耐温耐盐聚合物堵剂的制备及性能研究

针对高温高矿化度地质条件特点,合成了对苯乙烯磺酸钠–2–丙烯酰胺基–2–甲基丙磺酸–膨润土聚合物堵剂。采用不同浓度盐溶液、使用温度及时间评价其耐盐耐温性能,优化了携带液体系,采用岩芯模拟实验考察堵剂封堵效果及耐冲刷性能。结果表明：该堵剂在80130 ℃恒温放置60 d 后树脂的吸水率和强度基本保持不变,树脂耐温性能良好;在质量分数30% 的模拟盐水溶液中吸水率仍可达12.00 g
g..1,树脂的耐盐性能良好;树脂在含水40% 的乳化油中3 h 不膨胀;岩芯实验测定聚合物堵剂在高渗和中渗通道中封堵率达到99.96% 和96.41%,经30 PV 水长期冲刷封堵率仍可达95.12% 和94.43%。     

Separation occurring during the drop weight tear test of thick-walled X80 pipeline steels

A separation phenomenon occurring during the drop weight tear test of commercial thick-walled API (American Petroleum Institute) X80 strip steel was investigated in this work. Microstructural analysis showed that the band structure of bainite elongated along the rolling direction works as the initiation sites of separation. The propagation of separation can be promoted not only by the occurrence of the band structure of martensite/austenite constituent, prior austenite grain boundaries, and elongated bainite, but also by fine acicular ferrite and bainite. Wide separation formed in the former case, while the narrow one appeared in the latter case. Some methods were proposed to obtain fine and homogeneous acicular ferrite in thick-walled X80 pipeline steel in order to minimize the occurrence of separation.     

基于光纤光栅传感技术敞口混凝土管桩应力测试现场试验

基于4根足尺敞口混凝土管桩现场试验,在桩身刻槽预埋串联式的FBG传感器,成功地将准分布式FBG传感技术应用在贯入过程中桩身轴力的测试,研究了敞口混凝土管桩稳态贯入过程中桩端阻力和桩侧摩阻力的变化规律。试验表明：FBG传感技术能够准确分离桩端阻力和桩侧摩阻力,测试效果较为理想。桩端阻力和桩侧总摩阻力沿深度变化曲线反映土层的工程性质,桩端阻力受土层变化影响明显,硬质土层界面处桩端阻力平均增幅78.5%;桩侧摩阻力进入圆砾层时出现峰值,平均增长幅度为20.2%。桩端位于非硬质土层,桩端阻力、桩侧摩阻力变化不明显。贯入过程中桩身轴力变化曲线表明桩身下部侧摩阻力明显大于上部侧摩阻力。     

超高速低功耗4:1复接器设计、封装及测试

采用CSM 0.35 μm CMOS 工艺,设计了低功耗2.5～3.125 Gbit/s 4∶1复接器.该芯片既可以应用于光纤通信系统SDH STM-16(2.5 Gbit/s)速率级别的光发射机,又可以应用于万兆以太网IEEE 802.3ae 10GBASE-X(3.125 Gbit/s)速率级别的通道接口发送器.系统采用树型结构,核心电路由锁存器、选择器、分频器组成,并采用了CMOS逻辑实现.最高工作速率可达3.5 Gbit/s.芯片供电电压3.3 V,核心功耗为25 mW.该芯片采用SOP-16封装.芯片封装后焊接在高速PCB板上进行测试,封装后芯片最高工作速率为2.3 Gbit/s.     

三相电压型PWM整流器滑模变结构直接功率控制

摘 要：本文提出了一种基于滑模变结构控制理论的三相PWM整流器直接功率控制方案,它利用滑模变结构控制系统的鲁棒性和动态性能较好、参数整定简单的优点,解决了传统上基于PI算法的直接功率控制系统抗扰性能差、对PI控制参数较敏感、网侧电流总谐波含量（THD）较大的缺点;在MATLAB/SIMULINK环境中建立仿真模型,对滑模控制和PI控制两种方案进行仿真比较,结果表明滑模控制方案明显优于PI控制方案.     

