Damage mechanism at different transpassive potentials of solution-annealed 316 and 316l stainless steels

Electrochemical impedance spectroscopy (EIS), anodic polarization and scanning electron microscopy techniques were used to investigate the damage mechanism in the transpassive potential region of AISI ...     

Ballistic behavior of plain and reinforced concrete slabs under high velocity impact

This work presents a numerical simulation of ballistic penetration and high velocity impact behavior of plain and reinforced concrete slabs. In this paper, we focus on the comparison of the performance of the plain and reinforced concrete slabs of unconfined compressive strength 41 MPa under ballistic impact. The concrete slab has dimensions of 675 mm × 675 mm × 200 mm, and is meshed with 8-node hexahedron solid elements in the impact and outer zones. The ogive-nosed projectile is considered as rigid element that has a mass of 0.386 kg and a length of 152 mm. The applied velocities vary between 540 and 731 m/s. 6 mm of steel reinforcement bars were used in the reinforced concrete slabs. The constitutive material modeling of the concrete and steel reinforcement bars was performed using the Johnson-Holmquist-2 damage and the Johnson-Cook plasticity material models, respectively. The analysis was conducted using the commercial finite element package Abaqus/Explicit. Damage diameters and residual velocities obtained by the numerical model were compared with the experimental results and effect of steel reinforcement and projectile diameter were studies. The validation showed good agreement between the numerical and experimental results. The added steel reinforcements to the concrete samples were found efficient in terms of ballistic resistance comparing to the plain concrete sample.     

Evaluation of microbial toxins,trace elements and sensory properties of a high-theabrownins instant Pu-erh tea produced using Aspergillus tubingensis via submerged fermentation

Theabrownins (TB) are polymeric phenolic compounds associated with the multiple bioactivities of Pu-erh tea, a post-fermented Chinese dark tea. High-TB instant Pu-erh tea was produced via a novel submerged fermentation (SF) using Aspergillus tubingensis and compared with samples produced commercially via the conventional solid-state fermentation (SSF). Viable microorganisms and microbial toxins, especially aflatoxins B₁, G₁, B₂, G₂, cyclopiazonic acid, fumonisins B₁, B₂, B₃ and ochratoxin A, were below the detection limit in all samples. Fewer microbial metabolites were found in SF instant tea compared with the SSF teas. Based on an adult consuming 1 g of instant Pu-erh tea daily, the dietary intake of investigated elements was below the safe limits recommended by various authorities. Tasters viewed the instant tea infusions as very mild, smooth, mellow and full. This suggested that submerged fermentation using A. tubingensis offers a speedy and safe alternative to commercial production of instant Pu-erh tea.     

Kinetic,thermodynamic parameters and in vitro digestion of tannase from Aspergillus tamarii URM 7115

Tannase is an enzyme used in various industries and produced by a large number of microorganisms. The aim of this study was to evaluate tannase production to determine the biochemical, kinetic, and thermodynamic properties and to simulate tannase in vitro digestion. The tannase-producing fungal strain was isolated from “jamun” leaves and identified as Aspergillus tamarii. Temperature at 26°C for 67?h was the best combination for maximum tannase activity (6.35-fold; initial activity in Plackett–Burman design—15.53?U/mL and average final activity in Doehlert design—98.68?U/mL). The crude extract of tannase was optimally active at 40°C, pH 5.5 and 6.5. Moreover, tannase was stimulated by Na⁺, Ca²⁺, Mg²⁺, and Mn²⁺. The half-life at 40°C lasted 247.55?min. The free energy of Gibbs, enthalpy, and entropy, at 40°C, was 81.47, 16.85, and ?0.21?kJ/mol?·?K, respectively. After total digestion, 123.95% of the original activity was retained. Results suggested that tannase from A. tamarii URM 7115 is an enzyme of interest for industrial applications, such as gallic acid production, additive for feed industry, and for beverage manufacturing, due to its catalytic and thermodynamic properties.     

