An optimized numerical method to pre-researching the performance of solid-phase oxygen control in a non-isothermal lead–bismuth eutectic loop

In the present work,a new transient calculation method for parameters that can be used to evaluate the ability of oxygen control in a non-isothermal lead-bismuth eutectic(LBE)loop with solid-phase oxygen control was proposed.It incorporates the dissolution process of PbO particles and the oxygen mass transfer process,and an optimized method was used for finding out the optimized oxygen mass transfer coefficient.In numerical terms,three mass transfer models were simultaneously applied,and comparisons of calculated and experimental results from the CRAFT loop indicated that the optimized calculation method and these new oxygen mass transfer models were correct and applicable to other LBE loops.Through this calculation method,we aimed to optimize prediction of the distribution of oxygen and iron concentrations,time taken to establish the steady state of oxygen,and maximum dissolution/precipitation rates of corrosion products and corrosion depth across the entire LBE loop.We hope that this work will provide a potential reference for designing a more intelligent oxygen control system in the future.

Taxol Production in Suspension Cultures of Taxus chinensis as Affected by the Combination of Nutrient Feed with Dissolved Oxygen Control

Influence of the combination of nutrient feed with dissolved oxygen control on taxol production in suspension cultures of Taxus chinensis (Pilg.) Rehd. was investigated in bioreactors. Addition of feeding medium with 20 g/L sucrose on day 16 enhanced both the biomass and taxol production in 5-L bioreactors. Further investigation of the fed-batch cultures in a 20-L bioreactor showed that cultivation under a low dissolved oxygen tension (DOT) of 20% for the entire culture resulted in the highest taxol content of 0.98 mg/g DW, while the taxol production was lower than that with 40% and 60% DOT. Moreover, taxol accumulation was remarkably improved by the cultivation of cells initially under DOT of 60% for 20 d followed by changing the DOT to 20% for another 12 d. By combining the use of these two strategies, a maximum taxol content of 18.7 mg/L was obtained in a 20-L bioreactor.

Precisely Controlled Synthesis of Pt-Pd Octahedral Nanoframes as a Superior Catalyst towards Oxygen Reduction Reaction

Pt-based nanoframes represent a class of promising catalysts towards oxygen reduction reaction. Herein, we, for the first time, successfully prepared Pt-Pd octahedral nanoframes with ultrathin ridges less than 2 nm in thickness. The Pt-Pd octahedral nanoframes were obtained through site-selected deposition of Pt atoms onto the edge sites of Pd octahedral seeds, followed by selective removal of the Pd octahedral cores via chemical etching. Due to that a combination of three-dimensional opens geometrical structure and Pt-skin surface compositional structure, the Pt-Pd octahedral nanoframes/C catalyst shows a mass activity of 1.15 A/mgPt towards oxygen reduction reaction, 5.8 times enhancement in mass activity relative to commercial Pt/C catalyst （0.20 A/mgPt）. Moreover, even after 8000 cycles of accelerated durability test, the Pt-Pd octahedral nanoframes/C catalyst still exhibits a mass activity which is more than three times higher than that of pristine Pt/C catalyst.

Air flow control based on optimal oxygen excess ratio in fuel cells for vehicles

Air flow control is one of the most important control methods for maintaining the stability and reliability of a fuel cell system, which can avoid oxygen starvation or oxygen saturation. The oxygen excess ratio （OER） is often used to indicate the air flow condition. Based on a fuel cell system model for vehicles, OER performance was analyzed for different stack currents and temperatures in this paper, and the results show that the optimal OER was affected weakly by the stack temperature. In order to ensure the system working in optimal OER, a control scheme that includes an optimal OER regulator and a fuzzy control was proposed. According to the stack current, a reference value of air flow rate was obtained with the optimal OER regulator and then the air compressor motor voltage was controlled with the fuzzy controller to adjust the air flow rate provided by the air compressor. Simulation results show that the control method has good dynamic and static characteristics.