缩放平行板间插入旋流片的复合强化传热

为了研究新型换热器--矩形管束换热器的传热性能,通过在缩放平行板间插入一组旋流片来研究旋流片下游的传热与流阻,并与光滑平行板、无旋流片缩放平行板的传热效果进行比较.实验结果表明:在实验范围内(19000相似文献   

Performance Analysis of Data Hiding in MPEG-4 AAC Audio

A high capacity data hiding technique was developed for compressed digital audio. As perceptual audio coding has become the accepted technology for storage and transmission of audio signals, compressed audio information hiding enables robust, imperceptible transmission of data within audio signals, thus allowing valuable information to be attached to the content, such as the song title, lyrics, composer’s name, and artist or property rights related data. This paper describes simultaneous low bitrate encodin...     

Synthesis of biodiesel from rapeseed oil using K2O/ γ -Al2O3 as nano-solid-base catalyst

Nano-solid-base catalyst K₂O/γ-Al₂O₃ was prepared and adopted for the synthesis of biodiesel by transesterification of rapeseed oil with methanol. The particle diameter of the catalyst was about 50 nm, which was measured by transmission electron microscopy (TEM). The variables affecting the yield of biodiesel during transesterification, such as mass ratio of KNO₃ to γ-Al₂O₃, calcination temperature, calcination time, and catalyst content, molar ratio of methanol to oil, reaction temperature and reaction time were investigated. The catalyst obtained by calcining a mixture of KNO₃ and γ-Al₂O₃ at 600 °C for 3 h, was found to be the optimum one, which gave the highest catalytic activity in reaction. With 3% (m _catalyst/m _oil) catalyst, when the transesterification carried out at a molar ratio of methanol to oil 12:1, a reaction temperature of 70 °C, and a reaction time of 3 h, yield of 94% was achieved. Foundation item: Supported by the National High-Technology Research and Development Program of China (863 Program) (2007AA100703)     

桂产新鲜马樱丹叶及花的香气成分的HS-SPME-GC-MS分析

以无需溶剂的简捷的顶空固相微萃取结合气相色谱-质谱法分析了广西产新鲜马樱丹叶及花的挥发性香气成分.从叶的香气中分离出44个峰,鉴定出39种化合物,占香气成分总质量的98.83%.叶的挥发性香气主要成分及其质量分数为:橙花叔醇(16.77%),β-石竹烯(16.51%),α-姜黄烯(10.50%),α-长叶松烯(9.47%),β-榄香烯(8.85%),姜烯(7.91%),α-石竹烯(6.88%),α-香柠檬烯(3.61%),松油烯(3.04%).从花的香气中分离出50个色谱峰,鉴定出个43个成分,占香气成分总质量的98.54%.花的挥发性香气主要成分及其质量分数为:β-石竹烯(13.11%),β-榄香烯(12.55%),α-长叶松烯(11.84%),姜烯(10.48%),α-姜黄烯(9.63%),α-石竹烯(5.79%),橙花叔醇(5.28%),α-香柠檬烯(4.81%),α-松油烯(3.71%).     

马尔可夫时滞网络控制系统的稳定性

针对同时具有马尔可夫(Markov)链跳变特性时滞和随机丢包现象的网络控制系统,建立了网络控制系统的离散模型,利用李亚普诺夫稳定性理论、线性矩阵不等式和自由权矩阵方法,分析了系统的均方稳定性和均方可镇定性,并基于线性不等式给出了系统均方稳定、镇定判据.该方法能判定具有马尔可夫时滞和丢包的网络控制系统的均方稳定性,并设计出同等条件下的均方可镇定时滞依赖控制器.与现有方法相比.能更准确地描述网络时滞特性,有效减小系统保守性,结果更具一般性.最后通过仿真实例证明了方法的有效性.