由于超滤技术对颗粒物和微生物去除效果的优越性和持续性,已经被越来越多地应用于给水处理.然而,膜污染问题影响了超滤膜的应用,在介绍超滤应用于给水处理现状的基础上,从颗粒物/胶体、有机物和微生物3个方面分析了超滤膜污染的主要成因,总结了控制膜污染的预处理技术.
According to the structural features and the Raman spectroscopy characteristics of fuel, a treatment method for fuel to remove Raman fluorescence background by means of the graphitized carbon black (GCB) was put forward in this article. Comparing the Raman spectroscopy and GC?MS analysis results of both untreated samples and the corresponding filtering adsorption processed fuel samples by GCB, the proposed novel pretreatment method was proved effective. The conclusion is reached that the main substances in the fuel resulting in fluorescence are the derivants of phenanthrene, anthracene, pyrene and other polycyclic aromatic hydrocarbon (tricyclic and above) and sulfur, nitrogen hetero atoms aromatic hydrocarbon compounds, which can be effectively dealt with by GCB as well as little influence on Raman spectroscopy characteristics of fuel.
With alumina sol as additive, the effect of the mass fraction of alumina sol on mechanical properities of cement?based materials was investigated and its mechanism was analyzed by the heat of hydration test, XRD and SEM analysis. The results reveal that with the increase of mass fraction of alumina sol, the fluidity of cement mortar specimens decreases continually, the flex?ural and compressive strength of cement mortar specimens cured for different ages increase first and decrease later. When the mass fraction of alumina sol is 2%, the strengths reach the peak. The heat flow rate of hydration of cement specimens increases and hydra?tion induction period is shortened when alumina sol is added to cement paste, so as to accelerate the process of hydration of cement. In addition, with alumina sol incorporation, Ca(OH)2 generated by hydration of cement is consumed and more C-S-H, C-A-H gel and so on that are advantageous to the strength are produced, resulting in that the internal structure of cement mortar specimens be?comes more uniform and denser and its compactness and strength are improved.
The backbone network based on the structure of the clusters’networks in GAF protocolis utilized to research the problems caused by the tree?like hot spot of unfair delay and data packets loss. An MAC layer rotating sleep algorithm named ST?MAC which is based on the DMAC protocol is proposed and simulated by the software Matlab. The results show that the algorithm can balance the node data delays in different layers of the network tree and reduce both packet loss probability and energy consumption.
Based on the basic principles of both the mechanics of materials and fluids, an analytical mathematic model is con?structed to reveal the relationship between the working head and the variation of the polyurethane hose’s inner diameter. And a new method featuring the consideration of pipe expansion effects is derived to calculate the friction loss for polyurethane hose. Verifica?tion of the proposed method in this paper is made by utilizing the pressure loss data provided by the National Fire Equipment Quali?ty Supervision and Inspection Center and the experimental records of transportation tests for a certain type of military hose line in our army. The pump station placement results from both the traditional and the new friction loss calculation methods are compared and analyzed. The results show that the traditional method ignores the hose’s pipe expansion effects under working pressure and in?troduces a liner friction loss increment while the pipe length extends and will generate quite a significant error, while the proposed new method takes into account the expansion of hose with the increasing pressure and the friction loss will increase more slowly when the pipe length increases. The new method is more accurate than the traditional method and thus makes the application of polyurethane hose especially the long distance one more economical. The method has the potential to be an universal method for hose pipe, in which the pipe expansion effects must be taken in consideration.
The design method of the flexural capacity of SAP concrete beam reinforced with fiber reinforce plastic was ana?lyzed, the bending performance of this beam was explored based on stiffness control and creep characteristics, and on which design theories for this beam was systemically studied. Computing formulas of the ultimate bearing capacity and the cracking moment of the component had been put forward, respectively. Four 6?meter long SAP concrete beams reinforced with carbon?glass fiber tendon were prepared for performing destructive bending test by loading onto two points. Then the beams are tested under static flexural loading to investigate the cracking patterns under all levels of load. The modes of failure, characteristic of deformation and load?car?rying capacities are evaluated in the test. It turns out that the design method is reasonable, and calculated values of bearing capacity are in close agreement with the experiment results.
针对支持向量机分类中存在盲区的问题,在分析多分类支持向量机构建方法的基础上,采用二叉树支持向量机,通过类型知识库动态更新,建立了二叉树支持向量机动态多分类模型;选取径向基函数作为核函数,给出了提高多分类模型性能的核参数和惩罚因子寻优遗传算法;以卫星整流罩空调系统表冷器控制单元为仿真实验对象,建立了传感器偏置故障、漂移故障、完全故障和精度下降故障的多分类模型,验证了提出方法的有效性.
