具有时滞效应的air2stream河流水温模型及应用研究

高精度河流水温模型对于深入了解水温的时空变化特征和河流生态修复具有重要意义。基于数据驱动的air2stream模型在保证预测精度的同时,避免了计算的复杂性,已成为河流水温模拟常用的模型。由于水的热惯性及水文条件等的影响,河流水温变化往往显著滞后于气温变化,而air2stream原模型并未考虑滞后效应,导致该模型在流量未知情况下实际精度偏低。为解决该问题,采用气温-水温皮尔逊相关系数计算时滞天数,构建具有时滞的air2stream新模型,进一步根据长江中下游地区两个监测站的多年实测数据验证新模型的有效性和稳定性。结果表明:新模型在不引进额外观测数据的条件下具有更高精度且性能更稳定。相比原模型,在两个监测站新模型的均方根误差分别降低约4.29%和5.85%。新模型具有精度高、水文要素需求少的特点,可为长江中下游的水环境影响评价和生态保护提供依据。

高温环境因素对固-液混合燃料物理稳定性的影响

固-液混合燃料的物理稳定性对于燃料的质量和安全性均有重要的意义。高温环境引发的易挥发液体组分的气化将对燃料的物理稳定性产生极为复杂的影响。通过自主设计的实验装置模拟、加速燃料物理稳定性改变,并分别从液体燃料析出及密度分布变化趋势,分析高温环境因素的作用。结果表明:自然堆垛状态下燃料的顶部受饱和蒸汽压的改变影响较大,而中部、底部则由于燃料的紧密堆积,形成各自独立的气液平衡。同时,液体燃料于高温环境中对固体的润湿效果随之增强,更有利于液体组分完成对固体颗粒的吸附。在303~333 K的温度条件下,固液体积比为1.25∶1,硝基甲烷占液体组分40%的固-液混合燃料保持最佳的物理稳定性。

Physical Properties of Crushed Air-cooled Blast Furnace Slag and Numerical Representation of Its Morphology Characteristics

Physical properties and geometrical morphologies of crushed air-cooled blast furnace slag （SCR） and crushed limestone （LCR） were comparatively investigated. The shape, angularity, surface texture and internal pore structure of aggregate particles for different size and gradation were numerically represented by sphericity （ψ） and shape index （SI）, angularity number （AN）, index of aggregate particle shape and texture （IAPST）, porosity and pore size, respectively. The results show that SCR is a porous and rough aggregate. Apparent density, void, water absorption and smashing index of SCR are obviously higher than those of LCR with the same gradation, respectively. However, bulk density of SCR is lower than that of LCR with the same gradation. SI, AN, IAPST and porosity of SCR are obviously higher than those of LCR with the same gradation, respectively. The smaller particle size of SCR, the larger of its AN, IAPST and porosity.

Application of Air-cooled Blast Furnace Slag Aggregates as Replacement of Natural Aggregates in Cement-based Materials：A Study on Water Absorption Property

The influence of air-cooled blast furnace slag aggregates as replacement of natural aggregates on the water absorption of concrete and mortar was studied, and the mechanism was analyzed. The interface between aggregate and matrix in concrete was analyzed by using a micro-hardness tester, a laser confocal microscope and a scanning electron microscope with backscattered electron image mode. The pore structure of mortar matrixes under different curing conditions was investigated by mercury intrusion porosimetry. The results showed that when natural aggregates were replaced with air-cooled blast furnace slag aggregates in mortar or concrete, the content of the capillary pore in the mortar matrix was reduced and the interfacial structure between aggregate and matrix was improved, resulting in the lower water absorption of mortar or concrete. Compared to the concrete made with crushed limestone and natural river sand, the initial absorption coefficient, the secondary absorption coefficient and the water absorption capacity through the surface for 7 d of the concrete made from crushed air-cooled blast furnace slag and air-cooled blast furnace slag sand were reduced by 48.9%, 52.8%, and 46.5%, respectively.

