Cold Simulation of Oxygen Transfer Rate in BOF

By measuring the mass transfer coefficient of benzoic acid between water and oil, the oxygen transfer rate in BOF bath was researched, and the influence of top and bottom blowing gas flow rate on the mass transfer between metal and slag was discussed. The results show that with increasing the bottom blowing gas flow rate under the conditions of fixed top blowing, the mass transfer rate evidently increases, and the influence of fixed top blowing on the mass transfer is 10% of bottom blowing. The stirring intensity was determined as a function of top blowing gas flow rate, bottom blowing gas flow rate, and lance height. The equation of the mass transfer coefficient between metal and slag was established. The relationship between the emulsification ratio of oil to water and the bottom blowing gas flow rate under the conditions of top and bottom blowing was obtained. The result shows that with the increase in the bottom blowing gas flow rate, the emulsification ratio increases linearly, which increases the mass transfer rate of benzoic acid between water and oil.

Determination of real-time oxygen transfer rate based on an electrochemical method

The interfacial oxygen transfer rate is one of the main factors to control the composition of alloys.The commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis;however,it is difficult to be studied in situ.Here,a new method of measuring the oxygen transfer rate at the gas-slag and slag-metal interfaces was reported based on electrochemical analyses.The interfacial oxygen transfer rate in the smelting process of Inconel 718 superalloy was investigated at 1723,1773,1823,and 1873 K.The experimental results show that the electrochemical method can measure the real-time oxygen content;hence,this method is promising in controlling the oxygen content in alloys.As the temperature increased,both the equilibrium oxygen content and the rate of oxygen absorption increased significantly,and the increase was the most obvious when the temperature was 1873 K.The possible reason is that the increase in temperature weakens the mass transfer resistance of the electric double layer at the interface,thus accelerating the oxygen transfer rate.

Boosting the Information Transfer Rate of an SSVEP-BCI System Using Maximal-Phase-Locking Value and Minimal-Distance Spatial Filter Banks

For Brain-Computer Interface(BCI) systems, improving the Information Transfer Rate(ITR) is a very critical issue. This study focuses on a Steady-State Visually Evoked Potential(SSVEP)-based BCI because of its advantage of high ITR. Unsupervised Canonical Correlation Analysis(CCA)-based method has been widely employed because of its high efficiency and easy implementation. In a recent study, an ensemble-CCA method based on individual training data was proposed and achieved an excellent performance with ITR of 267 bit/min.A 40-target SSVEP-BCI speller was investigated in this study, using an integration of Minimal-Distance(MD) and Maximal-Phase-locking value(MP) approaches. In the MD approach, a spatial filter is developed to minimize the distance between the training data and the reference sine signal, and in this study, two different types of distance were compared. In the MP approach, a spatial filter is developed to maximize the Phase-Locking Value(PLV)between the training calibration data and the reference sine signal. In addition to the fundamental frequency of stimulation, the harmonics were used to train MD and MP spatial filters, which formed spatial filter banks. The test data epoch was multiplied by the MP and MD spatial filter banks, and the distances and PLVs were extracted as features for recognition. Across 12 subjects with a 0.4 s-data length, the proposed method realized an average classification accuracy and ITR of 93% and 307 bit/min, respectively, which is significantly higher than the current state-of-the-art method. To the best of our knowledge, these results suggest that the proposed method has achieved the highest ITR in SSVEP-BCI studies.

Prediction of Heat Transfer Rates for Shell-and-Tube Heat Exchangers by Artificial Neural Networks Approach

This work used artificial neural network(ANN)to predict the heat transfer rates of shell-and-tube heatexchangers with segmental baffles or continuous helical baffles,based on limited experimental data.The BackPropagation (BP) algorithm was used in training the networks.Different network configurations were alsostudied.The deviation between the predicted results and experimental data was less than 2%.Comparison withcorrelation for prediction shows ANN superiority.It is recommended that ANN can be easily used to predict theperformances of thermal systems in engineering applications,especially to model heat exchangers for heattransfer analysis.

