Sensitivity Analysis of Injection Characteristic to Structural Parameters of GDI Injector Nozzle Hole

The nozzle inner-flow characteristic of the“spray G”injector was studied by the computational fluid dynamics(CFD)simulation,and the sensitivity of cycle fuel mass to the conicity and entrance radius of the nozzle hole were analyzed.Results show that the inner conicity of nozzle hole inhibits the development of cavitation phenomena,and increases the injection rate.While the outer conicity of nozzle hole promotes the diffusion of cavita-tion,leading to reductions of the liquid volume fraction of the nozzle outlet and the local flow resistance of the nozzle hole.The sensitivity of cycle fuel mass to inner-cone nozzle hole is stronger than that of the outer-cone noz-zle,especially at the smaller hole conicity.The increase of injection pressure enhances the sensitivity of the injection characteristics to the nozzle hole structure,in which inner-cone nozzle has higher sensitivity coefficient than the outer-cone nozzle hole.However,the increase of injection pressure aggravates the offset of liquid jet to the nozzle axis of the outer-cone nozzle hole.With the increase of the inner conicity of nozzle,the sensitivity of the injection characteristics to the entrance radius of the hole decreases.With the increase of the outer conicity of nozzle hole,the sensitivity of the injection characteristics to the entrance radius of the hole increases.

New details indicated by different stainings during conjugation of ciliated protozoa Paramecium

During conjugation of Paramecium caudatum, nuclear events occur in a scheduled program. Morphological studies on nuclear behavior during conjugation of P. caudatum have been performed since the end of the 19th century. Here we report on new details concerning the conjugation of P. caudatum through the staining of conjugating ceils with protargol, carbol fuchsin solution, Hoechst 33342 and immunofluorescence labeling with monoclonal antibody of anti-a tubulin. 1） The crescent nucleus is a characteristic of the meiotic prophase of P. caudatum, has an unstained area. We stained this area with protargol, which was separated from the chromatin area and was not detected by the other stainings. 2） In regards to the four meiotic products, it has long been considered that only one product enters the paroral cone region （PC） and survives after meiosis. However, our protargol and immunofluorescence labeling results indicated that PC entrance of the meiotic product happened before the completion of meiosis instead of after. 3） In our previous study, protargol staining indicated the presence of a swollen structure around the central part of the ＂U＂ and ＂V＂ shaped spindles connecting the two types of prospective pronuclei. However, immunofluorescence labeling with anti-a tubulin antibodies gave a different image from protargol. All these observations form the basis for further studies of their molecular mechanisms.

Coastal Current Systems and the Movement and Expansion of Suspended Sediment from Changjiang River Estuary

This paper, with NOAA/AHHRR data for 2 years, discusses the expanding path and extent of suspended sediment from the Changjiang River, and the relationship between the suspended sediment expanding and coastal current systems by analyzing the thermal infrared imagery with the sediment imagery, which is acquired by correlating the atmosphere corrected AVHRR imagery with in-situ suspended sediment data. The coastal current systems affecting the sediment dispersal mainly include： the Taiwan Warm Current （TWC）, the Huanghai Sea Mixed Water （HSMW）, North Jiangsu near-shore current, and Zhejiang near-shore current etc. In winter, the current systems are stable. Their distribution affects the sediment from north Jiangsu expanding toward the Changjiang estuary in some degree .The front between Zhejiang coastal current and TWC blocks the expanding of sediment toward the sea. In the flood season, apart from the limitation by coastal current systems, the spatial and temporal distribution of suspended sediment is also affected by the runoff, which shows as the jet stream and fresh water. Spring and autumn are the transitional periods of the forming of expanding patterns of flood season and winter respectively. In addition, the re-suspended sediment caused by the wind wave may make the expanding range of near-shore sediment larger.

