Study on Semi-Continuous Technology System for Soft Material Stripping in Large Surface Mines

Continuous and semi-continuous mining technology has become the main trend of modern surface mines in the world. According to the deposit characteristics of coal basin in China and Chinese situation,this paper discussed the new semi-continuous technology── shovel - transfer wagon-belt conveyor and its application prospect in large surface coal mines in China.

Effect of Packing Materials and Other Parameters on the Air Stripping Process for the Removal of Ammonia from the Wastewater of Natural Gas Fertilizer Factory

Air-stripping method was used to remove ammonia from the wastewater collected from natural gas fertilizer factory. Different materials were used as packing materials for the air stripping system. The effect of pH over 10.5, air-water flow ratio, nature of packing materials, height of materials and initial influent concentration of ammonia on air stripping unit were investigated. An attempt has been made to find out the stripping con-stant. Stripping constant was found to be .001, 0014, .001 and .0009 for coal, plastic ring, stone chips and wood chips, respectively. Best result was found for plastic ring for its higher surface area. Wood chips did not give good result, because the chips amalgamate with each other and hence reduces the surface area.

ANTI-PLANE FRACTURE ANALYSIS OF FUNCTIONALLY GRADIENT MATERIAL INFINITE STRIP WITH FINITE WIDTH

The special case of a crack under mode Ⅲ conditions was treated, lying parallel to the edges of an infinite strip with finite width and with the shear modulus varying exponentially perpendicular to the edges. By using Fourier transforms the problem was formulated in terms of a singular integral equation. It was numerically solved by representing the unknown dislocation density by a truncated series of Chebyshev polynomials leading to a linear system of equations. The stress intensity factor （SIF） results were discussed with respect to the influences of different geometric parameters and the strength of the non-homogeneity. It was indicated that the SIF increases with the increase of the crack length and decreases with the increase of the rigidity of the material in the vicinity of crack. The SIF of narrow strip is very sensitive to the change of the non-homogeneity parameter and its variation is complicated. With the increase of the non-homogeneity parameter, the stress intensity factor may increase, decrease or keep constant, which is mainly determined by the strip width and the relative crack location. If the crack is located at the midline of the strip or if the strip is wide, the stress intensity factor is not sensitive to the material non-homogeneity parameter.

Separating trash and solid materials from the wastewater ammonia stripping tower UASB biological oxidation pond processes for the treatment of the swine factory＇s wastewater

By making the use of the processes which includes separating trash and solid materials from the wastewater-ammonia stripping tower-UASB-biological oxidation pond, we have treated the wastewater which comes from the swine factory. The treated wastewater can meet the primary standard of The People＇s Republic of China based on sewage discharge standards and the wastewater treatment project design contract （GBl8596-2001）, and the effluent will be used as irrigation-water. We introduce this project including the quality of influent and effluent and the flow scheme, the statement of every part, the investment and the effect, etc. The operation indicated that this process has many merits such as the stability in operation-effect and the convenience in management. So it will provide some help for the similar wastewater treatment.

Powell's optimal identification of material constants of thin-walled box girders based on Fibonacci series search method

A dynamic Bayesian error function of material constants of the structure is developed for thin-walled curve box girders. Combined with the automatic search scheme with an optimal step length for the one-dimensional Fibonacci series, Powell＇s optimization theory is used to perform the stochastic identification of material constants of the thin-walled curve box. Then, the steps in the parameter identification are presented. Powell＇s identification procedure for material constants of the thin-walled curve box is compiled, in which the mechanical analysis of the thin-walled curve box is completed based on the finite curve strip element （FCSE） method. Some classical examples show that Powell＇s identification is numerically stable and convergent, indicating that the present method and the compiled procedure are correct and reliable. During the parameter iterative processes, Powell＇s theory is irrelevant with the calculation of the FCSE partial differentiation, which proves the high computation efficiency of the studied methods. The stochastic performances of the system parameters and responses axe simultaneously considered in the dynamic Bayesian error function. The one-dimensional optimization problem of the optimal step length is solved by adopting the Fibonacci series search method without the need of determining the region, in which the optimized step length lies.

