富氧燃烧条件对加热炉板坏加热过程的影响

富氧燃烧具有提高理论燃烧温度、降低过剩空气系数和增强烟气辐射能力等优点,因此成为工业炉窑领域研究的热点。为了获得富氧燃烧布置形式及氧气体积分数对加热炉热工特性及板坏加热过程的影响,以某钢厂2250机组步进式加热炉为研究对象,建立了两种富氧布置形式(JC-1和JC-2)的燃烧模型,利用数值模拟研究了氧气体积分数从21vo1%变化到49vo1%时加热炉热工特性与板坏加热特性的变化。结果表明,JC-2工况的富氧燃烧布置形式优于JC-1工况;氧气体积分数为21vo1%~37vo1%时,加热炉板坏出炉温度、炉膛热效率的增长速率较高,因此37vo1%为富氧燃烧最佳氧体积分数。本研究可为现有加热炉实施富氧燃烧改造提供参考。

Radiative cooling for long-term building energy efficiency:An experimental comparison of seven coatings

Radiative cooling coatings are widely used owing to their excellent cooling performance and energy efficiency.However,there is a lack of comprehensive research on their weather resistance,long-term performance and effects on building load.To fill this research gap,seven coatings were selected for experimental observation and simulation research.The results revealed noticeable differences among different coatings regarding anti-aging properties,cooling performance and building load reduction.Some coatings exhibited yellowing,cracking and peeling after weathering tests,accompanied by a decline in their radiative properties.Long-term tests showed that the cooling performance of all coatings gradually decreased due to natural aging,and the rate of decline was proportional to the weathering of the coatings.Building load simulations revealed the potential effect of coating selection on cooling and heating loads,thereby suggesting that different coatings should be selected based on actual usage scenarios in different climatic zones.

层流冷却传热系数对金属物料温度场的影响

层流冷却的冷却强度决定着金属物料微观组织结构,从而影响产品的性能,而传热系数直接影响着冷却强度的大小。本工作提出了一种获得层流冷却传热系数的方法,通过工艺分析得到其分布形式为以喷头为中心由半波正弦和直线构成的分段函数,给出了通过结构参数、运行参数和实验数据获得函数特征参数的方法。以实验台验证了该方法的准确性,同时分析了特征参数变化对金属物料温度场的影响规律。结果表明,振幅增加1W/(m^(2)·K),金属物料表面温度相对下降量在最后一个区域达到最大值,为-0.36m^(2)·K^(2)/W,断面温差最大相对变化量为0.07m^(2)·K^(2)/W;周期减小1s,金属物料表面温度相对增加量在最后一个区域达到最大值,为13.24K/s,断面温差呈现周期性变化,变化范围为-2.5~0 K/s。

Neural network-based adaptive sliding mode control for underactuated dual overhead cranes suffering from matched and unmatched disturbances

To improve transportation capacity,dual overhead crane systems(DOCSs)are playing an increasingly important role in the transportation of large/heavy cargos and containers.Unfortunately,when trying to deal with the control problem,current methods fail to fully consider such factors as external disturbances,input dead zones,parameter uncertainties,and other unmodeled dynamics that DOCSs usually suffer from.As a result,dramatic degradation is caused in the control performance,which badly hinders the practical applications of DOCSs.Motivated by this fact,this paper designs a neural network-based adaptive sliding mode control(SMC)method for DOCS to solve the aforementioned issues,which achieves satisfactory control performance for both actuated and underactuated state variables,even in the presence of matched and mismatched disturbances.The asymptotic stability of the desired equilibrium point is proved with rigorous Lyapunov-based analysis.Finally,extensive hardware experimental results are collected to verify the efficiency and robustness of the proposed method.

