Resistance Factor of Caisson-Tip with Internal Fillet for Suction Caissons Penetrating into Clay

This paper presents failure mechanisms of the soil at the caisson-tip with fillet during suction-assisted penetration of suction caissons in undrained clay.Theoretical solutions of resistance factor N_c of the caisson-tip are obtained in terms of the caisson-tip geometry ratio of the flat section of the caisson-tip to the caisson wall thickness m/t and adhesion factorsα_i along inside of caisson wall andα_b at the base of the caisson-tip.It is indicated that the factor N_c increases with the increase of m/t,α_i and a_b.The resistance factors N_c for the rough base(α_b=1)are larger by 0.57than that for the smooth base(α_b=0).Besides,the factors N_c of caisson-tip with flat base(m=t)are larger by 1.14 than that with full internal fillet(m=0).The required suction to penetrate suction caissons with various fillets is obtained in terms of the force equilibrium in vertical direction.The finite element limit analysis and centrifuge model test results are used to verify the rationality of the presented failure mechanisms and theoretical predictions.

The Electric Mechanism of Surface Pretreatments for Dye-Sensitized Solar Cells Based on Internal Equivalent Resistance Analysis

Based on the optimization of dye-sensitized solar cell (DSC) photoelectrodes pretreated with different methods such as electrodeposition,spin-coating and TiCl_(4) pretreatment,theoretical calculations are carried out to interpret the internal electric mechanism.The numerical values,including the series resistance R_(s) and the shunt resistance R_(sh) corresponding to the equivalent circuit model,are well evaluated and confirm that the DSC has good performance with a high R_(sh) and a low R_(s) due to good electrical contact and a low charge recombination after the different modifications.The Ⅰ-Ⅴ curves are fifted in the case without series resistance,and account for the role of R_(s) in the output characteristics.It is found that when R_(s) tends to the infinitesimal,the short-circuit current Isc,the open-circuit voltage V_(oc) and the fill factor can be improved by almost 0.8-1.4,2.9 and 2.1-6.8%,respectively.

Estimation of equivalent internal-resistance of PEM fuel cell using artificial neural networks

A practical method of estimation for the internal-resistance of polymer electrolyte membrane fuel cell (PEMFC) stack was adopted based on radial basis function (RBF) neural networks. In the training process, k-means clustering algorithm was applied to select the network centers of the input training data. Furthermore, an equivalent electrical-circuit model with this internal-resistance was developed for investigation on the stack. Finally using the neural networks model of the equivalent resistance in the PEMFC stack, the simulation results of the estimation of equivalent internal-resistance of PEMFC were presented. The results show that this electrical PEMFC model is effective and is suitable for the study of control scheme, fault detection and the engineering analysis of electrical circuits.

Data-driven short circuit resistance estimation in battery safety issues

Developing precise and fast methods for short circuit detection is crucial for preventing or mitigating the risk of safety issues of lithium-ion batteries(LIBs).In this paper,we developed a Convolutional Neural Networks(CNN)based model that can quickly and precisely predict the short circuit resistance of LIB cells during various working conditions.Cycling tests of cells with an external short circuit(ESC)are produced to obtain the database and generate the training/testing samples.The samples are sequences of voltage,current,charging capacity,charging energy,total charging capacity,total charging energy with a length of 120 s and frequency of 1 Hz,and their corresponding short circuit resistances.A big database with~6×10^(5)samples are generated,covering various short circuit resistances(47~470Ω),current loading modes(Constant current-constant voltage(CC-CV)and drive cycle),and electrochemical states(cycle numbers from 1 to 300).Results show that the average relative absolute error of five random sample splits is 6.75%±2.8%.Further parametric analysis indicates the accuracy estimation benefits from the appropriate model setups:the optimized input sequence length(~120 s),feature selection(at least one total capacity-related variable),and rational model design,using multiple layers with different kernel sizes.This work highlights the capabilities of machine learning algorithms and data-driven methodologies in real-time safety risk prediction for batteries.