A METHOD FOR PREDICTING BUCKLING LOADS OF COMPOSITE LAMINATED STRIPS WITH A SURFACE NOTCH

Surface notches lower the stiffness of laminated strips, so they lower the buckling loads of the laminated strips, too. In this paper a new method is proposed to predict the buckling loads of the laminated strips with a surface notch. The theoretical and experimental results show that the buckling loads decrease as the depth or width of the surface notches increase; when the stacking sequence of the laminated strips is [0°/0°/+ θ/-θ/0°/0°/+θ/-θ] s , the buckling load decrease as θ increases. It proves that the method is reliable and significant.

Coupled Dynamic Modeling of Rolls Model and Metal Model for Four High Mill Based on Strip Crown Control

The crown is a key quality index of strip and plate, the rolling mill system is a complex nonlinear system, the strip qualities are directly affected by the dynamic characteristics of the rolling mil. At present, the studies about the dynamic modeling of the rolling mill system mainly focus on the dynamic simulation for the strip thickness control system, the dynamic characteristics of the strip along the width direction and that of the rolls along axial direction are not considered. In order to study the dynamic changes of strip crown in the roiling process, the dynamic simulation model based on strip crown control is established. The work roll and backup roll are considered as elastic continuous bodies and the work roll and backup roll are joined by a Winkler elastic layer. The rolls are considered as double freely supported beams. The change rate of roll gap is taken into consideration in the metal deformation, based on the principle of dynamic conservation of material flow, the two dimensional dynamic model of metal is established. The model of metal deformation provides exciting force for the rolls dynamic model, and the roils dynamic model and metal deformation model couple together. Then, based on the two models, the dynamic model of rolling mill system based on strip crown control is established. The Newmark-13 method is used to solve the problem, and the dynamic changes of these parameters are obtained as follows： （1） The bending of work roll and backup roll changes with time; （2） The strip crown changes with time; （3） The distribution of rolling force changes with time. Take some cold tandem rolling mill as subject investigated, simulation results and the comparisons with experimental results show that the dynamic model built is rational and correct. The proposed research provides effective theory for optimization of device and technological parameters and development of new technology, plays an important role to improve the strip control precision and strip shape quality.

FRACTURE ANALYSIS OF A FUNCTIONALLY GRADED STRIP UNDER PLANE DEFORMATION

In this paper the plane elasticity problem for a functionally graded strip containing a crack is considered. It is assumed that the reciprocal of the shear modulus is a linear function of the thickness-coordinate, while the Possion＇s ratio keeps constant. By utilizing the Fourier transformation technique and the transfer matrix method, the mixed boundary problem is reduced to a system of singular integral equations that are solved numerically. The influences of the geometric parameters and the graded parameter on the stress intensity factors and the strain energy release rate are investigated. The numerical results show that the graded parameters, the thickness of the strip and the crack size have significant effects on the stress intensity factors and the strain energy release rate.

Effects of Strip Casting and Annealing on Electrochemical Properties of LPCNi_(3.55)Co_(0.75)Mn_(0.4)Al_(0.3) Hydrogen Storage Alloys

The effect of thickness (1 similar to 10 mm) of the ingots on the electrochemical properties of as-cast and annealed strip cast LPCNi3.55Co0.75Mn0.4Al0.3 hydrogen storage alloys was investigated. It is found that the 0.2 C discharge capacity of as-cast LPCNi3.55Co0.75Mn0.4Al0.3 alloy increases with the increase of the thickness of the ingots. As-east alloy with the thickness of 10 mm shows better activation property, higher 1C discharge capacity and better cyclic stability than others. It is mainly contributed to its larger unit cell volume and less internal stress. Annealed LPCNi3.55Co0.75Mn0.4Al0.3 alloy with the thickness of 3 mm shows much better comprehensive electrochemical properties than as-east one; The cyclic. stability of the alloy with the thickness of 6 mm and the activation properties of the alloys with the thickness of 3 similar to 6 mm are improved after annealing. It is mainly owing to the great release of internal stress and the decrease of the segregation of Mn in the alloys.

