Measurement scheme to detect α relaxation time of glass-forming liquid

A measurement scheme for detecting theαrelaxation time(τ)of glass-forming liquid is proposed,which is based on the measured ionic conductivity of the liquid doped with probing ions by low-and middle-frequency dielectric spectroscopy and according to the Nernst-Einstein,Stokes-Einstein,and Maxwell equations.The obtainedτvalues of glycerol and propylene carbonate by the scheme are consistent with those obtained by traditional dielectric spectroscopy,which confirms its reliability and accuracy.Moreover,theτof 1,2-propanediol in a larger temperature range is compared with existing data.

CONTROL OF FORMABILITY OF EMC LIQUID METAL COLUMN

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Existence forms of water in solid liquid systems

Two approaches, named pressure filtration (PF) and vaporization dewatering (VD), for qualitative and quantitative analysis of the water forms were presented. The principle of VD is that with the process of heating, the free water, surface water and capillary water are in turn vaporized at different rates, then the turning points of the rates are determined and the quantitative analysis can be made. Some experiments with suspension of water and CaCO 3 powder were given and discussed by applying the vaporization dewatering approach. [

Shape formation of closed-cell aluminum foam in solid–liquid–gas coexisting state

The mold pressing process was applied to investigate the formability of closed-cell aluminum foam in solid–liquid–gas coexisting state.Results show that the shape formation of closed-cell aluminum foam in the solid–liquid–gas coexisting state was realized through cell wall deformation and cell movement caused by primary α-Al grains that slid,rotated,deformed,and ripened within cell walls.During formation,characteristic parameters of closed-cell aluminum foam were almost unchanged.Under proper forming conditions,shaped products of closed-cell aluminum foam could be fabricated through mold pressing.

基于镓基液态金属的柔性传感的研究进展

镓基液态金属(Gallium-based liquid metal,Ga-LM)具有高导电性、高拉伸性、高生物相容性和低毒性等优异性能,在柔性电子领域表现出巨大的应用潜力。然而由于Ga-LM特殊的流变性和氧化性,在控制成型和实际应用方面带来了一定的挑战。基于此,本文综述了Ga-LM在柔性传感领域研究与应用进展,介绍了Ga-LM传感器的不同基底特性及成型工艺,并分析了各自对应的优势、存在的问题和解决方案,旨为Ga-LM在柔性传感器领域的进一步研究和应用提供经验与参考。

成膜剂对粉底液持妆性能的应用研究

将4种不同类型的成膜剂分别添加在粉底液配方中,采用Visia-CR测定其对人体面部皮肤粉底液持妆性能的影响。研究表明,添加成膜剂的样品组对比空白对照组存在显著性差异,说明添加成膜剂对粉底液持妆性能有增效作用;含三甲基硅烷氧基硅酸酯或丙烯酸(酯)类/聚二甲基硅氧烷共聚物、环五聚二甲基硅氧烷配制的粉底液持妆效果优于含聚甲基倍半硅氧烷或VP/十六碳烯共聚物配制的粉底液。本次试验对持久型底妆的配方设计具有指导意义。

高效液相色谱-原子荧光光谱联用技术测定化妆品中4种砷形态

为了准确测定护肤类化妆品中毒性类金属元素砷的形态,尤其毒性最高的无机砷——砷酸盐[As(Ⅴ)]与亚砷酸盐[As(Ⅲ)]的含量,通过优化建立适用于化妆水、乳液、霜膏类化妆品的前处理方法,开发简单高效的高效液相色谱串联原子荧光光谱(HPLC-AFS)分析方法,有效地对化妆品中无机砷的含量检测提供技术支持。样品经0.15 mol/L硝酸浸提过夜,于90℃超声提取2.5 h。提取完后经6000 r/min离心15 min。取上清液加入正己烷振荡离心,取下层清液经0.45μm有机滤膜过滤。以15 mmol/L磷酸氢二铵溶液(pH=6.0)作为流动相,结合HPLC-AFS法对护肤类化妆品中无机砷的含量进行测定。按保留时间定性,外标法定量。4种不同砷形态化合物在12 min内有效分离,且各自的线性关系良好(r>0.999)。添加4个不同浓度As(Ⅲ)与As(Ⅴ)的样品回收率为86.7%~101%,相对标准偏差为1.7%~8.4%,方法检出限为0.02 mg/kg。方法简便、快速、灵敏度高、精密度好,可以满足化妆品中无机砷的检测需求。按照实验方法测定市场上护肤类化妆品中总砷及其无机砷含量,结果发现样品中有不同程度的总砷检出,且无机砷含量最高可达到0.98 mg/kg。由此可见,市场上化妆品样品参差不齐,其砷元素含量尤其无机砷有部分检出,可以为化妆品的安全评价及市场监管提供参考。

