Determination and Evaluation of Strength Characteristics of Dry Jet Mixing

Dry jet mixing (DJM) for soft soil stabilization has been widely used since 1980s. The quality and strength of stabilized columns are fundamental parameters to evaluate the stabilization work. This paper presents the standard penetration test (SPT) method and its test results on cement columns. It is shown that SPT is an effective and simple method for inspecting and evaluating cement columns. The strength characteristics along the length of the column, a good correction between SPT blow count and the unconfined compressive strength are achieved.

Accuracy comparison of dry matter intake prediction models evaluated by a feeding trial of lactating dairy cows fed two total mixed rations with different forage source

Dry matter intake （DMI） prediction models of NRC （2001）, Fox et aL （2004） and Fuentes-Pila et aL （2003） were targeted in the present study, and the objective was to evaluate their prediction accuracy with feeding trial data of 32 lactating Holstein cows fed two total mixed rations with different forage source. Thirty-two cows were randomly assigned to one of two total mixed ration groups： a ration containing a mixed forage （MF） of 3.7% Chinese wildrye, 28.4% alfalfa hay and 26.5% corn silage diet and another ration containing 33.8% corn stover （CS） as unique forage source. The actual DMI was greater in MF group than in CS group （P=0.064）. The NRC model to predict DMI resulted in the lowest root mean square prediction error for both MF and CS groups （1.09 kg d-1 vs. 1.28 kg d-1） and the highest accuracy and precision based on concordance correlation coefficient for both MF and CS diet （0.89 vs. 0.87）. Except the NRC model, the other two models presented mean and linear biases in both MF and CS diets when prediction residuals were plotted against predicted DMI values （P〈0.001）. The DMI variation in MF was caused by week of lactation （55.6%）, milk yield （13.9%）, milk fat percentage （7.1%） and dietary neutral detergent fiber （13.3%）, while the variation in CS was caused by week of lactation （50.9%）, live body weight （28.2%）, milk yield （8.4%）, milk fat percentage （5.2%） and dietary neutral detergent fibre （3.8%）. In a brief, the NRC model to predict DMI is comparatively acceptable for lactating dairy cows fed two total mixed rations with different forage source.

Research on Properties of Metasilicate Bonded Carbon-free Basic Dry Vibration Mix

Carbon-free basic dry vibration mix was prepared using middle grade magnesia and fused magnesia as main starting materials,metasilicate replacing phenolic resin as binder,adding a certain amount of medium and low temperature intensifiers. Effects of binder,grain composition,and additives on basic dry vibration mix for tundish were studied,and the bonding mechanism was also analyzed. The results show that：（1） when using metasilicate as binder,the higher strength can be acquired; （2） the suitable grain composition is q=0.48,the critical granularity is 5 or 3 mm,the fines addition is 10%-20% （mass percent）; （3） the strength and corrosion resistance of the basic dry vibration mix can be improved by the melting compound of metasilicate and additives; （4） with temperature rising,the bonding type in dry vibration mix changes from cohere bonding to reaction bonding,and then to ceramic bonding at last.

Effect of Al Addition on Properties of Al_2O_3-SiC-C Dry Ramming Mixes for BF Trough

Aluminium powders were introduced to Al2O3-SiC-C dry ramming mixes in order to improve sintering properties and oxidation resistance according to their service conditions and installation methods. Properties such as bulk density, porosity, modulus of rupture, crushing strength and hot modulus of rupture as a function of aluminium addition were investigated in the present work. The microstructure and thermodynamics for the heat treated specimens were also analyzed. The results show that as aluminium addition increasing, the bulk density of the specimen treated at 220℃ tends to decrease and the apparent porosity increases, the strength of the specimens treated at 1100℃ and 1450℃ increases markedly, the bulk density tends to increase, apparent porosity and linear shrinkage decrease. The HMOR at 1400℃ is enhanced from 1.0 MPa to 3.5 MPa with 3% aluminium. Aluminium is served as sintering agent and anti-oxidant and it will react with CO and CO2 forming Al2O3 , which is helpful to enhance the strength, densify the structure and improve the overall properties.

Effects of Dietary Supplement of Fermented Tomato Pomace on Dry Matter Intake and Nutrient Apparent Digestibility of Dairy Cows

This study was carried out to evaluate the effects of replacing corn silage with ensiled tomato pomace on dry matter intake and apparent digestibility of diets.Eight close up dry Holstein cows were used in 2 × 2 Latin square design.The animals were fed control(0% tomato pomace silage) and experimental(10% corn silage replaced by tomato pomace silage) diets.The result showed that dry matter intake in experimental group was 9.77 ± 0.44 kg/d,which was significantly higher than in control group(p < 0.05).Dry matter digestibility in experimental and control group was 73.9% and 70.2%,respectively,but there was no difference between two groups(p > 0.05).The substitution of tomato pomace silage in diet was associated with an increase of dry matter intake,dietary supplement of ensiled tomato pomace without any adverse effect on their health performance.

