper occurrence established based on the atmospheric circulation indices could be used for actual forecast.

Simulation of mold filling and prediction of gas entrapment on practical high pressure die castings

Element parameters including volume filled ratio,surface dimensionless distance,and surface filled ratio for DFDM(direct finite difference method)were proposed to describe shape and location of free surfaces in casting mold filling processes.A mathematical model of the filling process was proposed specially considering the mass,momentum and heat transfer in the vicinity of free surfaces.Furthermore,a method for gas entrapment was established by tracking flow of entrapped gas.The model and method were applied to practical ADC1 high pressure die castings.The gas entrapment prediction was compared with the fraction and maximum size of porosities in the different casting parts.The comparison shows validity of the proposed model and method.The study indicates that final porosities in high pressure die castings are dependent on both gas entrapment during mold filling process and pressure transfer within solidification period.

Reversal of monthly East Asian winter air temperature in 2020/21 and its predictability

In this study,the reversal of monthly East Asian winter air temperature(EAWT) in 2020/21 and its predictability were investigated.The reversal of monthly EAWT in 2020/21 was characterized by colder temperatures in early winter(December 2020 to mid-January 2021) and warmer temperatures in late winter(mid-January to February 2021).Results show that the reversal in the intensity of the Siberian high(SH) also occurred between early and late winter in 2020/21.In early winter,as the Barents-Laptev sea ice in the previous September(i.e., in2020) reached a minimum for the period 1981-2020,the SH was strengthaned via a reduction of the meridional gradient between the Arctic and East Asia.In late winter,as a sudden stratospheric warming occurred on 5 January 2021,the stratospheric polar vortex weakened,with the weakest center shifting to North America in January.Subsequently,the negative Arctic Oscillation-like structure shifted towards North America in the middle and lower troposphere,which weakened the SH in late winter.Furthermore,the predictability of the reversal in EAWT in 2020/21 was validated based on monthly and daily predictions from NCEP-CFSv2(National Centers for Environment Prediction-Climate Forecast System,version 2).The results showed that the model was unable to reproduce the monthly reversal of EAWT.However,it was able to forecast the reversal date(18 January 2021)of EAWT at lead times of 1-20 days on the daily scale.

Ab initio Predictions of Structural and Thermodynamic Properties of Zr2AIC Under High Pressure and High Temperature

The structural and thermodynamic properties of Zr2A1C at high pressure and high temper- ature are investigated by first principles density functional theory method. The calculated lattice parameters of Zr2A1C are in good agreement with the available theoretical data. The pressure dependences of the elastic constants, bulk modulus, shear modulus, Young＇s mod- ulus, and Vickers hardness of Zr2A1C are successfully obtained. The elastic anisotropy is examined through the computation of the direction dependence of Young＇s modulus. By using the quasiharmonic Debye model, the thermodynamic properties including the Debye temperature, heat capacity, volume thermal expansion coefficient, and Griineisen parameter at high pressure and temperature are predicted for the first time.

Impingement capability of high-pressure submerged water jet: Numerical prediction and experimental verification

At jet pressures ranging from 80 to 120 MPa, submerged water jets are investigated by numerical simulation and experiment. Numerical simulation enables a systematic analysis of major flow parameters such as jet velocity, turbulent kinetic energy as well as void fraction of cavitation. Experiments facilitate an objective assessment of surface morphology, micro hardness and surface roughness of the impinged samples. A comparison is implemented between submerged and non-submerged water jets. The results show that submerged water jet is characterized by low velocity magnitudes relative to non-submerged water jet at the same jet pressure. Shear effect serves as a key factor underlying the inception of cavitation in submerged water jet stream. Predicted annular shape of cavity zone is substantiated by local height distributions associated with experimentally obtained footprints. As jet pressure increases, joint contribution of jet kinetic energy and cavitation is demonstrated. While for non-submerged water jet, impingement force stems exclusively from flow velocity.