Effect of Crushed Air-cooled Blast Furnace Slag on Mechanical Properties of Concrete

Morphology characteristics of mix aggregates with crushed air-cooled blast furnace slag（SCR） and crushed limestone（LCR） with 5-20 mm and 20-40 mm gradation were represented by numerical parameters including angularity number（AN） and index of aggregate particle shape and texture（IAPST）.The effect of mix aggregates containing SCR on compressive strength and splitting tensile strength of concrete was investigated.Fracture characteristics of concrete,interfacial structure between aggregates and matrix were analyzed.The experimental results show that porous and rough SCR increases contact area with matrix in concrete,concave holes and micro-pores on the surface of SCR are filled by mortar and hydrated cement paste,which may increase interlocking and mechanical bond between aggregate and matrix in concrete.SCR can be used to produce a high-strength concrete with better mechanical properties than corresponding concrete made with LCR.The increase of AN and IAPST of aggregate may enhance mechanical properties of concrete.

Optimization of the Air Deck Blasting Parameters on the Basis of the Holmquist-Johnson-Cook Constitutive Model

The present study considers the so-called air deck blasting,one of the most commonly used techniques for the improvement of blasting efficiency in mining applications.In particular,it aims to improve the operating conditions of large-scale equipment,increase the efficiency of the slope enlarging process,and reduce the mining cost.These objectives are implemented through a two-fold approach where,first,a program for slope enlarging based on the middle air-deck charge blasting-loosening technology is proposed,and second,the physical mechanism responsible for the stress wave attenuation in the rock is analyzed in the framework of a Holmquist–Johnson–Cook constitutive model.Field test results verify that the proposed approach is highly efficient and economical when used in medium-hard rock blasting and thus provides a basis for the practical implementation of slope enlargement for high benches in Open-Pit Mines.

High Strain-Rate and Shock Response of Carbon SupercompositeTM

This study focuses on assessing the dynamic behaviors of carbon SupercompositeTM laminates when subjected to high strain-rates and air blast loads, using a shock tube for testing. The investigation aims to understand the response of these advanced materials under extreme conditions, which is crucial for applications in aerospace, military, and other high-performance industries. SupercompositeTM (CZE) prepreg, made up of a 3K plain weave carbon fabric with milled carbon fibers as interlaminar reinforcements impregnated with epoxy, is used to create SupercompositeTM (CZE) laminates. A woven carbon composite (CBE) laminate was also created using 3K plain weave Carbon/Epoxy (CBE) prepreg. Both types of laminates were designed and fabricated using the autoclave process. The dynamic behaviors of CZE and CBE laminate under transverse compression loads were evaluated using a modified Split Hopkinson Pressure Bar (SHPB). The study found that the 3D reinforcement with milled carbon fibers significantly affected the dynamic behavior of the CZE laminate. Stereo imaging videos, captured using two SHIMADZU high-speed video cameras in shock tube experiments, recorded the time history of back surface deflection. The plate specimens exhibited low deflections without any visible damage. The experimentally observed center point deflections of the CZE plates decayed sooner than those of the CBE laminates, indicating an improvement in damping due to the presence of 3D reinforced milled carbon fibers. This research shows that optimized utilization of milled carbon fibers as 3D reinforcement can withstand high stress in the thickness direction and higher energy absorption when subjected to impact and high strain-rate loading.

Synthesis of (Ca, Mg)-α′-Sialon-AlN-BN powders from boron-rich blast furnace slag by microwave carbothermal reduction-nitridation

(Ca, Mg)-α′-Sialon-AlN-BN powders were synthesized by the carbothermal reduction and nitridation (CRN) method using boron-rich slag, one of the intermediate products from pyrometallurgy separation of pageit, as the staring material. The influences of synthesis temperature and holding time on the phase composition and microstructure during the microwave CRN were studied by XRD, SEM and EDS. The comparison between two heating techniques, conventional and microwave heating, on the synthesized powder was presented as well. The experimental results revealed that the phase compositions and microstructures of the synthesized products were greatly affected by the synthesis temperature and holding time. With an increase in the synthesis temperature or holding time, the relative amount of α′-Sialon increased and α′-Sialon became the main crystalline phase at 1400 °C for 6 h. The synthesized products also contained AlN, BN and a small amount of β-SiC. Elongated α′-Sialon grains, short rod AlN grains, aggregate nanoscale BN grains were observed in the synthesized powders. The reaction temperature of microwave heating method was reduced by 80 °C, the reaction time was shortened by 2 h, and more elongated α′-Sialon grains with large aspect ratio were observed.