Reactive oxygen species—Control and management using amphiphilic biosynthetic hydrogels for cardiac applications

The reactive oxygen species (ROS) originated from endogenous and exogenous sources play a dominant role in the initiation and propagation of several diseases. It is therefore an urgent need to explore substances capable of encountering the ROS and resist the damage caused by ROS. The present paper deals with various aspects of generation and implications of ROS in the management of myocardial infarction. The use of biosynthetic amphiphilic biodegradable hydrogels in the control and management of ROS in myocardial infarction was studied using a biosynthetic hydrogel (PA-PEGDA) comprising poly(propylene fumarate)-co-alginate copolymer cross-linked with calcium and polyethylene glycol diacrylate (PEGDA). The effect of ROS on the cell growth was studied using H2O2 as model ROS molecule. The present hydrogel resists the penetration of ROS in the cell which was evident from the live/dead assay, increased intra cellular GSH levels when compared with the H2O2 treated positive and curcumin treated negative control cells. The Comet assay reveals genomic integrity of the cells exposed to the present hydrogel. The hydrogel is a promising injectable material for the management of myocardial infarction and ischemia.

Simulation of VGT control based on charge oxygen concentration

A turbocharged diesel engine model was built with the GT-Power software,and experimentally verified.Then two different control variables for the control of the variable geometry turbocharger（VGT）were described,and their distinct effects on engine performance,i.e.NOxand soot emissions and fuel consumption,were simulated and compared on the basis of this model.The results showed that NOxemissions decreased obviously with the increase of exhaust gas recirculation（EGR）rate at constant boost pressure condition,but soot emissions and fuel consumption considerably increased.It was a good way to reduce NOxemissions without increasing fuel consumption and soot emissions when VGT was controlled to maintain the excess oxygen ratio unchanged as EGR rate increases.

Novel Oxygen Storage Components Promoted Palladium Catalysts for Emission Control in Natural Gas Powered Engines

A three-way catalyst comprised novel oxygen storage components for emission control in natural gas powered engines was prepared. The addition of novel oxygen storage components to the Pd/γ-Al2O3 catalysts resulted in improved activities of the fresh and aged catalyst by lowering the light-off temperature for methane in natural gas engines exhaust.

Simulation of oxygen transfer in liquid lead under influence of nanoparticles by using lattice Boltzmann method

Oxygen transfer presents a serious challenge in the application of liquid lead as a nuclear coolant in advanced reactors. To mitigate corrosion by liquid lead in contact with steel, carefully controlling the oxygen concentration has been used as an effective way. Oxygen needs to mix in liquid lead uniformly and quickly. To enhance oxygen transport in liquid lead, nanoparticles are added to the liquid metal. In the current study, a lattice Boltzmann method is applied to investigate natural convection of copper/lead and aluminum oxide/lead in two-dimensional simplified container. Two thermal boundary cases are evaluated in order to check the effect of different natural convection flow patterns on oxygen transport. Some useful information are obtained such as improvement in natural convection and reduction in oxygen equilibrium time.

Control-Net网络技术在污水处理厂的应用

Control -net网络是一个开放的、高速的、确定性的工业局域网,用于传输对时间有苛刻要求的信息,为对等通信提供实时控制和报文传送。可实现PC机、控制器、操作界面设备、I/O模块等不同设备间的联网通信。网络成功地应用在多种工业自动控制系统上。

Applicable scope of oxygen-reduced air flooding and the limit of oxygen content

The mechanisms of oxygen-reduced air flooding(ORAF)and the explosion limit and the corrosion control approaches were studied based on the pilots of oxygen-reduced air flooding(ORAF)in the Dagang,Changqing and Daqing oil fields in China.On the foundation of indoor investigations and pilots,the explosion limits,oxygen reduction limits and corrosion control approaches were clarified.When the temperature of reservoir is equal to and higher than 120℃,there is a violent reaction between oxygen and crude oil,that means the effect of low temperature oxidation would be fully taken use of to enhance oil recovery by air flooding directly;nitrogen dominated immiscible flooding with oxygen-reduced air should be applied in cases where reservoir temperature is below 120℃ with little oxygen consumption and little heat generated.The oxygen-reduced air flooding is suitable for 3 types of reservoirs:low permeability reservoir,water flooding development reservoir of high water-cut and high temperature and high salinity reservoir.In the process of development,in order to ensure safety,the oxygen reduction limits should be controlled fewer than 10%,while oxygen-reduced air can obviously reduce the corrosion rate of pipes;The surface pipelines and injection wells don’t need to consider about oxygen corrosion with no water,special materials and structure of pipe or corrosion inhibitor can be applied to the surface pipelines and injection wellbores with water.Air/oxygen-reduced air is a low-cost displacement medium and it could be applied in many special conditions of low permeability reservoir for energy supplement,huff and puff and displacement,that means oxygen-reduced air flooding has become the most potential strategic technology in 20 years.