Metformin effect on internal carotid artery blood flow assessed by area under the curve of carotid artery Doppler in women with polycystic ovarian syndrome

BACKGROUND Insulin resistance(IR)was reported in most polycystic ovarian syndrome(PCOS)cases.Metformin,a biguanide drug,successfully reduced IR.Homeostatic Model Assessment for IR(HOMA-IR)and Doppler parameters assessed metformin's effectiveness.AIM To verify whether the area under the curve of the internal carotid artery(AUC-ICA)Doppler wave can be a useful marker for assessing IR among PCOS cases who presented with menstrual irregularity and were treated with metformin over 6 mo.METHODS An observational,cross-sectional study recruited 54 eligible PCOS women;the anthropometrics were as follows:age,body mass index(BMI),menstrual cycle days,biochemical serum cholesterol,low and high-density lipoprotein,sex hormone-binding globulin,fasting blood glucose,and HOMA-IR,hormonal testosterone,luteinizing hormone over follicle-stimulating hormone ratio,and ultrasonic pulsatility index(PI)and resistance index(RI),carotid artery intima-media thickness(CIMT)and(AUC-ICA)parameters were initially recorded and repeated 3 mo and 6 mo later with metformin tab 500 mg;three times/day for 6 mo.In addition,AUC-ICA was assessed by taking repeated systolic and diastolic wave height measurements.RESULTS Metformin caused a progressive reduction in BMI,menstrual cycle days,biochemical hormonal,and Doppler parameters(CIMT,PI,RI,and AUC-ICA).AUC-ICA correlated strongly to all PCOS parameters.AUC-ICA correlated inversely with treatment time(r=-0.98,P<0.001)and positively with HOMA-IR(r=0.98,P<0.0001).Via the best subset regression model,the AUC-ICA had the highest predictive value for HOMA-IR.CONCLUSION AUC-ICA preceded PI,RI,and CIMT with a strong,meaningful correlation to all PCOS parameters,making it a reliable marker for the assessment of IR,especially during metformin therapy.Further studies are recommended to promote the application in practice.

Effect of Black Plate on Corrosion Resistance of T5 Tinplate

The effect of black plate on corrosion resistance of T5 tinplate was studied by glow discharge spectrograph, X-ray diffractometer （XRD）, stress tester, roughness tester and metallographic microscope. The result shows that black plate influences corrosion resistance of T5 tinplate intensely. It also indicates that the increase of content of manganese, phosphorus, silicon and aluminum in black plate would reduce the corrosion resistance of T5 tinplate and the increase of degree of crystal orientation on （200） crystal face, ｜X-Y｜ value （internal stress difference within two orientation）, roughness and exposure degree of iron grain after the same acid wash of black plate would enhance the corrosion resistance of T5 tinplate and the grain number of black plate has small effect on corrosion resistance of T5 tinplate.

Low Cycle Fatigue and Strengthening Mechanism of Cold Extruded Large Diameter Internal Thread of Q460 Steel

large diameter internal thread of high-strength steel（LDITHSS） manufactured by traditional methods always has the problems of low accuracy and short life. Compared with traditional methods, the cold extrusion process is an effective means to realize higher accuracy and longer life. The low-cycle fatigue properties of LDITHSS are obtained by experiments, and the initiation and propagation of fatigue cracks are observed by scanning electron microscope（SEM）. Based on the mechanical properties, surface microstructure and residual stress, the strengthening mechanism of cold extruded large diameter internal thread（LDIT） is discussed. The results show that new grains or sub-grains can be formed on the surface of LDIT due to grain segmentation and grain refinement during cold extrusion. The fibrous structures appear as elongated and streamlined along the normal direction of the tooth surface which leads to residual compressive stress on the extruded surface. The maximum tension stress of LDIT after cold extrusion is found to be 192.55 k N. Under low stress cycling, the yield stress on thread increases, the propagation rate of crack reduces, the fatigue life is thus improved significantly with decreasing surface grain diameter and the average fatigue life increases to 45.539×10~3 cycle when the maximum applied load decreases to 120 k N. The low cycle fatigue and strengthening mechanism of cold extruded LDIT revealed by this research has significant importance to promote application of internal thread by cold extrusion processing.

Resistance to FLT3 inhibitors in acute myeloid leukemia: Molecular mechanisms and resensitizing strategies

FMS-like tyrosine kinase 3(FLT3) is classified as a type Ⅲ receptor tyrosine kinase, which exerts a key role in regulation of normal hematopoiesis. FLT3 mutation is the most common genetic mutation in acute myeloid leukemia(AML) and represents an attractive therapeutic target. Targeted therapy with FLT3 inhibitors in AML shows modest promising results in current ongoing clinical trials suggesting the complexity of FLT3 targeting in therapeutics. Importantly, resistance to FLT3 inhibitors may explain the lack of overwhelming response and could obstruct the successful treatment for AML. Here, we summarize the molecular mechanisms of primary resistance and acquired resistance to FLT3 inhibitors and discuss the strategies to circumvent the emergency of drug resistance and to develop novel treatment intervention.

