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1.
A novel metallo-organic chemical vapor deposition (MOCVD) technique has been applied to the preparation of the photocatalytic titanium dioxide supported on activated carbon. The effects of various condition parameters such as carrier gas flow rate, source temperature and deposition temperature on the deposition rate were investigated. The maximum deposition rate of 8.2 mg/(g·h) was obtained under conditions of carrier gas flow rate of 400 ml/min, source temperature of 423 K and deposition temperature of 913 K. The deposition rate followed Arrhenius behavior at temperature of 753 K to 913 K, corresponding to activation energy Ea of 51.09 kJ/mol. TiO2 existed only in anatase phase when the deposition temperature was 773 K to 973 K. With increase of deposition temperature from 1073 K to 1273 K, the rutile content sharply increased from 7% to 70%. It was found that a deposition temperature of 773 K and a higher source temperature of 448 K resulted in finely dispersed TiO2 particles, which were mainly in the 相似文献
2.
Due to large-scale dredging operations, a large amount of sludge is inevitably produced. Large areas of land are occupied when the dredged sludge is discarded in the disposal site as waste material. The sludge dewatering with aeration-vacuum (SDAV) method is suit for treating the sludge with high water content and high clay content in the disposal site. The water in the sludge can be discharged out. The volume of the sludge can be reduced quickly, and the recycling of the land can be accelerated by this method. Most importantly, this technique is an efficient way to deal with clogging problems when pumping water from high water content, high clay content dredged sludge. Vacuum degree range tests, the aeration rate range tests, and the influencing factors of sludge dewatering behavior tests were conducted with a self-developed SDAV model test device. Sludge samples were taken from the South-to-North Water Diversion East Line Project in Huai’an White-Horse Lake disposal site, Jiangsu Province, China. The optimal range of vacuum degree and aeration rate were obtained through the test results, and the mechanisms for how the two factors work and how they affect the sludge dewatering behavior were analyzed. The suitable vacuum degree range in SDAV is below 50 kPa, and the suitable aeration rate is about 1.0 m3/h. The low-vacuum degree contributes to reduce the ad-sorption effect of micro-channels on soil particles in filter material and to maintain the arch structures. Aeration has the effects of expansion, disturbance, changing Reynolds number, and dynamic sieve separating. The pump quantity of water per meter of filter tube (m) has different change rules as the vacuum degree changes under different aeration rates. The reason is that the formed arch structures’ conformation and permeability differ greatly under different combined-conditions of vacuum degree and aeration rate. The optimal combined-condition for dewatering the sludge is 35 kPa with 1.0 m3/h. 相似文献
3.
Calcium carbide slag, generated in the hydrolysis process of calcium carbide, is an potential carbon capture reagent because its main ingredient is Ca(OH)2. Calcium carbide slag, a by-product of a resin factory was used as carbon capture reagent. The change of pH and electrical conductivity (EC) of the calcium carbide slag slurry with different solid-to-liquid ratios, as well as the capture efficiency and dynamics under different temperatures and flow rates of CO2 were studied. The properties of solid were characterized with XRD, TG-DTA, SEM and FT-IR before and after capturing carbon. The results show that the change of pH and EC were greater with low solid-to-liquid ratio than that with high solid-to-liquid ratio. The analysis of XRD and SEM show that the content of CaCO3 increased significantly, which improved that Ca(OH)2 and free CaO were reacted with CO2. The results of TG-DTA and FT-IR show that the physicochemical properties and microstructure of the slag changed after capturing CO2 because of the increase of CaCO3 content. All the results mentioned above improve the feasibility of utilizing calcium carbide slag to capture CO2 and offer a practical way for carbon emission reduction and disposal of wasted calcium carbide slag. 相似文献
4.
