Modeling and Simulation of Heat Transfer in Loaded Continuous Heat Treatment Furnace

Continuous furnaces are widely used in the heat treatment of mass-produced parts. However, the heating up process of parts in continuous furnace is still decided by experience. In this paper the heat transfer in the continuous furnace is formulated firstly. The heat balance in each zone is discussed and equations are given. Coupled with the model for heat transfer between workpieces and furnace and the heat transfer in the workload as well presented in the former developed CHT-6/ for batch furnaces, a program CHT- for continuous furnaces was developed. The model deals with two typical movements of parts: continuous or step by step. The moving speed of parts and load pattern can be optimized based on the calculated temperature distributions and curves, especially, the fastest heated and slowest-heated temperature-distance profiles. A case study is carried out for the heat treatment of a kind of hook-shaped part. The calculated results are analyzed and in good agreement with the measured ones.

Conjugate Heat Transfer Analysis of an Ultrasonic Molten Metal Treatment System

In piezoceramic ultrasonic devices,the piezoceramic stacks may fail permanently or function improperly if their working temperatures overstep the Curie temperature of the piezoceramic material.While the end of the horn usually serves near the melting point of the molten metal and is enclosed in an airtight chamber,so that it is difficult to experimentally measure the temperature of the transducer and its variation with time,which bring heavy difficulty to the design of the ultrasonic molten metal treatment system.To find a way out,conjugate heat transfer analysis of an ultrasonic molten metal treatment system is performed with coupled fluid and heat transfer finite element method.In modeling of the system,the RNG model and the SIMPLE algorithm are adopted for turbulence and nonlinear coupling between the momentum equation and the energy equation.Forced air cooling as well as natural air cooling is analyzed to compare the difference of temperature evolution.Numerical results show that,after about 350 s of working time,temperatures in the surface of the ceramic stacks in forced air cooling drop about 7 K compared with that in natural cooling.At 240 s,The molten metal surface emits heat radiation with a maximum rate of about 19 036 W/m2,while the heat insulation disc absorbs heat radiation at a maximum rate of about 7922 W/m2,which indicates the effectiveness of heat insulation of the asbestos pad.Transient heat transfer film coefficient and its distribution,which are difficult to be measured experimentally are also obtained through numerical simulation.At 240 s,the heat transfer film coefficient in the surface of the transducer ranges from–17.86 to 20.17 W/（m2？K）.Compared with the trial and error method based on the test,the proposed research provides a more effective way in the design and analysis of the temperature control of the molten metal treatment system.

The Influence of Carburizing Parameters on Carbon Transfer Coefficient

Definition of coefficient of carbon transfer in European Standard (EN 10052) is presented as: "Mass of carbon transferred from carburizing medium into the steel, per unit surface area per second for a unit difference between the carbon potential, and actual surface carbon content". In this paper, a model is presented of carbon transfer from endothermic atmospheres to carbon steel. The carbon transfer coefficient values were determined experimentally by the foil technique and on specimens, taking into account the following parameters: chemical composition of atmospheres, carbon potential, temperature and time of the carburizing process. Some examples of the variation of the carbon transfer coefficient for two steps of the carburizing process, including soaking before quenching, are given, based on results obtained. The effect of carbon transfer coefficient on carbon content at the steel surface is given.

Morphological and Electromyogram Analysis for the Spinal Accessory Nerve Transfer to the Suprascapular Nerve in Rats

For many years, nerve transfer has been commonly used as a treatment option following peripheral nerve injury, although the precise mechanism underlying successful nerve transfer is not yet clear. We developed an animal model to investigate the mechanism underlying nerve transfer between branches of the spinal accessory nerve (Ac) and suprascapular nerve (Ss) in rats, so that we could observe changes in the number of motor neurons, investigate the 3-dimensional localization of neurons in the anterior horn of the spinal cord, and perform an electromyogram (EMG) of the supraspinatus muscle before and after nerve transfer treatment. The present experiment showed a clear reduction in the number of γ motor neurons. The distributional portion of motor neurons following nerve transfer was mainly within the neuron column innervating the trapezius. Some neurons innervating the supraspinatus muscle also survived post-transfer. Compared with the non-operated group, the EMG restoration rate of the supraspinatus muscle following nerve transfer was 60% in the experimental group and 80% in a surgical control group. Following nerve transfer, there was a distinct reduction in the number of γ motor neurons. Therefore, γ motor neurons may have important effects on the recovery of muscular strength following nerve transfer. Moreover, because the neurons located in regions innervating either the trapezius or supraspinatus muscle were labeled after Ac transfer to Ss, we also suggest that indistinct axon regeneration mechanisms exist in the spinal cord following peripheral nerve transfer.