Analysis of Factors Influencing Pregnancy Rate in Frozenthawed Embryo Transfer

Objective To analyse factors influencing the outcome of frozen-thawed embryo transfer （FET）. Method A retrospective analysis was performed in our center on 129 thawing cycles from March 2001 to April 2003. The related parameters were compared between conceived and non-conceived cycles. Results There were totally 129 clinical pregnancies in these transfers （pregnancy rate： 27.1%）. Frozen-thawed embryos were transferred to natural cycles and CC cycling and hormone replacement treatment had equal success. Groups of IVF and ICSI did not differ significantly in pregnancy rates （P〉0.05）. The pregnancy rates for one, two, three and four pre-embryos transfer were 0, 20.0%,44.1% and 75.0%, respectively （P〈0.05）. There were statistical differences between pregnancy group or non- pregnancy group in the endometrial thickness, CES, CES/No. of embryo. A higher pregnancy rate was observed in embryo transfers which had at least one 4-cell grade I embryo （d 2）（P〈0.01）. Conclusions The most important factors influencing the implantation rate and pregnancy rate of frozen-thawed embryo transfer are age, endometrium thickness, and the number, morphology and growth rate of transferred frozen embryos of women participants.

THE CALCULATION OF RATE CONSTANT OF ELECTRON TRANSFER REACTION AT ELECTRODES

After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated by the perturbed degeneration theory and the Fermi golden rule,, the rate constant is gotten. Compared with the experimental results, it is satisfactory.

Analyzing Service Rates for File Transfers in Peer-to-peer File Sharing Systems

When examining the file transfer performance in a peer-to-peer file sharing system, a fundamental problem is how to describe the service rate for a file transfer. In this paper, the problem is examined by analyzing the distribution of server-like nodes' upstream-bandwidth among their concurrent transfers. A sufficient condition for the service rate, what a receiver obtains for downloading a file, to asymptotically be uniform is presented. On the aggregate service rate for transferring a file in a system, a sufficient condition for it to asymptotically follow a Zipf distribution is presented. These asymptotic equalities are both in the mean square sense. These analyses and the sufficient conditions provide a mathematic base for modeling file transfer processes in peer-to-peer file sharing systems.

Kidding after Transfer of in Vitro Produced Saanen Goat Embryos into Local Ukrainian Breed Recipients in Different Seasons

In recent years, the demand for goat products has been growing due to the fact that goat milk has a number of advantages over cow milk, for example, it is low in lactose, and is considered less allergenic and easier to digest. To increase production during both breeding and non-breeding seasons and reduce the price of dairy products, it is necessary to effectively use reproductive management and assisted reproductive technologies. In vitro embryo production makes it possible to obtain a large number of eggs from goats, which for some reason are unable to conceive, but have genetic value. Afterward in vitro produced embryos can be transferred into recipient goats of other less genetically valuable breeds, such as the Ukrainian local breed. Therefore, the aim of the present study was to investigate the effectiveness of transfers of in vitro produced embryos of Saanen goats into surrogate sires of the Ukrainian local breed in different seasons. All manipulations with animals were carried out following ethical standards (Strasbourg, 1986). Six Saanen goats were selected as the oocyte donors. After the hormonal stimulation oocytes were retrieved by laparoscopic ovum pick-up. In vitro produced embryos were transferred laparotomically into 24 recipients of Ukrainian local breed. Fifty days after embryo transfers, pregnancies were determined by ultrasound diagnostics. Although the embryo development rate in the breeding season was 20% higher than in the non-breeding season, there was no difference in pregnancy and kidding rates between seasons. In conclusion, the transfer of in vitro produced Saanen goat embryos to recipients of the Ukrainian local breed gives the opportunity to achieve pregnancy and kidding regardless of the breeding season, which will enable a faster and more efficient increase in the livestock of highly productive goats in Ukraine in the post-war period.

