The penetration depth of atomic radicals in tubes with catalytic surface properties

Catalysis of molecular radicals is often performed in interesting experimental configurations.One possible configuration is tubular geometry.The radicals are introduced into the tubes on one side,and stable molecules are exhausted on the other side.The penetration depth of radicals depends on numerous parameters,so it is not always feasible to calculate it.This article presents systematic measurements of the penetration depth of oxygen atoms along tubes made from nickel,cobalt,and copper.The source of O atoms was a surfatron-type microwave plasma.The initial density of O atoms depended on the gas flow and was 0.7×10^(21)m^(-3),2.4×10^(21)m^(-3),and 4.2×10^(21)m^(-3)at the flow rates of 50,300,and 600 sccm,and pressures of 10,35,and 60 Pa,respectively.The gas temperature remained at room temperature throughout the experiments.The dissociation fraction decreased exponentially along the length of the tubes in all cases.The penetration depths for well-oxidized nickel were 1.2,1.7,and 2.4 cm,respectively.For cobalt,they were slightly lower at 1.0,1.3,and 1.6 cm,respectively,while for copper,they were 1.1,1.3,and 1.7 cm,respectively.The results were explained by gas dynamics and heterogeneous surface association.These data are useful in any attempt to estimate the loss of molecular fragments along tubes,which serve as catalysts for the association of various radicals to stable molecules.

Neutron penetration in labyrinths under different beam losses

Multiple analytical methods and Monte Carlo simulations were performed to evaluate neutron penetration in straight and curved labyrinths. Factors studied included variations in beam losses of off-axis point source,on-axis point source,and line source. For the straight labyrinth, it was found that the analytical expressions neglect the dose rate platform appearing at the bend of the labyrinth, and the agreement between analytical methods and Monte Carlo estimation was related to the type of neutron source term. For the curved labyrinth, the neutron attenuation length obtained under different conditions was nearly identical and appeared to be in quite good accord with the empirical formula calculation. Moreover, the neutron energy spectra along the centerline distance of the labyrinth were also analyzed. In the first leg, differences in beam loss led to variance in the distribution of spectra,while in the second and subsequent legs, the spectra were similar, where the main contributors were thermal neutrons. This work is valuable for practical design of the labyrinths in the accelerator facilities.

Stability analyses of the mass abrasive projectile high-speed penetrating into concrete target. Part Ⅰ: Engineering model for the mass loss and nose-blunting of ogive-nosed projectiles

The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator,obviously reducing the penetration efficiency of penetrator.Provided that the work of friction between projectile and target is totally transformed into the heat to melt penetrator material at its nose surface,an engineering model is established for the mass loss and nose-blunting of the ogive-nosed projectile.A dimensionless formula for the relative mass loss of projectile is obtained by introducing the dimensionless impact function I and geometry function N of the projectile.The critical value V c0of the initial striking velocity is formulated,and the mass loss of projectile tends to increase weakly nonlinearly with I/N when V0〉V c0,whilst the mass loss is proportional to the initial kinetic energy of projectile when V0

Parametric study on mass loss of penetrators

Earth penetration weapon （EPW） is applicable for attacking underground targets protected by reinforced concrete and rocks. With increasing impact velocity, the mass loss/abrasion of penetrator increases, which significandy decreases the penetration efficiency due to the change of nose shape. The abrasion may induce instability of the penetrator, and lead to failure of its structure. A common disadvantage, i.e. dependence on corresponding experimen- tal results, exists in all the available formulae, which limits their ranges of application in estimating the mass loss of penetrator. In this paper, we conduct a parametric study on the mass loss of penetrator, and indicate that the mass loss of penetrator can be determined by seven variables, i.e., the initial impact velocity, initial nose shape, melting heat, shank diameter of projectile and density and strength of target as well as the aggregate hardness of target. Further discussion on factors dominant in the mass abrasion of penetrator are given, which may be helpful for optimizing the target or the projectile for defensive or offensive objectives, respectively.

Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC): Occlusive Effect and Penetration Enhancement Ability

Objective: This work compares the occlusive effect and the penetration enhancement ability of solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), through in vitro skin. Methods: SLN and NLC were prepared by high shear homogenization and characterized by size, polydispersity index, zeta potential, morphology and physical stability. Occlusive effect was assessed by an in vitro test and by measuring TEWL using pig skin. Skin treated with the lipid carriers was visualized by SEM. A penetration test through skin, followed by tape stripping, was carried out using Nile red as a marker. Results: SLN (200 ± 6 nm) and NLC (192 ± 11 nm) were obtained. An occlusion factor of 36% - 39% was observed for both systems, while a reduction in TEWL of 34.3% ± 14.8% and 26.2% ± 6.5% was seen after treatment with SLN and NLC, respectively. SEM images showed a film formed by the lipid carriers, responsible for the occlusion observed. No differences were found between the occlusive effect produced by SLN and NLC in both tests. NLC allowed the penetration of a greater amount of Nile red than SLN: 4.7 ± 1.3 μg and 1.7 ± 0.4 μg, respectively. Conclusion: Both carriers form a film on the skin, providing an occlusive effect with no differences between these two systems. The penetration of a marker (Nile red) into the stratum corneum was quite higher for NLC than for SLN, suggesting an influence of the composition of these particles on their penetration enhancing ability.

Resistance of Cement-based Grouting Materials with Nano- SiO_(2) Emulsion to Chloride Ion Penetration

The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.

中药挥发油透皮促渗苷类成分效果与经皮水分散失量的相关性研究

目的研究中药挥发油透皮促渗苷类成分效果与对经皮水分散失量(Transepidermal water loss,TEWL)的相关性。方法采用HPLC法测定3种苷类成分(栀子苷、龙胆苦苷、芍药苷)的含量及油水分配系数,采用改良Franz扩散池法以离体SD大鼠腹部皮肤为透皮吸收屏障进行体外透皮实验,考察高良姜、干姜、薄荷、胡椒和吴茱萸5种中药挥发油对3种苷类成分的体外透皮促渗效果,采用经皮水分散失量评价5种中药挥发油对大鼠皮肤屏障功能的影响,通过相关性分析考察中药挥发油透皮促渗苷类成分效果与其对皮肤屏障功能影响之间的相关性。结果高良姜油、干姜油、薄荷油、胡椒油能促进3种苷类成分的透皮吸收,也能显著降低大鼠的皮肤屏障功能,相关性分析结果表明中药挥发油对苷类成分的透皮促渗效果与其对皮肤经皮水分散失量的影响显著相关。结论TEWL为中药挥发油透皮促渗剂的快速筛选提供了一种简便快捷的在体评价方法。

太赫兹信号在几种塑料材料遮挡下的透射衰减

随着物联网时代的到来,人们对于更高带宽和更快速率的需求日益增加。太赫兹频段的引入为这一问题提供了一种新的解决方案。太赫兹信号具有穿透力强、对非金属材料具有较好的穿透性以及较高的分辨率等特点,在通信和成像领域具有巨大的潜力。本文基于光子辅助原理,搭建了利用光子外差拍频的方式产生386.2 GHz和438.4 GHz两个频率的太赫兹信号的太赫兹传输系统,并测量了太赫兹信号在聚4-甲基戊烯(TPX)、聚乙烯(PE)、聚丙烯(PP)和聚甲基丙烯酸甲酯(PMMA)这4种常见的塑料材质遮挡下的穿透损耗,得到了在室内环境下这些材料的衰减特性,且将实验结果与比尔吸收定律拟合。从实验结果发现5 mm厚的PP板和PE板对于太赫兹信号的衰减在1 dB以下,很薄的PP板和PE板对386.2 GHz和438.4 GHz两个频率的太赫兹信号的遮挡作用很微弱;实验所选频段的太赫兹信号几乎无法穿透15 mm厚的PMMA板。太赫兹信号在塑料材质中的透射衰减特性的探索与研究对毫米波通信系统中合适的天线材料的选择具有参考价值,在实际应用中起着重要的指导作用。

Research on mass loss and nose shape evolution of kinetic energy projectiles penetrating concrete at high velocity

The high-speed penetration of concrete targets by kinetic energy projectiles results in apparent mass loss,which blunts the nose of the projectile and decrease its penetration performance.The friction work between the projectile and the concrete target,the plastic deformation of the projectile,and the cutting of aggregates to the projectile significantly affect the mass loss of the projectile.To address these effects,a discrete iterative model is developed for the mass loss and nose shape evolution of the projectile by coupling three mechanisms based on the effect of temperature on strength.In the model,both friction work and plastic work increase the temperature of the projectile's surface layer,thereby weakening the strength of this part and rendering it easier for mass loss to occur due to aggregate cutting.The model discretizes the projectile and penetration process with respect to the space and time dimensions,respectively.The mass loss and nose shape evolution of the projectile are obtained by iteratively calculating a point-by-point regression.The predicted depth of penetration(DOP),mass loss,and residual projectile profile are compared with experimental data to validate the model.The comparison shows satisfactory agreement between the calculated results and experimental data.Additionally,the deceleration,velocity,DOP,and mass loss during penetration are analyzed with respect to time.Finally,based on the model,the effects of projectile strength,caliber-radius-head(CRH),and concrete target strength on penetration are discussed.