In the test of bonding performance between inorganic polymer concrete and rebar at high temperatures, different treatment methods for exposed reinforcing rebar in central drawing test will affect the final test results. However, the fire resistance performances of inorganic polymer concrete and ordinary concrete are different. In order to select the appropriate way of wrapping package, rebar was wrapped by adding material layer by layer, following with drawing test at high temperature and measurement of its internal temperature. The main conclusions are as follows. Without being wrapped, the drawing test specimen will be transferred heat into along the rebar at high temperature so that its internal temperature will be higher about 30%~40%than the actual condi?tion, and which will affect the experimental results of drawing test. The package way has a great influence on the internal tempera?ture and ultimate bond strength of specimen. The suitable treatment methods selected by drawing test for rebar can lay firm founda?tion for further bond test for inorganic polymer concrete and rebar at high temperature.
In order to analyze the penetration resistance mechanism of flexible honeycomb protective structure made of high density polyethylene (HDPE), the finite element model (FEM), which can reflect the mechanical characteristics of the structure when it is undertaking the ballistic impact, is built. By comparing the FEM simulation results and the actual gun?shooting experi?ments, it is found that the FEM has consistent phenomenon with the gun?shooting test. Besides, by adding the influent factors such as the bullets’number, the bullet position and angle, the influence and the damage effect of the factors can be figured out from the FEM. The results show that:the bullet angle can make effect on the trajectory and obstruction of itself. Two bullets shot one by one can penetrate deeper that one bullet, which means that this structure, to some extent, can dissipate some energy and its second strike resistance capability is considerable.
In view of the impact damage of the medium and high voltage asynchronous motor starting to the electric power sys?tem, the mechanical transmission device and the motor itself, and based on the analysis of the basic principle of motor soft starting, the power electronic technology and microcomputer control technology are applied to design the switch transformer medium and high voltage asynchronous motor soft?starting equipment. The structure and function of the device are introduced, and the key meth?ods of the zero cross signal detection, high voltage thyristor trigger, torque ripple in the initial stage of isolation starting, motor power?factor angle, starting under heavy loading and processing method with large motor power are proposed. The actual industrial applica?tion test results show that the equipment has the expected soft starting performance and wide application prospect.
A comparative experiment of two air conditioners charged with R290 respectively for cooling is explored at actual working conditions. The internal and external parameters of the air conditioners were measured. The influence of indoor and outdoor temperature on the operating parameters and operating characteristics of R290 was analyzed. Through the economic analysis, the ini?tial cost and running cost of two air conditioners charged with R290 respectively were compared. The results show that the air condi?tioner charged with R290 can work correctly. And compared with the original air conditioner, the air supply parameters, cooling ca?pacity and EER (energy efficiency ratio) of the R290 air conditioner are close to the original air conditioner, or even better than the original. Under the premise of ensuring the safety, the air conditioner directly charging with R290 has excellent benefits of energy saving and environmental protection.
Layered double hydroxides (LDHs) with excellent anion exchange capacity have drawn increasing interests in the removal of anionic contaminants. In this work, NiCoFe?LDHs with different amount of substance were prepared by the conventional co?precipitation method. The effect of contact time and initial mass concentration on adsorption of pollutants were investigated by XRD FT?IR,SEM,BET,et al. It is found that the amount of substance of Ni2+, Co2+, Fe3+was 1∶3∶1, the sample performed best up?take capability than other samples. The adsorption rate can reach 93%when methyl orange initial mass concentration was 10 mg/L. The results indicate that the adsorption behaviors of these pollutants follow the pseudo?second?order model, and the adsorption iso?therms fitted well with both Langmuir isotherm and Freundlich model at different initial mass concentration. The possible adsorption behavior includes two processes: external surface and interlayer anion exchange. The monolayer saturated adsorption capacity of Ni1Co3Fe1?LDHs is found to be 460.83 mg/g for methyl orange. These findings show that the NiCoFe?LDHs are regarded as promis?ing adsorbents for wastewater treatment.
The growth of microbes especially fungus in aviation fuel storage tanks and aircraft wing tanks can cause fuel filter plugging, corrosion, and maintenance costs increasing associated with these problems. Despite the fact that good maintenance prac?tices can reduce the risk of microbial contamination, it is recognized that application of bactericide is the only realistic and effective way to solve this problem quickly and effectively once the aviation fuel is contaminated. Combination with related literature reports, a newly aerosol fuel bactericide was developed, and its bactericidal effect on four characteristic fungi was discussed in this paper.