基于Control Logix5000控制器的风机变频系统设计

为了维持某污水处理厂曝气池内溶解氧恒定,采用变频控制技术与PID算法,来满足曝气池内溶解氧的需求。介绍了基于罗克韦尔PLC的风机变频系统的硬件配置和硬件设计,利用罗克韦尔上位机组态软件RSview设计流程控制界面,风机变频系统的软件设计,最后对风机变频系统的节能效果做了分析。

Problems in Water Environmental Control—Sense and Nonsense in Measurement of Water Protection

Water environmental control and process refinement inside a wastewater treatment plant (WWTP) is fundamentally based on sampling, analysis and on-line measurements on water and sludge streams. The problems related to an accurate and reliable control and thus an efficient water protection are addressed in the following. Four different crucial points whenever a sampling and control scheme is planned: 1) Where should a sampling and on-line measurement take place? 2) When should sampling take place? 3) How should the sampling and on-line measurement take place? 4) Which variables should be controlled? Examples are given from different plants demonstrating ways to address the questions. Especially the relevance of the adopted parameter BOD (Biochemical Oxygen Demand) is discussed. It is finally suggested to even abandon the use of BOD as consent variable in favor of on-line measurement of Suspended Solids, Nitrogen and Phosphorous.

循环流化床锅炉节能减碳运行调控及工程验证

构建基于烟气中氧气体积分数及炉膛出口压力的锅炉运行协同控制模型,可以实时、准确地预测烟气中氧气体积分数的变化趋势,提前给定锅炉二次风机和引风机控制指令,显著减小了不同负荷条件下锅炉烟气中氧气体积分数、负压等关键运行参数的波动.在300 t/h循环流化床锅炉上的工业验证结果表明:利用协同控制模型可以提高锅炉运行控制的品质,锅炉变负荷工况条件下烟气中氧气体积分数控制在目标值±0.25%范围内,炉膛出口压力控制在目标值±45 Pa范围内的统计概率为99%.运行一周的统计结果表明,相比于原有控制,协同控制模型投运后单位产汽量耗煤可以减小1.508%,单位产汽量风机耗电可以减少1.886%.

市政污水生化处理过程中曝气控制系统研究进展

为了促进污水处理厂(WWTPs)的低碳可持续运营管理,近年来致力于改善出水质量、削减运营成本和降低温室气体排放的智能曝气控制技术蓬勃发展,但关于可持续污水处理厂的最佳曝气控制策略尚未达成共识。系统综述了曝气过程中溶解氧浓度对于N2O释放的影响,通过分析对比不同曝气控制策略的差异及优缺点,提出曝气控制策略进一步优化的建议,为实现市政污水处理厂溶解氧的综合科学管理提供理论支撑,旨在为污水处理行业提供科学依据和技术支持,促进环境保护和可持续发展。在曝气控制系统中加入N2O排放量化模型来实现出水水质、曝气能耗、温室气体排放三者之间的平衡是未来的关键研究方向,需开发更准确、更合适的温室气体量化模型、灵活的控制方法和智能曝气策略,以满足污水处理厂更多的需求。

锅炉炉膛含氧量神经元PID控制及其仿真

燃煤锅炉炉膛中过低的含氧量会使燃烧不充分,过高的含氧量又会使送风带走较多的热能。在一定的给煤速度之下,必须选择合适的送风量才能使炉膛燃烧维持在最佳状态。故必须给出送风量的调节控制方案。为此,首先对于锅炉炉膛的含氧量和送风之间的非线性关系进行数学建模,进而尝试PID补偿控制设计,用根轨迹法确定使闭环系统能稳定的增益.另外,还采用了一种人工神经网络控制方案,比较了两种方法的计算机仿真结果,验证了人工神经元PID控制的有效性。