Investigation of Coercivity Mechanism for Nd-Fe-B Magnets Prepared by Combination of Strip-Casting with Hydrogen Decrepitation Techniques

The coercivity mechanism of Nd Fe B magnets prepared by combination of strip casting with hydrogen decrepitation techniques was investigated. The microstructure of (Nd 0.935 Dy 0.065 ) 14.5 Fe 79.4 B 6.1 magnet was observed. The average grain size is about 6～12 μm. The magnetizing field dependence of the hardmagnetic properties for the (Nd 0.935 Dy 0.065 ) 14.5 Fe 79.4 B 6.1 and the temperature dependence of the coercivity for the Nd 14.5 Fe 79.4 B 6.1 were investigated. Results show that the coercivity for magnets prepared by the combination of strip casting with hydrogen decrepitation techniques is controlled by the nucleation mechanism.

Influence of solidification rate on the microstructure of (Nd,Dy)_(12.8)(Fe,Co)_(80.7)B_(6.5) cast strips

The influence of solidification rate on the microstructure of (Nd,Dy)(12.8)(Fe,Co)(80.7)B-6.5 cast strips was reported in this paper. The strips prepared at different wheel speeds were analyzed by X-ray diffraction (XRD). The microstructure of the strips was investigated by backscattered scanning microscope (BSM). The XRD results show that the strips are mainly composed of the main phase (T-1) existing apparent alignment along [00L]. The thickness of T-1 columnar grains is larger when the solidification rate is lower and the over-small isotropic microcrystalline appear on the cooling surface of the strips when the solidification rate is too high. The adequate wheel speed for obtaining the optimum microstructure of the strips is about V = 2.0 m/s. The strip prepared at V = 2.0 m/s possesses suitable thickness and the highest alignment degree of T-1 columnar grains, uniformly distributed Nd-rich phase, and no existence of alpha-Fe phase. This kind of cast strip is an ideal starting material for preparing sintered magnets with high magnetic properties.

Development of Strip Casting Technology in Rare Earth Permanent Magnet Alloys and Hydrogen Storage Alloys in China

The SC technique is now being applied widely in material preparation, especially in rare earth functional materials in virtue of its advanced process and high performance product. The applications of SC technique in rare earth permanent magnet alloys and hydrogen storage alloys were analyzed integrative, on the basis of summary of SC technique development in this paper. The paper mainly includes development history of SC technology, effect of SC technology on alloy microstructure, application of SC technology in RE storage hydrogen alloy and sintered Nd-Fe-B alloy, development of SC equipment and SC product industry. At the same time, the paper points out the existing problem of SC products.

Power Stripping of Asbestos-Containing Insulation from Electrical Cable

Efforts to recycle copper from electrical conductors have led to the development of specialized machines, which automatically remove insulating covers from wires and cable products. In the past, certain wire and cable products were insulated using chrysotile asbestos. This research was undertaken to determine the asbestos fiber exposure risks associated with power stripping machinery to remove asbestos-containing insulation materials from electrical wire or cable. A Rigby Machinery, Inc., Model 4H electric powered wire/cable insulation stripping machine was acquired along with approximately 42 m of asbestos insulated cable. During two separate, but nearly identical, test sessions, a laborer used the wire stripper to remove the asbestos-containing insulation from the subject cable. This work took place within a closed metal building with a total interior volume of 2500 m3. Industrial hygiene personal and area air samples were collected for airborne fibers throughout all wire stripping periods. Collected air samples were analyzed using phase contract microscopy (PCM) and transmission microscopy (TEM). The results of analysis using PCM for personal samples (n = 3) taken during periods of continuous cable stripping activity showed test period airborne fiber exposures ranging from 0.034 to 0.068 (mean 0.056 f/cc). Follow-up analysis of these personal samples using TEM indicated asbestos adjusted PCM exposures ranging from 0.017 to 0.045 (mean 0.033 f/cc). Area air samples taken at distances ranging from 2 to 9 meters from the wire stripper (n = 16) showed asbestos adjusted PCM concentrations ranging from less than 0.0001 to 0.041 f/cc (mean 0.007 f/cc). The process of power stripping asbestos-containing insulation from electrical wires and cables can cause exposure to airborne asbestos fibers. However, the levels of such exposure are not expected to exceed the current occupational exposure limits for asbestos of 0.1 f/cc as an 8-hr TWA or 1.0 f/cc averaged over a 30-minute exposure period.

