使用槽道平均模型的多叶片排N-S方程并行计算

The use of Navier-Stokes simulation in the daily design process of multistage compressor requires extremely large computer resources. A less expensive alternate is the development of parallel numerical simulation on a workstations cluster for parallel distributed supercomputer. An average-passage model was introduced to include the unsteady flow effects and wake blockage and to make all of the flow variables are continues at the interface planes. A parallel Navier-Stokes solver has been developed for multistage high pressure ratio compressor based on domain decomposition methodology. This multiblade row solver was applied to analyze the flow field of the first 3 stage blade rows of a 7 stage high pressure ratio compressor at the design point.

地质雷达图的点平均和道平均处理

本文简述了点平均和道平均滤波技术在地质雷达图中的应用及其效果,指出了该方法的应用前提。

基于道平均的钢筋砼衬砌缺陷识别

高铁隧道钢筋混凝土衬砌内部质量缺陷识别是探地雷达检测的难点。为抑制二衬钢筋对混凝土内部脱空缺陷反射的影响,首先,提出利用在滑动窗口内将相邻雷达记录道进行叠加平均,使合成后的雷达记录道中钢筋反射能量因相邻道间相位差的存在而得到抑制的道平均算法。然后为验证算法的可行性,根据高铁隧道衬砌设计参数分别建立了钢筋混凝土及素混凝土衬砌模型,并进行了探地雷达正演模拟,经道平均处理后的探地雷达模拟剖面显示:钢筋及钢拱架等弧形反射同相轴得到明显抑制,预设的脱空缺陷特征得到有效增强。最后,通过对某在建高铁隧道的探地雷达实测数据进行道平均处理,识别出1处钢筋混凝土衬砌内部脱空缺陷,结果得到了钻孔及孔内电视验证,表明将道平均技术应用于钢筋砼衬砌缺陷识别是可行的。

高温超导电性与价层轨道平均能的关系

研究了各种类型的氧化铜的高温超导电性与原子价层轨道能的关系，发现在６０种氧化铜超导体中，不管是全部阳离子和阴离子的价层轨道平均能的平均值或是阳离子的价层轨道平均能的平均值与阴离子的价层轨道平均能的平均值之差都集中在一个狭窄的范围。显然，超导电性与原子价层轨道能之间的这种关系将有助于了解晶格上电子的静电作用与超导机理之间的联系。

平均道次压缩率对钢丝性能的影响

经铅浴淬火且磷化处理后的 6 5钢丝由 4 .0mm拉拔到 1.70mm ,分别采用 7道次和 9道次进行拉拔 ,平均道次压缩率分别为 2 1.6 6 %和 17.2 9%。实验结果表明 :随着平均道次压缩率的减小 ,钢丝的扭转值平均提高 2 .6 1次 ,扭转性能合格率由 6 9%提高到 92 % ;弯曲次数平均提高 0 .6 3次 ;钢丝抗拉强度值变化不大。

“道—琼斯平均数”和“香港恒生指数”指的是什么?

道—琼斯股价指数是国际上历史最悠久并最有影响,而又为公众所熟悉的股价指数,它是以1928年10月1日为基期,基期指数为100。以后各期的股票价值同基期相比,算出百分比。

湿式拉拔对钢帘线单丝抗拉强度的影响

钢帘线单丝湿拉过程中,抗拉强度是钢丝考核的一个重要指标。将Φ1.80 mm钢丝拉拔至Φ0.30 mm,平均道次压缩率分别为13.87%与14.43%时,对应的钢丝抗拉强度平均值分别为3 292 MPa和3 336 MPa。拉拔道次相同,总压缩率和平均道次压缩率相同,前几道次压缩率较大,中间道次压缩率较小时,钢丝抗拉强度平均值为3 381 MPa;前几道次压缩率较小,中间道次压缩率较大时,钢丝抗拉强度平均值为3 347 MPa;前几道次压缩率处于中间时,钢丝抗拉强度平均值为3 369 MPa。采用拉丝模工作锥角分别为9°和11°的拉丝模拉拔后,钢丝抗拉强度平均值分别为3 324 MPa和3 213 MPa,2种拉丝模工作锥角对钢丝的扭转性能影响较小。