数智化全自动标本转移系统在手术病理标本前处理流程中的应用

目的:探讨在数智化管理背景下,由手术室护士主导的数智化全自动标本转移系统在手术病理标本前处理流程中的应用效果,为提高手术病理标本质量提供参考。方法:构建数智化全自动标本转移系统,并将其应用于手术病理标本前处理流程中,比较系统应用前(2023年4月—7月)和系统应用后(2023年8月—11月)的病理标本送检效率、送检质量、手术室护士心理压力及医护人员满意度。结果:应用数智化全自动标本转移系统后,病理标本前处理流程时长较应用前平均减少3.66 min,一次性接收合格率由87.07%提高至96.42%,病理送检质量满意率较高,护士工作压力显著缓解,医务人员满意度明显提高,以上差异均具有统计学意义(P<0.05)。结论:数智化全自动标本转移系统应用于手术标本前处理流程中可有效提高手术标本前处理效率并缓解护士工作压力,保障病理标本送检质量,为医疗诊断提供可靠的依据,有效减少医务人员职业暴露,提升医护人员满意度。

A FACILE APPROACH FOR THE SURFACE MODIFICATION OF POLY(VINYLIDENE FLUORIDE) MEMBRANE VIA SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

A novel approach for the surface modification of poly(vinylidene fluoride)(PVDF)membrane was successfully realized through alkaline treatment,UV-induced bromine addition,and followed by surface-initiated atom transfer radical polymerization(ATRP)of methyl methacrylate(MMA).Chemical changes on the PVDF membrane before and after modification were analyzed with attenuated total reflectance Fourier transform infrared spectroscopy(ATR/FT-IR)and X-ray photoelectron spectroscopy(XPS).Primary kinetic study revealed...

Identification of Heat Transfer Coefficients by Use Conditions of Quenching Oil

Heat transfer coefficients of the quench medium are necessary for heat-treatment simulation. Cooling characteristics of quenching oil vary with kinds and usage greatly. Users are selecting oil solutions that come up to their desired hardness and quenching distortion requirements. In particular cooling performance rises by agitation and decompression. Therefore we identified a heat transfer coefficient by usage and kinds of quenching oil. Cooling characteristics are different greatly by a kind of quenching oil. A difference of a cooling characteristic by a kind of oil depends on a temperature range of a boiling stage and the maximum heat transfer coefficient mainly. On the other hand, in a convection stage, there are few changes in a boiling stage. Even if quenching oil temperature is changed, heat transfer coefficients do not change greatly. When quenching oil stirred, heat transfer coefficients of vapor blanket stage and a convection stage rise, but there are a few changes in a boiling stage. When quenching oil is decompressed a temperature range of a high heat transfer coefficient moves to the low temperature side. In addition, a heat transfer coefficient in a vapor blanket stage comes down. For precision improvement of heat-treatment simulation, it is important that the heat transfer coefficient is calculated in conformity to the on-site use reality.

A multi-objective decision-making method for the treatment scheme of landslide hazard

The treatment engineering of landslide hazard is a complicated systemengineering. The selecting treatment scheme is influenced by many factors such as technology,economics, environment, and risk. The decision-making of treatment schemes of landslide hazard is aproblem of comprehensive judgment with multi-hierarchy and multi-objective. The traditional analysishierarchy process needs identity test. The traditional analysis hierarchy process is improved bymeans of optimal transfer matrix here. An improved hierarchy decision-making model for the treatmentof landslide hazard is set up. The judgment matrix obtained by the method can naturally meet therequirement of identity, so the identity test is not necessary. At last, the method is applied tothe treatment decision-making of the dangerous rock mass at the Slate Mountain, and its applicationis discussed in detail.

