Materials,preparation,performances and mechanism of polyurethane modified asphalt and its mixture:A systematic review

With the rapid development of asphalt pavement technology,it has attracted considerable attention to improving the durability of asphalt pavement.An effective action is to use modified asphalt with high performance and durability.Polyurethane(PU)has been used in asphalt pavement engineering to enhance the durability and service life of asphalt pavement because of its excellent high-temperature performance,toughness,wear resistance,aging resistance and oil resistance.However,PU modified asphalt technology is still in the exploratory stage.The preparation,modification mechanism and working performances of PU modified asphalt need to be further clarified.Therefore,this paper summarized the research progress of PU modified asphalt and its mixture.The composition of PU modified asphalt was introduced.The addition methods of PU materials and preparation process parameters of the PU modified asphalt were determined.The modification mechanism of PU on asphalt was discussed.The effects of polyurethane on asphalt were analyzed and the road performances of its mixture were evaluated.Finally,the development tendency towards PU modified asphalt and its mixture were forecasted.

Using a Modified Soil-Plant-Atmosphere Scheme(MSPAS)to Simulate the Interaction between Land Surface Processes and Atmospheric Boundary Layer in Semi-Arid Regions

This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary layer processes and land surface processes. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feasibility of the model is well proved in this paper. The numerical simulation results from MSPAS show good agreement with reality. The scheme is used to obtain reasonable simulations for diurnal variations of heat balance, potential temperature of boundary layer, and wind field, and spatial distributions of temperature, specific humidity, vertical velocity, turbulence kinetic energy, and turbulence exchange coefficient over desert and oasis. In addition, MSPAS is used to simulate the interaction between desert and oasis at night, and again it obtains reasonable results. This indicates that MSPAS can be used to study the interaction between land surface processes and the atmospheric boundary layer over various underlying surfaces and can be extended for regional climate and numerical weather prediction study.

Three-dimensional analysis of the modified sloping cooling/shearing process

A self-designed setup of modified sloping cooling/shearing process was made to prepare the semisolid Al-3wt%Mg alloy. A three-dimensional simulation model was established for the analysis of preparing the semisolid Al-3wt%Mg alloy. Through simulation and experiment, it is shown that the sloping angle of the plate greatly affects temperature and velocity distributions, and the temperature and velocity of the alloy at the exit of the sloping plate increase with the increase of the sloping angle. The alloy temperature decreases linearly from the pouring mouth to the exit. The alloy temperature at the exit increases obviously with the increase of pouring temperature. To prepare the semisolid Al-3wt%Mg alloy with good quality, the sloping angle θ=45° is reasonable, and the pouring temperature is suggested to be designed above 650-660℃ but under 700℃.

Enhanced biological nutrient removal in modified carbon source division anaerobic anoxic oxic process with return activated sludge pre-concentration

A pilot-scale modified carbon source division anaerobic anoxic oxic(AAO) process with pre-concentration of returned activated sludge(RAS) was proposed in this study for the enhanced biological nutrient removal(BNR) of municipal wastewater with limited carbon source. The influent carbon source was fed in step while a novel RAS pre-concentration tank was adopted to improve BNR efficiency, and the effects of an influent carbon source distribution ratio and a RAS pre-concentration ratio were investigated. The results show that the removal efficiency of TN is mainly influenced by the carbon source distribution ratio while the TP removal relies on the RAS pre-concentration ratio. The optimum carbon source distribution ratio and RAS pre-concentration ratio are 60% and 50%, respectively, with an inner recycling ratio of 100% under the optimum steady operation of pilot test, reaching an average effluent TN concentration of 9.8 mg·L-1with a removal efficiency of 63% and an average TP removal efficiency of 94%. The mechanism of nutrient removal is discussed and the kinetics is analyzed. The results reveal that the optimal carbon source distribution ratio provides sufficient denitrifying carbon source to each anoxic phase, reducing nitrate accumulation while the RAS pre-concentration ratio improves the condition of anaerobic zone to ensure the phosphorus release due to less nitrate in the returned sludge. Therefore, nitrifying bacteria, denitrifying bacteria and phosphorus accumulation organisms play an important role under the optimum condition, enhancing the performance of nutrient removal in this test.

