机场冬季应急除胶除线新工艺探究

自2019年发生抛丸损伤航空器事件抛丸除胶、除线技术禁用后,目前机场道面除胶、除线主要为高压水冲洗法。鉴于高压水冲洗法不能彻底清除拉毛处胶漆、清洗后刻槽侧壁有残留、水射流对拉毛和刻槽有损伤以及不适宜冬季施工等问题,对等离子技术以及碳酸氢钠微晶体清洗技术进行试验研究,以便寻求一种无损、彻底并且适宜冬季施工的新工艺来完成冬季道面应急除胶、除线工作。

水泥混凝土跑道标线漆清除方法探讨

以某机场跑道废旧标志线清除为例,针对水泥混凝土跑道的特点,提出了热熔除线机与BLASTRAC抛丸机相结合的除线方式,并介绍了除线过程中的注意事项,指出该方法不损伤跑道,除线效果良好。

机场水泥混凝土道面冷漆标线处理方法分析

本文结合云南某机场清除停机坪废旧标线工作,通过现场试验对比分析了多种除线方法的优劣,并根据工程实际提出了化学试剂法和擦刷清除法相结合的除线方法。施工实践证明,该方法能够较好地达到机场除线要求,对相关的研究和类似工程具有一定的借鉴意义。

机场道面高压水射流法清除标线的试验研究

高压水射流道路标志线清洗是目前普通道路有效的标志线清洗工艺,但机场道面对于除线作业过程的效率、安全、环保等有较高要求,本文针对高压水射流道路标志线清洗在机场道面的应用效果进行了试验研究。

高压水射流法清除标志线的试验研究

对高压水射流法和抛丸机法两种机场标志标线清除的方法进行了试验研究,分别介绍了各方法的工作原理与试验过程,并从标线漆的去除效果及除线后的环境两方面对比了两种方法的清除效果,指出抛丸机优于高压水射流法。

关于机场水泥混凝土道面标志标线清除方法分析

机场标志标线是航空器运行、机动车行驶的重要引导标志,肩负着飞机起飞、着陆、停放等航空器运行的关键保障环节,随着规范、运行规则调整、改扩建、资源优化等方面需要,高效、低成本清除旧线成为重要课题。本文结合山东某机场机坪旧标志线常用的清除方法及施工经验,对比覆盖法、机械清除法、化学药剂清除法、高压水清除法的优缺点,并结合实际情况提出覆盖法在非低温环境下能够较好的达到除线、改线及维持道面原有性能的要求,对机场机坪施工、运行有一定的借鉴意义。

考虑输电线路安全的机械除冰次序优化

机械除冰是应对输电线路覆冰灾害的重要手段,现有研究主要集中在除冰方法的改进,而对机械除冰实施过程的影响研究较少。研究发现在机械除冰过程中,如果按照从输电线路一端开始顺序除冰的策略,杆塔承受的最大不平衡力可能超过设计标准,影响输电线路安全,而不同的除冰次序会产生不同的最大不平衡力。为此,有必要对机械除冰的除冰次序进行优化,提高机械除冰的安全性。首先分析了机械除冰过程中除冰次序对杆塔平衡力的影响,然后建立了输电线路机械除冰次序优化模型。由于该模型为非线性、多约束模型,采用遗传算法对不同档导线覆冰清除的次序进行优化。仿真分析表明,优化后的除冰次序能够有效地降低杆塔承受不平衡力,提高机械除冰过程中输电线路的安全性。

日本加强进口蔬菜农药残留检测

近来日本商检机构已对进口日本蔬菜的农药残留加强检测,检查的农药品种达数十种,日方检测的农药品种如下。1 甲基嘧啶磷(安定磷、虫螨磷) 2乙嘧硫磷 3甲拌硫(3911) 4二嗪农5氯线磷(除线磷、VC乳剂)6 甲基毒死蜱 7敌敌畏 8毒死蜱

Preoperative predictors of short-term survival after hepatectomy for multinodular hepatocellular carcinoma

