瓦斯抽采高保压二次注浆封孔工艺及工程应用

针对郑州矿区“三软”煤层瓦斯抽采现有封孔工艺存在的密封不严等缺陷,研发高保压二次注浆封孔工艺,该新型注浆封孔工艺包括初次注浆封孔和二次注浆封孔,初次注浆封孔为低压注浆,即利用高膨胀性初次注浆材料(GPM)优异的膨胀性支护压密钻孔,同时堵塞钻孔浅部围岩漏气通道;二次注浆为高压注浆,即利用聚氨酯基有机二次注浆材料(JEM)良好的可注性,对钻孔周围微小裂隙进行注浆。数值模拟结果表明:高保压二次注浆封孔工艺配合GPM和JEM,能够保障浆液在钻孔围岩充分扩散,证明该工艺的可行性。在超化煤矿底抽巷穿层钻孔进行工业试验,结果表明,与超化矿“两堵一注”封孔工艺相比,高保压二次注浆封孔工艺改善了瓦斯抽采效果,提高了瓦斯利用率,钻孔瓦斯体积分数衰减也得到了有效控制,验证了该新型注浆封孔工艺的优越性。

基于高保压与开模发泡的微孔发泡注塑产品发泡行为控制与泡孔结构改善

针对微孔发泡注塑技术存在的工艺和产品质量问题,构建高保压和开模发泡微孔发泡注塑系统,试验研究不同工艺条件下微孔发泡注塑co-PP的熔体发泡行为和产品泡孔结构演变。结果表明,高保压和开模发泡能够良好调控微孔发泡注塑熔体的发泡行为,改善产品泡孔结构。在高保压压力和长保压时间作用下,微孔发泡注塑熔体填充过程中形成的泡孔进一步变形并重新溶回到熔体中,同时填充结束后发泡的熔体保持不发泡,使型腔中的熔体整体回复到一个较稳定的未发泡状态。开模发泡时,模具打开一定距离,给予熔体一个充足的发泡空间,使型腔中的未发泡熔体压力迅速下降,泡孔稳定长大,最终得到具有高发泡倍率和良好泡孔结构的微孔发泡注塑产品。微孔发泡注塑熔体发泡行为及其对应产品泡孔结构的调控与改善,关键在于对其填充过程中发泡的控制和填充结束后发泡的促进两方面。

NEW PRINCIPLE FOR DIRECTIONAL COMPARISON CARRIER PROTECTION OF EHV TRANSMISSION LINES

The increasing scale and complexity of power systems require high performance and high reliability of power system protection.Protective relaying based on directional comparison with power line carrier or microwave channels is the most suitable protection scheme for long distance EHV transmission lines and is widely used in power systems.The key element of such protection is a directional relay used to discriminate the fault direction.In order to overcome the disadvantages of conventional directional relays,the authors of this paper put forward the directional comparison carrier protection based on the artificial neural network(ANN).The protection is extensively tested using electromagnetic transient program (EMTP) under various electric power system operating and fault conditions.It is proved that the directional comparison carrier protection based on ANN,which can recognize various fault patterns of the protected transmission line(such as fault direction,fault phases etc.)correctly in any kind of operating and fault conditions and the whole process,is satisfactory for EHV transmission line protection.

Surface wave attenuation based polarization attributes in time-frequency domain for multicomponent seismic data

In the paper, we propose a surface wave suppression method in time-frequency domain based on the wavelet transform, considering the characteristic difference of polarization attributes, amplitude energy and apparent velocity between the effective signals and strong surface waves. First, we use the proposed method to obtain time-frequency spectra of seismic signals by using the wavelet transform and calculate the instantaneous polarizability at each point based on instantaneous polarization analysis. Then, we separate the surface wave area from the signal area based on the surface-wave apparent velocity and the average energy of the signal. Finally, we combine the polarizability, energy, and frequency characteristic to identify and suppress the signal noise. Model and field data are used to test the proposed filtering method.