A novel multimode process monitoring method integrating LCGMM with modified LFDA

Complex processes often work with multiple operation regions, it is critical to develop effective monitoring approaches to ensure the safety of chemical processes. In this work, a discriminant local consistency Gaussian mixture model(DLCGMM) for multimode process monitoring is proposed for multimode process monitoring by integrating LCGMM with modified local Fisher discriminant analysis(MLFDA). Different from Fisher discriminant analysis(FDA) that aims to discover the global optimal discriminant directions, MLFDA is capable of uncovering multimodality and local structure of the data by exploiting the posterior probabilities of observations within clusters calculated from the results of LCGMM. This may enable MLFDA to capture more meaningful discriminant information hidden in the high-dimensional multimode observations comparing to FDA. Contrary to most existing multimode process monitoring approaches, DLCGMM performs LCGMM and MFLDA iteratively, and the optimal subspaces with multi-Gaussianity and the optimal discriminant projection vectors are simultaneously achieved in the framework of supervised and unsupervised learning. Furthermore, monitoring statistics are established on each cluster that represents a specific operation condition and two global Bayesian inference-based fault monitoring indexes are established by combining with all the monitoring results of all clusters. The efficiency and effectiveness of the proposed method are evaluated through UCI datasets, a simulated multimode model and the Tennessee Eastman benchmark process.

Control for Modified University of Cape Town Process Using Oxidation-Reduction Potential in the Second Anoxic Zone

The aim of this work is to evaluate the feasibility of applying the technology of oxidation-reduction potential （ORP） control on the municipal wastewater treatment system for nitrogen and phosphorus removal. Meanwhile the relation between the optimal ORP （ ORPopt ） and influent C/N ratio was evaluated, in which the influent chemical oxygen demand （ COD ） concentration was stabilized at （290 ± 10 ） mg/L, the influent total phosphorus （TP） concentration was stabilized at （7.0 ± 0.5 ） mg/L. The results indicated that： （1） the ORP in the second anoxic zone had effect on nitrogen and phosphorus removal capability, and the average percentages of phosphorus uptake in ANO2 zone （ ηa ） increased with increasing ORP, i. e. , increasing from 12. 0% at - 143 mV to 22.0%,30.0%,37.0%, and45.0% at -123, -111, -105 and -95 mV, respectively; （2） the ORPopt as function of influent C/N ratio could be calculated by the equation： y ffi 252. 73e〈 -x/3.39） _ 131.01 ; the maximum percentage of phosphorus uptake in ANO2 as function of the ORPopt could be calculated by the equation： y ffi -0.49e（x/15.58） ＋ 1. 51. The ORPopt was the important process control parameter that must be optimized for operation of enhanced biological phosphorus removal （ EBPR ） system. Moreover, ORP sensor is very simple, and the industrial applications of this strategy is practical.

Modified constitutive model and workability of 7055 aluminium alloy in hot plastic compression

To obtain flow behavior and workability of 7055 aluminium alloy during hot deformation,hot compression tests at different temperatures and strain rates are conducted.True stress?strain curves of 7055 aluminium alloy under different conditions are obtained and the flow stress increases with ascending strain rate and descending temperature.For Arrhenius constitutive equation,each material parameter is set as a constant,which will bring forth large error for predicting flow behavior.In this work,material parameters are fitted as a function of temperature or strain rate based on experimental results and a modified constitutive equation is established for more accurate prediction of flow behavior of 7055 aluminium alloy.The effects of temperature and strain rate on power dissipation and instability are analyzed to establish a processing map of 7055 aluminium alloy.The dominant deformation mechanism for microstructure evolution at different deformation conditions can be determined and high efficiency of power dissipation may be achieved from power dissipation map.Meanwhile,proper processing parameters to avoid flow instability can be easily acquired in instability map.According to the processing map,optimized processing parameters of 7055 aluminium alloy are temperature of 673?723 K and strain rate of 0.01?0.4 s^?1,during which its efficiency of power dissipation is over 30%.Finite element method(FEM)is used to obtain optimized parameter in hot rolling process on the basis of processing map.