AIM： To investigate preoperative factors associated with poor shore-term outcome after resection for multi- nodular hepatocellular carcinoma （HCC） and to assess the contraindication of patients for surgery, METHODS： We retrospectively analyzed 162 multi- nodular HCC patients with Child-Pugh A liver function who underwent surgical resection. The prognostic significance of preoperative factors was investigated by univariate analysis using the log-rank test and by multivariate analysis using the Cox proportional hazards model. Each independent risk factor was then assigned points to construct a scoring model to evaluate the in- dication for surgical intervention. A receiver operating characteristics （ROC） curve was constructed to assess the predictive ability of this system.RESULTS： The median overall survival was 38.3 mo （range： 3-80 too）, while the median disease-free sur- vival was 18.6 mo （range： 1-79 too）. The 1-year mor- tality was 14%. Independent prognostic risk factors of 1-year death included prealburnin 〈 170 rng/L [hazard ratio （HR）： 5.531, P 〈 0.001], alkaline phosphatase 〉 129 U/L （HR： 3.252, P = 0.005）, α fetoprotein 〉 20 μg/L （HR： 7.477, P = 0.011）, total tumor size 〉 8 cm （HR： 10.543; P 〈 0.001）, platelet count 〈 100×109/L （HR： 9.937, P 〈 0.001）, and y-glutamyl transpeptidase 〉 64 U/L （HR： 3.791, P 〈 0.001）. The scoring model had a strong ability to predict 1-year survival （area under ROC： 0.925, P 〈 0.001）. Patients with a score ≥5 had significantly poorer short-term outcome than those with a score 〈 5 （1-year mortality： 62% vs 5%, P 〈 0.001; 1-year recurrence rate： 86% vs 33%, P 〈 0.001）. Patients with score ≥5 had greater possibility of microvascular invasion （P 〈 0.001）, poor tumor dif- ferentiation （P = 0.003）, liver cirrhosis with small nod- ules （P 〈 0.001）, and intraoperative blood transfusion （P = 0.010）. CONCLUSION： A composite preoperative scoring model can be used as an indication of prognosis of HCC patients after surgical resection. Resection should be considered with caution in patients with a score ≥5, which indicates a contraindication for surgery.

Study on the Free Radical Scavenging Activity of Sea Cucumber (Paracaudina chinens var.) Gelatin Hydrolysate

Gelatin from the sea cucumber(Paracaudina chinens var.) was hydrolyzed by bromelain and the hydrolysate was found to have a high free radical scavenging activity. The hydrolysate was fractionated through an ultrafiltration membrane with 5 kDa molecular weight cutoff(MWCO). The portion(less than 5 kDa) was further separated by Sephadex G-25. The active peak was col-lected and assayed for free radical scavenging activity. The scavenging rates for superoxide anion radicals(O2·-) and hydroxyl radi-cals(·OH) of the fraction with the highest activity were 29.02% and 75.41%,respectively. A rabbit liver mitochondrial free radical damage model was adopted to study the free radical scavenging activity of the fraction. The results showed that the sea cucumber gelatin hydrolysate can prevent the damage of rabbit liver and mitochondria.

Albumin as a prognostic marker for ulcerative colitis

AIM To evaluate the role of albumin at the time of ulcerative colitis(UC) diagnosis in predicting the clinical course of disease.METHODS Nationwide cohort of patients with newly diagnosed UC in the Veterans Affairs health care system was identified and divided into two categories: hypoalbuminemia(i.e.,≤ 3.5 gm/dl) or normal albumin levels(i.e.,> 3.5 gm/dl) at the time of UC diagnosis. The exposure of interest was presence of hypoalbuminemia defined asalbumin level ≤ 3.5 g/dl at the time of UC diagnosis. Patients were then followed over time to identify the use of ≥ 2 courses of corticosteroids(CS),thiopurines,anti-TNF medications and requirement of colectomy for UC management. RESULTS The eligible study cohort included 802 patients,but 92(11.4%) patients did not have their albumin levels checked at the time of UC diagnosis,and they were excluded. A total of 710 patients,who had albumin levels checked at time of UC diagnosis,were included in our study. Amongst them,536 patients had a normal albumin level and 174 patients had hypoalbuminemia. Patients with hypoalbuminemia at diagnosis had a higher likelihood of ≥ 2 courses of CS use(adjusted HR = 1.7,95%CI: 1.3-2.3),higher likelihood of thiopurine or anti-TNF use(adjusted HR = 1.72,95%CI: 1.23-2.40) than patients with normal albumin level at diagnosis. There was a trend of higher likelihood of colectomy in hypoalbuminemic patients,but it was not statistically significant(Adjusted HR = 1.7,95%CI: 0.90-3.25).CONCLUSION Hypoalbuminemia at disease diagnosis can serve as a prognostic marker to predict the clinical course of UC at the time of diagnosis.