Enhanced energy-storage density and temperature stability of Pb_(0.89)La_(0.06)Sr_(0.05)(Zr_(0.95)Ti_(0.05))O_(3) anti-ferroelectric thin film capacitor

As the fundamental energy storage components in electronic systems,dielectric capacitors with high power densities were demanded.In this work,the anti-ferroelectric Pb_(0.89)La_(0.06)Sr_(0.05)(Zr_(0.95)Ti_(0.05))O_(3)(PLSZT)ceramics and thin film capacitor were successfully fabricated by a solid-state reaction route and pulsed laser deposition method,respectively.The ferroelectric,dielectric,energy-storage properties,and temperature stability of anti-ferroelectric PLSZT capacitor were investigated in detail.By compared with the PLSZT ceramic(energy storage density is 1.29 J/cm^(3) with an efficiency of 78.7%under 75 kV/cm),the anti-ferroelectric PLSZT thin film capacitors exhibited the enhanced energy storage density of 52.6 J/cm^(3) with efficiency of 67.7%under an electric field as high as 2068.9 kV/cm,and the enhanced energy-storage temperature stabilities from room temperature(RT)to more than 200℃ were demonstrated,and the oxygen defects mechanism and size effect were discussed.Moreover,the fast charging(~0.05 μs)and discharging(~0.15 μs)time were certified for the anti-ferroelectric PLSZT film capacitor.These findings broaden the horizon for PLSZT anti-ferroelectrics in high energy storage properties and show promising for manufacturing pulse power capacitor.

Large electrocaloric effect obtained in BaSn_(x)Ti_(1-x)O_(3) lead-free ceramics using direct and indirect measurements

The electrocaloric effect(ECE)in lead-free BaSn_(x)Ti_(1-x)O_(3)(BSnT,x=0.05,0.10 and 0.15)ceramics were investigated using a direct ECE measurement.Results indicate that the maximum ECE occurs near the Curie temperature and it slightly shifts towards high temperatures.The directly measured ECE is larger than that calculated using the Maxwell relation and P-E loops.A maximum electrocaloric efficiencyΔT=ΔE=0.49-10-6 KmV-1 was procured for the composition with x=0.15 at T=299.2 K.And it also shows a broad peak in the temperature range of 250–320 K.

Genetic Architecture of Childhood Kidney and Urological Diseases in China

Kidney disease is manifested in a wide variety of phenotypes,many of which have an important hereditary component.To delineate the genotypic and phenotypic spectrum of pediatric nephropathy,a multicenter registration system is being imple-mented based on the Chinese Children Genetic Kidney Disease Database(CCGKDD).In this study,all the patients with kidney and urological diseases were recruited from 2014 to 2020.Genetic analysis was conducted using exome sequencing for families with multiple affected individuals with nephropathy or clinical suspicion of a genetic kidney disease owing to early-onset or extrarenal features.The genetic diagnosis was confirmed in 883 of 2256(39.1%)patients from 23 provinces in China.Phenotypic profiles showed that the primary diagnosis included steroid-resistant nephrotic syndrome(SRNS,23.5%),glomerulonephritis(GN,32.2%),congenital anomalies of the kidney and urinary tract(CAKUT,21.2%),cystic renal disease(3.9%),renal calcinosis/stone(3.6%),tubulopathy(9.7%),and chronic kidney disease of unknown etiology(CKDu,5.8%).The pathogenic variants of 105 monogenetic disorders were identified.Ten distinct genomic disorders were identified as pathogenic copy number variants(CNVs)in 11 patients.The diagnostic yield differed by subgroups,and was highest in those with cystic renal disease(66.3%),followed by tubulopathy(58.4%),GN(57.7%),CKDu(43.5%),SRNS(29.2%),renal calcinosis/stone(29.3%)and CAKUT(8.6%).Reverse phenotyping permitted correct identification in 40 cases with clinical reassessment and unexpected genetic conditions.We present the results of the largest cohort of children with kidney disease in China where diagnostic exome sequencing was performed.Our data demonstrate the utility of family-based exome sequencing,and indicate that the combined analysis of genotype and phenotype based on the national patient registry is pivotal to the genetic diagnosis of kidney disease.