基于指纹图谱和多成分含量测定的护肝解毒汤标准煎液量值传递研究

目的:建立护肝解毒汤标准煎液的指纹图谱及多指标成分含量测定方法,为其标准煎液及制剂的质量评价研究提供参考。方法:采用HPLC法结合中药色谱指纹图谱相似度评价系统,对15批护肝解毒汤标准煎液进行指纹图谱、相似度分析及共有峰的指认,并建立煎液中5种指标性成分的同时检测方法,计算各成分的转移率。结果:15批标准煎液指纹图谱相似度>0.90,有22个共有峰,对照品比对出绿原酸、葛根素、芍药苷、甘草素、落新妇苷、黄藤苷、盐酸小檗碱、五味子醇甲、黄柏酮、梣酮10个成分,15批标准煎液中绿原酸、葛根素、落新妇苷、盐酸小檗碱、五味子醇甲的转移率分别为48.26%~63.80%、20.30%~31.50%、28.24%~39.11%、2.89%~5.60%、13.51%~21.85%。结论:采用指纹图谱、出膏率及指标性成分含量测定相结合的模式,对护肝解毒汤标准煎液的量值传递过程进行分析,可初步拟定护肝解毒汤标准煎液的质量标准,为其后续新药开发及相关制剂的质量控制提供依据。

Effect of bubble morphology and behavior on power consumption in non-Newtonian fluids’aeration process

Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate(kLa) and initial bubble size(d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0was regulated within 2-5 mm,an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.

补体C3水平对冻融胚胎移植妊娠结局的早期预测价值

目的探讨补体C3对冻融胚胎移植(F-ET)妊娠结局的早期预测价值。方法前瞻性收集378个F-ET周期相关资料,依据补体C3预测F-ET妊娠结局的最佳截断值分为A组(补体C3≤1.05)120个周期;B组(补体C3>1.05)258个周期,比较两组结局。分析B组补体C3预测F-ET自然流产的最佳截断值。结果年龄是F-ET妊娠成功的危险因素(P<0.05);补体C3和胚胎类型是F-ET妊娠成功的保护因素(P<0.05)。补体C3对F-ET妊娠结局的受试者工作特征曲线(ROC)曲线下面积为0.702,最佳截断值为1.05 g/L,其预测临床妊娠灵敏度为87.60%、特异度为52.00%。B组临床妊娠率(67.05%)和胚胎着床率(52.75%)明显高于A组,差异有统计学意义(P<0.05)。补体C3早期预测F-ET后自然流产最佳截断值为1.32 g/L,ROC曲线下面积为0.760,灵敏度为69.00%、特异度为81.20%。结论补体C3对早期预测F-ET妊娠结局有一定的临床意义,当补体C3超过1.32 g/L可能会导致自然流产率升高。

基于CCA融合FFT的SSVEP脑机接口分类算法

为解决多目标刺激范式的稳态视觉诱发电位脑电信号识别准确率低和信息传输率低的问题,提出了一种快速傅里叶变换同典型相关分析相结合的方法,通过快速傅里叶变换将信号训练成对应频率的训练模板,并作为参考信号与实时采集的信号进行典型相关分析来计算频率的识别准确率。6名受试者参与并完成了180组实验,在时间窗口长度为1.5 s的条件下,基于快速傅里叶变换-典型相关分析的稳态视觉诱发电位信号识别算法的平均识别准确率为93.98%,比典型相关分析算法提升了14.75%,信息传输率为62.30 bit·min^(-1),比典型相关分析算法提升了55.63%。实验结果表明,快速傅里叶变换-典型相关分析算法性能更优。

地热储层岩体粗糙裂隙的热流耦合效应研究

为了解决地热开采涉及复杂的多物理场耦合问题,提高开采效率,本文针对开采过程中的渗流-传热问题以离散元软件3DEC构建岩体粗糙裂隙热-流耦合数值模型。考虑不同三维形貌特征的岩体裂隙,模拟水力开度为19.17μm在不同流速时的水-岩温度变化规律。结果表明:由于裂隙形貌的阻滞作用,粗糙面出水口温度下降较慢,出水口温度有所上升,模型达到稳态所需的时间随流速和对流换热系数的增大而减小。裂隙形貌对流体和岩体温度分布均有影响,粗糙裂隙面的冷锋形态和裂隙面的形貌密切相关。光滑裂隙热突破快于粗糙裂隙,增加裂隙面的粗糙度有助于延长热突破时间。粗糙裂隙面相对于光滑裂隙面的总热量提取率略有提升,流速和对流换热系数的增加显著提高总热量提取率。通过本文研究可以为地热能系统的设计提供重要参数和指导,能够提高地热能开发利用效率。