悠幽斋

太发赶着坐火车，他刚一进站。火车就开动了。他连跑带喊让停车，火车就是不理他，而且越开越快，气得他跺脚发誓：“好吧，咱明天再算账!” 第二天，他提前买好票，早早坐在候车室里，检票了，他第一个排队进了站，可就是不上车。眼看火车慢慢地开走了，他才举着手里的车票，抽了火车一眼说：“哼!昨天你轻轻闪了我—下，我今天可美美闪你一下，看你以后还敢吗？”

Clinical analysis of surgical treatment of portal hypertension

AIM： To review the experience in surgery for 508 patients with portal hypertension and to explore the selection of reasonable operation under different conditions. METHODS： The data of 508 patients with portal hypertension treated surgically in 1991-2001 in our centers were analyzed. Of the 508 patients, 256 were treated with portaazygous devascularization （PAD）, 167 with portasystemic shunt （PSS）, 62 with selective shunt （SS）, 11 with combined portasystemic shunt and portaazygous devascularization （PSS＋PAD）, 9 with liver transplantation （LT）, 3 with union operation for hepatic carcinoma and portal hypertension （HCC＋PH）. RESULTS： In the 167 patients treated with PSS, free portal pressure （FPP） was significantly higher in the patients with a longer diameter of the anastomotic stoma than in those with a shorter diameter before the operation （P〈0.01）. After the operation, FPP in the former patients markedly decreased compared to the latter ones （P〈0.01）. The incidence rate of hemorrhage in patients treated with PAD, PSS, 55, PSS＋PAD, and HCC＋PH was 21.09% （54/256）, 13.77 （23/167）, 11.29 （7/62）, 36.36% （4/11）, and 100% （3/3）, respectively. The incidence rate of hepatic encephalopathy was 3.91% （10/256）, 9.58% （16/167）, 4.84% （3/62）, 9.09% （1/11）, and 100% （3/3）, respectively while the operative mortality was 5.49% （15/256）, 4.22% （7/167）, 4.84% （3/62）, 9.09% （1/11）, and 66.67% （2/3） respectively. The operative mortality of liver transplantation was 22.22% （2/9）. CONCLUSION： Five kinds of operation in surgical treatment of portal hypertension have their advantages and disadvantages. Therefore, the selection of operation should be based on the actual needs of the patients.

Portal venous arterialization resulting in increased portal inflow and portal vein wall thickness in rats

AIM： To explore the influence of portal vein hemodynamic changes after portal venous arterialization （PVA） on peribiliary vascular plexus （PVP） morphological structure and hepatic pathology, and to establish a theoretical basis for the clinical application of PVA. METHODS： Sprague-Dawley rats were randomly divided into control and PVA groups. After PVA, hemodynamic changes of the portal vein and morphological structure of hepatohilar PVP were observed using Doppler ultrasound, liver function tests, ink perfusion transparency management and three-dimensional reconstruction of computer microvisualization, and pathological examination was performed on tissue from the bile duct wall and the liver. RESULTS： After PVA, the cross-sectional area and blood flow of the portal vein were increased, and the increase became more significant over time, in a certain range. If the measure to limit the flow in PVA was not adopted, the high blood flow would lead to dilatation of intrahepatic portal vein and its branches, increase in collagen and fiber degeneration in tunica intima. Except glutamic pyruvic transaminase （GPT）, other liver function tests were normal. CONCLUSION： Blood with a certain flow and oxygen content is important for filling the PVP and meeting the oxygen requirement of the bile duct wall. After PVA, It is the anatomic basis to maintain normal morphology of hepatohilar bile duct wall that the blood with high oxygen content and high flow in arterialized portal vein may fill PVP by collateral vessel reflux. A adequate measure to limit blood flow is necessary in PVA.

Portal hypertensive colopathy in patients with liver cirrhosis

AIM: In patients with liver cirrhosis and portal hypertension, portal hypertensive colopathy is thought to be an important cause of lower gastrointestinal hemorrhage. In this study, we evaluated the prevalence of colonic mucosal changes in patients with liver cirrhosis and its clinical significance. METHODS: We evaluated the colonoscopic findings and liver function of 47 patients with liver cirrhosis over a 6-year period. The main cause of liver cirrhosis was post-viral hepatitis (68%) related to hepatitis B (6%) or C (62%) infection. All patients underwent upper gastrointestinal endoscopy to examine the presence of esophageal varices, cardiac varices, and congestive gastropathy, as well as a full colonoscopy to observe changes in colonic mucosa. Portal hypertensive colopathy was defined endoscopically in patients with vascular ectasia, redness, and blue vein. Vascular ectasia was classified into two types: type 1, solitary vascular ectasia; and type 2, diffuse vascular ectasia. RESULTS: Overall portal hypertensive colopathy was present in 31 patients (66%), including solitary vascular ectasia in 17 patients (36%), diffuse vascular ectasia in 20 patients (42%), redness in 10 patients (21%) and blue vein in 6 patients (12%). As the Child-Pugh class increased in severity, the prevalence of portal hypertensive colopathy rose. Child-Pugh class B and C were significantly associated with portal hypertensive colopathy. Portal hypertensive gastropathy, esophageal varices, ascites and hepatocellular carcinoma were not related to occurrence of portal hypertensive colopathy. Platelet count was significantly associated with portal hypertensive colopathy, but prothrombin time, serum albumin level, total bilirubin level and serum ALT level were not related to occurrence of portal hypertensive colopathy. CONCLUSION: As the Child-Pugh class worsens and platelet count decreases, the prevalence of portal hypertensive colopathy increases in patients with liver cirrhosis. A colonoscopic examination in patients with liver cirrhosis is indicated, especially those with worsening Child-Pugh class and/or decreasing platelet count, to prevent complications such as lower gastrointestinal bleeding.

