IRIS reactor core with thorium fuel

This work is aimed at running the first IRIS reactor core with mixed thorium dioxide fuel（ThO₂-UO₂ and ThO₂-PuO₂）.Calculations are performed by using Dragon 4.0.4 and Citation codes.The results show the multiplication factor(K_eff) for central and peripheral assemblies as a function of burnup.To ensure the proliferation resistance,the value of ²³⁵U enrichment is < 20%.The K_eff is calculated using Dragon 4.0.4 for a single fuel rod and the model developed to fuel assembly,while the whole core was calculated using Citation code.For a fuel burnup,the use of increased enrichment fuel in the IRIS core leads to high reserve of reactivity,which is compensated with an integral fuel burnable absorber.The self-shielding of boron is in an IRIS reactor fuel.The effect of increased enrichment to the burn-up rates,and burnable poison distribution on the reactor performance,are evaluated.The equipment used in traditional light water reactors is evaluated for designing a small unit IRIS reactor.     

Numerical and experimental investigation on the breast cancer tumour parameters by inverse heat transfer method using genetic algorithm and image processing

This study presents numerical and experimental investigation on breast cancer tumour parameters by inverse heat transfer method using genetic algorithm (GA) and image processing (IP) to determine the depth and rate of heat generation of a breast cancer tumour. To simulate the problem, using the energy equation in a cylinder including a heater, the surface temperature distribution was obtained. Then, the temperature surface of the cylinder was analysed by the GA in MATLAB software to determine the depth and rate of heat generation of heater. The validity of the numerical method was evaluated using the IP from a laboratory sample. A thermal heater was placed inside a cylinder and was covered by a tissue similar to the human body tissue. According to the obtained results, it was determined that the results of the laboratory sample and the numerical method were in agreement with each other. Finally, these steps were applied on the thermal image of a patient’s cancer breast to determine the depth and rate of heat generation of the breast tumour. It is shown that the average computational error between numerical and experimental results in this method to determine the depth of the tumour is about 8–10% and to determine the rate of tumour heat generation is about 0.01–1%.     

Superelastic behavior of nanostructured Ti50Ni48Co2 shape memory alloy with cold rolling processing

Effects of cold rolling followed by annealing on microstructural evolution and superelastic properties of the Ti₅₀Ni₄₈Co₂ shape memory alloy were investigated. Results showed that during cold rolling, the alloy microstructure evolved through six basic stages including stress-induced martensite transformation and plastic deformation of martensite, deformation twinning, accumulation of dislocations along twin and variant boundaries in martensite, nanocrystallization, amorphization and reverse transformation of martensite to austenite. After annealing at 400 °C for 1 h, the amorphous phase formed in the cold-rolled specimens was completely crystallized and an entirely nanocrystalline structure was achieved. The value of stress level of the upper plateau in this nanocrystalline alloy was measured as high as 730 MPa which was significantly higher than that of the coarse-grained Ni₅₀Ti₅₀ and Ti₅₀Ni₄₈Co₂ alloys. Moreover, the nanocrystalline Ti₅₀Ni₄₈Co₂ alloy had a high damping capacity and considerable efficiency for energy storage.     

桥面板与覆层结合界面的干燥收缩诱导应力估算

采用三维非线性有限元分析方法评价与估算了桥面板与混凝七覆层间结合界面的干燥收缩诱导应力.并采用修正Fowler准则测算了桥面板与聚合物覆层间的热诱导应力.在评价覆层与面板问相对厚度to/ts的影响时,ts取常数200mm;在评价相对弹性模量Eo/Es的影响时,Es取常数,27.5GPa,并设定了3个Eo/Es比值,分别...     

基于系统设计的产品机能结构要素探究

以现代系统科学原理为启示,结合工业设计方法,经过分析一般产品设计开发流程中经常出现的概念设计与后期结构设计的衔接问题,论述了产品机能结构要素在产品系统设计中的重要作用,提出了系统设计中产品系统整体目的性概念,以及产品机能结构要素与产品系统整体目的性之间的辩证关系,对产品系统设计中机能结构要素的选择与评价提出了可行性建议。     

基于Faster R-CNN的城市道路目标检测

本文针对当前城市道路复杂场景下目标检测精度低下问题,提出了一种多尺度Faster R-CNN模型应用于城市道路目标检测,为提高了特征图卷积后的特征精度,引入了特征金字塔结构,以融合不同尺度特征,以提高检测精度。通过区域建议网络（RPN）解决了区域对物体或背景的判断,同时利用回归模型对目标框进行修正。在BDD 100K数据集进行实验验证,结果表明本文方法与常见的目标检测方法检测的查准均都高。     

C-S-H晶种与硫酸铝作用下PC-CSA的凝结硬化性能

利用凝结时间、抗压强度等测试,系统评价了水化硅酸钙（C-S-H）晶种与硫酸铝（AS）对硅酸盐-硫铝酸盐复合胶凝体系（PC-CSA）凝结硬化性能的影响,并通过水化进程、水化产物和微观结构分析探究其内在作用机理.结果表明：C-S-H晶种与AS均能显著缩短PC-CSA的凝结时间;复掺C-S-H晶种与AS显著促进了PC-CSA中硅相矿物的水化,提高了微观结构的致密性,提升了PC-CSA的抗压强度;当单掺AS时,PC-CSA中水化产物C-S-H的成核与长大过程均受抑制,而C-S-H晶种的加入通过提供成核位点,减缓了对水化产物C-S-H成核过程的抑制效果,促进了硅相矿物的反应,有助于解决喷射混凝土速凝与早强不协调的问题.     

Identification of a class of time-variable linear systems via its output covariance function

The main concern of this paper is to determine the state-space representation of a class of linear time-variable, periodic system, such that when excited by stationary white noise it results in a random process with prescribed covariance function. It is shown that by using a proper transformation on the state covariance matrix of the system it is possible to find a new matrix which has periodicity properties and satisfies a periodic matrix Riceati differential equation; therefore, the time interval of interest, on which the matrix Riceati equation must be solved using previous approaches, will collapse into one period.