大高宽比矩形腔体侧向正弦加热下对流扰动的成长和传热特性

为了研究矩形腔体侧向正弦周期加热条件下对流扰动的成长和传热特性,本研究对流体力学方程组进行了数值模拟。结果表明:随着格拉晓夫数Gr的增加,对流扰动的最大振幅Amax的成长率变大,线性成长阶段的时间变短。对于高宽比A=10,腔体宽度d=2cm的腔体,普朗特数Pr=6.949的流体,对流扰动的成长率γ_(m)随着格拉晓夫数Gr变化的经验式为γ_(m)=9×10^(-8)Gr^(1.2343);对于高宽比A=10、腔体宽度d=6cm的腔体,普朗特数Pr=0.703的流体,成长率m随着格拉晓夫数Gr的变化关系式为m=8×10^(-4)Cr^(0.52)。当Pr=0.0272时,热壁面平均努塞尔数Nu和格拉晓夫数Gr的关联式为Nu=0.00002Gr^(1.17);当Pr=6.949时,Nu=0.00024Gr^(1.05)。随着格拉晓夫数Gr数增加,右壁面的传热能力增强。

卵巢功能减退患者多周期累积与非累积胚胎移植临床结局比较

目的探讨卵巢功能减退(DOR)患者多周期累积与非累积胚胎移植体外受精-胚胎移植(IVF-ET)临床结局的差异。方法回顾性分析2019-01至2022-12于首都医科大学附属北京妇产医院生殖医学科进行IVF-ET治疗的卵巢储备功能减退的不孕患者174例的临床资料,纳入患者均已完成所有胚胎移植及最终随访。收集患者的基础内分泌、抗苗勒管激素水平及窦卵泡计数,记录促排卵治疗后的卵巢反应参数及妊娠结局等相关临床资料,比较多周期累积胚胎移植(累积组)与非累积胚胎移植(非累积组)两种IVF-ET治疗的临床结局。结果DOR患者多周期累积胚胎移植与非累积胚胎移植两组间的累积妊娠率(35.24%vs.27.54%)、早期流产率(32.43%vs.26.32%)及累积活产率(21.90%vs.18.84%)差异无统计学意义(P>0.05);纳入移植策略、BMI、首次取卵年龄、AMH、胚胎移植数、优质胚胎移植数、累积获卵数等多个因素后进行logistic回归分析,两种不同的胚胎移植策略(OR=1.522,95%CI 0.608~3.814)对活产无明显影响(P>0.05)。结论对于DOR患者,进行多周期重复取卵后的累积胚胎移植并不能提高患者的累积妊娠率及活产率。

子宫内膜癌增强MRI定量参数变化与临床特征的关系及对预后的预测价值分析

目的 探究子宫内膜癌(EC)增强MRI定量参数变化与临床特征关系,分析其对预后的预测价值。方法 选取2019年3月~2022年3月本院收治的EC患者98例作为研究组,另选同期子宫内膜良性病变患者98例作为对照组。比较两组增强MRI定量参数[速率常数(K_(ep))、容量转移常数(K^(trans))、血管外细胞外间隙容积比(V_(e))]。比较研究组不同临床特征患者增强MRI定量参数,分析其与临床特征相关性。比较研究组不同预后患者增强MRI定量参数,分析其对预后的预测价值。结果 研究组K_(ep)、K^(trans)、V_(e)高于对照组(P<0.05);K_(ep)、K^(trans)、V_(e)病理分期、淋巴结转移、宫颈间质累及情况、子宫肌层浸润深度呈正相关,而与分化程度呈负相关(p<0.05)预后不良者K_(ep)、K^(trans)、V_(e)高于预后良好者,且与预后不良显著相关(P<0.05);K_(ep)、K^(trans)、V_(e)联合预测预后不良的AUC大于各参数独独预测(P<0.05)。结论 EC患者增强MRI定量参数K_(ep)、K^(trans)、V_(e)升高,且与临床特征、预后密切相关,联合检测各参数对预后不良具有一定预测价值。

