Hybrid model for BOF oxygen blowing time prediction based on oxygen balance mechanism and deep neural network

The amount of oxygen blown into the converter is one of the key parameters for the control of the converter blowing process,which directly affects the tap-to-tap time of converter. In this study, a hybrid model based on oxygen balance mechanism (OBM) and deep neural network (DNN) was established for predicting oxygen blowing time in converter. A three-step method was utilized in the hybrid model. First, the oxygen consumption volume was predicted by the OBM model and DNN model, respectively. Second, a more accurate oxygen consumption volume was obtained by integrating the OBM model and DNN model. Finally, the converter oxygen blowing time was calculated according to the oxygen consumption volume and the oxygen supply intensity of each heat. The proposed hybrid model was verified using the actual data collected from an integrated steel plant in China, and compared with multiple linear regression model, OBM model, and neural network model including extreme learning machine, back propagation neural network, and DNN. The test results indicate that the hybrid model with a network structure of 3 hidden layer layers, 32-16-8 neurons per hidden layer, and 0.1 learning rate has the best prediction accuracy and stronger generalization ability compared with other models. The predicted hit ratio of oxygen consumption volume within the error±300 m^(3)is 96.67%;determination coefficient (R^(2)) and root mean square error (RMSE) are0.6984 and 150.03 m^(3), respectively. The oxygen blow time prediction hit ratio within the error±0.6 min is 89.50%;R2and RMSE are0.9486 and 0.3592 min, respectively. As a result, the proposed model can effectively predict the oxygen consumption volume and oxygen blowing time in the converter.

Measurement of solidprecipitation and blowing snow: current status and challenges

In this article,the relevant instruments and techniques for measuring solid precipitation and blowing snow are reviewed,with a focus on the in situ instrument measurements.Moreover,a literature review and specific observation activities for solid precipitation are provided,the working principles of several instruments are introduced,and the advantages and disadvantages,measurement performance,and specific application scenarios of the instruments are evaluated.Currently,there are numerous solid precipitation measurement instruments available,and the standardization and sustainability of these measurements also need to be considered.The purpose of the review is not to be exhaustive but to provide readers with information on the current status of the development of relevant technologies and the prospects for their application in the polar regions.

Blown Film Extrusion Process for Polybags: Technical Overview and Applications

The choice of extrusion process is a decisive factor that affects the finished product quality for polybag manufacturing. One important component influencing the quality of the finished product is the selection of the extrusion technique. Two popular procedures that vary in the kind of dye used and the final product’s texture are cast film and blown film. In the horizontal extrusion moulding method known as “cast film”, heated resin is injected into a flat dye and allowed to cool on chill rolls. The film produced is clear, lightweight, and appropriate for lamination;its thickness varies based on the winding speed and the film is slower to crystallize and has less clarity but more durability because the resin molecules have reoriented, facing limitation of high wastage generation. This study primarily focused on the preparation of polybag film using the blown film extrusion process, utilizing high-quality polymer resins such as polyester polyethylene (PP) and linear low-density polyethylene (LLDPE) to minimize waste generation. The novelty of the process was reflected in minimising the waste generation. The control parameters considered in this study are temperature, pressure, and air intake volume. We investigated the influence of these critical process control parameters on the gauge thickness, optical properties, and mechanical strength of the polybag film produced through blown film extrusion. Additionally, we replicated the blown film process using simulation software developed at Pennsylvania College of Technology. The simulation results confirmed the overall stability of the polybag film produced through the blown film extrusion process.

Exploration and Practice of Nitrogen Addition Process for LF Refining Ladle Bottom Blowing Nitrogen Steel Liquid

This article discusses and analyzes the law of nitrogen increase in liquid steel and the main factors affect-ing the nitrogen increasing of molten steel,through the way of adding nitrogen to molten steel by bottom blowing nitrogen gas in LF refining process.It is considered that the main factors affecting the nitrogen increasing instability of molten steel are the initial temperature of LF refining,nitrogen relative element,surface active elements[O]and[S]of steel liquid,and bottom blowing rate of ladle.The large-scale production practice shows that T[O]not more than 50×10-6 and[S]is not more than 0.020 in LF refining at the initial temperature of not less than 1570.The liquid steel nitrogen enrichment test is carried out by ladle bottom blowing nitrogen gas after 20 min of refining,the flow rate is set as(6.0~7.0)NL/min per ton,and it is turned to 2 NL/min at 6 min before the end of refining,the nitrogen increasing rate of liquid steel is basically stable at(5~6)×10-6 per minute.