Efficacy and Risk Factors Associated to Resistance to Single-Agent Chemotherapy in Low-Risk Gestational Trophoblastic Neoplasia

Objectives: This study aimed to assess efficacy of intramuscular methotrexate 8-day protocol in the treatment of low-risk gestational trophoblastic neoplasia and also identify prognostic factors associated with treatment failure, necessitating second line chemotherapy. Methods: This study was performed at Gynaecologic and Obstetric Clinic of Dakar Teaching Hospital, the reference Centre of Gestational Trophoblastic Disease in Senegal. At the beginning of 2011, patients were followed according to FIGO’s recommendations. From 2011 to 2014, we diagnosed 88 low-risk gestational trophoblastic neoplasia (GTN) patients (WHO score < 7). Low-risk patients started their treatment with methotrexate (MTX) based on the 8-day protocol consisting of 1 mg/kg MTX in combination with 0.1 mg/kg folinic acid (FA) every other day. Resistance to treatment was the main outcome. We studied the association of different prognostic factors included in the World Health Organisation (WHO) scoring system and resistance to the initial single agent chemotherapy. Results: Eighty-eight patients were diagnosed for GTN during the study period. Average age was 31 years. The antecedent pregnancy was molar in 98.1% of cases. Seventy-four patients underwent remission after single agent-chemotherapy. Resistance rate to single-agent chemotherapy was 15.9% (14 patients). Nine of them achieved remission after second line chemotherapy. WHO score was significantly associated with the risk of resistance to single-agent chemotherapy. Other variables included in the WHO as age, antecedent pregnancy, pre-treatment hCG, tumour size and FIGO stage were not significantly associated with resistance. We report five fatal cases. Conclusion: The 8-day protocol consisting of 1 mg/kg MTX in combination with 0.1 mg/kg folinic acid (FA) every other day is effective for women with LRGTN. The only significant prognostic factor for failure is pretreatment WHO score. We highly recommend the use of this protocol particularly in developing countries where methotrexate is available, affordable and relatively safe.

Prediction and parametric analysis of 3D borehole and total internal thermal resistance of single U-tube borehole heat exchanger for ground source heat pumps

The borehole and total internal thermal resistance are both significant parameters in evaluating the thermal performance of the ground source heat pump.This study aimed to obtain the accurate correlation of the 3D borehole and total internal thermal resistance(R_(b,3D)and R_(a,3D))and analyze the impacts of parameters on the R_(b,3D)and R_(a,3D).Firstly,eight parameters affecting the R_(b,3D)and R_(a,3D),including the borehole diameter,pipe diameter,pipe-pipe distance,borehole depth,soil thermal conductivity,grout thermal conductivity,pipe thermal conductivity,and fluid velocity inside the pipe,were considered and an L-54 design matrix was generated.Then,the 3D numerical model,coupling with the four-resistance model,was proposed to calculate R_(b,3D)and R_(a,3D)for each case.After that,the response surface methodology was employed to obtain and verify the correlation of R_(b,3D)and R_(a,3D),which were compared with the existing resistance calculation methods.Lastly,analysis of variance was carried out to reveal parameters that have statistically significant impacts on the R_(b,3D)and R_(a,3D).Results show that the rationality and accuracy of the correlation of R_(b,3D)and R_(a,3D)can be verified by the determination coefficient and P value of regression model,as well as the P value of lack-of-fit.The existing resistance calculation methods are more or less inaccurate and the discrepancies in some cases can be up to 86.74%and 111.35%for the borehole and total internal thermal resistance.The pipe and grout thermal conductivity,pipe and borehole diameter,and the pipe-pipe distance can be seen as the significant contributory factors to the variation of R_(b,3D)and R_(a,3D).

