The effect of Ti and Zr content on the structure,mechanics and energy-release characteristics of Ti—Zr—Ta alloys

Energetic structural materials(ESMs)are a new type of structural materials with bearing and damage characteristics.In this work the microstructure,mechanical properties and energy release characteristics of multi-element Ti-Zr-Ta alloys with good casting performance were studied.The microstructure of the Ti_(x)ZrTa alloys gradually change from BCC+HCP to single BCC structure with the increase of Ti.While the Ti_(2)Zr_(y)Ta alloys was still uniform and single BCC structure with the increase of Zr.The evolution of microstructure and composition then greatly affect the mechanical properties and energy-release characteristics of Ti-Zr-Ta alloys.The synergistic effect of dual phase structure increases the fracture strain of Ti_(x)ZrTa(x=0.2,0.5)with the Ti content decreases,while the fracture strain of Ti_(x)ZrTa(x=2.0,3.0,4.0)gradually increase with the Ti content increases caused by the annihilation of the obstacles for dislocation movement.And as Zr content increases,the fracture strain of Ti_(2)Zr_(y)Ta alloys decrease,then the oxidation reaction rate and fragmentation degree gradually increase.The higher oxidation rate and the lager exposed oxidation area jointly leads the higher releasing energy efficiency of Ti_(x)ZrTa alloys with low Ti content and Ti_(2)Zr_(y)Ta alloys with high Zr content.

Characteristics and Performance of Novel Water-Absorbent Slow Release Nitrogen Fertilizers

In this article, a research on the characteristics and performance of water-absorbent slow release nitrogen fertilizer （WASRNF） using infrared spectroscopy （IR）, scanning electronic microscopy （SEM）, differential scanning calorimetry （DSC）, and thermogravimetry analysis （TGA）, was present. The results indicate that the water absorbency and nitrogen analysis of WASRNF is 103 g g^-1 and 30%, respectively, and WASRNF exhibits approximately neutral pH and very low salt index. WASRNF is a copolymer of nitrogen fertilizer and super absorbent polymer （SAP） monomers which is formed through hydrogen bond interaction, and the molecule contains hydrophilic groups, which is responsible for the absorption and water retention capacity of the molecule. WASRNF is a gel that exhibits the ability to swell, but does not dissolve in water. WASRNF shows non-homogenous nature as a whole, but in local zone it is homogenous, the copolymer molecule shows chain network that is the physical structure responsible for absorption and retention of water in WASRNF. The water retained in WASRNF exists as free and nonfreezing bound and freezing bound water states, with the free and the nonfreezing water accounting for more than 95% of water retained in WASRNF, and the nonfreezing bound water for less than 5%. WASRNF functions in delaying the release of nitrogen from it, thereby serving a novel slow release nitrogenous fertilizer.

The Production of Organic-Inorganic Compound Film-Coated Urea and the Characteristics of Its Nutrient Release

The effect of different concentrations of natural macromolecular compound on the characteristics of nutrient release in the membrane materials of organic-inorganic compound film-coated urea was discussed, and the optimal concentrations for better nutrient release was proposed. The characteristics of nutrient release of film-coated urea were evaluated by soil column leaching experiment. Organic-inorganic compound film-coated urea showed good characteristics of nutrient release, which could be well simulated by Logistic curve. The two parameters in this curve, a and r, can be used to present nutrient release of film-coated urea, and followed the order of B 〉 C 〉 A and C 〈 B 〈 A, respectively, indicating that the release was stronger with the increasing concentration of natural macromolecular compound in the membrane, which implied better controllability of nutrient release. The concentration of 5% of natural macromolecular compound showed better characteristic of nutrient release and can be utilized as a membrane material combined with inorganic mineral powders to develop film-coated slow-release fertilizer.

Force-displacement characteristics of simply supported beam laminated with shape memory alloys

As a preliminary step in the nonlinear design of shape memory alloy（SMA） composite structures,the force-displacement characteristics of the SMA layer are studied.The bilinear hysteretic model is adopted to describe the constitutive relationship of SMA material.Under the assumption that there is no point of SMA layer finishing martensitic phase transformation during the loading and unloading process,the generalized restoring force generated by SMA layer is deduced for the case that the simply supported beam vibrates in its first mode.The generalized force is expressed as piecewise-nonlinear hysteretic function of the beam transverse displacement.Furthermore the energy dissipated by SMA layer during one period is obtained by integration,then its dependencies are discussed on the vibration amplitude and the SMA＇s strain（Ms-Strain） value at the beginning of martensitic phase transformation.It is shown that SMA＇s energy dissipating capacity is proportional to the stiffness difference of bilinear model and nonlinearly dependent on Ms-Strain.The increasing rate of the dissipating capacity gradually reduces with the amplitude increasing.The condition corresponding to the maximum dissipating capacity is deduced for given value of the vibration amplitude.The obtained results are helpful for designing beams laminated with shape memory alloys.