Experimental Research on Flow Maldistribution in Plate-Fin Heat Exchangers

The flow maldistribution and the effect of different inlet configuration on the flow distribution in platefin heat exchangers were studied experimentally. It is found that the flow maldistribution is serious because of the defects of inlet configurations, while the inlet configuration and Reynolds number are the main factors affecting the flow distribution. The improved inlet configurations, which are the header with a two-stage distributing configuration and the guide vane with a fluid complementary cavity were proposed and tested in this paper. The experimental results show that the improved inlet configurations can effectively improve the performance of flow distribution in heat exchangers.

Research on the width of filling body in gob-side entry retaining with high-water materials

To determine the filling body's width along the gob-side remained roadway which is underneath the gob,the authors analyzed the interaction mechanism between the roof and the supporting body along the remained roadway, based on the elastic thin plate theory of the stope roof. The stress state and mechanical response of the filling body along the remained roadway were studied. Specifically, firstly, the supporting pressure of the coal pillar which is on one side of the gob-side remained roadway was deduced.Also, an equation that is used to calculate the width of the balance area in the stress limit state was acquired. Then, an equation that is used to calculate the roof cutting force on one side of the supporting body was obtained. By using FLAC3D, the authors investigated the displacement field and stress field response laws of rock masses around the roadway with different filling body's widths. The results show that with the filling body's width increasing, the supporting ability of the filling body increases.Meanwhile, the rock mass displacement around the roadway and the filling body deformation decrease.The better the filling body's supporting effect is, the higher the roof cutting force will be. When the filling body's width is larger than 3.0 m, its internal bearing ability becomes stable and the filling body's deformation became non-apparent. Finally, analysis shows that the filling body's width should be 2.5 m.Furthermore, the authors conducted field tests in the supply roadway 1204, using high-water materials and acquired expected outcomes.

Portal vein embolization before major hepatectomy

To discuss the rationale, techniques and the unsolved issues regarding preoperative portal vein embolization (PVE) before major hepatectomy. After a systematic search of Pubmed, we reviewed and retrieved literature related to PVE. Preoperative PVE is an approach that is gaining increasing acceptance in the preoperative treatment of selected patients prior to major hepatic resection. Induction of selective hypertrophy of the nondiseased portion of the liver with PVE in patients with either primary or secondary hepatobiliary, malignancy with small estimated future liver remnants (FLR) may result in fewer complications and shorter hospital stays following resection. Additionally, PVE performed in patients initially considered unsuitable for resection due to lack of sufficient remaining normal parenchyma may add to the pool of candidates for surgical treatment. The results suggest that PVE is recomm-endable in treating the cirrhotic patients before major liver resection.

Absorption of Sulphur Dioxide with Sodium Citrate Buffer Solution in a Rotating Packed Bed

Absorption of SO2 from a SO2/air mixture with sodium citrate buffer solution was investigated using a rotating packed bed(RPB) in laboratory scale.The effects of operating parameters,such as the rotation speed of RPB,liquid-gas ratio,inlet gas flow rate,inlet concentration of SO2 in flue gas,sodium citrate buffer concentration and initial pH of absorption solution,on the SO2 concentration in the absorption solution or removal efficiency of SO2 were examined.Incremental rate of sulfate radical ions in the absorption solution was also examined.Experimental results indicate that the efficiency of this regenerative process will be improved by using RPB under appropriate operating conditions,and the generation of SO2-4 will be restrained in the process in RPB.