In order to solve the problem that dynamics and continuity of application are ignored in present application reliabil?ity research, the continuous multi?state model of node performance is put forward by application flow combining with time and rele?vance of application flow, and then the application reliability evaluation indicators that show the quality of accomplishment of appli?cation flow are established. The simulation and analysis on one local area network with three?tier architecture are experienced. The results of experiences show that increasing the capacity and throughput rate of network equipment on convergence layer have signifi?cant improvement on application reliability;however, that on access layer has little improvement on application reliability.
在"混合型负载"数据中心的虚拟机迁移过程中,针对主机性能和能源额外损耗问题,提出了一种基于迁移成本感知的迁移决策算法.为减少频繁迁移对数据中心的扰动,设计了利用自回归模型预测物理主机资源利用率并结合双阈值的迁移触发策略,建立了迁移性能和能耗成本评估模型,确定了待迁移物理主机上虚拟机的迁移优先级.仿真实验结果表明,该算法能够在保证服务级别协议不被破坏的条件下,降低"混合型负载"数据中心的迁移次数和能耗.
In order to enhance the adaptability and concealment of the Honghe border’s military scout barracks, the best way is to combine the barracks with the geographical space. Regional design is the most common way to adapt the modern architecture to the environment, and integrating with the environment. Through the analysis of the inner spatial layout and external space organiza?tion of the individual building of soil room with the traditional architecture form in Honghe mountainous region, and the application of regional materials and technology, the possibility and practical strategy of combining the regional design with Honghe border mili?tary scout barracks are discussed, which provides a new design idea for improving the concealment of military scout barracks in the border areas.
The efficient degradation of dye in aqueous solution is still a challenge. The γ?Fe2O3/reduced graphene oxides (rGO) magnetic nanocomposites were used as adsorbents for adsorption removal of methyl blue. Firstly, theγ?Fe2O3/rGO magnetic nanocomposites were prepared with one step synthesis method by means of the redox reaction. And then, X?ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and X?ray photoelectron spectroscopy (XPS) analysis were applied to characterize the property and structure of the synthesized nanocom?posites. The results of isotherm show that the methyl blue can be degraded efficiently. The maximum adsorption capacity reachs to 86.732 mmol/g. Meanwhile, theγ?Fe2O3/rGO magnetic nanocomposites show better reusability and stability. The removal efficiency is still 50.17%after theγ?Fe2O3/rGO magnetic nanocomposites’5th cycle application.
With the good thermal conductivity and adsorption properties of expanded graphite (EG), heneicosane/expanded graphite composite phase change material was prepared by melt blending method with the expanded graphite as the carrier and he?neicosane (HE) as phase change material. Characterization of the composite phase change materials were analyzed by means of scan?ning electron microscopy, differential scanning calorimetry, the Fourier infrared spectrometer and comprehensive thermal analyzer. The results show that the expanded graphite has network like porous structure and its stability can increase while it is packaged by physical combination with heneicosane;and with the increase of the mass fraction of EG, the thermal conductivity of the composite phase change material increases, the weight loss interval prolonges, and the thermal stability enhances. The phase transition tem?perature of the composite phase change material is slightly lower than that of the HE. The over cooling phenomenon improves, and the latent heat of phase transformation is high. The time of reserving and releasing heat decreases, and the efficiency increases.
Current mining algorithm of association rule based on item constraints often contains a large number of redundant worthless rules for the designer’s ignoring the fore?part and rear?part set of the rules in which the user is interested. In order to solve this problem, a mining algorithm called AR_F&R is proposed for association rules with constraint on fore?part and rear?part of rules. According to the needs of the users, the algorithm constructs the designated fore?part set and rear?part set of these interested rules firstly. Subsequently the frequent item sets and association rules which user needs are obtained. The contrast experiments be?tween AR_F&R and algorithm Recorder, which is a representative item constraint association rule mining algorithm, shows that AR_F&R has a higher mining efficiency and its execution time is also reduced.
为有效提高战时导弹火力打击的效果,对多波次条件下打击任务分配与运输决策相结合的问题进行研究.根据实际战场情况进行模拟,构建了战时导弹火力打击任务分配与运输决策模型,设计出基于聚类分析和Floyd最短路径的综合性算法,运用分步讨论的方法依次求解各个参数,并通过线性加权的方式将多目标优化问题转化为单目标优化问题,进而找出最优方案,最后运用仿真算例验证了该模型的可行性及算法的有效性.