Study on energy release characteristics of reactive material casings under explosive loading

Reactive Materials(RMs),a new material with structural and energy release characteristics under shockinduced chemical reactions,are promising in extensive applications in national defense and military fields.They can increase the lethality of warheads due to their dual functionality.This paper focuses on the energy release characteristics of RM casings prepared by alloy melting and casting process under explosive loading.Explosion experiments of RM and conventional 2A12 aluminum alloy casings were conducted in free field to capture the explosive fireballs,temperature distribution,peak overpressure of the air shock wave and the fracture morphology of fragments of reactive material(RM)warhead casings by using high-speed camera,infrared thermal imager temperature and peak overpressure testing and scanning electron microscope.Results showed that an increase of both the fireball temperature and air shock wave were observed in all RM casings compared to conventional 2A12 aluminum ally casings.The RM casings can improve the peak overpressure of the air shock wave under explosion loading,though the results are different with different charge ratios.According to the energy release characteristics of the RM,increasing the thickness of RM casings will increase the peak overpressure of the near-field air shock wave,while reducing the thickness will increase the peak overpressure of the far-field air shock wave.

Relationships between Potential Risk of Hazardous Material Releases and Socio-Economic Demographic Characteristics Using Geospatial Analysis

The problem investigated in this research is about the potential risk of technological hazards, which poses a perilous threat to humankind and the environment. Rapid urbanization has been increasing the population density in an area, elevating the risk of exposure to technological disasters. Therefore, it is necessary to detect the areas with higher chemical risk to spread awareness about the potential risk zones and reduce actual damage and casualties resulting from the hazardous substance events. The basic design of the study utilizes geospatial analysis to map the TRI (Toxics Release Inventory) facilities in the communities of Texas to establish a relationship between potential hazardous material release zones and the human population at risk. The study identified the vulnerable counties as well as investigated how those risk areas are related to race/ethnicity, income and education. The research would contribute to the policymakers acting on the hazard situation and keep them better prepared for chemical hazards. In addition, it would help the residents and emergency managers to better understand the circumstance to mitigate the consequences as well as increase their awareness to be ready for the uncertainties in the hotspots involved in high risk of the hazards.

Influence of quick release valve on braking performance and coupler force of heavy haul train

We establish a simulation model based on the theory of air flow to analyze the accelerated release effect of the quick release valve inside the air brake control valve.In addition, the combined simulation system of train air brake system and longitudinal train dynamics is used to analyze how the parameters of the quick release valve in the 120/120–1 brake control valve affect the propagation characteristics of the train brake pipe pressure wave, the release action range of the accelerated brake, and the longitudinal coupler force for a 20,000-ton heavy haul train on the section of the Datong–Qinhuangdao Railway. The results show that the quick release valve can effectively accelerate the rising speed of the train brake pipe pressure during the initial release, as the accelerated release effect is evident before the train brake pipe pressure reaches582 k Pa. The quick release valve can effectively accelerate the release of the rear cars, reducing the longitudinal coupler force impact due to time delay of the release process. The quick release valve can effectively reduce the tensile coupler force in the train by as much as 20% in certain cases.

Effects of different types of slow-and controlled-release fertilizers on rice yield

This experiment explored the effects of single application of seven types of slow-and controlled-release fertilizers on rice yield and various population characteristics.Based on a study of the nitrogen(N)release characteristics of these fertilizers,pot experiments were conducted in 2018 and 2019 with split fertilization(CK,urea applied split equally at basal and panicle initiation stages,respectively)as control,which assessed the effects on SPAD value,yield and yield components,dynamic changes of rice tillers and dry matter accumulation.The results showed that the N release characteristics of different types of slow-and controlled-release fertilizers were significantly different.Polymer-coated urea(PCU)showed a controlledrelease mode and provided sustained release throughout the whole growth stages.Sulfur-coated urea(SCU)exhibited a slow-release mode,providing insufficient release at the middle and late stages.Urease inhibitor urea(AHA)and ureaformaldehyde(UF)yielded a rapid-release mode,with an explosive N release at the early stage and no release at the middle and late stages.These results showed that PCU delayed the peak seedling stage.Compared with CK,dry matter accumulation and SPAD showed no significant differences,and due to the continuous release of N throughout the growth stages,rice yield,spikelets per panicle,seed setting rate,and 1000-grain weight were all increased.Owing to the lack of N supply at the late stage and the low number of spikelets,SCU led to a reduction of rice yield,which is nevertheless not statistically significant.AHA and UF were susceptible to environmental factors and had varying effects on rice yield.The results of this experiment indicated that given a fixed amount of N applied in a pot,the stronger the N supply capacity and the longer the effective duration time of the fertilizer,the higher the dry matter accumulation at the late growth stage,and the higher the rice yield.