Predicting Western Pacific Subtropical High Using a Combined Tropical Indian Ocean Sea Surface Temperature Forecast

Weather and climate in East China are closely related to the variability of the western Pacific subtropical high(WPSH), which is an important part of the Asian monsoon system. The WPSH prediction in spring and summer is a critical component of rainfall forecasting during the summer flood season in China. Although many attempts have been made to predict WPSH variability, its predictability remains limited in practice due to the complexity of the WPSH evolution. Many studies have indicated that the sea surface temperature(SST) over the tropical Indian Ocean has a significant effect on WPSH variability. In this paper, a statistical model is developed to forecast the monthly variation in the WPSH during the spring and summer seasons on the basis of its relationship with SST over the tropical Indian Ocean. The forecasted SST over the tropical Indian Ocean is the predictor in this model, which differs significantly from other WPSH prediction methods. A 26-year independent hindcast experiment from 1983 to 2008 is conducted and validated in which the WPSH prediction driven by the combined forecasted SST is compared with that driven by the persisted SST. Results indicate that the skill score of the WPSH prediction driven by the combined forecasted SST is substantial.

Predictors and clinical outcomes for spontaneous rupture of hepatocellular carcinoma

AIM:To determine the risk factors for hepatocellular carcinoma(HCC) rupture,and report the management and long-term survival results of patients with spontaneous rupture of HCC.METHODS:Among 4209 patients with HCC who were diagnosed at Eastern Hepatobiliary Surgery Hospital from April 2002 to November 2006,200(4.8%) patients with ruptured HCC(case group) were studied retrospectively in term of their clinical characteristics and prognostic factors.The one-stage therapeutic approach to manage ruptured HCC consisted of initial management by conservative treatment,transarterial embolization(TACE) or hepatic resection.Results of various treatments in the case group were evaluated and compared with the control group(202 patients) without ruptured HCC during the same study period.Continuous data were expressed as mean ± SD or me-dian(range) where appropriate and compared using the unpaired t test.Categorical variables were compared using the Chi-square test with Yates correction or the Fisher exact test where appropriate.The overall survival rate in each group was determined using the Kaplan-Meier method and a log-rank test.RESULTS:Compared with the control group,more patients in the case group had underlying diseases of hypertension(7.5% vs 3.0%,P =0.041) and liver cirrhosis(87.5% vs 56.4%,P < 0.001),tumor size >5 cm(83.0% vs 57.4%,P < 0.001),tumor protrusion from the liver surface(66.0% vs 44.6%,P < 0.001),vascular thrombus(30.5% vs 8.9%,P < 0.001) and extrahepatic invasion(36.5% vs 12.4%,P < 0.001).On multivariate logistic regression analysis,underlying diseases of hypertension(P = 0.002) and liver cirrhosis(P < 0.001),tumor size > 5 cm(P < 0.001),vascular thrombus(P = 0.002) and extrahepatic invasion(P < 0.001) were predictive for spontaneous rupture of HCC.Among the 200 patients with spontaneous rupture of HCC,105 patients underwent hepatic resection,33 received TACE,and 62 were managed with conservative treatment.The median survival time(MST) of all patients with spontaneous rupture of HCC was 6 mo(range,1-72 mo),and the overall survival at 1,3 and 5 years were 32.5%,10% and 4%,respectively.The MST was 12 mo(range,1-72 mo) in the surgical group,4 mo(range,1-30 mo) in the TACE group and 1 mo(range,1-19 mo) in the conservative group.Ninety-eight patients in the control group underwent hepatic resection,and the MST and median diseasefree survival time were 46 mo(range,6-93 mo) and 23 mo(range,3-39 mo) respectively,which were much longer than that of patients with spontaneous rupture of HCC undergoing hepatic resection(P < 0.001).The 1-,3-,and 5-year overall survival rates and the 1-,3-and 5-year disease-free survival rates in patients with ruptured HCC undergoing hepatectomy were 57.1%,19.0% and 7.6%,27.6%,14.3% and 3.8%,respectively,compared with those of 77.1%,59.8% and 41.2%,57.1%,40.6% and 32.9% in 98 patients with-CONCLUSION:Prolonged survival can be achieved in selected patients undergoing one-stage hepatectomy,although the survival results were inferior to those of the patients without ruptured HCC.