Effect of gas blowing nozzle angle on multiphase flow and mass transfer during RH refining process

A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up,and measurements were carried out to validate the mathematical model.The results show that,with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min^(-1),the mixing time predicted by the mathematical model agrees well with the measured values.The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations,where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value.In addition,the circulation flow rate was 9 kg·s^(-1).When the gas blowing nozzle was horizontally rotated by either 30° or 45°,the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle,due to the rotational flow formed in the up-snorkel.Furthermore,the mixing time at the monitoring point 1,2,and 3 was shortened by around 21.3%,28.2%,and 12.3%,respectively.With the nozzle angle of 30° and 45°,the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.

Successful treatment of a rare subcutaneous emphysema after a blow-out fracture surgery using needle aspiration:A case report

BACKGROUND Many cases of emphysema associated with blow-out fractures occur before surgery due to trauma.However,emphysema can occur even after surgery,and most of such cases are managed conservatively and allowed to resolve.Swelling in the periorbital area due to emphysema that occurs after surgery can make early recovery difficult.CASE SUMMARY Herein,we describe a case of postoperative subcutaneous emphysema that was treated using a simple needle aspiration method.A 48-year-old male patient visited the hospital with a blow-out fracture of the left medial orbital wall and nasal bone fracture.One day postoperatively,swelling and crepitus in the left periorbital area were observed,and follow-up computed tomography showed emphysema in the left periorbital subcutaneous area.Needle aspiration using an 18-gauge needle and syringe was used to relieve the emphysema.The symptoms of sudden swelling improved immediately,and no recurrence was observed.CONCLUSION We conclude that needle aspiration is a useful method that could help in relieving symptom,resolving discomfort,and enabling early return to daily life in patients with postoperative subcutaneous emphysema.

Eco-friendly physical blowing agent mass loss of bio-based polyurethane rigid foam materials

Through systematical experiment design, the physical blowing agent(PBA) mass loss of bio-based polyurethane rigid foam(PURF)in the foaming process was measured and calculated in this study, and different eco-friendly PBA mass losses were measured quantitatively for the first time. The core of the proposed method is to add water to replace the difference, and this method has a high fault tolerance rate for different foaming forms of foams. The method was proved to be stable and reliable through the standard deviations σ1and σ2for R1(ratio of the PBA mass loss to the material total mass except the PBA) and R2(ratio of the PBA mass loss to the PBA mass in the material total mass) in parallel experiments. It can be used to measure and calculate the actual PBA mass loss in the foaming process of both bio-based and petroleumbased PURF. The results show that the PBA mass loss in PURF with different PBA systems is controlled by its initial mass content of PBA in PU materials ω. The main way for PBA to dissipate into the air is evaporation/escape along the upper surface of foam. This study further reveals the mechanism of PBA mass loss: the evaporation/escape of PBA along the upper surface of foam is a typical diffusion behavior. Its spread power comes from the difference between the chemical potential of PBA in the interface layer and that in the outside air. For a certain PURF system, R1has approximately linear relationship with the initial mass content of PBA in PU materials ω, which can be expressed by the functional relationship R1= kω, where k is a variable related to PBA’s own attributes.

具零阶耗散的Degasperis-Procesi方程的Blow-up现象

研究了具有零阶耗散的Degasperis-Procesi方程的初值问题,应用Kato定理得到了方程初值问题解的局部适定性,然后研究了解的blow-up现象.

具非线性源的多孔介质方程解的Blow-up时间对初值的相依性

考虑多孔介质方程的Dirichlet问题,讨论在解的Blow-up时间T有限的情况下,当初值出现一个小的扰动函数h(x)时,相应方程的Blow-up时间Th随之发生的变化情况,证明了Blow-up时间|T-Th|和‖h‖L1(Ω)之间连续相依性的结果,其中QT=Ω×(0,T),0≤u0(x)∈L∞(Ω),h(x)∈L∞(Ω),ΩRN是一有界区域,其中对指标m,p的限制满足1<m<p.

THE BLOW-UP PROPERLIES OF SOLUTIONS TO SEMILINEAR HEAT EQUATIONS WITH NEUMANN BOUNDARY CONDITIONS

This paper deals with the blow-up properties of solutions to semilinear heat equation ut-uxx= up in (0, 1) × (0, T) with the Neumann boundary condition ux(0, t) = 0, u:x1, t) = 1 on [0, T). The necessary and sufficient conditions under which all solutions to have a finite time blow-up and the exact blow-up rates are established. It is proved that the blow-up will occur only at the boundary x = 1. The asymptotic behavior near the blow-up time is also studied.