General Situation of Green Manure Germplasm Resources in China and Research Progress on Decomposition Characteristics and Fertility Improvement of Green Manures

As a kind of biological fertilizer sources, green manure can improve soil fertility and the quality of agricultural products. This paper introduced the germplasm resource of green manures in the major provinces in China, mainly summarized the characteristics of decomposition and nutrients release of returning green manures to soils, as well as the influence on soil fertility and succeeding crops, with the aim to provide references for rational utilization of green manures and the scientific management of farmland nutrients.

Analysis of NO_X Emission Characteristics of Pulverized Coal Combustion in Different Atmosphere

Researches on the NOX emission characteristics of HT(Huangtai coal),LC(Laicheng)coal are carried out in different atmosphere.The results show that the NOX emission time is postponed in O2/N2 atmosphere mixed with CO.The releasing times of volatile nitrogen and char nitrogen approach,the amount of NOX reduces.In high O2 concentration atmosphere mixed with CO2,the nitrogen releasing times come ahead of time,NOX congregate in the beginning of the combustion.On the contrary,nitrogen releases separately,and the amount of NOX reduces greatly.

Gas release characteristics during carbonization of iron coke hot briquette and influence of heating rate

The release characteristics of CH_(4),H_(2),CO and CO_(2) from iron coke hot briquette(ICHB)during carbonization were studied.The results show that compared with briquette without iron ore,Fe_(3)O_(4) can inhibit the release rate of H2 and promote the production of CO and CO_(2).In addition,when the heating rate increases from 3 to 7℃/min,the release rates of CH4 and H2 increase,while the release rates of CO and CO_(2) first increase and then decrease.The carbonization process of ICHB was segmented,and corresponding kinetic analysis was carried out.The results show that the activation energy of StageⅡand StageⅣis higher in the carbonization process of ICHB,and the active pyrolysis of coal and the reduction of iron ore occur in these two stages.In addition,the effect of heating rate on the kinetic parameters of ICHB carbonization process was investigated.It was found that when the heating rate increased,the reaction activation energy of StageⅣdecreased first and then increased,which was consistent with the release law of CO and CO_(2).The analysis showed that the increase in heating rate leads to more reactions at higher temperatures,resulting in an increase in the release rate of some gases.In addition,thermal hysteresis can also cause some processes to fail to fully react at the end of heating.It is also found that the apparent activation energy and preexponential factor have kinetic compensation effect during the car-bonization of ICHB.

机车充风能力对重载列车缓解性能及车钩力影响研究

机车充气与排气性能是列车制动系统重要指标,目前机车制动系统验收指标仅对排气性能有明确要求,对充气性能无要求。机车供风能力不仅影响重载列车缓解特性和车钩力,而且严重制约重载列车在循环制动中的操纵方法。了解机车充气能力对缓解特性和车钩力的影响规律,以及重载列车安全运行和制动系统设计具有重要意义。通过建立列车空气制动系统仿真模型,分析机车充风能力对重载列车缓解特性和车钩力的影响。分析发现,机车充风能力对列车再充风时间、缓解波传播和车钩力都有明显影响;充风能力越弱,则缓解波传递越慢,车钩力越大。在本文研究范围内,合适的充气能力将比弱充风能力首尾车缓解时间差缩短3 s,最大车钩力降低16.2%。建议机车验收时增加机车充风能力检测,并给出了建议检测标准。针对重载列车充风能力,建议多部门联合系统性开展实验与仿真研究,制订重载列车制动系统检测标准与方法。