Corona noise model of high-voltage AC transmission lines and engineering applications

In order to predict the levels of corona noise from high-voltage alternating current （AC） transmission lines, the mechanism of corona noise and the corresponding theoretical prediction model are investigated. On the basis of Drnde model, the motion of positive and negative ions produced by high-voltage corona is analyzed, and the mechanism of corona noise is discovered. The theoretical prediction model is put forward by using Kirchhoff formula, which is verified by the well agreement between our result and others＇ , considering the case of three- phase single lines. Moreover, the calculation results show that for both single and bundled lines, the sound pres- sure level of the typical frequency, i.e. twice the power frequency, attenuates slowly and leads to an obviously in- terferential phenomenon near the transmission lines, but the level of the bundled lines is smaller than that of the single ones under the same transmission voltage. Based on the mechanism of corona noise and the prediction model, it is obvious that bundled lines and/or increased line radius can be adopted to reduce corona noise in the practical engineering applications effectively. This model can also provide a theoretical guidance for the high-volt- age AC transmission line design.

Spatial batch optimal design based on self-learning Gaussian process models for LPCVD processes

Low pressure chemical vapor deposition(LPCVD) is one of the most important processes during semiconductor manufacturing.However,the spatial distribution of internal temperature and extremely few samples makes it hard to build a good-quality model of this batch process.Besides,due to the properties of this process,the reliability of the model must be taken into consideration when optimizing the MVs.In this work,an optimal design strategy based on the self-learning Gaussian process model(GPM) is proposed to control this kind of spatial batch process.The GPM is utilized as the internal model to predict the thicknesses of thin films on all spatial-distributed wafers using the limited data.Unlike the conventional model based design,the uncertainties of predictions provided by GPM are taken into consideration to guide the optimal design of manipulated variables so that the designing can be more prudent Besides,the GPM is also actively enhanced using as little data as possible based on the predictive uncertainties.The effectiveness of the proposed strategy is successfully demonstrated in an LPCVD process.

Oil production rate predictions for steam assisted gravity drainage based on high-pressure experiments

Dual-well steam assisted gravity drainage(SAGD) has significant potential for extra-heavy oil recovery.China is conducting two dual-well SAGD pilot projects in the Fengcheng extra-heavy oil reservoir.Quick,direct predictions of the oil production rate by algebraic models rather than complex numerical models are of great importance for designing and adjusting the SAGD operations.A low-pressure scaled physical simulation was previously used to develop two separate theoretical models corresponding to the two different growth stages observed in the SAGD steam chambers,which are the steam chamber rising stage and the steam chamber spreading stage.A high-pressure scaled model experiment is presented here for one dual-well SAGD pattern to further improve the prediction models to reasonably predict oil production rates for full production.Parameters that significantly affect the oil recovery during SAGD were scaled for the model size based on the reservoir characteristics of the Fengcheng reservoir in China.Experimental results show the relationship between the evolution of the steam chamber and the oil production rate during the entire production stage.High-pressure scaled model test was used to improve the gravity drainage models by modifying empirical factors for the rising model and the depletion model.A new division of the SAGD production regime was developed based on the relationship between the oil production rate and the evolution of steam chamber.A method was developed to couple the rising and depletion models to predict oil production rates during the SAGD production,especially during the transition period.The method was validated with experiment data and field data from the literature.The model was then used to predict the oil production rate in the Fengcheng reservoir in China and the Athabasca reservoir in Canada.

Numerical Investigation of High Pressure and High Reynolds Diffusion Flame Using Large Eddy Simulation

Today,with nonstop improvement in computational power,Large-Eddy Simulation(LES) is a high demanding research tool for predicting engineering flows.Such flows on high pressure condition like diesel engines is extensively employed in ground and marine transportation,oblige the designer to control and predict toxic pollutants,while maintaining or improving their high thermal efficiency.This becomes one of the main challenging issues in decades.In the present work,numerical investigation of diffusion flame dynamics is performed in the near-field of high-Reynolds jet flow on high pressure condition encountered in diesel engine applications.This work discusses the implementation of Partially Stirred Reactor(PaSR) combustion model by the approaches of large eddy simulation(LES).The simulation results show that LES,in comparison with Reynolds-Averaged Navier-Stokes(RANS) simulation predicts and captures transient phenomena very well.These phenomena such as unsteadiness and curvature are inherent in the near-field of high Reynolds diffusion flame.The outcomes of this research are compared and validated by other researchers' results.Detailed comparisons of the statistics show good agreement with the corresponding experiments.