Blow-up Sets to a Coupled Heat System

This paper deals with a heat system coupled via local and localized sources subject to null Dirichlet boundary conditions. In a previous paper of the authors, a complete result on the multiple blow-up rates was obtained. In the present paper, we continue to consider the blow-up sets to the system via a complete classification for the nonlinear parameters. That is the discussion on single point versus total blow-up of the solutions. It is mentioned that due to the influence of the localized sources, there is some substantial difficulty to be overcomed there to deal with the single point blow-up of the solutions.

Thermodynamic behavior and morphology of impurities in metallurgical grade silicon in process of O_2 blowing

Gas blowing is a valid method to remove the impurities from metallurgical grade silicon（MG-Si） melt.The thermodynamic behavior of impurities Fe,Al,Ca,Ti,Cu,C,B and P in MG-Si was studied in the process of O2 blowing.The removal efficiencies of impurities in MG-Si were investigated using O2 blowing in ladle.It is found that the removal efficiencies are higher than 90% for Ca and Al and nearly 50% for B and Ti.The morphology of inclusions was analyzed and the phases Al3Ni,NiSi2 and Al3Ni were confirmed in MG-Si by X-ray diffraction.It was found that SiB4 exists in Si？B binary system.The chemical composition of inclusions in MG-Si before and after refining was analyzed by SEM-EDS.It is found that the amount of white inclusion reduces for the removal of most Al and Ca in the forms of molten slag inclusion and the contents of Fe,Ni and Mn in inclusion increase for their inertia in silicon melt with O2 blowing.

具非线性边界条件的拟线性抛物型方程解的Blow-up

本文考虑一类具非线性边界条件的拟线性抛物方程初边值问题解的整体性态 .通过构造与解有关的适当积分 ,利用“凸性方法”及非线性抛物型方程的极大值原理 ,证明了在某些条件下 ,问题的光滑解u(x ,t)只能在一个有界区间 (0 ,T0 )中存在 ,即有 :limt→T-0sup‖u(· ,t)‖ ∞ =+∞ .

16轮Blow-CAST-Fish的弱密钥攻击

Blow-CAST-Fish的轮函数F由作为算法子密钥的四个S盒构成。如果S盒产生碰撞,则可构造F函数的输入差分为非零、输出差分为零的差分特征,进而对算法进行差分分析以获取其他子密钥。研究单个S盒的碰撞,构造F函数的差分特征,并测试使特征成立的弱密钥比例,给出了特征概率为2-49,弱密钥比例为2-52.4的14轮差分特征,并以此为基础,攻击16轮Blow-CAST-Fish。

一类非线性扩散方程解的blow up速率估计

利用F riedm an-M cleod方法和变动尺度方法研究了一类具有非线性边界条件的非线性扩散方程解的b low up问题,证明了解在有限时间b low up,并且得到了b low up速率估计.

具有非线性记忆的抛物型方程解的Blow up

讨论了m(t)不具单调性的条件下,具有非线性记忆的抛物型方程解的Blow up.

一类推广了的非线性Schrdinger方程初边值解的blow-up

研究一类推广了的非线性Schrdinger方程的初边值问题ut-iΔu=f(u,Dxu,D2xu)+Δg(u),u(x,0)=u0(x),uΩ=0.作为ut-iΔu=f(u,Dxu,D2xu)及ut-iΔu=-Δg(u)的推广,用特征函数法,在某些条件下,证明了此问题整体解的不存在性与有限时间blow-up.

奇异半线性发展方程组解的Blow-up问题

讨论奇异半线性发展方程组解的B low-up问题时,通常先对解进行估计,然后讨论在一定条件下解的B low-up.论文继续用这种方法讨论奇异半线性发展方程组解的B low-up问题,得到一定条件下解会B low-up.

低轮Blow-CAST-Fish算法的差分攻击

对作为Blow-CAST-Fish算法子密钥的4个S盒的碰撞性进行分析,构造输入差分为非零、输出差分为零的轮函数F的差分特征,通过对算法进行差分分析,获取相关子密钥,并测试使特征成立的弱密钥概率。在此基础上,成功利用特征概率为2-61、弱密钥概率为2-12的6轮差分特征攻击8轮Blow-CAST-Fish算法。

一类非线性反应扩散方程解的Blow-up问题

本文利用极大值原理研究一类非线性反应扩散方程在各种边界条件下解的Ｂｌｏｗ－ｕｐ问题，给出了整体解不存在的一系列定理，并得到了Ｂｌｏｗ－ｕｐ时间Ｔ的上界．