基于改进电量法及前推回代法的高渗透率新能源配电网线损计算研究

分布式电源(DG)的高比例接入使得配电网潮流双向流动,传统的线损计算方法不再适用。首先,针对传统电量法电压与功率因数需全网一致假设条件的限制,提出电压电量法和电压功率因数电量法;然后,对多种分布式电源进行节点类型建模,提出改进前推回代法,实现对高渗透率配电网线损的精细求解;最后,对某地区实际配电线路进行计算,探究各种线损计算方法的误差及适用条件,并通过3种场景对比分析分布式电源接入容量、位置及其他参数对配电网电压以及线损的影响,验证了改进电量法以及改进前推回代法的可行性,对配电网线损计算具有参考意义。

分布式发电注入容量与接入位置的优化配置分析

针对配电网中引入分布式发电(Distributed Generation,DG)后对线路损耗的影响,首先对DG接入电网后,潮流的分布进行定性分析。在线损最小时,定性上确定了DG的注入容量和接入位置;然后,抽取对线损变化起决定作用的部分网络进行合理的简化等效,以线损最小为目标,分别从DG的注入容量和接入位置两方面对电网线损的影响进行了定量的理论推导,得出了分布式电源注入容量与接入位置之间关系的两个重要公式。最后与仿真结果进行对比,对比结果基本吻合,验证了所推导的结论的正确性,为工程的实际运用提供了借鉴。

彭页HF-1页岩气水平井钻井关键技术

水平井是开发页岩气的有效方式,但页岩气水平井施工中存在井眼轨迹难以控制、摩阻扭矩大、机械钻速偏低、井壁稳定性差、固井质量难以保证等难题。在彭页HF-1井施工过程中,综合应用了旋转导向钻井技术、油基钻井液和双凝双密度水泥浆等,并进行了钻具组合和钻头的优选,钻井周期比设计周期缩短13d。对该井的轨迹控制情况、井身质量、摩阻扭矩、固井质量等进行了分析,全井平均机械钻速达到6.28m/h,狗腿度保持在6°/30m以下,摩阻保持在150～250kN,施工效果良好。该井实钻效果表明,旋转导向钻井技术和油基钻井液是页岩气水平井施工成功的关键,对国内其他页岩气水平井施工具有指导和借鉴作用。

卵形弹体超高速侵彻砂浆靶的响应特性

为研究砂浆靶目标在动能弹超高速撞击下的破坏响应,利用2级轻气炮开展卵形头部钢杆弹以12002400 m/s速度侵彻砂浆靶的实验。根据侵彻实验结果,分析得到:靶体开坑直径和开坑深度与撞击速度呈线性关系;随着撞击速度的增加,侵彻深度呈现先线性增加、后逆减、再缓慢增加的趋势,分别对应刚性侵彻、半破碎侵彻和破碎侵彻3种截然不同的侵彻机制。基于前述分析,以内摩擦理论为基础,结合弹体质量损失函数,推导得到刚性侵彻和半破碎侵彻深度计算公式,并与实验结果进行对比。结果表明:考虑弹体质量损失的侵彻深度计算模型理论计算结果与实验结果吻合较好,解释了超高速侵彻过程中侵彻深度逆减的特殊现象,揭示了砂浆靶中侵彻深度变化规律的内在机理。

国内外水力振荡器的研究现状及展望

针对目前定向井段和水平段钻进过程中为提高机械钻速使用水力振荡器出现的问题,分析了水力振荡器的研究现状与现场应用状况。首先介绍了国内外不同水力振荡器的结构,分析了其优缺点;然后结合现场资料,通过实例对比了水力振荡器和旋转导向钻井工具的提速效果;最后针对水力振荡器在应用时出现的一系列问题给出了相关建议。现场应用效果统计资料表明,水力振荡器能降低摩阻,提高机械钻速,缩短钻井周期,降低钻井成本,与旋转导向工具相比,机械钻速可提高29.8%,钻井成本可降低38万元。但存在实际工作排量达不到设计要求、安放位置不合理、自身压耗高、损坏MWD等精密仪器和耐冲蚀性偏差等问题,严重影响了水力振荡器的应用。为解决这些问题,需要对水力振荡器进行持续完善和改进。