Simulation of Airblast Load and Its Effect on RC Structures

In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpressure, but also the impulse (hence the duration). For structures with a regular geometry, the blast load may be fairly well estimated using appropriate empirical formulae; however, for more complex situations, a direct simulation using appropriate computational techniques is necessary. This paper presents a numerical simulation study on the prediction of the blast load in free air using a hydrocode, with focus on the sensitivity of the simulated blast load to the mesh grid size. The simulation results are compared with empirical predictions. It is found that the simulated blast load is sensitive to the mesh size, especially in the close-in range, and with a practically affordable mesh grid density, the blast load tends to be systematically underestimated. The study is extended to internal blast cases. An example concrete slab under internal explosion is analyzed using a coupled analysis scheme. The internal blast load from the simulation is examined and the response of the RC slab is commented.

Experimental Investigation on Shock Wave Characteristics of Aluminized Explosives in Air Blast

To investigate the shock wave characteristics of RDX-based aluminized explosives,air blast tests were conducted for measuring the parameters of 10 kg aluminized explosives which contained 0-40% aluminum.The results showed that with the increasing of aluminum content,the overpressures and impulses increase at first and then decrease within 7 m or 5 m,which reached the maximum when aluminum content was 20% or 30%.Power exponential formulas are used to fit the shock wave parameters vs scaled distance,where an equal weight of TNT is used to calculate the scaled distance.The overpressures of HL0 and TNT in tested locations not only conform to the similar law,but also conform to the same attenuation law after gaining the scaled distances of equal TNT mass.The pre-exponential factors of overpressure and impulse,kp and kI,decrease along with the increasing of Al content and keep the same pace as the calculated PCJ）.The attenuation coefficients a_P and aIincrease at first and decrease later with the increasing of aluminum content,and they reached the maximal values with30% Al containing,which keeps the same pace as the calculated QV.

基于LS-PrePost的不同形状装药爆炸仿真研究

LS-PrePost是一款功能强大、操作便捷的爆炸仿真软件。*INITIAL_VOLUME_FRACTION_GEOMETRY和*LOAD_BLAST是LS-PrePost中的关键字卡片,而SPH是一种光滑粒子流体动力学方法,都可以用来施加爆炸载荷。为研究球形装药爆炸仿真建模方法,使用以上方法进行建模,分析不同建模方法的优缺点及适用场景。选择最优建模方法研究1 kg TNT炸药不同形状装药爆炸产生空气冲击波的不同。本文在研究爆炸仿真建模现状的基础上,查阅文献资料,选择最优建模方法。在经过验证的有限元模型上进行爆炸仿真,模拟实验仅改变装药形状参数,对球形、柱形、方形装药的有限元爆炸模型进行求解,得到不同比例距离下的超压峰值,制作图表比较各组超压峰值数据的差异。结果表明,在比例距离小于等于1.0 m·kg^(-1/3)时,柱形装药的超压峰值与球形装药更接近,而方形装药超压峰值与球形装药差异更大;随着比例距离的增加,柱形装药的峰值超压与球形装药的比值变化不大,而方形装药的峰值超压与球形装药的比值逐渐增加,变化较大。不同装药形状对于爆炸产生的冲击波超压的影响是不容忽视的,在研究实际爆炸案件的装药及其爆炸破坏作用时,应尽可能采用最接近实际情况的装药形状。在通过爆炸仿真方法研究问题时,也要选择合适的建模方法和装药条件,才能保证分析结果的准确可靠。

Changes in Protein Content and Chitinase and β-1,3- glucanase Activities of Rice with Blast Resistance Induced by Ag-antibiotic 702

[Objective] The paper was to explore the effect of rice blast resistance induced by Ag-antibiotics 702 on protein content and chitlnase and β-1,3-glucanase activities in rice. [ Method] At the fourth leaf stage of Luliangyou 996, 15 μg/mL Ag-antibiotic 702 was sprayed, while Validamycin and distilled wa- ter were sprayed as positive control and negative control, respectively. All treatments were inoculated with spore fluid of Magnaporthe grisea at 48 h post spraying, and the rice inoculated with only distilled water was used as blank control. The enzymes activities （endochitinase, exochitinase and β-1,3-glucanase） and total pro- tein content in rice leaves were determined every 24 h within 168 h post spraying. [ Result] Compared with the blank control, the rice inoculated with spore fluid of M. grisea could significantly increase the total protein content and the activities of β-1,3-glucanase and chitinase. The induction effect of Ag-antibiotics 702 exceeded that of Validamycin treatment. And the changes in activities of β-1,3-glucanase and chitinase had obvious synchronicity. [ Conclusion] Ag-antibiotic 702 can significantly improve the total protein content and the activities of β-1,3-glucanase and chitinase, thus enhancing the resistance to rice blast.