Enhanced selective catalytic reduction of NO with NH3 via porous micro-spherical aggregates of Mn–Ce–Fe–Ti mixed oxide nanoparticles

We rationally designed a high performance denitration(De-NOx) catalyst based on a micrometer-sized spherical Mn–Ce–Fe–Ti(CP-SD)catalyst for selective catalytic reduction(SCR). This was prepared by a co-precipitation and spray drying(CP-SD) method. The catalyst was systematically characterized, and its morphological structure and surface properties were identified. Compare with conventional Mn–Ce–Fe–Ti(CP) catalysts, the Mn–Ce–Fe–Ti(CP-SD) catalyst had superior surface-adsorbed oxygen leading to enhanced 'fast NH3-SCR' reaction. The asobtained Mn–Ce–Fe–Ti(CP-SD) catalyst offered excellent NO conversion and N2 selectivity of 100.0% and 84.8% at 250℃, respectively, with a gas hourly space velocity(GHSV) of 40,000 h-1. The porous micro-spherical structure provides a larger surface area and more active sites to adsorb and activate the reaction gases. In addition, the uniform distribution and strong interaction of manganese, iron, cerium, and titanium oxide species improved H2O and SO2 resistance. The results showed that the Mn–Ce–Fe–Ti(CP-SD) catalyst could be used prospectively as a denitration(De-NOx) catalyst.

Experimental Research on Performances of Dry-grinding Fine Cement for Grouting

The performances of dry grinding fine cement (DFC) in grouting procedure were experimentally studied.The measurement of its fineness and simulated test for injectability showed that this DFC could be used to inject rock mass with micro fissure.In order to improve the grouting quality,the water cement ratio and discarding time of slurry should be controlled precisely.If the water cement ratio is over 2∶1 in slurry that is made from DFC,it is not suitable to grout.Finally,the influence of different mixing times on strength of hydrated cement made from the DFC is explained by microstructure analysis with SEM.

干硬性碱激发钢渣混凝土的力学性能优化试验研究

为了优化干硬性碱激发钢渣混凝土的力学性能,试验通过调整粉煤灰的掺量结合碱激发的掺量优化混凝土凝结时间和流动度,并采用正交试验法分析粉煤灰掺量、水玻璃模数、水玻璃掺量和养护方式4种因素对干硬性碱激发钢渣混凝土抗压强度的影响。结果表明,掺入粉煤灰可延长干硬性碱激发混凝土的凝结时间,减小维勃稠度,优化工作性能;干硬性碱激发钢渣混凝土的抗压强度受多因素综合影响,影响大小的顺序为:水玻璃掺量>水玻璃模数>养护方式>粉煤灰掺量;当采用2.0模数和20%掺量的水玻璃、替换率为25%粉煤灰优化配合比后,再结合浸水养护2 d,接着自然养护,干硬性碱激发钢渣混凝土的抗压强度最高。

微孔白云石加入量对镁钙质中间包干式料性能的影响

以白云石为原料,采用二步煅烧法制备的致密镁钙砂是镁钙质中间包干式料常用的耐火原料。然而二步煅烧法工艺复杂,资源耗费大,且致密镁钙砂不利于中间包干式料隔热性能的提升。以一步煅烧法(1400℃保温3 h)制备的微孔白云石和电熔镁砂为主要原料,分别于1100、1550℃热处理后制备了镁钙质干式料试样,研究了微孔白云石加入量(质量分数分别为0、15%、30%、45%和60%)对试样性能的影响。结果表明:随着微孔白云石加入量的增加,1100℃热处理后试样的线收缩率和体积密度呈减小趋势,常温耐压强度先增大后减小;1550℃热处理后试样的线收缩率先减小后显著增大,显气孔率增加,热导率大幅降低,但常温耐压强度和抗渣性能降低。当微孔白云石加入量为60%(w)时,1550℃热处理后试样在800℃下的热导率为2.410 W·m^(-1)·K^(-1),与传统镁质干式料相比下降了51.9%,同时常温耐压强度为26.0 MPa,在力学性能略微降低的情况下表现出优异的隔热性能。

湿法连续混炼工艺炭黑/天然橡胶复合材料的制备及性能研究

采用湿法连续混炼工艺制备炭黑/天然橡胶(NR)复合材料,并与传统干法混炼工艺相比,研究复合材料的性能和炭黑在复合材料中的分散性。结果表明:湿法工艺与连续混炼工艺结合,可实现复合材料的绿色环保混炼;与干法混炼工艺混炼胶相比,湿法连续混炼工艺混炼胶的门尼粘度增大,t90缩短;与传统干法混炼工艺硫化胶相比,湿法连续混炼工艺硫化胶的拉伸强度、耐磨性能和抗切割性能提高,Payne效应和60℃时的损耗因子减小,即其综合物理性能优异;湿法连续混炼工艺硫化胶的炭黑分散较为均匀,未出现大团聚体,炭黑分散等级X为7.9,平均团聚尺寸为3.4μm。