The deformation behavior of hot isostatic pressing (HIP) FGH96 superalloy was characterized in the temperature range of 1 000-1 100℃and strain rate range of 0.001-0.1s-1 using hot compression testing. The flow curves of HIP FGH96 superalloy during hot deformation was analyzed systematically. The results show that deformation temperature, strain rate and strain are the main influence factors on flow stress of HIP FGH96 superalloy during hot deformation. The flow stress displays a peak at a critical strain and then decreases with further increase in strain. For a given strain, the flow stress decreases with the increase of deformation temperature, and increases with the increase of strain rate. A mathematical model of these flow curves was established through regression analysis and taking the strain as a modification factor. The calculated stress values agree well with the experimental values. 相似文献
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This study provides a detailed report on the synthesis of spherical activated carbon with mesoporous structure using a soluble low molecular weight phenolic resol precursor through an ammonium alginate assisted sol–gel method. The effects of calcinating temperature and the addition of CaCO_3 as a pore-enlarging agent on texture structure and catalytic performance in isobutane dehydrogenation to isobutene were investigated. Characterization of N_2 sorption,mechanical strength tests,and optical photographs confirmed that the obtained carbon materials had high mechanical strength,a good degree of sphericity,and a large surface area. Introducing CaCO_3 as a pore-enlarging agent during the preparation process promoted the formation of a mesoporous structure of carbon spheres and evidently increased the surface area and oxygen content,which can improve isobutane conversion and isobutene selectivity of these carbon spheres. The conversion of isobutane reached up to 28% for this spherical activated carbon,and the selectivity of isobutene reached up to 96%. Isobutane conversion increased with an increase in calcination temperature due to an increase in the oxygen content,whereas the selectivity of isobutene decreased due to the slight decrease in the specific surface area. 相似文献
6.
Carbon encapsulated iron nanoparticles(CEINPs) with very thin shells and good core-shell structures were prepared by DC arc discharge at argon intake temperature(AIT) of 800 ℃. The results of high resolution transmission electron microscope(HRTEM), energy dispersive X-ray(EDX) spectroscope, X-ray diffraction(XRD), and X-ray photoelectron spectroscope(XPS) characterizations on the product B show that the thickness of the carbon shells of CEINPs in the product B is in the range of ca. 0.5—5.3 nm, i. e., which can be as thin as only two layers of graphite. The average diameter of the CEINPs is about 24. 7 nm. The total content of Fe element in the product B is 77.0 wt%. The saturation magnetization(Ms) and coercivity(Hc) of the product B are 107.4 emu/g and 143 Oe, respectively. The formation of the CEINPs in the product B is discussed briefly. 相似文献
7.
Objective: To determine the range of body temperature in a group of healthy Chinese term neonates over the first 72 hours of life and to assess the influence of body weight, gestational age and route of delivery. Method: All 200 consecutive cases of neonates delivered at our hospital from March to August 2001 were included in this retrospective study. Temperatures were measured immediately after delivery, after 30 minutes, 1 hour, 2 hours, 8 hours and 15 hours and on the 2nd and 3rd day. Axillary temperatures ranging from 36.5 oC to 37 oC were regarded as normal. No cases of maternal fever or systemic infection of the newborns were discovered. All infants were discharged in good general condition. Results: The mean rectal temperature at birth was 37.19 ℃. The lowest average temperature was reached at 1 hour after delivery (36.54 ℃) with a significant difference between natural delivery (36.48 ℃) and section (36.59 ℃) (P<0.05). Temperature subsequently rose to 36.70 ℃ at 8 hours and 36.78 ℃ at 15 hours (P<0.05). Hypothermia was seen in 51.8% and hypothermia in 42.5% of the patients. On the 3rd day after delivery, 96% of all temperatures were in the normal range. A significant relation was found between hypothermia and both low birth weight (P<0.001) and low gestational age (P<0.05). Conclusion: The reference range presently used did not include all physiological temperatures in the first 72 hours of life. Considering other factors, such as birth weight, route of delivery, gestational age and body temperature on the 2nd and 3rd day of life, may help to correctly assess the significance of temperatures beyond the reference range. 相似文献
8.
《天津大学学报(英文版)》2015,(3)
This work focused on exploring a computational fluid dynamics(CFD)method to predict the macromixing characteristics including the mean flow field and impeller capacity for a 45° down-pumping pitched blade turbine(PBT)in stirred tanks. Firstly, the three typical mean flow fields were investigated by virtue of three components of liquid velocity. Then the effects of impeller diameter(D)and off-bottom clearance(C)on both the mean flow field and three global macro-mixing parameters concerning impeller capacity were studied in detail. The changes of flow patterns with increasing C/D were predicted from these effects. The simulation results are consistent with the experimental results in published literature. 相似文献
9.