TRANSIENT RESPONSE OF A CRACKED PIEZOELECTRIC STRIP UNDER ARBITRARY ELECTRO:MECHANICAL IMPACT

By using the well-developed integral transform methodology, the dynamic response of stress and electric displacement around a finite crack in an infinite piezoelectric strip are investigated under arbitrary dynamic anti-plane loads. The dynamic stress intensity factors and electric displacement are obtained analytically. It is shown that the dynamic crack-tip stress and electric field still have a square-root singularity. Numerical computations for the dynamic stress intensity factor show that the electric load has a significant influence on the dynamic response of stress field. The higher the ratio of the crack length to the width of the strip, the higher the peak value of the dynamic stress intensity factor is. On the other hand, the dynamic response of the electric field is determined solely by the applied electric load. The electric field will promote or retard the propagation of the crack depending on the time elapse since the application of the external electro-mechanical loads. (Author abstract) 9 Refs.

STRESSES AND DISPLACEMENTS IN ORTHOTROPIC LONG STRIP LOADED BY SYMMETRIC LOCAL UNIFORM FORCES

ＳＴＲＥＳＳＥＳＡＮＤＤＩＳＰＬＡＣＥＭＥＮＴＳＩＮＯＲＴＨＯＴＲＯＰＩＣＬＯＮＧＳＴＲＩＰＬＯＡＤＥＤＢＹＳＹＭＭＥＴＲＩＣＬＯＣＡＬＵＮＩＦＯＲＭＦＯＲＣＥＳＳＴＲＥＳＳＥＳＡＮＤＤＩＳＰＬＡＣＥＭＥＮＴＳＩＮＯＲＴＨＯＴＲＯＰＩＣＬＯＮＧＳＴＲ...

融合膨胀卷积与ECA的钢材缺陷检测算法

针对带钢材料表面缺陷检测中感受野受限导致目标漏检率高的问题,基于YoloX-s模型提出一种膨胀卷积与注意力机制融合的目标检测算法。在Backbone部分采用SPPF结构替换SPP结构,在Neck部分引入混合膨胀卷积模块用以增大检测的感受野,嵌入注意力机制ECA-net模块,保留特征图更多的通道信息,减少漏检率。后处理阶段采用CIoU损失函数,提高模型召回率。实验结果表明,改进算法在NEU-DET数据集上的mAP达到80.8%,较原模型提高4.6%,检测速度达到160 f/s,在带钢材料表面缺陷检测中具有一定的使用价值。

种植密度对北疆灌区带状间作青贮玉米-大豆物质积累及产量的影响

【目的】为明确北疆灌区青贮玉米-大豆带状间作最佳密度配置,挖掘群体生物产量潜力。【方法】采用二因素裂区试验设计,主因素为玉米密度:A1、A2、A3(2021年:6.75、8.25、9.75万株/hm^(2);2022年:9、10.5、12万株/hm^(2)),副因素为大豆密度:B1、B2、B3 (2021年:12、15、18万株/hm^(2);2022年:15、18、21万株/hm^(2)),拟分析不同种植密度对带状间作玉米大豆物质积累和群体生物产量的影响。【结果】玉米密度从6.75万株/hm^(2)增至12万株/hm^(2),玉米单株干物质平均下降35.46%,花前积累量平均下降25.42%,达到最大生长速率时间(T_(max))、最大生长速率生物量(W_(max))和活跃生长期(P)平均下降10.99%、39.48%和1.78%。玉米生物产量、干物质日积累量、花后积累量、最大生长速率(G_(max))和平均生长速率(G_(mean))随玉米密度增加呈先增后减趋势,均在10.5万株/hm^(2)密度达到最大。随玉米密度和大豆密度增加,大豆单株干物质、花前积累量、W_(max)、G_(max)和G_(mean)呈下降趋势,花后积累量、T_(max)和P呈上升趋势。2022年A2B3处理带状间作群体产量最高,为64.99 t/hm^(2),较A1B1增产11.98 t/hm^(2),对群体干物质积累量(Y)和种植密度(A、B)回归分析得出,当A=10.84万株/hm^(2),B=19.41万株/hm^(2),Y取得极大值24.87 t/hm^(2)。【结论】玉米10.5万株/hm^(2)和大豆21万株/hm^(2)密度带状间作群体生物产量最大,可为北疆灌区带状间作玉米大豆适宜种植密度提供参考。