High-performance channel estimation and compensation scheme for OFDMreceivers with IQ imbalances

A pilot pattern across two orthogonal frequency division multiplexing OFDM symbols with a special structure is designed for the channel estimation of OFDM systems with inphase and quadrature IQ imbalances at the receiver.A high-efficiency time-domain TD least square LS channel estimator and a low-complexity frequency-domain Gaussian elimination GE equalizer are proposed to eliminate IQ distortion.The former estimator can significantly suppress channel noise by a factor N/L＋1 over the existing frequency-domain FD LS where N and L＋1 are the total number of subcarriers and the length of cyclic prefix and the proposed GE requires only 2N complex multiplications per OFDM symbol.Simulation results show that by exploiting the TD property of the channel the proposed TD-LS channel estimator obtains a significant signal-to-noise ratio gain over the existing FD-LS one whereas the proposed low-complexity GE compensation achieves the same bit error rate BER performance as the existing LS one.

基于机器视觉的信号交叉口运行效率分析模型

为了客观分析城市道路信号交叉口运行效率,文章基于机器视觉选取YOLO V5s与DeepSort的多目标追踪算法对信号交叉口机动车进行检测追踪,获取运行轨迹及运动参数等交通信息,在此基础上从空间、时间及受阻状况三方面提出排队长度、平均通行时间和进口道平均延误的提取方法,将最大排队长度、进口道平均延误、平均通行时间共三个交通参数作为分析指标建立模糊综合评价模型对信号交叉口运行效率进行分析,选取南京市信号交叉口实例对模型进行验证。结果表明,模型成果能够有效测度信号交叉口运行效率,对信号交叉口运行效率水平的提升提供了一定的技术支持。

股指期货标的指数设计的国际比较与借鉴

随着我国证券市场的发展 ,市场对推出股指期货的呼声越来越高 ,设计科学合理的标的指数是股指期货成功推出的关键 ,作者首先介绍国际上主要标的指数的设计经验 ,进而分析我国现有主要股价指数的缺陷 ,最后提出我国标的指数设计中应坚持的原则。

Characteristics of a Drainage Channel with Staggered Indented Sills for Controlling Debris Flows

The characteristics of a new type of drainage channel with staggered indented sills for controlling debris flows were studied. The intermediate fluid in the non-viscous debris flow exhibited a helical movement, whereas the fluid near the sidewall had a stop-start movement pattern; the viscous debris flow exhibited a stable structure between the indented sills. The experimental results indicate that the mean velocity of the debris flow increased with increasing channel gradients, and the debris flow velocity was slightly affected by the angle of the sills. The average velocity of the non-viscous debris flow increased in the range of(0.5–1.5) interval between the indented sills, whereas the average velocity of the viscous debris flow increased initially and then decreased in the range of(0.75–1.25) interval between the indented sills. The depth of the non-viscous debris flow tended to gradually increase as the channel gradients increased, whereas the depth of the viscous debris flow gradually decreased as the channel gradients increased. When the discharge of the debris flow was constant, the angle and the interval between the indented sills had a slight effect on the depth of the viscous debris flow, whereas the depth of the non-viscous debris flow exhibited a different trend, as the sill angles and intervals were varied.