Removal of cadmium from aqueous solution by immobilized Microcystis aeruginosa:Isotherms,kinetics and thermodynamics

The Microcystis aeruginosa(MA) was immobilized on sodium alginate and used as biosorbent for removal of Cd(Ⅱ) ions from aqueous solution.The biosorption process is pH dependent,and the optimum biosorption was observed at pH 6.0 with the biosorption capacity of 98.38 mg/g.Among Langmuir,Freundlich and Temkin isotherm models,the Freundlich and the Temkin isotherm fit well with the experimental data.Cd(Ⅱ) ions biosorption follows the pseudo-second-order kinetic model.The rate controlling mechanism study reveals that film diffusion is the rate-limiting step and intraparticle diffusion is also involved in biosorption.Thermodynamic parameters,such as Gibbs free energy(ΔG°),the enthalpy(ΔH°) and entropy(ΔS°) were calculated,and revealed that the biosorption process is spontaneous,exothermic and random.Furthermore,the immobilized MA can be regenerated using 0.1 mol/L HCl solutions.

Clinical course of ulcerative colitis patients who develop acute pancreatitis

To investigate the clinical course of ulcerative colitis (UC) patients who develop acute pancreatitis.METHODSWe analyzed 3307 UC patients from the inflammatory bowel disease registry at Asan Medical Center from June 1989 to May 2015. The clinical course of UC patients who developed acute pancreatitis was compared with that of non-pancreatitis UC patients.RESULTSAmong 51 patients who developed acute pancreatitis, 13 (0.40%) had autoimmune, 10 (0.30%) had aminosalicylate-induced, and 13 (1.73%) had thiopurine-induced pancreatitis. All 13 patients with autoimmune pancreatitis (AIP) had type 2 AIP. Two (15.4%) patients had pre-existing AIP, and three (23.1%) patients developed AIP and UC simultaneously. Compared to non-pancreatitis patients, AIP patients had UC diagnosed at a significantly younger age (median, 22.9 years vs 36.4 years; P = 0.001). AIP and aminosalicylate-induced pancreatitis patients had more extensive UC compared to non-pancreatitis patients. All patients with pancreatitis recovered uneventfully, and there were no recurrences. Biologics were used more frequently in aminosalicylate- and thiopurine-induced pancreatitis patients compared to non-pancreatitis patients [adjusted OR (95%CI), 5.16 (1.42-18.67) and 6.90 (1.83-25.98), respectively]. Biologic utilization rate was similar among AIP and non-pancreatitis patients [OR (95%CI), 0.84 (0.11-6.66)]. Colectomy rates for autoimmune, aminosalicylate-induced, and thiopurine-induced pancreatitis, and for non-pancreatitis patients were 15.4% (2/13), 20% (2/10), 15.4% (2/13), and 7.3% (239/3256), respectively; the rates were not significantly different after adjusting for baseline disease extent.CONCLUSIONPancreatitis patients show a non-significant increase in colectomy, after adjusting for baseline disease extent.