Formation of TiO2 Modified Film on Carbon Steel

A new technique for preparing TiO2 modified film on carbon steel was accomplished by electroless plating and sol-gel composite process. The artificial neural network was applied to optimize the preparing condition of TiO2 modified film. The optimized condition for forming TiO2 modified film on carbon steel was that NiP plating for 50 min, dip-coating times as 4, heat treatment time for 2 h, and the molar ratio of complexing agent and Ti(OC4HZ9)4 kept 1.5:1. The results showed that TiO2 modified film have good corrosion resistance. The result conformed that it is feasible to design the preparing conditions of TiO2 modified film by artificial neural network.

Simulation of the plasticizing behavior of composite modified doublebase(CMDB)propellant in grooved calendar based on adaptive grid technology

The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process.To improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh refinement.In addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two rollers.The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet.Compared with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging.Meanwhile,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant slurry.The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process conditions.Based on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.

Exact Run Length Evaluation on a Two-Sided Modified ExponentiallyWeighted Moving Average Chart for Monitoring

A modified exponentially weighted moving average (EWMA) scheme is one of the quality control charts suchthat this control chart can quickly detect a small shift. The average run length (ARL) is frequently used for theperformance evaluation on control charts. This paper proposes the explicit formula for evaluating the average runlength on a two-sided modified exponentially weighted moving average chart under the observations of a first-orderautoregressive process, referred to as AR(1) process, with an exponential white noise. The performance comparisonof the explicit formula and the numerical integral technique is carried out using the absolute relative change forchecking the correct formula and the CPU time for testing speed of calculation. The results show that the ARL ofthe explicit formula and the numerical integral equation method are hardly different, but this explicit formula ismuch faster for calculating the ARL and offered accurate values. Furthermore, the cumulative sum, the classicalEWMA and the modified EWMA control charts are compared and the results show that the latter is better for smalland intermediate shift sizes. In addition, the explicit formula is successfully applied to real-world data in the healthfield as COVID-19 data in Thailand and Singapore.

Highly Efficient Heavy-Metal-Ion Removal from Shellfish Processing Liquid with Low Protein and Polysaccharide Loss by Hybrid Mesoporous Silica Diol-APDC-SBA15

Heavy metal ions in shellfish products are harmful to human health,and their removal with low nutrient loss remains challenging.Herein,a new type of mesoporous silica(SBA15),modified internally with ammonium pyrrolidine dithiocarbamate(APDC)and externally with alkyl-diol groups,which was named as Diol-APDC-SBA15,was successfully developed and characterized by powder X-ray diffraction patterns,nitrogen adsorption,and Fourier transform infrared spectroscopy.The solutions with lead,chromium,cadmium,and copper were used to investigate the adsorption capacity of Diol-APDC-SBA15.Diol-APDC-SBA15 was adopted to remove heavy metals from cooking liquids of clams(Ruditapes philippinarum),hydrolysate liquids of oysters(Ostrea gigas Thunberg),and polysaccharide solution from the cooking liquid of R.philippinarum.The efficiencies of removing heavy metal ions and the loss rates of proteins and polysaccharides were examined.The results showed that the adsorption capacities of Diol-APDCSBA15 for Pb,Cr,Cd,and Cu in standard heavy-metal solutions were 161.4,166.1,29.6,and 60.2mgg^(−1),respectively.The removal efficiency of Diol-APDC-SBA15 for Pb in the three shellfish processing liquids ranged from 60.5%to 99.6%.The Cr removal efficiency was above 99.9%in the oyster hydrolysate liquid.Meanwhile,the percentages of polysaccharide loss were 5.5%and 3.7%in the cooking liquid of clam and polysaccharide solution,respectively,and the protein loss was 1.2%in the oyster hydrolysate liquid.Therefore,the Diol-APDC-SBA15 material exhibits a great potential application in the removal of heavy metals from shellfish processing liquids with low losses of proteins and polysaccharides.

