基于炉区分段的BP神经网络钢坯温度预测

利用神经网络可以逼近任意非线性系统的特点,建立加热炉内钢坯温度预报模型。由于钢坯的边界热流系数和热传导系数、比热、重度等物理参数都是随温度变化的函数,所以,按加热炉的分区采用多个BP神经网络进行分段预测,以适应钢坯的物理参数的变化。仿真结果表明:所建模型简单,精度高,能满足工程实际需要。     

"团队项目训练法"在市场营销实践教学中的应用——以"与爱同行"营销策划综合训练为例

“团队项目训练法”是充分利用各种市场资源,按照市场营销工作实际,让学生自组团队、自寻商机、自设项目,理论联系实际分析营销环境．对真实对象进行市场营销方案设计、实施、评估,亲历市场营销的完整过程,以此进一步掌握理论,训练技能,提高能力。介绍了重庆科技学院对市场营销专业本科生运用“团队训练法”进行实践教学的做法及效果。     

酱渣多肽及其美拉德热反应产物的抗氧化性

测定不同水解度（DH）时酱渣多肽及其美拉德反应产物（MRPS）的抗氧化性,结果表明：随反应物浓度增加,两者抗氧化性增强;两者的DPPH.清除率与DH并非呈线性关系;DH〈14.2%时,两者的.OH清除率随DH的升高而降低;两者的还原力变化趋势不同,DH〉12.2%时,酱渣多肽还原力随DH增大逐渐减少,DH〉8.2%时,MRPS的还原力随DH提高逐渐增大.与某些多肽类物质和MRPS相比,酱渣多肽及其MRPS具有较高的抗氧化性和很好的应用价值.     

Two-step flotation recovery of iron concentrate from Donganshan carbonaceous iron ore

The flotation of pure and natural carbonaceous iron ore samples in the oleate flotation system was investigated. Starch can depress hematite effectively in a wide pH range, but cannot depress siderite efficiently in neutral conditions. The flotation recovery of pure hematite, siderite, and quartz in the oleate-starch-CaCl₂ system is significantly different when the slurry pH varies from 4 to 12. A novel two-step flotation process was developed for the separation of iron concentrate from Donganshan carbonaceous iron ore through which the siderite concentrate is first recovered and the high quality hematite concentrates with relative high iron recovery can be obtained in the second step flotation. The siderite concentrate may be utilized directly or undergo further concentration steps to increase iron grade.     

Numerical simulation on the microstress and microstrain of low Si-Mn-Nb dual-phase steel

According to the stress-strain curves of single-phase martensite and single-phase ferrite steels,whose compositions are similar to those of martensite and ferrite in low Si-Mn-Nb dual-phase steel,the stress-strain curve of the low Si-Mn-Nb dual-phase steel was simulated using the finite element method(FEM).The simulated result was compared with the measured one and they fit closely with each other, which proves that the FE model is correct.Based on the FE model,the microstress and microstrain of the dual...     

Dependence of domain wall structures on repetition n in[Pt（0.5 nm）/Co（0.4 nm）]n/NiO（1.1 nm）/[Co（0.4 nm）/Pt（0.5 nm）]n multilayers

The magnetic force microscopy and a sample vibrating magnetometer have been used to investigate the domain structure in two antiferromagnetically coupled Co/Pt multilayers.In the antiferromagnetic coupled[Pt(0.5 nm)/Co(0.4 nm)]_n/NiO(1.1 nm)/[Co(0.4 nm)/Pt(0.5 nm)]_n multilayers with perpendicular anisotropy,the antiferromagnetic interlayer coupling strength increases linearly with the repetition number n in Co/Pt multilayers.In demagnetized states,relatively shifted domain walls in the two Co/Pt multila...     

Luminescent properties dependence of water-soluble CdTe quantum dots on stabilizing agents and reaction time

The influence of stabilizing agents and reaction time on the luminescent properties of water-soluble CdTe quantum dots (QDs) was discussed. The thioglycolic acid (TGA)-CdTe ODs were characterized by TEM, XRD and FTIR. It is found that larger-size QDs can be synthesized more easily when L-cysteine (Cys) or golutathione (GSH) is chosen as stabilizing agent and TGA is proper to prepare highly luminescent QDs because of the effect between Cd²⁺ and sulfhydryl group. Furthermore, the absorption wavelength, full width at half maximum (FWHM), stokes shift, photoluminescence (PL) quantum yield and PL stability of TGA-CdTe are strongly dependent on reaction time, in which the absorption wavelength changes against reaction time with an exponential function. The TGA-CdTe QDs prepared at 2 h possess more excellent luminescent properties.     

Sodium-modification of Ca-based bentonite via semidry process

In order to improve the quality of Hunyuan inferior Ca-based bentonite (Ca-Bent), semidry process was used to modify Ca-Bent into superior Na-based bentonite (Na-Bent). The factors affecting sodium-modification were investigated. The optimized experimental parameters are obtained as follows: Na₂CO₃ dosage 4.0%, ageing time 25 d, briquetting pressure 25 MPa and briquetting moisture 20%. Under the optimization conditions, the modified Na-Bent has a colloid value of 73.6 mL/(3g), dilation of 38 mL/g and water absorption in 2 h (2HWA) of 465%, respectively. The balling results indicate that the modified Na-Bent pellets have higher drop strength and compression strength than the Ca-Bent pellets.     

Sensorless control for hysteresis compensation of AFM scanner by modified Rayleigh model

A novel modified Rayleigh model was developed for compensating hysteresis problem of an atomic force microscope (AFM) scanner. In high driving fields, piezoelectric actuators that integrated a scanner have severe hysteresis, which can cause serious displacement errors. Piezoelectric hysteresis is from various origins including movement of defects, grain boundary effects, and displacement of interfaces. Furthermore, because its characteristic is stochastic, it is almost impossible to predict the piezoelectric hysteresis analytically. Therefore, it was predicted phenomenologically, which means that the relationship between inputs and outputs is formulated. The typical phenomenological approach is the Rayleigh model. However, the model has the discrepancy with experiment result as the fields increase. To overcome the demerit of the Rayleigh model, a modified Rayleigh model was proposed. In the modified Rayleigh model, each coefficient should be defined differently according to the field direction due to the increase of the asymmetry in the high fields. By applying an inverse form of this modified Rayleigh model to an AFM scanner, it is proved that hysteresis can be compensated to a position error of less than 5%. This model has the merits of reducing complicated fitting procedures and saving computation time compared with the Preisach model.     

半导体封装生产线工艺流程分析

本文介绍了半导体生产线后道封装流程,并对相关设备的自动化程度进行分析。