Absorption of NO2 into Na2S solution in a stirred tank reactor 总被引：1，自引：1，他引：0
To understand the absorption mechanism of nitrogen dioxide into a sodium sulfide solution, a stirred tank reactor with a plane gas-liquid interface was used to measure the chemical absorption rate of diluted nitrogen dioxide into sodium sulfide solution. The absorption rates under various experimental conditions were measured and the effects of experimental conditions on nitrogen dioxide absorption rate were discussed. The results show that, in the range of this study, nitrogen dioxide absorption rate increases with increasing sodium sulfide concentration, nitrogen dioxide inlet concentration, and flue gas flow rate, but decreases with increasing reaction temperature and oxygen content in flue gas. 相似文献
10.
Study on oxidizing cellulose to 2.3-dialdehyde cellulose by sodium periodate （NalO4） was carried out. The effects of reaction conditions such as pH of solution, temperature, oxidant concentration, oxidation time. the particle size of 2,3-dialdehyde cellulose and alkali treatment temperature on the dialdehyde concentration ot cellulose were investigated in detail, The results show that the aldehyde group content was created while reaction temperature and alkali treatment temperature increased. The most principal factors affecting the aldehyde group content of 2,3-dialdehyde cellulose were found out and the best oxidation conditions were as follows： the pH was 2. the reaction temperature was 45℃. the mass ratio of cellulose to NalO4 was 1/2, the reaction time was 4 h, the alkali treatment temperature was 70℃ and smaller particle size was 0.80 mm. 相似文献
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Boronising of steels is a hardening process to get high surface hardness. The erosion resistance of boronised steels was researched with the use of four kinds of erodent, i.e. glass, alumina, quartz and silicon carbide. The erosion rate increases rapidly with erodent hardness and severe erosion occurs with high impacting angle range of hard particles. SEM analysis indicated that chipping is caused by repetitive impacting of glass and quartz, whereas by alumina and silicon carbide impacting, chipping, and that plastic flow take place simultaneously and the erosion rate reaches the peak value when the impacting angle is above 60°. 相似文献
13.
通过单因素试验和正交试验分析料液比、浸提温度、浸提时间和浸提次数对人工北虫草僵虫（菌核）粗多糖得率的影响,结果表明：随浸提温度、浸提时间和浸提次数的增加,粗多糖得率逐渐上升;随料液比提高,粗多糖得率呈先上升后下降的趋势;影响粗多糖得率的主效因素是浸提温度,其次为浸提时间和浸提次数;确定最佳浸提条件为：浸提温度100℃,料液比1∶20,浸提时间3h,浸提2次,在此条件下北虫草僵虫粗多糖得率为8.497%. 相似文献
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张丁非 《重庆大学学报(英文版)》2004,3(2):12-15
IntroductionFe-C-Si-Mnalloyisamaterialusedforcommonbladesinhydroelectricgenerators.Itscurrentchemicalcompositionintermsofmassfractionwisasfollows:w(C)withintherangefrom0.17%to0.25%,w(Si)0.40%to0.8%,w(Mn)1.2%to1.6%,w(S)≤0.045%andw(P)≤0.045%.Thebladeserviceconditionrequiresgoodstrength,ductilityandwearresistance.AnormalprocessingandheattreatingprocedureofFe-C-Si-Mnalloybladesincludesinsequence:casting,920°Cnormalizing,600°Ctempering,andwelding.Thevolumeofabladeissohugethatitscentralare… 相似文献
16.
成土母质是影响土壤有效硅水平的主要因素，不同母质发育的水稻土有效硅平均含量顺序为：黄土性古河湖相沉积物＞近代黄泛＞淮河冲积＞石灰岩＞湖积物＞下蜀黄土＞长江冲积＞紫色砂页岩和第四纪红土＞板页岩和酸性结晶岩。土壤pH值和土壤有机质含量与土壤有效硅呈极显著正相关。安徽省水稻土有效硅含量不同地区差异很大，淮北平原＞江淮丘陵岗地＞沿江平原＞皖西山地＞皖南丘陵山地． 相似文献
17.
目的：建立宝宝乐颗粒中芍药苷的高效液相色谱（HPLC）测定方法。方法：采用Diamonsil C18（4．6×250mm,5um）色谱柱,以乙腈-水-磷酸（20：80：0．05）为流动相,检测波长：230nm,流速：1．0mL/min,柱温：35．0℃。结果：芍药苷在0．1540ug～1．2320ug范围内与峰面积线性关系良好,相关系数为r=0．9999,平均回收率为99．82％（RSD=0．301％,n=5）。结论：HPLC法操作快速、简便、结果准确,可作为宝宝乐颗粒中芍药苷的定量分析方法。 相似文献
18.