Draping Behavior of Carbon Non-Crimp Fabrics and Its Effects on Mechanical Performance of the Hemispherical Composites

In order to investigate the draping behavior of non-crimp fabrics（NCFs）, two types of carbon NCFs with tricot-chain stitches or chain stitches were formed on a hemispherical mould via a stretch forming process. The shear angle and forming defects of the fabrics were measured on the hemisphere, under different blank holder forces（BHFs）. The results showed that increasing BHF could enhance the shear angle slightly, reduce the asymmetry for the deformation of the fabrics, and change the main type of the process-induced defects. Besides, compression tests were performed on the corresponding composite components. By analyzing the change of fiber volume fraction and structural parameters of the textile reinforcements, the effects of draping behavior of NCFs on the mechanical performance of the composites were studied. The results reveal that draping process has distinguishable impacts on the mechanical properties of the final components, which is closely related to the stitching pattern of the NCFs.

Influence of flux treatment on the glass forming ability of Pd-Si binary alloys

Pd81Si19 amorphous alloys were prepared by combination methods of melt spinning and B2O3 flux treatment. A compari- son between the ribbons prepared from the fluxed ingots and the non-fluxed ones has been carried out. The result reveals that after fluxing treatment the glass transition temperature of the as-prepared glassy ribbons is reduced while the initial crystallization tem- perature is enhanced. It results in that the supercooled liquid region (defined as the difference between the initial crystallization tem- perature and the glass transition temperature) of the glassy alloy treated with fluxing technology has been increased from 31 to 42 K. This shows that fluxing technique can enhance the glass forming ability (GFA) of the binary alloy and improve the thermal stability of supercooled liquid of the glassy alloy.

Study on the Effects of Guiqi Oral Liquid (归芪口服液) in Promoting Recovery of Hematopoiesis in AcuteIrradiation Injured Mice

Objective： To explore the effects and possible mechanisms of Guiqi Oral Liquid （归芪口服液, GQOL） on the recovery of hematopoiesis in acute irradiation injured mice. Methods： The acute irradiation injured mice were randomly divided into 2 groups： the treated group and the control group, and also a normal control group was set up with 6 mice in it receiving no treatment. After the mice in the former two groups were irradiated by 6.0 Gy ^60Coγ-ray, every one of them was given 0.4 ml GQOL or saline in equal volume through a gastric tube twice a day for 14 days. On the 4th, 8th and 14th day after irradiation, the bone marrow mononuclear cells （BMMNC） and megakaryocytes in bone marrow tissues of the mice were counted, the proportion of hematopoietic tissues （by area） was measured, and the expression of adhesion molecules, CD44 and CD54, in bone marrow were estimated by immunochemistry. The colony forming unit of spleen （CFU-S） in the mice were counted on the 8th day after irradiation. Results： On the 4th, 8th, 14th day after irradiation, the count of BMMNC and megakaryocyte, and the proportion of hematopoietic tissues in the treated group were higher than those in the control group （P〈0.01 or P〈0.05）. CD44 and CD54 expression in the treated group were higher than those in the control group on the 4th and 8th day （P〈0.01）, but near normal on the 14th day （P〈0.01）. On the 8th day, CFU-S count in the treated group was higher than that in the control group （P〈0.01）. Conclusion： GQOL can regulate the expression of adhesion molecules, CD44 and CD54, in the bone marrow of the acute irradiation injured mice, which may be one of the mechanisms of GQOL in accelerating the early phase hematopoiesis recovery of mice.

Glass forming ability of Zr-and Fe-based alloys at quenching from melts

The master alloy ingots (MAI) with the nominal composition Zr 52.5 Ti 5Cu 17.9 Ni 14.6 Al 10 and Fe 61 Co 7Zr 10 Mo 5W 2B 15 (at%) were prepared by arc melting in Ti gettered Ar atmosphere. The Zr based buttons of 6 mm and 9 mm in diameter were fully amorphous, but those of 13 mm in diameter experienced crystallization. The glass forming ability (GFA) of Fe based alloys was relatively lower, and the buttons obtained were fully crystallized. The microhardness of the Zr based buttons was about 500(Hv), and the Fe based rod obtained by injection technique exhibited a high Vickers hardness of 1329. In addition, an amorphous crystalline transition layers were observed in both the buttons and the rods.