电石渣改性制备高效CO_(2)复合吸收剂

电石渣是典型的高钙工业固体废弃物,具有优异的CO_(2)吸收性能,但是在钙循环中纯电石渣的反应活性和CO_(2)吸收性能会随着循环次数的增加而降低。本文以电石渣为钙源,以MgO和ZnO为掺杂剂合成高效稳定的钙镁锌复合吸收剂,在固定床反应器中探究了合成工艺条件及掺杂量对复合吸收剂CO_(2)吸收性能的影响,以及循环吸收过程中吸收剂内部结构的变化。结果表明,利用干物理混合法合成的吸收剂比湿混合法具有更丰富的孔隙结构,Mg和Zn元素在电石渣表面分散均匀,有效改善了电石渣的抗烧结性能和反应活性,改性后的复合吸收剂在循环过程中具有更高的CO_(2)吸收性能,且20次循环后,干物理混合法合成的复合吸收剂CO_(2)吸收量仍可达0.42 g/g。

浆料固含量对电池型电容器性能的影响

研究固含量对浆料物理化学性质、极片微观形貌和电容器性能等的影响,建立浆料固含量、浆料分散稳定性、电极片导电网络结构与电容器功率之间的关联,以改善电池型电容器的功率特性。在干混捏合搅拌工艺的基础上,选取对电容器浆料和极片性能影响较大的固含量(45%、50%、55%)进行研究。当固含量为50%时,浆料悬浮液的接触角和表面张力较小;该固含量制得的极片具有较强的剥离强度(1.66 N)、较低的电阻率和优良的三维导电网络结构。50%固含量更适合高功率电池型电容器工业生产的制浆工艺,可改善浆料和极片的物理化学性能及工业批生产的极片质量。制备的电池型电容器极限脉冲功率可达4513.5 W,以10 C充电、20 C放电(100%DOD)循环2000次,容量保持率仍有93.15%。

湿法混炼胶料性能研究

研究对比采用湿法混炼工艺和干法混炼工艺的混炼胶性能和成品轮胎性能。结果表明:湿法混炼工艺不仅能提高填料在橡胶基体中的分散性,而且环保、生产周期短、能耗低;与干法混炼胶料相比,湿法混炼胶料的300%定伸应力、撕裂强度和耐磨性能等都有不同程度的提高;胎面采用湿法混炼胶料的成品轮胎的滚动阻力降低,耐磨性能提高。

不同比例百香果皮对发酵型全混合日粮品质和干物质消化率的影响

试验旨在探究不同比例百香果皮对发酵全混合日粮(FTMR)发酵品质和干物质消化率的影响。试验设定FTMR粗精比为7∶3,粗蛋白含量理论值为13%。各处理组百香果皮分别替代0(对照组,T0)、5%(T1)、10%(T2)和15%(T3)的王草。密封发酵60 d,使用体外瘤胃液培养方法测定干物质消化率及瘤胃发酵参数。结果表明:各处理组pH值、乙酸含量和氨态氮/总氮无显著差异(P>0.05),添加5%、10%和15%百香果皮的FTMR的乳酸含量均显著升高(P<0.05)。经6 h体外培养后,各组瘤胃液pH值在6.970~6.997之间(P>0.05)。当百香果皮添加量达到15%(T3)时,瘤胃产气量和干物质消化率均达到最高。研究表明,百香果皮可以作为发酵全日粮中的优质原料,具有促进发酵和提升干物质消化率的效果,添加量最高可达15%。

初始含水量和水泥掺入比对水泥土抗剪强度的影响研究

粉喷桩在加固湿陷性黄土地基工程中得到了广泛应用。为更好地掌握桩体的力学参数,本文基于室内直剪试验分析了初始含水量和水泥掺入比对固化土抗剪强度的影响。结果表明,固化土的抗剪强度随着初始含水量的增加呈现出先增加后降低的趋势,随着水泥掺入比的增加则呈现出逐渐增加的趋势。本文的室内试验结果对于粉喷桩原位加固湿陷性黄土地基具有重要的指导作用。