不同位置及加香水平对加热卷烟释放行为的影响

【目的】探索不同位置及加香水平对加热卷烟释放行为的影响。【方法】通过控制单支加热卷烟香精总量在一定的允差范围内,设计6组薄荷味加热卷烟并考察了烟碱、丙三醇、薄荷醇和N,2,3-三甲基-2-异丙基丁酰胺(WS-23)的释放规律。【结果】(1)对于烟碱和丙三醇,6组加热卷烟中烟碱的释放率和转移率都要大于丙三醇。(2)对于薄荷醇和WS-23,6组加热卷烟的释放率和转移率均存在较大差异,其中1#、2#、5#加热卷烟的释放率和转移率较高。释放率和转移率的波动受加热卷烟各段加香差异的影响。(3)每种成分的释放量均表现出先增大再减小的趋势,其中5#加热卷烟表现出相对较好的稳定性。

多级孔MOF的制备及其吸附分离应用研究进展

金属有机框架材料(MOF)因其具有高比表面积、丰富孔隙率、孔径可调的优点,受诸多学者关注,被认为是用于吸附分离的理想吸附剂。但是在实际应用中,大部分微孔MOF材料在吸附过程中的内在传质速率严重受限,而且构建多级孔的方法一般不具有普遍性。本文介绍了调节剂策略、模板策略、后处理策略等构建多级孔MOF的方法,制备了兼具介孔、大孔的多级孔材料,并结合应用场景评价各方法的优缺点,以获得在相对温和条件下构建孔径可调的多级孔MOF的普适性策略。针对多级孔MOF材料在气体吸附分离领域的应用问题,着重剖析了构建多级孔MOF对CO_(2)气体吸附提升的案例,发现多级孔的构建增加了孔径,提高了MOF的比表面积,提供了额外的孔通道,使气体分子的吸附容量和传质速率得到提升,表明多级孔MOF在气体吸附分离方面有优异的性能。最后讨论了多级孔MOF合成和应用存在的问题,并对多级孔MOF面临的合成过程绿色可重复等挑战进行了展望。

电生理快速定量菜心杂种优势

本研究以温室培养的14个品种的菜心为材料,测定了饱水与不饱水状态下菜心的基本电生理参数,并基于能斯特(Nernst)方程计算得到叶片相对持水量(LIWHC)、叶片胞内水分转移速率(LIWTR)、叶片胞内持水时间(LIWHT)、叶片营养主动传输能力(NAT)、叶片营养被动传输能力(NPT)、耐低营养能力(RLN)、营养利用效率(NUE)和植物相对代谢活力(MA)等电生理指标,探究其与杂种优势的关系。结果表明,杂交50的胞内水分传输效率均显著低于其他品种的菜心,其RLN和NUE值则显著高于其他品种,但MA则显著高于其他品种。采用隶属函数法对供试品种水分及养分代谢进行综合评价,结果表明,参试的4个品种中,菜心杂交50的综合评价优于其他3个品种。因此,可以通过测定植物的电生理信息来计算水分、养分代谢状况以及植物的相对代谢活力等来鉴定植物的杂种优势。

自走式烟叶采摘机采摘机构的设计与试验

烟叶采摘机一直受到烟叶破损率高问题的掣肘,从而影响烟农的经济效益,如何降低烟叶的破损率是目前烟叶采摘车的发展方向。为此,结合以前的烟叶采摘车,设计一种烟叶采摘机构,旨在降低烟叶的破损率,提高烟农的经济效益。所设计的采摘机构由采摘刀、传送辊、隔叶板及导流板等组成,采摘刀和传送辊均由橡胶材料制成,传送辊由橡胶辊和光轴组成,隔叶板和导流板均由钢板制作而成。通过对采摘刀和传送辊进行力学分析,得到了烟株不被采摘刀蹭倒和烟叶在传送辊不打滑的临界条件,为降低烟叶的破损率提供了理论依据。三因素(采摘刀的转速、采摘车的行驶速度、烟株的株距)正交旋转试验表明:采摘刀的转速为240~260r/min、采摘车的行驶速度为1.38~1.42km/h、株距为570~590mm时,烟叶的破损率符合大纲要求。试验结果表明:影响烟叶破损率因素的主次顺序为采摘刀的转速>采摘车的行驶速度>烟株的株距,在烟株的株距为579mm、采摘刀的转速为246r/min、烟叶采摘车的行驶速度为1.4km/h时,烟叶的破损率为9.36%,达到了预期要求。