Experiment and mechanism investigation on advanced reburning for NOx reduction： influence of CO and temperature 总被引：4，自引：0，他引：4
Wang ZH Zhou JH Zhang YW Lu ZM Fan JR Cen KF 《Journal of Zhejiang University. Science. B》2005,6(3):187-194
Pulverized coal reburning, ammonia injection and advanced reburning in a pilot scale drop tube furnace were investigated. Premix of petroleum gas, air and NH3 were burned in a porous gas burner to generate the needed flue gas. Four kinds of pulverized coal were fed as reburning fuel at constant rate of 1g/min. The coal reburning process parameters including 15%～25% reburn heat input, temperature range from 1100 ℃ to 1400 ℃ and also the carbon in fly ash, coal fineness, reburn zone stoichiometric ratio, etc. were investigated. On the condition of 25% reburn heat input, maximum of 47% NO reduction with Yanzhou coal was obtained by pure coal reburning. Optimal temperature for reburning is about 1300 ℃ and fuel-rich stoichiometric ratio is essential; coal fineness can slightly enhance the reburning ability. The temperature window for ammonia injection is about 700 ℃～1100 ℃. CO can improve the NH3 ability at lower temperature. During advanced reburning, 72.9% NO reduction was measured. To achieve more than 70% NO reduction, Selective Non-catalytic NOx Reduction (SNCR) should need NH3/NO stoichiometric ratio larger than 5, while advanced reburning only uses common dose of ammonia as in conventional SNCR technology. Mechanism study shows the oxidization of CO can improve the decomposition of H2O, which will rich the radical pools igniting the whole reactions at lower temperatures. 相似文献
19.
A cold-model vertical multi-tube circulating fluidized bed evaporator was designed and built to conduct a visualization study on the pressure drop of a liquid-solid two-phase flow and the corresponding particle distribution.Water and polyformaldehyde particle (POM) were used as the liquid and solid phases,respectively.The effects of operating parameters such as the amount of added particles,circulating flow rate,and particle size were systematically investigated.The results showed that the addition of the particles increased the pressure drop in the vertical tube bundle.The maximum pressure drop ratios were18.65%,21.15%,18.00%,and 21.15%within the experimental range of the amount of added particles for POM1,POM2,POM3,and POM4,respectively.The pressure drop ratio basically decreased with the increase in the circulating flow rate but fluctuated with the increase in the amount of added particles and particle size.The difference in pressure drop ratio decreased with the increase in the circulating flow rate.As the amount of added particles increased,the difference in pressure drop ratio fluctuated at low circulating flow rate but basically decreased at high circulating flow rate.The pressure drop in the vertical tube bundle accounted for about 70%of the overall pressure drop in the up-flow heating chamber and was the main component of the overall pressure within the experimental range.Three-dimensional phase diagrams were established to display the variation ranges of the pressure drop and pressure drop ratio in the vertical tube bundle corresponding to the operating parameters.The research results can provide some reference for the application of the fluidized bed heat transfer technology in the industry. 相似文献
20.
近32年来洞庭湖流域气候变化规律分析 总被引：2，自引：0，他引：2
利用近32年来洞庭湖流域30个气象站点1982—2013年的气温和降水数据,采用趋势分析法、MannKendall检验法和Morlet小波分析法对气温和降水量的年变化特征进行了分析。结果表明:(1)时间上,1982—2013年,洞庭湖流域内年平均气温变化在15.6~17.7℃之间,年均温呈现显著上升趋势,气候倾向率为以0.38℃/10年;年降水量在975.2~1 833.6 mm之间,降水量呈下降趋势,气候倾向率为-18.9 mm/10年。(2)空间上,整个流域气温上升,增温幅度较大的地区是流域东北部,有五峰(0.98℃/10年)和长沙(0.7℃/10年)两个极值中心,其他区域增温幅度较小;流域内大部分区域降水量呈递减趋势,递减幅度较大的区域是流域北部和东部,而桑植、吉首、沅江和道县等部分地区降水量呈递增趋势。(3)气温呈上升-下降趋势,1998年为气温突变年份;降水量呈递减-上升-递减趋势,降水量突变点出现在1993和2009年。(4)洞庭湖流域年平均气温存在6年的强显著周期,还有14年和23年尺度的变化周期;年降水量存在3年的强显著周期,6年和16年尺度的变化周期。近32年来,洞庭湖流域总体气候呈现明显暖干化趋势。 相似文献