Study on structural characteristics and adsorption performance of ultrasonic treated Mn-containing sulfur transfer agent

To prepare manganese-containing spinel sulfur transfer agent with acid peptization, ultrasonic wave is used for the first time to modify the structure of sulfur transfer agent in this work. Mini fixed bed reactor was used to investigate the effect of ultrasonic power, time and temperature on the structure and oxidation adsorption performance of sulfur transfer agent and the adsorption kinetics and mechanism of SO2 were analyzed. SEM, TEM, XRD and N2 adsorption-desorption techniques were employed to characterize and analyse the function of sulfur transfer agent. The results indicated that manganese-containing spinel is a kind of promising sulfur transfer agent and exhibits higher sulfur capacity and desulfurization degree under the selected conditions of the ultrasonic wave power of 60%, and with the treatment period for 3 h at a temperature of 60 ℃.

北京协和医院药学门诊服务模式探索与实践

目的:探索建立北京协和医院(以下称我院)药学门诊服务模式。方法:查阅国内外文献、开展调查研究,结合实践经验,归纳总结我院药学门诊服务管理制度、操作规程、服务内容和质控体系;分析药学门诊服务发展的挑战,提出促进药学门诊服务发展的建议。结果:初步搭建我院药学门诊服务模式,门诊类型包括线下药学门诊和互联网药学门诊,就诊途径包括患者自主挂号和医生院内转诊,覆盖专科包括妊娠哺乳期、糖尿病、冠心病、抗栓治疗、呼吸系统疾病、多重慢病、消化系统疾病、神经精神系统疾病、免疫系统疾病、肺癌抗肿瘤、营养药学、综合药学共12个方向的药物治疗管理,电子记录采用定制的药学门诊电子表单,既能满足药学门诊工作需求,又能实现与临床诊疗病历互查。截至2023年10月31日,线下药学门诊接诊患者426例,其中接收院内转诊病例92例,占比21.6%,药学门诊意见采纳率为87.8%;互联网药学门诊接诊患者543例,为临床患者切实解决了用药难题。结论:线上+线下药学门诊服务模式可以更好地满足患者的医疗需求,实现以患者为中心的药学服务转型。

基于承载特性的挤扩支盘桩加固深厚软基作用机理研究

针对深厚软土地基中挤扩支盘桩布置,结合汕头软基区挤扩支盘桩应用工程的单桩静载试验建立三维数值模型,探究了支盘桩在沉降过程中的荷载分担特点和盘-土相互作用机制。结果表明:未贯穿深厚软基的挤扩支盘桩桩端的荷载分担率远低于等截面直孔桩;挤扩支盘桩群桩效应系数η_(g)与桩体数目N和桩间距Sp密切相关,推荐桩间距S_(p)=8d为深厚软基区支盘桩的最优间距;支盘端部尤其下部支盘端部在极限沉降状态下分担大量荷载至盘周土体,盘净距S_(b)通过改变支盘结构持力土层性质而影响基桩承载能力。

污水中四环素类抗性基因的深度处理研究进展

四环素类抗生素在养殖、医疗行业的大量使用对细菌造成了持续的选择压力,导致四环素类抗性基因(tetracycline resistance gene,TRGs)在环境中广泛分布;多种TRGs被列为Ⅰ级环境风险等级,严重威胁人类健康和生态安全。污水处理厂(wastewater treatment plants,WWTPs)是TRGs的重要储存库,同时也是消减抗性基因的重要途径。总结了WWTPs中TRGs的赋存特征,对比分析了常规处理工艺,重点探索了新型深度处理工艺,以期为进一步有效去除TRGs和全面防控抗生素抗性基因污染提供参考。