Study of road tunnel threshold zone lighting reduction coefficient

The luminance in the road tunnel threshold zone attracts broad attention due to its enormous energy consumption and direct influence on tunnel transportation security.Current lighting design methods in threshold zones mostly adopt the reduction coefficient method.However,the determination of reduction coefficient k simply considers tunnel design speed and flow rate,while excluding outside tunnel luminance and threshold zone color temperature and luminance,which have a major impact on driver visual adaptation.Existing problems in the determination of k value are analyzed;a visual performance experiment is utilized;and the reaction time of drivers in changeable outside tunnel luminance and threshold zone color temperature and luminance conditions is obtained;thus,the equations concerning reduction coefficient variation law are derived.In the end,a comparative analysis is made of the k values of the reduction coefficient stipulated by various norms under different color temperature conditions.

Performance of Dual-throat Supersonic Separation Device with Porous Wall Structure

In this paper, a dual-throat supersonic separation device with porous wall has been proposed to solve the starting problem of supersonic separator, and the feasibility of the proposed device has been tested numerically and experimentally. Its flow characteristics have been investigated and the effect of some important parameters includ-ing nozzle pressure ratio(RNP), inlet temperature and swirl intensity were examined. In the device, the supersonic flow state and strong centrifugal acceleration of 240000g can be obtained, which are necessary for the condensation and separation of water vapor. The supersonic region in the device enlarged and the shock wave shifted downstream along with the increasing RNP. The separation performance was improved with the increasing RNP and the inlet temperature. The best separation performance in this study was obtained with ΔTd? 28 K.

Rectosigmoid findings are not associated with proximal colon cancer: Analysis of 6 196 consecutive cases undergoing total colonoscopy

AIM: To review the risk of proximal colon cancer in patients undergoing colonoscopy.METHODS: We estimated the risk of advanced proximal adenomas and cancers in 6 196 consecutive patients that underwent colonoscopy (mean age 60 years, 65% males,without prior history of colorectal examination). Neoplasms were classified as diminutive adenoma (5 mm or less),small adenoma (6-9 mm), advanced adenoma (10 mm or more, with villous component or high-grade dysplasia)and cancer (invasive adenocarcinoma). The sites of neoplasms were defined as rectosigmoid (rectum and sigmoid colon) and proximal colon (from cecum to descending colon).RESULTS: The trend of the prevalence of advanced proximal adenoma was to increase with severe rectosigmoid findings, while the prevalence of proximal colon cancer did not increase with severe rectosigmoid findings. Among the 157 patients with proximal colon cancer, 74% had no neoplasm in the rectosigmoid colon. Multivariate logisticregression analysis revealed that age was the main predictor of proximal colon cancer and existence of rectosigmoid adenoma was not a predictor of proximal colon cancer.CONCLUSION: Sigmoidoscopy is inadequate for colorectal cancer screening, especially in older populations.

Control effect of fluid entry pressure on hydrocarbon accumulation

The micromigration of oil-drive-water and gas-drive-water in oil and gas fields was studied,by using core slices and micro-experimental technology,and the migration processes and characteristics of oil and gas in pores and throats were observed,as well as entry pressures of oil/gas migration.Research shows that entry pressures of both oil-drive-water and gas-drive-water increase obviously as porosity decreases,and the statistical regularity observes the power function variation.However,there is a complex changing relationship between porosity and different entry pressure values of the two replacement processes,forming three curve sections,each representing a different accumulation significance.When the porosity is over 10%-12%,the difference between oil-drive-water and gas-drive-water entry pressures is small.Both oil and gas can migrate and accumulate in this kind of reservoir.The probabilities of oil and gas reservoir formation are nearly equal,forming conventional oil/gas pools.When porosity is between 5% and 10%-12%,the difference between the two is obvious,which indicates that this kind of reservoir can seal oil,but can also be a reservoir for gas,easily forming unconventional hydrocarbon pools(deep-basin gas pools).When porosity is less than 5%,the difference is indistinct and the entry capillary pressures show the same sealing function for oil and gas.In this condition,both oil and gas pools are difficult to form.Experimental results give a rational explanation for the difference of accumulation probability between deep-basin gas and deep-basin oil,and also for the mechanism of tight sand acting as cap rock.