基于多变量控制策略的生物发酵罐溶解氧浓度控制

为解决当前生物发酵罐中溶解氧浓度饱和问题,设计了基于多变量控制策略的生物发酵罐中溶解氧浓度控制新系统。该控制系统通过控制两个变量(培养液的进气气流速率和搅拌器搅拌速度)来调节生物培养液的溶解氧浓度,并通过选择合适的空气流量水平,避免氧气溶解饱和,而且还可通过调整搅拌速度控制器的参数,适应控制点的实时变化。仿真实验结果表明,所设计控制系统可根据系统中控制条件切换搅拌控制器参数,来保证对空气流的正确切换和主动控制器的正确选择,并最终保证控制回路稳定运行。对实际系统的测试结果表明,当培养液因搅拌而出现溶解氧饱和时,所设计控制系统通过有效改变气流,避免培养液中溶解氧饱和问题的出现。所设计控制系统能够实现生物发酵罐中溶解氧浓度的高效控制。

Preparation and Properties of Modified Sol-Gel Sensing Membrane for Fiber Optic Oxygen Sensor

Modified sensing membranes based on fluorescence quenching were prepared by the sol-gel method,using formamide as the drying control chemical additive,tetraethoxysilane as the main material,Ru(phen) 3Cl 2 as the indicator.The membrane with the optimum thickness of 20-50μm is uniform and crack-free,in which the indicator has a very small leaking rate.The membrane is immersed in water for 50h,the membrane sensing parameter M decreases by less than 5%.The fiber optic oxygen sensor with the sensing membrane has a detection limit of 5×10 -6M(ppm),a response time of less than 30s,excellent reproducibility and stability.

堆积结构对液态铅铋合金固态氧控影响规律

在铅铋反应堆中,固态氧控技术用于有效地抑制液态LBE(铅铋合金)对结构材料的腐蚀。目前固态氧控中堆积颗粒状态对氧传质影响的研究不足,这阻碍了设备的设计与优化。为了研究固态氧控中不同形状颗粒堆积床对高温液态铅铋中湍流氧传质的影响,建立固态氧控质量交换器数值模型,采用离散单元法生成堆积颗粒,并考虑湍流传质的数学模型。通过对不同数值模型的验证和案例分析,结果表明非均匀介质对LBE中氧传质有显著影响,均匀化的多孔介质模型低估了传质速率。颗粒形状对氧传质起到重要作用,不同形状颗粒堆积床的压力分布、速度分布和有效扩散系数有所不同。虽然单个圆环形颗粒具有较高的溶解速率,但堆积床内的总溶解速率较低。

沙滩椅体位及控制性降压下肩关节手术病人脑氧饱和度与脑部血流速度改变及其对术后神经认知的影响

目的分析沙滩椅体位及控制性降压下肩关节手术中脑氧饱和度(rScO_(2))与脑部血流速度的变化,及其对病人术后神经认知的影响。方法选取拟于本院以沙滩椅体位接受肩关节手术治疗的病人60例,均为美国麻醉医师协会(ASA)分级Ⅰ、Ⅱ级,在静脉全身麻醉及控制性降压干预下,于麻醉前、麻醉并转入沙滩椅体位后5 min、手术开始时以及手术开始后每隔20 min直至手术结束进行rScO_(2)、大脑中动脉血流速度(VMCA)和有创血压(心脏水平和耳道水平)的检测,并记录脑氧欠饱和事件(CDE)的发生。同时,于术前和术后24 h对病人进行神经认知能力测试。结果转入沙滩椅体位后所有病人的rScO_(2)和VMCA相比麻醉前都有所下降。经历CDE的病人耳道水平平均动脉压、rScO_(2)和VMCA均显著低于未经历CDE的病人,并且术后24 h时连线测试成绩也更低,组间差异有统计学意义(P<0.05)。结论对于ASA分级Ⅰ、Ⅱ级病人,沙滩椅体位及控制性降压下肩关节手术中部分病人的rScO_(2)和VMCA较麻醉前显著下降并发生CDE,进而对术后神经认知产生不利影响。

基于自适应平滑死区逆的航天气化炉氧气流量控制

航天气化炉氧气流量对象具有大噪声、非线性和强干扰特性,氧气流量控制系统自动化程度低。由于氧气阀门具有死区非线性,人工操作和常规控制策略常常无法获得理想的控制效果,因此提出了一种自适应平滑死区逆算法,补偿氧气阀门的死区非线性,再引入氧气主管压力的变化速度作为前馈量,补偿氧气压力波动带来的干扰。自适应平滑死区逆与前馈控制成功应用于航天气化炉氧气流量控制系统,控制效果明显改善。