NaBH₄Sodalites, Synthesized by Modified Methods: (1) Autothermal Synthesis and (2) Crossover Reaction from Gel to Melt Flow

NaBH4 sodalites were obtained by two new modified methods of crystallization: (1) autothermal synthesis and (2) crystallization with crossover from gel to melt flow in NaOH flux. Syntheses results were presented according to XRD, SEM and FTIR. Besides important features of both synthesis procedures product properties like crystal size and morphology were investigated. Spherical agglomerates of microcrystalline sodalite of composition Na7[AlSiO4]6BH4(H2O)2 were already observed after 4 h without any external heating by the autothermal procedure. Sodalites of the same average composition but in form of agglomerated nanoparticles are crystallized after very short times (2 h 30’) by the crossover reaction from gel to melt flow. Hydrogen release by heating was further studied for two selected samples with comparable composition from each synthesis procedure. Total hydrogen release by hydrolysis reaction with the internal cage water was found during heating of the autothermal product in synthetic air up to 550°C. In contrast hydrogen release from the nanocrystalline sample of crossover synthesis was not completed when heated under the same conditions. These differences were discussed in terms of crystal size and an earlier loss of the internal water from the nanocrystals of the crossover

体育器材领域用二步法硅烷交联改性聚乙烯

通过化学方法与物理方法改善聚乙烯性能,使其拥有更具优势、更优异的力学性能,从而实现在体育器材领域的广泛应用。二步法硅烷交联改性工艺,不仅可促使改性聚乙烯内部呈现三维网状结构,还可有效改进材料综合力学性能。概述了聚乙烯硅烷交联改性工艺,以二步法工艺为例制备了体育器材领域用改性聚乙烯,进而详细分析了改性聚乙烯在体育器材领域的实际应用。

基于MEEMD算法的二冲程柴油发动机机体振动分析

二冲程低速柴油机具有复杂的振动特性,传统的经验模态分解(Empirical Mode Decomposition,EMD)算法对其振动信号处理效果不理想。为此,采用修正多元集合经验模态分解(Modified Ensemble Empirical Mode Decomposition,MEEMD)算法对低速柴油机机体振动信号进行分解。首先,采用三轴加速度计测量发动机机体振动。然后利用均方根(Root Mean Square,RMS)对三轴振动强度进行分析。最后,对x轴上的信号进行MEEMD分析。结果表明:砌块在x轴方向的振动强度最大;与EMD算法相比,MEEMD算法可以抑制模态混合,有助于更好地识别块振动激励。

表面修饰石墨烯制备工艺及其在金属材料中的应用研究

为解决石墨烯在金属基复合材料应用中易团聚、难分散、与金属基体之间的润湿性差、高温下易与Al、Ti、Fe等金属发生界面反应的问题,对石墨烯进行表面修饰制得镀铜石墨烯,研究了镀覆过程中镀覆温度、镀覆时间、镀液pH对镀铜石墨烯镀层连续性、完整性的影响,优化镀覆工艺参数,获得了质量优良的表面修饰石墨烯;并将其分别添加到铁基摩擦材料和W-Mo-Cu复合材料中,对其作用效果进行了研究。结果表明:石墨烯在50℃、pH为12.5的化学镀液中镀覆30 min可以获得连续性、完整性较好的镀层,从而制得缺陷密度较小、质量较好的表面修饰石墨烯;在铁基摩擦材料中添加0.8%(质量分数)表面修饰石墨烯可以使材料晶粒细化并获得片层间距较小的珠光体组织,材料硬度提高30%,磨损率降低约70%,摩擦系数下降约12%;添加了0.2%(质量分数)表面修饰石墨烯的W-Mo-Cu材料,其组织均匀性和致密度均获得了提高,电导率提升约21%,硬度提高8%。证实了表面修饰石墨烯的添加能够促进金属基复合材料综合性能的提高。