氧气底吹熔炼氧枪浅析

系统地论述了氧气底吹熔炼氧枪的结构、工作原理、设计计算方法、材质及蚀损机理．指出了延长氧枪使用寿命的措施。     

双河油田注入水适应性及注水井酸化解堵研究

考察了双河油田双河联、江河联注入水堵塞地层的因素;膨胀性黏土，悬浮固体颗粒。细菌及悬浮污油。含膨胀性黏土的双河南、双河北及不含膨胀性黏土的双江岩心粉，在注入水中相对于地层水中的体积膨胀度分别为14．5％、11．1％及0．02％；注入100PV不含悬浮颗粒的等体积比地层水、注入水混合水使双河、双江岩心渗透率分别下降7％和4％、9％和7％。注入水中悬浮颗粒引起岩心渗透率下降，粒径越大、颗粒浓度越大、注入量越大，则渗透率越低。在粒径2．1μm或颗粒浓度3mg／L前后下降幅度变化较大。注入水中硫酸盐还原菌引起岩心渗透率下降，含菌量越大则渗透率开始下降时的注水量越小，注入含菌50个／L的水100PV使岩心渗透率下降7％。岩心对注水合油量敏感，注入含油量20mg／L的水50PV使岩心渗透率下降20％。在岩心注水实验中渗透率下降最严重的是双河南岩心，其次是双河北岩心．江河岩心较轻，注入精细过滤水的双河北岩心渗透率下降大大减少．说明悬浮固体是造成注水堵塞的主要因素。为了解除双河油田注水井的堵塞，研制了含黏土稳定剂、缓蚀剂、铁离子稳定剂、互溶剂的土酸液，与南阳油田使用的低伤害酸液一起，用于1口注水井的解堵，效果良好。图7表4参5。     

油气储层敏感性伤害机理识别方法及应用实例

从油气储层岩石学分析入手,阐述了砂岩储层4类敏感性发生的原因及作用机理,结合几个实例,论述了油气开发实践中,必须针对砂岩储层的非均质性特点,对症下药,在充分掌握储层伤害机理的基础上,研制保护与改造油气层的措施,才能取得实效。本文的研究方法可为陆相复式油气区同类砂岩储集层的勘探、开发提供借鉴。     

MEG钻井液在吐哈油田小井眼侧钻井中的应用

吐哈油田小井眼开窗侧钻井主要采用混原油钻井液,不利于环境保护。从研究MEG单体的作用机理入手,以钻井液润滑性、抑制防塌性为主要评价指标,对MEG钻井液配方进行了优选,并对优选配方钻井液性能进行了评价。该钻井液在4口小井眼开窗侧钻井进行了试验应用。结果表明:应用井无阻、卡现象,平均钻井周期缩短了7.2d;在未混原油的情况下钻井液润滑系数比乳化原油(15%~20%)钻井液降低了34.6%;油层保护效果好,其中温5-41C井日产油14.4t,同比温五区块平均产量提高了128.4%,神218C井是神229区块目前唯一的自喷井。表明优选出的MEG钻井液具有优良的润滑性、抑制防塌性及良好的储层保护效果,特别适合强水敏地层及大斜度井和水平井等特殊复杂工艺井的钻进。     

Progressive damage modelling of SMC composite materials

The present work deals with the modelling of damage behaviour for sheet moulding compound (SMC) composite materials using a finite element analysis package. Specifically, a comparison is made between the results obtained experimentally for a three-point bending test, and those obtained from numerical simulation using a material model already implemented. The simulation has been performed for the material models available within the PAM-CRASH software. The simulation results are compared and validated with respect to experimentation.     

解决高速公路沥青路面早期损坏的技术途径

在对国内大量高速公路调查研究的基础上,论述了我国高速公路沥青路面早期损坏的两种类型:属于短时期内发生的水损坏、车辙、开裂损坏,以及沥青路面的耐久性差、使用寿命短的深层次早期损坏。针对水损坏、车辙、裂缝等局部性质的早期损坏,从路面结构、材料、施工、设计、管理等各方面分析了原因,提出了一系列有效防治高速公路早期损坏的技术措施。