Gibbs Free Energy and Activation Energy of ZrTiAlNiCuSn Bulk Glass Forming Alloys

The Gibbs free energy differences between the supercooled liquid and the crystalline mixture for the (Zr_(52.5)Ti_5Al_(10)-Ni_(14.6)Cu_(17.9))_((100-x)/100)Sn_x (x=0, 1, 2, 3, 4 and 5) glass forming alloys are estimated by introducing the equationproposed by Thompson, Spaepen and Turnbull. It can be seen that the Gibbs free energy differences decrease firstas the increases of Sn addition smaller than 3, then followed by a decrease due to the successive addition of Snlarger than 3, indicating that the thermal stabilities of these glass forming alloys increase first and then followed by adecrease owing to the excessive addition of Sn. Furthermore, the activation energy of Zr_(52.5)Ti_5Al_(10)Ni_(14.6)Cu_(17.9) and(Zr_(52.5)Ti_5Al_(10)Ni_(14.6)Cu_(17.9))_(0.97)Sn_3 was evaluated by Kissinger equation. It is noted that the Sn addition increases theactivation energies for glass transition and crystallization, implying that the higher thermal stability can be obtainedby appropriate addition of Sn.

Research on the Forming Mechanism of Micro/Nano Features during the Cast Molding Process

Cast molding process has provided a reliable, simple and cost-effective way to fabricate micro structures since decades ago. In order to obtain structures with fine, dense and deep nano-size features by cast molding, it is necessary to study the forming mechanism in the process. In this paper, based on major steps of cast molding, filling models of liquid are established and solved; and the forming mechanism of liquid is revealed. Moreover, the scale effect between the liquid and the cavity on the filling velocity of liquid is studied.It is also interesting to find out that the wettability of liquid on the cavity may be changed from wetting to dewetting depends on the pressure difference. Finally, we experimentally verify some of our modeling results on the flowing and filling state of the liquid during the cast molding process.

高超声速气流中支板液体喷注的数值研究

斜爆轰发动机燃烧室爆轰燃烧是预混燃烧,发动机进气道燃料预混是斜爆轰发动机运行的前提和关键.现有研究多集中于气相燃料,针对更加接近工程实际的液体燃料研究较少.高超声速来流与液相作用伴随着更多流动物理过程,影响参数多,研究更为复杂.文章采用数值模拟手段,求解二维可压缩雷诺时均Navier-Stokes(RANS)方程,结合CLSVOF(coupled level set and volume of fluid)相界面捕捉方法.以高超声速横向来流与液相射流作用模型,系统研究了来流马赫数、液相射流角度和速度对液相燃料破碎、输运及混合的动力学行为的影响规律.在高超声速气流作用下,射流液柱受压力梯度影响向下游弯曲随气流运动,逐步呈现出液柱、连续液膜、液丝状、液块状和气液混合层5种液相演化形态.液相射流角度和速度对液相连续液膜特征和破碎距离有一定作用,进而对下游截面液相分布以及剪切层扰动造成影响.来流马赫数对压力梯度有一定作用,通过压力梯度对下游液相分布的纵向高度造成影响.综合参数分析,液相燃料射流穿透深度与总压损失成正比,改变射流角度是增加穿透深度、提升发动机性能更为有效的方式.

双作用液环压缩机壳体型线响应面分析及多目标优化

为探究双作用液环压缩机壳体型线对其内流场及性能的影响机理,采用DFFD参数化方法对多级双作用液环压缩机椭圆形壳体型线进行响应面优化分析,并结合NSGA-II多目标优化方法对吸排气区壳体型线进行协同优化。采用VOF多相流模型对该液环压缩机全流域进行非定常计算,双作用液环泵内相态场、压力场基本呈径向对称分布,吸排气区域及叶轮壳体内流场与单作用液环泵分布规律基本一致,随着级数增大液环内的气相区域逐渐减小。响应面结果表明吸气量的大小主要取决于吸气口始端和末端的壳体型线,当R_(A)值趋于0水平,R_(B)处于低水平时,吸气量趋于最大值。轴功率主要受吸、排气口始端位置壳体型线影响,R_(A),R_(C)值越小,轴功率越小。效率的大小主要取决于吸气口始端和末端的壳体型线,且R_(A)值越大,R_(B)值越小,效率越高。在额定出口压比条件下,以吸气量和效率作为优化目标对液环压缩机进行NSGA-II多目标优化,获得其Pareto前沿的最优效率设计J和和最优流量设计K,J方案流量和效率分别高于原方案1.40%和2.53%,K方案流量和效率分别高于原方案16.4%和0.61%。