收敛约束法在挤压性围岩隧道中的应用

由于挤压性围岩隧道围岩性质与应力环境的特殊性,其围岩特征曲线与常规隧道有明显差异。为研究挤压性围岩隧道围岩-支护相互作用关系,考虑支护效应修正围岩特征曲线,研究不同变形等级对修正围岩特征曲线的影响规律,优化挤压性围岩双线铁路隧道初期支护。研究结果表明,毛洞状态下,受双线隧道断面应力集中影响,拱脚和墙脚为安全控制位置;随着变形等级和侧压力系数增加,支护特征曲线与修正围岩特征曲线不再相交;Ⅰ、Ⅱ级变形采用单层支护可满足安全要求,锚杆只需布置在拱部和边墙位置,Ⅱ级及以上变形锚杆需要全环布置;Ⅳ级变形在采用双层支护的同时,需考虑改善洞室形状、超前加固等措施。

地铁车站月平均气温随运营年限演化特性

建立了地铁车站空气热平衡理论模型,基于区间隧道空气温度和车站围岩土体蓄放热量,得到车站月平均气温在运营初期、中期和远期的逐年演化特性。研究结果表明:随着地铁车站运营年限的增长,月平均气温呈现逐年上升趋势,运营第15年较第1年,车站月平均气温在1月温升最低为3.1℃,8月温升最高为10.6℃;在现有地铁行车密度随运营年限增大的运行模式下,地铁车站运营初期行车密度仅为15对/h,夏季车站最高气温出现在第5年,为26.4℃,远低于夏季站厅站台空调设计温度平均值29℃,所以运营初期车站空调系统提供的冷量远大于车站的冷负荷需求,初期车站空调系统存在一定的节能空间。

加热卷烟芯基材料热性能及气溶胶释放特性分析研究进展

芯基材料是加热卷烟烟碱及香味成分的来源,加热卷烟烟草薄片是目前最常用的加热卷烟芯基材料,烟草薄片生产工艺主要有造纸法、干法造纸法、稠浆法和辊压法等,与传统卷烟烟草薄片相比,加热卷烟烟草薄片在理化特性和感官质量方面均存在较大差异。加热卷烟以低温加热方式供吸烟者抽吸,其气溶胶的释放特性也与传统卷烟有显著差异。本文结合近几年加热卷烟芯基材料研究工作,从制造工艺、热性能和气溶胶释放特性分析3个方面对加热卷烟芯基材料进行综述,为加热卷烟产品的设计开发和品质提升提供参考。

好氧堆肥污泥农用后溶解性有机质释放特征

研究污泥农用后溶解有机质(DOM)的释放特征,有助于评价和预测土壤中共存污染物的环境行为和效应。以河南省洛阳市某污泥处理厂好氧堆肥后的市政污泥作为样本,利用扫描电子显微镜(SEM)、总有机碳分析仪、紫外-可见吸收光谱(UV-Vis)、凝胶渗透色谱(GPC)、三维荧光光谱(3D-EEM)、傅里叶变换红外光谱(FTIR)和核磁共振波谱(NMR)等表征技术,研究污泥农用后释放DOM的浓度、分子量、组成和结构等性质的演变特征。结果表明,污泥还田60 d内,释放的DOM微观形貌上存在较大变化,由致密块状物变为不规则松散物质;污泥农用后释放溶解性有机碳(DOC)量在4.25~6.22 mg·g^(-1)污泥范围,呈现先上升后稳步下降的趋势;释放过程中,污泥DOM的分子量和芳香性等性质也存在显著的变化:污泥DOM重均分子量由0.5 d时2674 g·mol^(-1)的逐渐升高为60 d的129026 g·mol^(-1);污泥还田后释放的DOM分子中芳香性物质逐渐积累;3D-EEM结合平行因子分析(PARAFAC)模型分析污泥释放DOM中的荧光物质,发现DOM中荧光物质主要为类富里酸和类腐殖质,释放过程中,类腐殖质逐渐积累,DOM整体上呈现腐殖化趋势;FTIR图谱表征污泥DOM脂肪族烷烃类物质的减少和芳香烃物质生成。污泥还田后释放DOM数量和性质变化,显著改变土壤中共存污染物环境行为和生态效应。该研究可为评估和预测污泥农用后产生的环境影响提供理论依据,也对市政污泥的资源化利用具有一定指导意义。