Double balloon enteroscopy in the old: Experience from China

AIM: To evaluate the safety, efficacy and management of double balloon enteroscopy (DBE) carried out in those aged individuals with suspicious small intestine diseases. METHODS: DBE is a wonderful invention of the past decade and is widely used as an examination tool for the gastrointestinal tract. From January 2003 to July 2011, data from patients who were ≥ 65 years old and underwent DBE examination in the Nanfang Hospital were included in a retrospective analysis.RESULTS: Fifty-nine individuals were found and subsequently analyzed. The mean age was 69.63 ± 3.89 years (range 65-84), 34 were males. Indications for DBE were melena/hematochezia (36 cases), abdominal pain (15 cases), diarrhea (3 cases), stool change (1 case), weight loss (1 case), vomiting (2 cases), and debilitation (1 case). The average duration of symptoms was 33.34 ± 64.24 mo. Twenty-seven patients suffered from age-related diseases. Severe complications were not found during and after DBE. Comparison between systolic and diastolic blood pressure before and after DBE was statistically significant (mean ± SD, P < 0.01, P < 0.05, respectively). Small bowel pathologies were found by DBE in 35 patients, definite diagnoses were made in 31 cases, and detection rate and diagnostic yield for DBE were 68.6% and 60.8%, respectively. CONCLUSION: DBE is a safe and effective method for gastrointestinal examination in the aged population. Aging alone is not a risk factor for elderly patients with suspicious gastrointestinal diseases and thorough preparation prior to the DBE procedure should be made for individuals with multiple diseases especially cardiopulmonary disorders.

Gastrointestinal stromal tumors:Thirty years experience of an Institution

AIM:To report our experience of gastrointestinal stromal tumors (GISTs) during the last 29 years. METHODS:Thirty two cases of GIST referred to our Institution from the 1st January 1981 to the 10th June 2010 were reviewed. Metastases,recurrence and survival data were collected in relation to age,history,clinical presentation,location,size,resection margins and cellular features. RESULTS:Mean age was 63.7 years (range,40-90) and incidence was slightly higher in males (56%). R0 resection was performed in 90.7% of cases,R1 in 6.2% (2 cases) and R2 in 3.1% (one case). Using Fletcher's classification 8/32 (25%) had high risk,9/32 (28%) intermediate and 15/32 (47%) low risk tumors. Follow-up varied from 1 mo to 29 years,with a median of 8 years; overall survival was 75% (24/32),disease-free survival was 72% and tumor-related mortality was 9.3%. Three patients with high risk GIST were treated with imatinib mesylate:one developed a recurrence after 36 mo,and 2 are free from disease at 41 mo. CONCLUSION:Surgical treatment remains the gold standard therapy for resectable GISTs. Pathological and biological features of the neoplasm represent the most important factors predicting the prognosis.

Low-volume plus ascorbic acid vs high-volume plus simethicone bowel preparation before colonoscopy

AIM： To investigate the effectiveness of low-volume plus ascorbic acid [polyethylene glycol plus ascorbic acid （PEG ＋ Asc）] and high-volume plus simethicone [polyethylene glycol plus simethicone （PEG ＋ Sim）] bowel preparations. METHODS： A total of one hundred and forty-four outpatients （76 males）, aged from 20 to 84 years （median age 59.5 years）, who attended our Department, were divided into two groups, age and sex matched, and underwent colonoscopy. Two questionnaires, one for patients reporting acceptability and the other for endoscopists evaluating bowel cleansing effectiveness according to validated scales, were completed. Indications, timing of examination and endoscopical findings were recorded. Biopsy forceps were used as a measuring tool in order to determine polyp endoscopic sizeestimation. Difficulty in completing the preparation was rated in a 5-point Likert scale （1 = easy to 5 = unable）. Adverse experiences （fullness, cramps, nausea, vomiting, abdominal pain, headache and insomnia）, number of evacuations and types of activities performed during preparation （walking or resting in bed） were also investigated. RESULTS： Seventy-two patients were selected for each group. The two groups were age and sex matched as well as being comparable in terms of medical history and drug therapies taken. Fourteen patients dropped out from the trial because they did not complete the preparation procedure. Ratings of global bowel cleansing examinations were considered to be adequate in 91% of PEG ＋ Asc and 88% of PEG ＋ Sim patients. Residual Stool Score indicated similar levels of amount and consistency of residual stool; there was a significant difference in the percentage of bowel wall visualization in favour of PEG ＋ Sim patients. In the PEG ＋ Sire group, 12 adenomas≤ 10 mm diameter （5/left colon ＋ 7/right colon） vs 9 （8/left colon ＋ 1/right colon） in the PEG ＋ Asc group were diagnosed. Visualization of small lesions seems to be one of the primary advantages of the PEG ＋ Sim preparation. CONCLUSION： PEG ＋ Asc is a good alternative solution as a bowel preparation but more improvements are necessary in order to achieve the target of a perfect preparation.