煤矿井下干混砂浆吨包的应用

在矿山井巷,采用与锚杆支护相结合的喷射混凝土支护,是将水泥、砂、石、按一定的比例混合搅拌后,送入混凝土喷射机中,用压缩空气将干拌合料压送到喷头处,在喷头的水环处加水后,高速喷射到巷道围岩表面,起支护作用的一种支护形式和施工方法[1]。煤矿井下利用干混砂浆,将减少井下喷浆作业工人,能取消井下现场人工卸料、拌料、上料工作流程。使用干混砂浆(沙子、水泥)后,两个人利用单轨吊,将干混砂浆吨包吊起,通过吨包下料口,流入喷浆机上料口即可操作完成。众所周知含土量高的沙子,搅拌混凝土不结实,影响施工质量,泥土量超过3%的沙子要经过处理,所以,干混砂浆制作过程中,除尘系统将烘干过程中沙子里的土排走,提高了沙子的纯度,使用干粉砂浆喷射混凝土的强度高于井下现场人工搅拌沙子水泥混凝土强度。

混合菌株发酵板鸭的研究进展

板鸭作为传统腌腊制品,富含维生素B和维生素E,但在提倡健康饮食的今天,传统板鸭加工已不能满足需求。混合菌株发酵板鸭可以增加风味,提升板鸭品质,推动传统腌腊制品行业发展的重要技术支撑。介绍了发酵板鸭优势菌种、混合菌株发酵对板鸭品质影响以及混合菌株发酵板鸭工艺优化研究现状。并对混合菌株发酵板鸭未来发展做出展望,以期为传统板鸭加工工艺改进提供一定的参考。

CFB炉渣细骨料纤维砂浆干燥收缩特性研究

为了实现CFB炉渣的高效利用,提高预拌砂浆的抗裂性,以粉煤灰取代量(体积分数)、CFB炉渣细骨料取代量(体积分数)和PVA纤维掺量(体积分数)为因素,设计正交试验方案L_(16)(4~5),试验研究CFB炉渣细骨料纤维砂浆的干燥收缩特性,分析作用规律,建立回归模型。结果表明:增加粉煤灰取代量可以提高CFB炉渣砂浆稠度,增加CFB炉渣取代量和PVA纤维掺量不利于砂浆稠度的提升;粉煤灰取代量、CFB炉渣取代量为CFB炉渣纤维砂浆的干燥收缩特别显著性影响因素,PVA纤维掺量为显著性影响因素;粉煤灰取代量、PVA纤维掺量对CFB炉渣纤维砂浆的干燥收缩起明显的抑制作用,CFB炉渣使砂浆的干燥收缩呈先降低后增大的变化趋势;砂浆干燥收缩的模型预测相对残差在±5%以内,模型预测结果准确可信。

干拌法柔性阻隔墙在污染场地风险阻控中的应用及研究

随着“零填埋”时代的到来,中国将面临大量的存量垃圾填埋场,由于卫生填埋场防渗系统的易渗漏及非正规填埋场防渗系统的缺失,填埋场普遍存在渗漏污染地下水的风险。针对填埋场地下水风险管控,柔性阻隔墙具有渗透系数低、化学相容性好的特点,而现阶段应用相对较少。据此,文章以南方某非正规垃圾填埋场为研究对象,探究采用干拌、湿拌法工艺构筑阻隔墙的效果,发现干拌法施工工艺简单,操作便利且其构筑墙体的渗透系数达10 cm~7 cm/s级别,结合阻隔区内外的水头差可有效发挥风险阻控作用,阻隔区周边的地下水水质在监测周期内总体呈下降趋势。

本土酵母与商业酵母混菌发酵对“马瑟兰”干红葡萄酒品质的影响

从贺兰山东麓葡萄酒产区筛选出适合该产区“马瑟兰”干红葡萄酒的本土酵母,与酿酒酵母CECA以1∶1混合发酵“马瑟兰”干红葡萄酒。结果表明:通过葡萄酒理化指标检测结果可知,酿酒酵母(Saccharomyces cerevisiae,5号)、毕赤酵母属克鲁维毕赤酵母(Pichia kluyveri,8号)、有孢汉逊酵母属葡萄汁有孢汉逊酵母(Hanseniaspora uvarum,12号)、红酵母属胶红酵母(Rhodotorula mucilaginosa,13号)、梅奇酵终属美极梅奇酵母(Metschnikowia pulcherrima,14号)在葡萄酒酿造中均具有良好的酿酒特性和广阔的应用前景。通过葡萄酒香气成分检测结果可知,8号酵母菌与酿酒酵母CECA混合发酵和5号酵母菌单独发酵“马瑟兰”干红葡萄酒中乙酸异戊酯、异戊醇、己酸乙酯、辛酸乙酯、癸酸乙酯、9-癸烯酸乙酯、乙酸苯乙酯、乙酸乙酯、异戊酸乙酯、月桂酸乙酯、α-乙酸萜品酯、苯乙醇、香茅醇、异丁醇的浓度较高,具有果香与花香浓郁的特点,尤其8号酵母菌与酿酒酵母CECA混合发酵具有蜂蜜及淡甜味。