基于真空-堆载联合预压法的未打穿竖井地基固结分析

在未打穿竖井情况下,用真空-堆载联合预压法来处理软土地基,既高效又经济。针对这种地基处理方法,应用Laplace变换半解析法来进行分析。通过在竖井底面设置虚拟竖井来模拟竖井下三维渗流情况,并合理考虑真空度损失,得到真空度损失下竖井打入深度与沉降之间的关系。运用Laplace变换与逆变换,得到比较精确的解析解,并对影响竖井渗透作用的几个主要参数,如贯入度、井阻、真空度等进行对比分析,得到可供实际工程参考的竖井最优贯入度。

弹体高速侵彻岩石效应试验研究

为研究高速动能弹在岩石中的侵彻效应,在高速弹道炮上进行弹体对岩石靶体高速正侵彻的模型试验,试验最高弹体速度为1450m/s,得出侵彻深度与侵彻速度之间的关系,并建立弹体速度不大于弹体极限速度时弹体侵彻深度的经验公式,该公式与试验结果具有良好的一致性。同时,分析模型试验靶体破坏情况,对于一定尺寸的弹体和靶体,不同弹体速度将产生不同的靶体破坏类型。研究高速撞击条件下弹体侵彻能力、侵彻极限速度和质量损失等问题,分析影响弹体极限速度和质量损失的相关因素,可对高速动能弹侵彻岩石的侵深、加速度和质量损失等主要参数进行评估,为弹体战斗部和防护工程的设计提供有力的参考。与在混凝土靶体上的高速侵彻试验进行对比,说明无风化的硬质岩石可以作为良好的防护工程材料。

火山岩地层优快钻井技术

针对目前火山岩地层钻井存在的可钻性差、地层倾角大、井斜控制难度高、地层裂缝发育、漏失严重和井壁稳定性差等技术难点,从钻头优选与结构改进、欠平衡钻进配套技术及复合钻进配套技术的应用、加强防漏堵漏配套技术措施等几个方面着手,进行了火山岩地层快速钻井优化配套技术研究,形成了一套高效的提高火山岩地层钻井速度的配套技术措施。现场应用表明,采用该套技术措施,火山岩地层的钻井速度得到明显提高。最后指出,进行火山岩破岩机理、欠平衡钻井配套技术和防漏堵漏技术等方面的研究,是火山岩地层钻井技术的研究方向。

侵彻混凝土弹体磨蚀的若干研究进展

在侵彻混凝土和岩石加固与防护的深埋目标的过程中,弹体需保证尽可能小的变形以保持结构完整性,其理论模型常假设为刚性体;而真实弹体随侵彻速度增加,质量损失和局部侵蚀(简称磨蚀)造成的损失不断加剧,故不再能看作刚性体。弹体磨蚀过程会显著影响弹体侵彻性能,导致弹体破坏或失效,故磨蚀研究十分必要。从实验研究、经验及理论模型分析和数值模拟角度,总结了弹体侵彻粘结基靶体(混凝土或岩石)时,磨蚀的相关研究成果,并提出了对未来研究方向的建议。

基于Archard理论分析弹体质量侵蚀

基于模具与工件磨损中的Archard粘着磨损理论,分析弹体表面微粒的细观塑性变形,建立弹体质量侵蚀表征模型,运用动态空腔膨胀理论得到弹体表面应力,再通过差分计算得到高速侵彻中弹体宏观轮廓的钝化回退过程。计算得到的弹体外部轮廓、质量损失及侵彻深度等参数与实验结果基本吻合。结果表明;弹体侵蚀效应对侵彻时间和深度的影响随着撞击速度的增大愈加显著;弹体侵彻过程中最大过载与刚性条件下有较大区别,提高弹体材料的屈服强度能有效减少侵彻过程中弹体的质量损失,提高最终侵彻深度。

卵形头弹体对素混凝土高速侵彻的实验研究

利用二级轻气炮装置,选取材料为38CrMnSi的卵形头弹对素混凝土靶体进行了撞击实验。根据得到的实验数据以及实验后回收的弹体和靶体,分析了动能弹高速侵彻素混凝土时的弹靶响应特性,包括弹体质量损失规律及其机理、靶体损伤特征和侵彻深度随速度的变化规律。结果分析表明,弹体侵彻素混凝土靶体过程包括锥型弹坑阶段和隧道稳定阶段,从较低速到高速侵彻,弹体发生了CRH变小、头部半球化和锥形化的特征性现象,并伴随着不同程度的质量损失,由此引发侵彻深度在高速侵彻时较小的波动。进一步引用弹体侵彻混凝土靶响应模型进行了理论分析,发现在较低速撞击时,利用模型计算得到的值与实验结果比较吻合,而高速撞击条件下偏差则较大,需要考虑弹体头部形状变化对侵彻响应结果的影响。