禾豆间作系统水分和根系分隔对牧草氮素吸收利用及转移的影响

[目的]禾豆间作可兼顾生产和生态效益,提高氮素利用效率并减少氮肥污染。目前对不同水分条件下禾豆间作体系氮素利用吸收及转移分配过程尚不清晰。[方法]通过设置2时段总水量相同但间隔3,5天的不同频次水处理,结合根系分隔(不分隔、尼龙网分隔、塑料板分隔)和氮同位素标记方法,研究间作禾豆牧草的地上生物量、氮素的吸收利用、固氮率和氮转移率。[结果]间作披碱草的地上生物量、氮含量和氮素累积量相较单作披碱草显著提升,而苜蓿间作相比单作均降低。在总水量持平的情况下,高频水分处理使牧草的地上生物量比中低频水分处理分别提高6.28%,17.32%,苜蓿的固氮率也在高频水处理下比中低频水处理分别提高39.82%,44.81%,但部分中低频水分处理下氮含量和氮素累积量显著高于高频水分处理(p<0.05),且促进氮素的转移。根系分隔使禾豆相互作用减弱,表现为根系分隔增加间作苜蓿的地上生物量、各部位氮含量及地上部氮素累积量,减小间作披碱草的对应指标。间作苜蓿的固氮和氮转移率表现为不分隔>尼龙网分隔>塑料板分隔。[结论]适度的水分调控可以提高禾豆间作的优势,且根系互作是促进豆科牧草生物固氮和氮转移的关键。

尤昭玲教授诊疗早发性卵巢功能不全患者IVF-ET中医辅助方案的构建与临证实践

早发性卵巢功能不全(premature ovarian insufficiency, POI)是指女性在40岁之前出现性腺功能的减退,临床表现为继发性闭经、不孕,常伴有夜间睡眠过程中出汗、失眠、记忆力减退等围绝经期症状。本文主要介绍尤昭玲教授对患者行中医辅助IVF-ET论证思路及特色治疗。尤教授认为POI患者不孕的主要病因为肾元亏虚、血瘀致病,故在治疗上以固本培元、活血化瘀为主,并根据二期序贯与三期三法,采用尤氏“辨卵调泡八法”,妙用花药随证加减,同时佐以食疗巩固疗效。并附验案1则,以资佐证。

Y分子筛的氢转移反应性能及其调控机制

利用原位红外光谱技术考察了HY分子筛和镧离子改性Y(LaHY)分子筛的氢转移反应性能;结合分子筛晶体结构、织构性质和酸性质等表征数据,探讨了稀土改性以及水热处理对Y分子筛氢转移反应性能的调控机制。结果表明,Y分子筛的Brønsted(B)酸密度和强酸强度减弱,同时落位于超笼中的稀土物种形成弱Lewis(L)酸位,超笼中B酸和L酸位点的协同作用促进了氢转移反应的发生;经过水热处理,HY-LH和LaHY-LH分子筛的总酸量显著减少,同时超笼中与稀土物种有关的L酸中心完全消失,显著降低了HY分子筛氢转移反应性能。研究成果可为深入理解催化裂化反应过程中氢转移反应的规律,以及调控烯烃产物选择性和抑制结焦失活等提供理论指导。

基于“生长化收藏”理论分期干预IVF-ET临证策略

总结王昕教授将“生长化收藏”理论指导下的分期论治法应用于体外受精-胚胎移植(IVF-ET)技术全周期的临床经验。王昕教授将患者IVF-ET各阶段的治疗过程与“生长化收藏”理论相关联,并制定了分期治疗方案:降调期以镇静安巢为主;促排卵前期以滋阴育卵为主;促排卵后期以滋阴助阳为主;移植初期以培土育膜为主;移植后期、妊娠期以纳膜养胎为主,中西合参,分期而治,在临床实践中显著提高了IVF-ET妊娠率。