煤与生物质耦合燃烧的协同效应

生物质燃料是替代化石燃料的重要能源,在燃煤机组上掺烧生物质是当下生物质能利用的主要途径。由于煤和生物质耦合燃烧过程中存在协同效应,生物质燃料与煤耦合燃烧性能与二者单独燃烧的燃烧性能差异无法通过化学成分或相关性质算术平均来确定,与此同时,生物质中富含的碱金属K也会加重受热面结渣倾向。为研究煤与生物质混合燃烧过程中协同效应,选取神府烟煤与板栗壳作为试验样品,通过混合、研磨与压制,制备成圆饼形颗粒并在Hencken平焰燃烧器上进行燃烧试验。利用高速摄像机结合图像处理技术计算着火延迟时间,利用光谱仪结合自发辐射理论测量燃烧过程中火焰温度、气相K浓度。探讨耦合燃烧着火特性、燃烧特性与气相碱金属释放特性协同效应及其原因。最后,结合灰分分析结果计算各工况结渣指数,获得燃烧气相碱金属释放量与结渣指数相关性关系。结果表明:煤与生物质耦合燃烧着火延迟时间低于理论值,证明耦合燃烧着火存在协同效应,表现为促进着火。受纤维素热解与碱金属元素催化共同影响,生物质质量分数为50%时,着火延迟时间与理论值之差达到最大1.91 s,协同效应最大;耦合燃烧释放的碱金属低于理论值,说明耦合燃烧气相碱金属释放协同效应表现为抑制气相碱金属释放,由挥发分-焦炭相互作用与无机反应共同控制,无机反应中Si、Al元素与K反应占主导;随气相K释放量增大,碱酸比与硅比数值增大,结渣倾向升高,结渣指数与气相K释放量间相关性系数均大于95%,说明气相K释放量与结渣指数高度相关,可见在线监测获得的气相K释放浓度具有判别结渣特性潜力。

浅水爆炸冲击波特性及其毁伤效应研究进展

为阐明浅水爆炸条件下冲击波界面效应,分别从自由水面、水底以及自由水面和水底两个界面双重作用条件下归纳了冲击波线性反射和非线性反射理论、实验等研究进展。总结了浅水区混凝土障碍、舰船毁伤方式,分析了由于界面作用以及装药、起爆方式等的差异而导致冲击波在近场的非均匀分布性,采用爆炸能量调控改变在特定方位能量输出,从而提升浅水爆炸毁伤效应的可行性。指出浅水爆炸理论发展仍未完善,浅水爆炸近场能量结构控制、混凝土目标动态响应和毁伤效应,界面反射冲击波与气泡相互作用是重点研究方向。附参考文献129篇。

大米淀粉-多酚复合物在不同条件下的释放特性分析

该文研究了稻米中的主要单体酚(阿魏酸、没食子酸)与大米淀粉形成复合物后,多酚对α-淀粉酶和葡萄糖苷酶的活力的影响,以及复合物中多酚在不同条件下的释放特性。结果表明,在α-淀粉酶作用下,随着复合物中多酚含量从5%增加至20%,淀粉的水解率呈下降趋势(阿魏酸组由54%降至49.69%,没食子酸组由57.97%降至49.81%)。同样,在葡萄糖苷酶作用下,没食子酸的水解率显著降低(由65.72%降至57.13%)。对于消化特性,不同添加量(由5%增加至20%)的没食子酸的加入显著降低了RDS的含量(由80.76%降至64.62%),阿魏酸的SDS含量降低(由15.69%降至14.07%),RS含量显著增加(由11.26%增加至16.69%)。复合物中阿魏酸的释放量随着水溶液的温度(30~80℃)的升高增加了131.43%。随着pH值的增加(2~6),阿魏酸的释放量呈现先降后增的趋势,而没食子酸的释放量则呈现增加的趋势。在模拟胃肠消化实验中发现,阿魏酸在胃液中提前释放,而没食子酸(5%)在肠液中释放量减小(由2.19 mg降至1.56 mg)。该研究结果可为膳食多酚在淀粉基功能食品中的应用提供理论参考。

海上平台强引射放空火炬流动特性数值研究

针对一种强引射放空火炬,应用Fluent软件对辅助引射器和火炬头的流动特性进行了数值模拟研究。基本型计算表明,辅助引射器的引射系数为3.25,火炬头的引射比为0.77。正交分析表明,辅助引射器优化参数组合为:混合管道扩张角4°、喉部环空间隙7.5 mm、燃气入口直径7 mm、空气入口直径60 mm,优化结构引射系数为6.30;火炬头优化参数组合为:筒体扩张角7°、防风罩间隙207 mm、辅助引射器数量8、主放空管深度242 mm,优化结构引射比为0.89,引射性能提高16%。