AI大模型场景下智能计算技术选型分析

随着ChatGPT的诞生,AI大模型相关的产品和服务呈爆发式增长,国内互联网企业和运营商等纷纷加入“百模大战”。现有云平台中智能服务器采用传统GPU配置规格,无法满足大模型训练所需要的高性能算力和卡间互联带宽需求。本文主要研究扣卡模组形态的智能计算芯片技术,以及整机服务器的散热技术等内容,为后续建设智算中心提供选型依据。

差温轧制6063/7072铝合金复合板有限元模拟及翘曲影响因素

高能量密度动力电池的发展对液冷板提出了高安全、高性能制造要求,针对传统“冲压-钎焊”工艺焊合可靠性低、界面抗冲击性差等缺点,本工作提出“差温轧制-吹胀”新工艺以制备结合良好、界面质量高的6063/7072铝合金液冷板。但异质金属的轧制易形成翘曲缺陷,导致后续吹胀工艺无法正常进行,因此亟需研究轧制液冷板的翘曲机理及其影响规律。本工作通过ANSYS/LS-DYNA有限元仿真和实验相结合的方式,研究了其差温轧制过程中的翘曲行为及其机理,分析了工艺参数对翘曲曲率的影响规律。结果表明:轧制方向的应力不协调导致6063铝合金板相对7072铝合金板需产生更大形变以达到应力平衡,轧制方向的应力差可以用来表征6063/7072铝合金液冷板的翘曲情况;提高轧制压下率、增大轧制温度差以及减小6063铝合金板厚度比例可有效降低液冷板的翘曲曲率,从而提高液冷板成形精度;实验与仿真的翘曲曲率相对误差小于5.58%,表明本研究的有限元模型准确可靠;通过差温轧制实验得到了6063/7072铝合金复合板,表明差温轧制复合板技术方案可行,为液冷板的高性能制造提供了有效途径。

成形网对液压过滤材料性能稳定性的影响

液压过滤材料在过滤过程中会出现过滤比严重下降的问题,极大影响了滤材过滤性能的稳定性。首先利用Geodict软件模拟了滤材孔径分布不均匀对过滤性能的影响,结果表明,在平均孔径一定的情况下,滤材的最大孔径越大,滤材过滤性能的稳定性越差;然后采用实验探究了成形网目数对滤材孔径分布以及液体过滤性能的影响,结果表明,当成形网的目数大于等于400目时,不同直径、不同定量的滤材在成形过程中的流失率和孔径分布逐渐趋于稳定,在滤材的物理参数和过滤精度接近时,500目成形网制备的滤材过滤性能的稳定性要高于80目成形网制备的滤材。

1×××/7×××系铝合金液-固铸轧复合模拟研究

结合双辊立式铸轧机设备和技术参数,通过流-固耦合的方法进行了变参数正交模拟研究,揭示了1×××系铝液浇铸温度和铸轧速度对铸轧复合区内温度场、流场的影响。研究结果表明,最优铸轧参数区间为浇铸温度670~690℃、铸轧速度12~13 m/min。浇铸温度越高、铸轧速度越快越容易发生漏液,反之容易发生轧卡。

液氮溶浸时间对原煤力学及破坏形式的影响

为了研究液氮溶浸处理对煤样单轴和三轴加载力学性质及破坏形式的影响规律,采用三轴实验装置对不同液氮溶浸时间煤样进行单轴、三轴实验。结果表明:是否进行液氮溶浸处理对煤样单轴加载和三轴加载过程中力学特性演化趋势无明显影响,均为随着轴向应变增加,轴向应力先缓慢增加,后直线增大,达到煤样极限后迅速降低;液氮溶浸不同时间煤样单轴加载峰值轴向应力分别为4.28、7.21、2.32、2.34 MPa,三轴加载峰值轴向应力分别为44.31、25.73、37.74、39.78 MPa;随着液氮溶浸时间增加,煤样单轴加载峰值轴向应力呈现出先增大后减小的变化趋势,三轴加载峰值轴向应力呈现出先减小后增大的变化趋势;液氮溶浸煤样在单轴加载和三轴加载后局部破碎更彻底,但液氮溶浸时间越长,煤样破碎后生成的大块煤数量和体积都越多。