水环境中抗生素抗性基因研究进展

抗生素抗性基因(antibiotic resistance genes,ARGs)被世界卫生组织确定为目前严重的卫生问题之一,环境中的ARGs污染会导致产生“超级细菌”,对人类和生物的健康造成了巨大威胁。因此本文系统描述了ARGs的危害及其在环境中扩散机制,综述了ARGs在地表水、地下水、土壤中的污染情况及在污水处理中的现状。分析表明,ARGs的传播机制中起关键作用的是水平基因转移;地表水中ARGs污染问题较其他水资源更为严重,且进一步引起了土壤ARGs污染并危害人体健康;就污水处理系统的处理现状进行分析,尽管对ARGs去除效果最好的是高级氧化工艺,但膜生物反应器(membrane bio-reactor,MBR)凭借着其成本较低、经济效应好且处理效果较传统活性污泥工艺好的优点,有更好的应用前景。因此,结合现有工艺构建组合工艺成为了未来污水处理厂提标改造的方向。

一种空运集装箱式生物隔离转运救治装备的设计

目的:设计一种轻量化、模块化的空运集装箱式生物隔离转运救治装备,以实现对批量传染病患者高效、安全、可靠的救治和转运后送。方法:该装备箱体采用ISO 66840 ft(1ft=30.48 cm)标准箱,使用铝合金板+新型低密度保温材料+医用防火板制作,箱壁使用铝合金板蜂窝板+防火保温材料+内饰板制作,主要由负压控制及环控系统、生命支持系统、智能控制与信息交互系统和综合保障系统组成。其中,负压控制及环控系统主要由动力分布式无风道贯通型通风系统和梯度压差智能控制系统组成,生命支持系统主要由救治模块、保障模块和医技模块组成,智能控制与信息交互系统主要由集装箱信息自动监控与交互模块、多方式通信模块和医疗信息与远程医疗模块组成,综合保障系统由供电模块、供排水模块和供氧模块组成。结果:经测试,该装备的关键指标优于美国的集装箱式生物隔离防护系统,可满足对批量传染病患者的长航时航空转运及陆海空联运转运救治。结论:该装备具有生物安全性高、生命支持能力强等优点,在满足空运快速转运救治需求的同时,可为传染病患者的全域联运转运提供装备支撑。

新型城镇化进程与医保政策优化

党的二十届三中全会通过的《中共中央关于进一步全面深化改革推进中国式现代化的决定》明确提出,要“健全推进新型城镇化体制机制”。医疗保障作为减轻群众就医负担,增进民生福祉的一项重要制度安排,对于保障劳动力要素自由流动、推进城乡协调发展、实现高质量城镇化具有重要意义。近年来,我国加大跨地区医保制度的衔接和整合,在政策创新、管理创新、技术创新等方面进行了大胆尝试,通过提高统筹层次、落实属地参保、推进异地就医直接结算和医保关系转移接续等政策,不断满足新型城镇化进程中跨区域、跨制度流动人口的医疗保障可携带需求。随着新型城镇化深入推进,人口流动持久化、家庭化,就业形态转变等新形势对医保政策优化提出了更高要求。需进一步推动优化路径由制度衔接向制度切换乃至制度整合升级,放宽做实属地参保政策,完善转移接续,加快统筹层次提升,实现跨地区间医保权责平衡,推动新型城镇化进程中各类流动人口“应保尽保,各参其保”。

降阻煤油石墨烯纳米流体制备及传热强化研究

降阻煤油在流动过程中存在传热恶化现象。为降低高聚物添加剂带来的传热热阻,在降阻煤油中添加高导热性的纳米石墨烯和分散剂制备稳定的纳米流体,并分别研究了分散剂种类和添加量以及石墨烯纳米颗粒添加量对纳米流体稳定性和传热性的影响规律。结果表明:油胺作为分散剂对纳米颗粒的分散效果优于聚乙烯吡咯烷酮,且当油胺添加质量分数大于2%时,可在15 d内维持纳米流体的均一状态,无分层现象。添加石墨烯纳米颗粒后的流体比热容和导热系数相较于降阻煤油本身均有提升,且在质量分数0.09%的石墨烯纳米颗粒添加量下,所形成的纳米流体比热容相比于降阻煤油提高了8.04%。当纳米颗粒质量分数为0.05%~0.60%时,纳米流体导热系数仅提高约2%。以传热系数为衡量标准,所形成的纳米流体相较于降阻煤油的传热系数增强了21%。