基于响应面法的废口罩纤维改性沥青制备工艺研究

为有效高值再利用废弃口罩,将废口罩用作改性沥青的改性剂,利用响应面法确定废口罩纤维改性沥青的最佳制备工艺,分析废口罩改性沥青随剪切时间、剪切速率、剪切温度的变化规律。研究得到废口罩纤维改性沥青制备工艺的响应面模型,模型预测计算得到最佳制备工艺参数为剪切时间45 min、剪切速率4145 r/min、剪切温度167℃,与试验验证结果一致。在最佳制备工艺和掺量下,废口罩纤维改性沥青较基质沥青的软化点显著升高,延度、针入度下降。

泡沫混凝土的应用研究进展

介绍了泡沫混凝土的发展历程,制备泡沫混凝土的发泡工艺,包括物理发泡法和化学发泡法,并包含不同发泡工艺的发泡机理及发泡研究进展;分析了气泡结构、含量以及均匀性等泡沫的性质对泡沫混凝土理化性能的影响,包含力学性能、保温性能和声学性能等;阐述了目前关于泡沫混凝土的国内外改性研究以及应用的进展;提出了新型环保、多功能领域应用是今后泡沫混凝土的未来发展方向。

高产甾醇热带假丝酵母发酵工艺优化及富含甾醇调制乳的制备

该研究以脱脂奶粉及核桃油为主要原料,以高产甾醇热带假丝酵母(Candida tropicalis)1253、保加利亚乳杆菌(Lactobacillus bulgaricus)及嗜热链球菌(Streptococcus thermophilus)为发酵菌种制备甾醇冻干粉,并在此基础上研制富含甾醇调制乳。以甾醇产量为评价指标,通过单因素试验和响应面试验优化菌株1253发酵工艺,对富含甾醇调制乳品质和营养进行综合性评价,并分析其关键差异代谢物及代谢通路。结果表明,最佳发酵工艺为培养时间97 h,培养温度30℃,菌种接种量9.5%,核桃油添加量4%。在此优化条件下,甾醇产量为0.90 mg/g。富含甾醇调制乳感官评分为(86.44±2.06)分,甾醇含量为(22.7±0.6)mg/g。吡哆醛、胆甾醇、γ-氨基丁酸(GABA)、麦角甾苷和柠檬酸等关键差异代谢物通过富集维生素B6代谢、磷酸戊糖途径、乙氧基化物和二甲酸酯代谢、果糖和甘露糖代谢和柠檬酸循环等途径形成特征风味。

超声辅助制备SBS改性沥青空化泡数值模拟与性能研究

超声空化效应可以促进沥青的改性,利用Fluent流体仿真软件,对熔融SBS改性沥青流体中超声空化泡进行数值模拟,分析了单个空化泡在膨胀-压缩一个周期内的形态变化以及整个流体域的压强变化,从而计算出单个泡压缩或溃灭时产生的瞬时的高温高压环境以及释放的能量。同时结合超声辅助制备SBS改性沥青实验,通过常规性能的测试,说明超声能提高其高低温性能;离析实验以及荧光显微图像说明超声能细化SBS颗粒,改善SBS颗粒在沥青体系的分散效果;老化后的黏度变化和老化前后的FTIR说明了超声工艺可以提升改性沥青的抗老化性能。

改性乳化沥青冷再生技术及设备改进分析

在我国经济建设稳步推进的背景下,交通运输线路肩负着重要的功能作用,为解决路面损坏的问题,缓解其对于出行与运输安全造成的阻碍,该文提出改性乳化沥青冷再生技术的应用,其作为一种新型的路面翻修施工技术具有显著的优势。通过对改性乳化沥青冷再生技术的分析,对该技术工艺与设备进行全面了解,由此得出改性乳化沥青冷再生技术及设备改进具体性能结论,为沥青路面施工创造出更好的经济效益。