Portal hypertension: Imaging of portosystemic collateral pathways and associated image-guided therapy

Portal hypertension is a common clinical syndrome, defined by a pathologic increase in the portal venous pressure. Increased resistance to portal blood flow, the primary factor in the pathophysiology of portal hypertension, is in part due to morphological changes occurring in chronic liver diseases. This results in rerouting of blood flow away from the liver through collateral pathways to low-pressure systemic veins. Through a variety of computed tomographic, sonographic, magnetic resonance imaging and angiographic examples, this article discusses the appearances and prevalence of both common and less common portosystemic collateral channels in the thorax and abdomen. A brief overview of established interventional radiologic techniques for treatment of portal hypertension will also be provided. Awareness of the various imaging manifestations of portal hypertension can be helpful for assessing overall prognosis and planning proper management.

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.

Effect of temperature on soil-water characteristics and hysteresis of compacted Gaomiaozi bentonite

Laboratory tests under different constraint conditions were carried out to obtain the soil-water retention curves(SWRCs) of highly-compacted confined/unconfined Gaomiaozi(GMZ) bentonite at 20,40 and 80 ℃,respectively. The effect of temperature on the soil-water characteristics of the highly-compacted GMZ bentonite was analyzed. The results show that the water retention capacity of the highly-compacted GMZ bentonite decreases as the temperature increases under unconfined and confined conditions. At a certain temperature,the constraint conditions have little influence on the water retention capacity of the compacted bentonite at high suction,but the water retention capacity of the confined specimen is lower than that of the unconfined specimen at low suction. Under unconfined conditions,the hysteretic behaviour of the compacted bentonite decreases with increasing temperature. At high suction(>4 MPa) ,the hysteretic behaviour of the unconfined bentonite tends to increase with the decrease of the suction. In summary,the hysteretic behaviour of the compacted bentonite is not significant.

A very rare case of late diagnosis of cor triatriatum sinistrum

We presented a 73-year-old patient with a history of hospitalizations for heart failure as well as treatment for arterial hypertension and permanent atrial fibrillation and who was found to have cor triatriatum sinistrum in combination with bicuspid aortic valve. Patient refused surgical correction, but his condition improved on conservative therapy for heart failure and atrial fibrillation.

Overvoltage Suppression for UHV Transmission Lines

The overvoltage phenomena of ultra high voltage (UHV) transmission lines are analyzed and verified by EMTDC/PSCAD simulation. Referring to the theoretical analyses and operating experiences of extra high voltage (EHV) transmission lines in China and UHV transmission lines in Russia and Japan, the methods to suppress the internal overvoltage in UHV transmission lines by protection and control strategies are discussed. Through the cooperation among the recloser, shunt reactor, tripping and closing resistance, and metal oxide varistor(MOV), the overvoltage can be restrained within an acceptable level.

A new measuring technique in detecting of high voltage three phase induction motor for single phasing

Open phase in three phase induction motors is a common fault that can occur as a result of a fuse blowing or a pro- tective device failing on one phase of the motor. This paper introduces a new method,which is based on the transient mea- surement and can distinguish the fault of one phase connecting ground. The method has been proved to be in correspondence with the simulation results by Matlab and LabVIEW in practice, The method has merits of simplicity, accuracy and ease of USe.

The Design of the TZ-2 High Voltage Modulator

This paper introduces the design of the TZ-2 high voltage modulator for electron cyclotron resonance heating （ECRH） on HL-2A tokamak. The high voltage power supplies （HVPS） for the cyclotron have to operate advantageously and flexibly, with high stabilization and good insulation to high-voltage. Moreover, the HVPS must carry out the function of protection quickly, for insure the security of people and devices in the experiment on HL-2A. In this year, the HVPS with these modulators satisfies the requirement of the experiment of HL-2A.

Research on Intelligent Control and protection of flexible HVDC

This paper introduces the working principle of HVDC control and protection system. And the paper summarizes the flexible HVDC technology features and application fields and describes the composition and software intelligent flexible HVDC control and protection system configuration. Finally, the simulation results are also given, experimental results show： HVDC flexible intelligent control and protection has a good control effect in the steady state and transient process, suitable for practical engineering application.