大豆玉米带状复合种植对宁夏灌区玉米物质生产与分配的影响

本研究探讨了位于宁夏灌区的大豆玉米带状复合种植模式对玉米物质生产与分配的影响。试验涉及4种在当地示范种植的带状复合种植模式:大豆玉米S3:M2、S4:M2、S3:M4、S4:M4,对照为单作玉米(M)。玉米供试品种为‘先玉1225’,大豆供试品种为‘中黄30’,玉米种植密度8.25万株/hm2,大豆种植密度15万株/hm2。结果显示,相较于单作玉米,带状复合种植模式下,玉米成熟期单株干物质减少了7.9%~30.4%,S3:M4影响最小,S4:M2影响最大;成熟期干物质总量减少了4.3%~42.7%。成熟期雌穗干物质分配减少0.5%~40.5%,S3:M4影响最小,S4:M2影响最大。玉米产量减产25.1%~41.4%,收获有效穗数减少4.2%~14.9%,千粒重减少0.5%~3.6%,单穗粒数减少5.2%~10.8%。综上所述,大豆玉米带状复合种植模式相较于单种玉米,雌穗的干物质减少,在吐丝期雌穗干物质积累开始减少,产量降低。这些发现对于优化大豆玉米带状复合种植模式在农业生产上的应用具有重要的实践意义。

液相剥离法制备MoTe_(2)纳米片及其对三乙胺的气敏性能

二碲化钼(MoTe_(2))材料呈现层状结构,不利于气体的吸附。为了提高MoTe_(2)基传感器的气敏性能,采用液相剥离的方法制备了二维MoTe_(2)纳米片。扫描电子显微镜(SEM)、N2吸脱附分析仪以及Raman光谱仪的表征结果证明,相比于原始的MoTe_(2)材料,液相剥离的MoTe_(2)纳米片具有疏松的层状结构,液相剥离材料的比表面积(2.0648m^(2)/g)比原始材料(0.3578m^(2)/g)扩大约6倍,为气体分子的吸附提供了充足的活性位点。并且,经过液相剥离操作之后的材料对三乙胺气体的响应值以及选择性显著增高,MoTe_(2)基传感器在室温下对体积分数10ppm(1ppm=1×10^(-6))三乙胺气体的响应值由26.02%提升至39%。结果表明,液相剥离的二维MoTe_(2)纳米片对于三乙胺气体的检测具有很大的应用潜力。

Twin-roll strip casting of advanced metallic materials

Metallic materials have historic and served as critical enablers of human progress,wealth,and wellbeing over millennia.Recently,the global demand for the development of environment-friendly and energy-saving technology has been increasing,with the aim to support the sustainability of metallic materials.Twin-roll strip casting(TRC)is one of the most cutting-edge technologies and a near-net-shape manufacturing method in the steel industry,which conforms to the green fabrication trend of next-generation high-performance metallic materials.By utilizing the dominant characteristics of sub-rapid solidification,and integration of solidification,solid-state transformation,and deformation;TRC has become a meaningful way to deal with the most challenging issues in the processing of metallic materials,and made a significant contribution to materials manufacturing.Hence,we review the TRC process of various metallic materials,including plain carbon steels,stainless steels,Fe-Si electrical steels,high-strength steels,clad steels,aluminum alloys,magnesium alloys,metallic glasses,and so on.This paper offers an outlook of future opportunities for various advanced metallic materials development through the TRC process,and inspires more in-depth research.