Infliximab stopped severe gastrointestinal bleeding in Crohn's disease

To report the result of rapid ulcer healing by infliximab in Crohn's patients with severe enterocolic bleeding. During 2005 and 2010, inflammatory bowel disease database of King Chulalongkorn Memorial and Samitivej hospitals were reviewed. There were seven Crohn's disease (CD) patients (4 women and 3 men; mean age 52 ± 10.4 years; range: 11-86 years). Two of the seven patients developed severe gastrointestinal bleeding (GIB) as a flare up of CD whereas the other five patients presented with GIB as their first symptom for CD. Their mean hemoglobin level dropped from 12 ± 1.3 g/ dL to 8.7 ± 1.3 g/dL in a 3-d period. Median packed red blood cells units needed for resuscitation was 4 units. Because of uncontrolled bleeding, surgical resection was considered. However, due to the poor surgical candidacy of these patients (n = 3) and /or possible development of short bowel syndrome (n = 6), surgery was not pursued. Likewise angiographic embolization was not considered in any due to the risk of large infarction. All severe GIBs successfully stopped by one or two doses of intravenous infliximab. Our data suggests that infliximab is an alternative therapy for CD with severe GIB when surgery has limitation or patient is a high risk.

Epidemiological investigation of Barrett's esophagus in patients with gastroesophageal reflux disease in Northwest China

Objective： To investigate the prevalence and possible risk factors of Barrett＇s esophagus （BE） in patients with gastroesophageal reflux disease （GERD） in Northwest China. Methods： Patients older than 18 years who underwent regular health check-up or had upper gastrointestinal symptoms in the endoscopy centers of four major teaching hospitals located in four different provinces of Northwest China from September 2008 to February 2009 were included in the study. A face-to-face reflux diagnostic questionnaire including risk factors were taken and scale scores （So） were accumulated. Diagnostic criterion of GERD was Sc≥12 points. None of these subjects received anti-acid medication prior to their endoscopy done. Barrett＇s esophagus was diagnosed when specialized intestinal metaplasia was detected histologically. Results： A total of 528 patients met the criteria of GERD, among which 32 patients （20 male and 12 female） were diagnosed with BE. BE was present in 6.06% with a mean age of 51.2±11.6 years, which was significantly older than patients with GERD without BE （46.6±13.3 years） （P〈0.05）. There weresignificant differences between BE and GERD patients regarding gender, age, hiatus hernia, smoking and alcohol consumption （P〈0.05）, while no significant difference regarding symptoms of GERD. There was significant difference between short segment Barrett＇s esophagus and long segment （65.6% vs 34.4%, P〈0.05）. Conclusion： The prevalence of BE was 6.06% in patients with GERD in northwest China and was dominated by SSBE. The potential risk factors of Barrett＇s esophagus were older age, male, esophageal hiatal hernia, smoking and alcohol consumption.

利用属性统计对地震资料品质进行量化评价的研究

对地震勘探原始数据进行质量分析,既是对野外采集的原始资料进行监控和验收的需要,又是后期开展地震资料处理时进行叠前去噪和道编辑处理的依据。传统的定性评价方法带有一定的主观性,容易受人为因素的影响。通过对地震原始资料中与能量、频率等有关的部分物理属性的定量计算、分析和统计,以一个适当的标准作为参考,可以快速准确地对资料的品质做出客观的评价,对异常地震资料进行准确的查找和定位,对后续资料处理的流程和参数的确定也具有指导意义。