骨折内固定术后感染金黄色葡萄球菌患者的耐药监测及临床分析

目的 分析金黄色葡萄球菌在骨折内固定术后感染患者中的耐药情况。方法 回顾性分析四川省骨科医院2016年1月至2020年12月骨折内固定术后确诊为金黄色葡萄球菌感染的临床病例,共收集金黄色葡萄球菌467株。根据药物敏感性实验分为耐甲氧西林金黄色葡萄球菌(MRSA)组(145株)和甲氧西林敏感金黄色葡萄球菌(MSSA)组(322株),分析比较2组对常见抗菌药物的耐药情况。统计2016—2020年万古霉素对MRSA最低抑菌浓度(MIC)。结果 金黄色葡萄球菌对青霉素的耐药率达94.9%(443/467),对红霉素、克林霉素、苯唑西林、四环素耐药率较高,对左氧氟沙星、利福平、复方磺胺甲噁唑片、莫西沙星的耐药率较低[8.4%(39/467)、5.8%(27/467)、3.6%(17/467)、3.0%(14/467)],未发现对万古霉素、利奈唑胺、达托霉素耐药的菌株,万古霉素中介3株。MRSA组和MSSA组对克林霉素、苯唑西林、红霉素、左氧氟沙星、莫西沙星、青霉素、利福平、复方磺胺甲噁唑片、四环素的耐药率比较差异均有统计学意义(均P<0.05)。万古霉素对MRSA的MIC为2 mg/L的比例较高。结论 金黄色葡菌球菌引起的骨折内固定术后感染MRSA检出率较高,万古霉素MIC=2 mg/L的比例较高,降低了万古霉素治疗骨折内固定术后感染的达标率,且万古霉素骨组织渗透率不高,增加了临床治疗难度。因此万古霉素骨水泥植入,联合万古霉素静脉用药,或万古霉素静脉用药与利福平、喹诺酮类、磺胺类、利奈唑胺等联合用药可能是治疗骨折内固定术后感染的较好选择。

抗战时期西北国际通道初探

西北国际通道是抗战时期经中国西北地区运输外国援华物资、援华人员和中国易货物资的重要国际通道,西北国际通道的开辟与运行对于中国抗日战争胜利发挥了极为重要的历史作用。学界对西北国际通道研究十分关注,现有研究对其基本概念如名称、路线、里程认识并不一致。文章依据通道地理位置及运输状况将其定名为西北国际通道;通过梳理抗战时期报纸、期刊、书籍等资料,分析得出通道有三条线路,公路线起自今哈萨克斯坦萨雷奥泽克车站,终于兰州,航空线为阿拉木图至兰州,驿运线为印度列城至中国新疆叶城;以修建维护通道的新疆公路局、西北公路局等机构资料为依据,考订西北国际通道公路线里程为2934公里。

国产SiC功率模块热阻测试方法研究

为解决国产SiC功率模块的热阻不能准确测试的问题,开展了非开关式电学法在线测量模块热阻的研究。提出模块热阻测试方案,设计搭建模块热阻测试平台,结合器件结构特点和工艺特点,研究获得适用于模块的热阻测试方法,并选用两款典型SiC功率模块进行了验证,验证了测试结果的准确性。

健脾化痰汤结合针刺治疗成人鼾症(痰湿内阻型)临床疗效观察

目的:观察健脾化痰汤结合针刺治疗成人鼾症(痰湿内阻型)临床效果。方法:将我院收治的105例成人鼾症(痰湿内阻型)患者(2019年5月~2022年6月)纳入本次研究,并以随机数字表法分为常规治疗组(52例)与中医治疗组(53例),常规治疗组患者进行常规方案治疗,中医治疗组患者采取健脾化痰汤结合针刺治疗,数据比较:临床疗效、治疗前后中医证候积分(夜寐不实、睡则打鼾、憋醒、形体肥胖等)变化及ESS嗜睡量表评分变化、两组治疗前后体质指数(BMI)及最低血氧饱和度、氧减指数、最长呼吸暂停时间以及睡眠呼吸暂停低通气指数变化、治疗满意度。结果:中医治疗组患者总有效率(96.23%)高于常规治疗组(84.62%),P<0.05;治疗前,各组患者中医证候积分(夜寐不实、睡则打鼾、憋醒、形体肥胖等)、ESS评分、BMI、最低血氧饱和度、氧减指数、最长呼吸暂停时间以及睡眠呼吸暂停低通气指数等指标比较,P>0.05,治疗后各组患者中医证候积分(夜寐不实、睡则打鼾、憋醒、形体肥胖等)、ESS评分、BMI、最低血氧饱和度、氧减指数、最长呼吸暂停时间以及睡眠呼吸暂停低通气指数等指标均改善,中医治疗组患者治疗后中医证候积分(夜寐不实、睡则打鼾、憋醒、形体肥胖等)、ESS评分、BMI、最低血氧饱和度、氧减指数、最长呼吸暂停时间以及睡眠呼吸暂停低通气指数等指标均优于常规治疗组,P<0.05;中医治疗组患者治疗满意率(96.23%)高于常规治疗组(82.69%),P<0.05。结论:健脾化痰汤结合针刺治疗成人鼾症(痰湿内阻型)临床效果显著,患者症状好转,恢复较好,患者较为认可,值得应用。