Propane Dehydrogenation on PtSnNa/AlSBA-15 Catalyst:Influence of Tin as a Promoter

PtSnNa/AlSBA-15 catalysts with different amounts of Sn were prepared for propane dehydrogenation.The catalysts were characterized by XRF,BET,H2 chemisorption,NH3-TPD,H2-TPR,and TPO techniques.Test results indicated that the presence of tin not only modified the acid function and the interfacial character between metal and support,but also reduced the coke deposition effectively.Among these catalysts investigated thereby,the PtSn(0.7%)Na/AlSBA-15 catalyst had the best catalytic performance in terms of propane conversion and stability.With the continuous addition of Sn,more amounts of Sn0 species appeared,which was unfavorable to the reaction.The PtSn(0.7%)Na/AlSBA-15 catalyst was parametrically characterized in order to obtain necessary information to integrate the process operating conditions.A weight hourly space velocity of 3 h-1,a reaction temperature of 610 ℃ and a H2/C3H8 molar ratio of 0.25 were found to be optimum conditions for achieving a higher dehydrogenation activity of the catalyst.

Surgical Removal of a Giant Vegetation on Permanent Endocavitary Pacemaker Wire and Lead

PACEMAKER lead infections are rare.There are only about 0.4％-1.1％ of the patients who have been implanted permanent pacemakers suffering from serious infections which lead to endocarditis.1 Generally,removal of the infected pacemaker wire and lead,long-term anti-infection therapy,and implantation of a new pacemaker to another anatomic site are accepted approaches for these patients.

Probabilistic Tolerance Method for Omitting Small Fatigue Loads

The simplification of fatigue load spectrum,which can effectively reduce experimental cost,is of great importance for structural fatigue tests.By introducing random variables,the probabilistic tolerance method of removing small amplitude cycles proposed in this paper takes into account the randomness of both load and fatigue limit.The probability of the damage occurrence caused by the removed small loads is calculated to ensure that it cannot exceed the given probabilistic tolerance.Accordingly,the omission level is obtained and the truncated spectrum is formed.The unnotched aluminum sheet specimens are used to perform the fatigue test on the original fatigue spectrum and truncated fatigue spectrum of a transporter.The test results show that there is no statistical difference between the test life of the truncated spectrum and that of the original spectrum,which demonstrates the validity of the small-load-omitting method that considers randomness.

Polarization Oblique Projection Based Self-Interference Cancellation against PA Nonlinear Distortion in MIMO Full Duplex System

In MIMO full duplex system,power amplifier(PA) nonlinearity limits the self-interference(SI) cancellation seriously. Most existing methods need to model and estimate the PA nonlinearity in order to reconstruct the SI,however the estimation error caused by the mismatch between the estimated PA model and the actual PA property still impacts the cancellation ability,especially when the transmit power is high. In this paper we propose a polarization oblique projection based self-interference cancellation method which does not need to estimate the PA nonlinearity coefficients. It exploits the polarization state information of the signals which is immune to the PA nonlinearity,and establishes an oblique projection operator to cancel the SI. Numerical results and analysis demonstrate that it can cancel the nonlinear SI effectively. Moreover the signal to interfere plus noise ratio(SINR) and the achievable sum rate do not deteriorate when the transmit power is high. Further,the upper bound of the achievable sum rate can be more than twice that of the half duplex.

Swarm intelligence based dynamic obstacle avoidance for mobile robots under unknown environment using WSN

To solve dynamic obstacle avoidance problems, a novel algorithm was put forward with the advantages of wireless sensor network (WSN). In view of moving velocity and direction of both the obstacles and robots, a mathematic model was built based on the exposure model, exposure direction and critical speeds of sensors. Ant colony optimization (ACO) algorithm based on bionic swarm intelligence was used for solution of the multi-objective optimization. Energy consumption and topology of the WSN were also discussed. A practical implementation with real WSN and real mobile robots were carried out. In environment with multiple obstacles, the convergence curve of the shortest path length shows that as iterative generation grows, the length of the shortest path decreases and finally reaches a stable and optimal value. Comparisons show that using sensor information fusion can greatly improve the accuracy in comparison with single sensor. The successful path of robots without collision validates the efficiency, stability and accuracy of the proposed algorithm, which is proved to be better than tradition genetic algorithm (GA) for dynamic obstacle avoidance in real time.