组合称重法与分压法的C_(5)F_(10)O-PFK/Air混气制备技术研究

制备高精度的C5-PFK/Air混合气体有利于实现对C5-PFK气体-电气性能的科学论证。采用称重法与分压法实现了对不同混合比的C5-PFK/Air混合气体的制备,搭建C5-PFK/Air混气制备实验系统,建立了气相色谱-氢火焰离子化检测器(GC-FID)对制备的C5-PFK/Air混气中C5-PFK定性定量分析的仪器方法,可对实验结果进行溯源校准。研究结果表明,制备13%C5-PFK/Air混合气体的RSD为0.89%,最大示值误差为0.77%;压力为0.5 MPa时,12%~15%浓度范围内C5-PFK/Air混气中C5-PFK峰面积线性拟合系数R^(2)为0.995,一致性良好,可完全汽化;6个月的稳定性考察,气体特性值保持不变,稳定性良好。

Experimental Study on Coal-Breaking Pressure for Compressed Air

Based on lab model experiments and through the limit analysis, the theoretical formula of calculation coal breaking pressure with compressed air was derived. The experimental result shows that blasting pressure must exceed 84.0MPa to break coal with compressive strength of 13.2MPa. The research provides an important theoretical basis for the design of airshooting mining and industrial tests.

The Application of Air-flow to the Technological Process of Chemical Fiber

The air-flow’s states and ways acted on the technological process of chemical fiber are summed up, which includes chip drying, spinning quenching as well as airjet texturing (air texturing, tangling texturing and bulked continuous filament (BCF)),and the effect of air-flow on the process and quality of chemical fiber is studied,and the action of mechanics and heat on the bulked continuous filament are calculated.

Air-flow Analysis for BCF Texturing Tube

In this paper,the Reynolds number,velocity,pressureand kinetic energy of the BCF processing hot air-floware analyzed with the help of the aero-dynamic theory,and their distributions inside the texturing tube are ob-tained by pressure measuring.

Development and Application of Al_2O_3-Si_3N_4 Refractories Used in Blast Furnace

Newly developed Al2O3-Si3N4 composite refractories used for blast furnace is introduced in this work. Al2O3-Si3N4 composite refractories attacked by alkali vapor and blast furnace slag was investigated. High performance Al2O3-Si3N4 composite refractories was produced and used at both 2560m^3 blast furnaces of Tan-gsteel and No. 5 blast furnace of Shaosteel.

Effect of abrasive blasting on the internal surface of L80-13Cr tubing and casing

In this study,two sandblasting textures,namely,quartz and high-chromium(Cr)stainless steel sands,were used for sandblasting of the internal surface L80-13Cr tubing and casing.The contrastive analysis on the properties of the pipes before and after abrasive blasting was conducted,including the metallographic phase detection of the internal surface,simulating accelerated corrosion tests,and residual stress tests for the pipe after abrasive blasting.Based on the analysis results,it is explained why the API standard requires that no scale appears on the internal surface of L80-13Cr and iron contamination when internal sandblasting media are applied.The results show that abrasive blasting can effectively remove scales on the internal surface of L80-13Cr tubing and casing and improve corrosion resistance.The abrasive blasting process does not produce obvious residual stress on the internal surface of the tubing and casing.Also,the de-rusting effect of stainless sand is better than that of quartz sand,and the former does not produce iron contamination.

Non-water Injection Mix for Blast Furnace YB/T 4153-2006

1 Scope This standard specifies the classification, techni cal requirements, test methods, quality appraisal pro- cedures, packing, marking, transportation, storage, quality certificate, and construction manual of nonwater injection mix for blast furnace.

高炉煤气燃烧数值模拟在LOMA-MLB热风炉调试中的应用

LOMA-MLB热风炉为适用于高炉煤气的炉型,通过计算机建模和网格划分,使用Fluent软件数值模拟高炉煤气在热风炉中的燃烧情况,验证热风炉调试时配风所需的空燃比及烟气温度参考值。模拟结果表明,燃烧反应质量传递过程基本完成,实验数据比模拟数据计算的热值稍高,模拟燃烧燃尽率高,燃烧火焰中心最高温度为1 595K,出口处NOX含量仅为0.008 6ppm,高炉煤气钝体的设计有利于燃料与空气的混合和保持火焰的连续稳定。