电学计量中的量子标准与自然常数

介绍了库仑定律和安培定律在电学单位制中发挥的作用,依据机械功率与电功率等效的原理,选择电流单位安培(A)作为基本物理单位,并介绍了实用单位制和电学实物计量标准。阐述了三种电学计量的量子标准原理和溯源到自然常数的途径,分析了真空磁导率在安培定律公式中发挥的作用,探讨了电学量子三角形与欧姆定律兼容的问题。指出基本电荷量常数不是简单地从约瑟夫森常数K_(J-90)和冯·克里青常数R_(H-90)推导而来,而是由精细结构常数公式计算出来的,能量守恒原理是单位制中的第一性原理,是力学和电学计量单位的纽带。提出量子点之间的位移电流对单电子隧道泵有一定的影响,真空磁导率不再是理想的常数,真空磁导率的变化将成为后来理论界研究的重点。

适用2000 HSC CODE的高速船特点及总体设计要求

高速船由于其航速高、质量轻、营运特殊等特点,需要适用的规则与常规船型不同。2000年的《国际高速船安全规则》(简称2000 HSC CODE)作为较完备的适用于高速船的规则,被各海事主管机关广泛接受作为高速船的设计依据。文中简要介绍2000 HSC CODE的安全原理,以及该规则对各海事主管机关的适用程度;然后通过国内外高速船事故来分析该类船的事故类型及致因特点,并进一步介绍了适用高速船的风险控制及设计措施,包括营运限制、破舱稳性、防火要求和撤离分析等总体设计要求,以供理解高速船的安全原理并指导其设计。

不同老化阶段的锂离子电池热特性研究进展

研究锂离子电池不同老化阶段的热特性对于锂离子电池全寿命周期安全运行控制具有重要意义。首先梳理了不同老化阶段电池本征热特性参数和产热特性参数的实验研究进展,厘清相关参数随电池老化阶段变化的规律和内在机理;结合锂离子电池热特性研究的电模型、热模型和老化模型的全面综述与分析,总结了锂离子电池不同老化阶段的产热及温升随环境温度和倍率的变化规律。相关工作可为锂离子电池全生命周期热特性变化和热管理策略研究提供参考。

钢筋混凝土拱的水下抗爆性能

为探究水下爆炸荷载作用下钢筋混凝土拱的动力响应特性和破坏特征,制作了两个钢筋混凝土拱试件,并开展了水下爆炸试验。试验分为拱外爆炸和拱内爆炸两组,采用10 g乳化炸药,试验时爆源距结构面最小距离为10 cm(起爆点位于拱结构正上方和正下方),通过传感器记录爆炸试验中钢筋混凝土拱典型断面处的水压力及加速度时程曲线。基于Arbitrary Lagrange-Euler(ALE)算法,建立了空气-水-炸药-钢筋混凝土拱等多介质动态耦合作用模型,将数值模拟结果与试验结果对比,验证了数值方法的可靠性。采用验证后的数值模型进一步研究了拱外及拱内爆炸荷载作用下钢筋混凝土拱的动力响应差异。结果表明:相同炸药当量下,内部爆炸有更多的能量作用于混凝土拱,使结构的动力响应更强烈;外部爆炸下,拱顶、拱腰处产生较大裂缝;内部爆炸时,迎爆面裂缝数量明显增多,拱肩位置出现裂缝。钢筋混凝土拱形结构抵抗外部爆炸荷载的能力明显强于内部爆炸荷载。

中国和欧美国家养殖业抗生素使用负面问题及管理政策比较

畜禽养殖中抗生素的使用无疑推动了该产业的快速发展,但也引起了其耐药性威胁公共健康和养殖业可持续发展的担忧。本文系统梳理了兽用抗生素的使用,抗生素负面问题的显现、认知和管理政策的变化,分析了中国、美国、欧盟管理政策的差异及其背后的原因。本文认为,我国在推进农业现代化进程中:应长期关注养殖业中抗生素使用可能带来的负面问题,加快生产方式的绿色转型;应提升公众对抗生素耐药性的认识,引导公众参与遏制耐药性发展的行动;应考虑我国的发展目标,吸取美国因利益集团阻挠而反应缓慢的教训,综合考虑成本和收益,发挥我国的体制优势,找到政策上的最优解;支持、推动全球抗生素管理的国际协同行动。

替代法测量改装表内阻的误差分析

本文旨在探讨电表改装实验中,用替代法测量表头内阻时,电源电压的取值对改装表内阻测量的影响。通过理论计算和实验探究的方法,发现较大电源电压导致测量误差增加的本质原因是保护电阻在整个电路的电阻中占比太高。本文的研究结果为提高替代法测量电阻的精度提供改进方向。