Frequency Offset Compensation for Satellite Communication System with CE-OFDM

Constant envelope orthogonal frequency division multiplexing(CE-OFDM) is a waveform that can achieve 0d B peak-to-average power ratio and avoid the signal distortion caused by the nonlinear power amplifi er. However, the carrier frequency offset(CFO) in CE-OFDM systems can cause errors at phase unwrapper module. In this paper, a CFO estimation scheme is proposed for CEOFDM in satellite communication system. As the null subcarrier is inherent in the conjugate symmetric symbol structure at the transmitter, the proposed scheme uses the null subcarrier as prior information to estimate the CFO at the receiver. The ideal estimation range of normalized CFO is obtained by mathematical analysis. Simulation results show that the proposed scheme can estimate the CFO accurately under additive white Gaussian noise(AWGN) channel and multipath fading channel, especially for moderate and high signal-to-noise ratio(SNR).

Analytical Models for Velocity Distributions in Compound Channels with Emerged and Submerged Vegetated Floodplains

The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term to account for the effects of vegetation.The three cases considered for open channels were two-stage rectangular channel with emerged vegetated floodplain,rectangular channel with submerged vegetated corner,and two-stage rectangular channel with submerged vegetated floodplain,respectively.To predict the depth-averaged velocity with submerged vegetated floodplains,we proposed a new method based on a two-layer approach where flow above and through the vegetation layer was described separately.Moreover,further experiments in the two-stage rectangular channel with submerged vegetated floodplain were carried out to verify the results.The analytical solutions of the cases indicated that the corresponding analytical depth-averaged velocity distributions agree well with the simulated and experimental prediction.The analytical solutions of the cases with theoretical foundation and without programming calculation were reasonable and applicable,which were more convenient than numerical simulations.The analytical solutions provided a way for future researches to solve the problems of submerged vegetation and discontinuous phenomenon of depth-averaged velocity at the stage point for compound channels.Understanding the hydraulics of flow in compound channels with vegetated floodplains is very important for supporting the management of fluvial processes.

Comprehensive Treatment and Prognostic Factors in Patients with Carcinoma of the Cervical Stump

OBJECTIVE To evaluate the applicability of combined therapyand the prognostic factors in patients with carcinoma of thecervical stump (CCS).METHODS The clinical records of 60 CCS patients whounderwent combined treatment in our hospital during a periodfrom January 2000 to December 2007, were collected andretrospectively analyzed. The prognostic factors were studiedusing univariate analysis. Analytical evaluation of the independentprognostic factors was performed using COX proportionalhazardsregression model.RESULTS The 1-, 3- and 5-year survival rates of the 60 patientswere 95%, 78% and 68%, respectively, with a median survivaltime of 32 months. Univariate survival analysis showed thatthese independent prognostic factors included positive pelviclymph nodes (P = 0.001), lymphovascular tumor embolus (P =0.001), and adjuvant chemotherapy (P = 0.011). In the 60 cases,postoperative local recurrence in the pelvic cavity occurred in1 and distant metastasis in 3. Related complications, such asradiocystitis, recto-vaginal fistula and vesico-vaginal fistula werefound in 6 of the total cases (10%). The serum levels of squamousepithelium antigen detected before and after treatment weresignificantly different (P = 0.000). The incidence of CCS is low;however, the disease is difficult to cure due to the high incidenceof complications and to the frequency of distant metastasis.Therefore, individualized treatment is needed. Complications fromsubtotal hysterectomy (STH) should be treated and controlledaggressively. Careful follow-up as well as close monitoring andobservation for significant symptoms in the postoperative coursewill enhance clinical outcome.CONCLUSION Cancer of the cervical stump has a lowmorbidity and severe complications, and most recurrences aredistant metastases. Because it is difficult to cure, there is a needto design a treatment regimen for each individual patient basedon the factors deemed as high risk. The surgical indications forsubtotal uterine resection should be followed and close follow-upafter surgery should be maintained.