Portal venous stent placement for treatment of portal hypertension caused by benign main portal vein stenosis

AIM: To evaluate the value of endovascular stent in the treatment of portal hypertension caused by benign main portal vein stenosis.METHODS: Portal vein stents were implanted in six patients with benign main portal vein stenosis (inflammatory stenosis in three cases, postprocedure of liver transplantation in another three cases). Changes in portal vein pressure, portal vein patency, relative clinical symptoms, complications, and survival were evaluated.RESULTS: Six metallic stents were successfully placed across the portal vein stenotic or obstructive lesions in six patients. Mean portal venous pressure decreased significantly after stent implantation from (37.3±4.7) cm H2O to (18.0±1.9) cm H2O. The portal blood flow restoredand the symptoms caused by portal hypertension were eliminated. There were no severe procedure-related complications. The patients were followed up for 1-48 mo. The portal vein remained patent during follow-up. All patients survived except for one patient who died of other complications of liver transplantation. CONCLUSION: Percutaneous portal vein stent placement for the treatment of portal hypertension caused by benign main portal vein stenosis is safe and effective.

Biogeochemistry of Nutrient Elements in the Changjiang (Yangtze River) Estuary

Based on the biogeochemical studies on nutrient elements in the Changjiang estuary, the main results and recent progresses are reviewed in this paper, such as the nutrient fluxes into the sea, the mixing behaviors, the distribution characteristics and transportation as well as the biogeochemical behaviors of nutrients in the plume frontal region. The exploring directions and research emphases in the future are proposed.

Numerical Simulation of Seaplane Wave Ground Effect with Crosswind

Under the absolute coordinate system, the unsteady Reynolds averaged Navier-Stokes(URANS)equations and the k-ω SST turbulence model are solved using the finite volume method to simulate the aerodynamic characteristics of large seaplane flying with the ground-effect above wavy surface. The velocity inlet wave-making method and the volume of fluid model are used to accurately simulate the linear regular waves and to precisely capture the free surface. This paper studies the influence of the sideslip angle on the aerodynamic characteristics of large seaplane when it is cruising above wavy water. The results show that the wave surface mainly affects the pressure distribution on the lower surface of the wing. When the sideslip angle varies from 0° to 8°,the varying of frequency of aerodynamic forces is consistent with the wave encounter frequency,and both periods are 0.6 s. With the increase of the sideslip angle,the lift coefficient and the pitching moment coefficient decrease. However,when the sideslip angle is smaller than 4°,the decrease amplitude is small,and the significant decrease occurs above 4° and during the whole process of the change of sideslip angle,the aerodynamic fluctuation amplitude is almost unchanged. As the drag coefficient increases with the increase of sideslip angle,significant increase also occurs when the value is greater than4°,and the fluctuation amplitude does not show any correlations. The rolling moment coefficient and yaw moment coefficient increase with the increase of the sideslip angle,and the fluctuation amplitudes of both increase linearly with the increase of the sideslip angle.

Design of push-pull system to control diesel particular matter inside a dead-end entry

Diesel particulate matter （DPM） is considered to be carcinogenic after prolonged exposure. With more diesel- powered equipment used in underground mines, miners＇ exposure to DPM has become an increasing concern. This paper used computational fluid dynamics method to study the DPM dispersion in a dead-end entry with loading operation. The effects of different push-pull ventilation systems on DPM distribution were evaluated to improve the working conditions for underground miners. The four push-pull systems considered include： long push and short pull tubing; short push and long pull tubing, long push and curved pull tubing, and short push and curved pull tubing. A species transport model with buoyancy effect was used to examine the DPM dispersion pattern with unsteady state analysis. During the 200 s of loading operation, high DPM levels were identified in the face and dead-end entry regions. This study can be used for mining engineer as guidance to design and setup local ventilation, select DPM control strategies and for DPM annual training for underground miners.

DPM simulation in an underground entry: Comparison between particle and species models

The diesel particulate matter(DPM) emission from diesel powered equipment in underground mines can cause health hazards including cancer to the miners. The understanding of the DPM propagation pattern under realistic mining condition is required for selecting proper DPM control strategies and to improve working practices in underground mines. In this paper, three dimensional simulations of DPM emission from the exhaust tail pipe of a load-haul-dump(LHD) vehicle and its subsequent distribution inside an isolated zone in the typical underground mine are carried out using two different solution models available in Ansys Fluent. The incoming fresh air into the isolated zone is treated as a continuous phase and DPM is treated either as a continuous phase(gas) or as a secondary discrete phase(particle). Species transport model is used when DPM is treated as gas and discrete phase model is used when DPM is assumed to behave like a particle. The distributions of DPM concentration inside the isolated zone obtained from each method are presented and compared. From the comparison results, an accurate and economical solution technique for DPM evaluation can be selected.