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Numerical modeling of mass transfer processes coupling with reaction for the design of the ozone oxidation treatment of wastewater

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Frontiers of Chemical Science and Engineering 2021年第3期15卷 602-614页

作者： Hong Li Fang Yi Xingang Li Xin Gao School of Chemical Engineering and technology Tianjin UniversityTianjin 300072China national Engineering Research center of Distillation technology ollaborative Innovation Center of Chemical Science and Engineering(Tianjin)Tianjin 300072China

A computational model for an ozone oxidation column reactor used in dyeing wastewater treatment is proposed to represent,simulate,and predict the ozone bubble *** the hydrodynamics,mass transfer,and ozone oxidation reaction,coupling modeling can more realistically calculate the ozone oxidation bubble process than the splitting methods proposed in previous *** modeling is validated and shows great consistency with experimental *** verified model is used to analyze the effect of operating conditions,such as the initial gas velocity and the ozone concentration,and structural conditions,such as multiple gas *** ozone consumption is influenced by the gas velocity and the initial ozone *** ozone’s utilization decreases with the increasing gas velocity while nearly the same at different initial ozone *** results can be used in guiding the practical operation of dyeing wastewater treatment and in other ozonation systems with known rate constants in wastewater treatment.

关键词： ozone wastewater treatment numerical simulation mass transfer

Monitoring and diagnosis of complex production process based on free energy of Gaussian–Bernoulli restricted Boltzmann machine

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Journal of Iron and Steel Research International 2023年第5期30卷 971-984页

作者： Qian-qian Dong Qing-ting Qian Min Li Gang Xu Collaborative innovation center of Steel technology University of Science and Technology BeijingBeijing 100083China

Online monitoring and diagnosis of production processes face great challenges due to the nonlinearity and multivariate of complex industrial *** process monitoring methods employ kernel function or multilayer neural networks to solve the nonlinear mapping problem of ***,the above methods increase the model complexity and are not interpretable,leading to difficulties in subsequent fault recognition/diagnosis/location.A process monitoring and diagnosis method based on the free energy of Gaussian-Bernoulli restricted Boltzmann machine(GBRBM-FE)was ***,a GBRBM network was established to make the probability distribution of the reconstructed data as close as possible to the probability distribution of the raw *** this basis,the weights and biases in GBRBM network were used to construct F statistics,which represents the free energy of the *** smaller the energy of the sample is,the more normal the sample ***,F statistics can be used to monitor the production *** diagnose fault variables,the F statistic for each sample was decomposed to obtain the Fv statistic for each *** analyzing the deviation degree between the corresponding variables of abnormal samples and normal samples,the cause of process abnormalities can be accurately *** application of converter steelmaking process demonstrates that the proposed method outperforms the traditional methods,in terms of fault monitoring and diagnosis performance.

关键词： Process monitoring Fault diagnosis Gaussian–Bernoulli restricted Boltzmann machine Energy function Free energy Converter steelmaking production process

Safe semi-supervised learning: a brief introduction

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Frontiers of Computer Science 2019年第4期13卷 669-676页

作者： Yu-Feng LI De-Ming LIANG national Key Laboratory for Novel Software technology Nanjing University Nanjing 210023 China Collaborative innovation center of Novel Software technology and Industrialization Nanjing 210023 China

Semi-supervised learning constructs the predictive model by learning from a few labeled training examples and a large pool of unlabeled ones. It has a wide range of application scenarios and has attracted much attention in the past decades. However, it is noteworthy that although the learning performance is expected to be improved by exploiting unlabeled data, some empirical studies show that there are situations where the use of unlabeled data may degenerate the performance. Thus, it is advisable to be able to exploit unlabeled data safely. This article reviews some research progress of safe semi-supervised learning, focusing on three types of safeness issue: data quality, where the training data is risky or of low?quality;model uncertainty, where the learning algorithm fails to handle the uncertainty during training;measure diversity, where the safe performance could be adapted to diverse measures.

关键词： machine learning semi-supervised learning safe

Effects of chromium on the microstructure and hot ductility of Nb-microalloyed steel

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International Journal of Minerals,Metallurgy and Materials 2021年第6期28卷 1011-1021页

作者： Yang Liu Yan-hui Sun Hao-tian Wu Collaborative innovation center of Steel technology University of Science and Technology BeijingBeijing 100083China

It is well-known that the surface quality of the niobium microalloy profiled billet directly affects the comprehensive mechanical properties of the *** effects of chromium on theγ/αphase transformation and high-temperature mechanical properties of Nb-microalloyed steel were studied by Gleeble tensile and high-temperature in-situ observation *** indicated that the starting temperature of the γ→αphase transformation decreases with increasing Cr *** hot ductility of Nb-microalloyed steel is improved by adding 0.12wt% *** atoms inhibit the diffusion of carbon atoms,which reduces the thickness of grain boundary *** number fractions of high-angle grain boundaries increase with increasing chromium *** particular,the proportion is up to 48.7% when the Cr content is 0.12wt%.The high-angle grain boundaries hinder the crack propagation and improve the ductility of Nb-microalloyed steel.

关键词： phase transformation hot ductility chromium high-angle grain boundaries grain boundary ferrite

Longitudinal investigation of mineral composition in human milk and its correlation with infant anthropometric outcomes among Tibetan mother-infant dyads during the first 6 months postpartum

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Food Science and Human Wellness 2024年第5期13卷 2857-2865页

作者： Xiaomei Zhang Yaling Wang Junying Zhao Weicang Qiao Yanpin Liu Lijun Chen national Engineering Research center of dairy Health for Maternal and Child Beijing Sanyuan Foods Co.Ltd.Beijing 100163China Beijing Engineering Research center of dairy Beijing Technical Innovation Center of Human Milk ResearchBeijing Sanyuan Foods Co.Ltd.Beijing 100163China

Nutrients in human milk,including minerals,relate growth and development of breast-fed *** mother-infant dyads possess unique characteristics on early nutrition due to their featured long-lasting *** study longitudinally investigated the relationship between the mineral composition in human milk and the Z-scores of infants among Tibetan mother-infant dyads during their first 6 months postpartum through a prospective cohort *** results show that the minerals of Na,Mg,K,Ca,Cu,Zn,and Se were of higher levels in colostrum than other lactation *** minerals were below the recommended values for infants according to Chinese dietary ***,a large proportion of infant Z-scores were below-2 as lactation period *** statistical analysis revealed that classifications and correlations in varying degrees were observed between minerals in human milk and infant *** findings will be advantageous for research upon Chinese early nutrition and progress of tailor-made infant formula.

关键词： Tibetan mother-infant dyads Minerals Z-scores Classification and correlation Breastfeeding

Effect of cooling rate on microstructure, hardness, and residual stress of 0.28C-0.22Ti wear-resistant steel

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Journal of Iron and Steel Research International 2019年第8期26卷 866-874页

作者： Chen Dong Hui-bin Wu Xi-tao Wang Collaborative innovation center of Steel technology University of Science and Technology Beijing Beijing 100083 China

The microstructure, hardness, and residual stress of 0.28C-0.22Ti wear-resistant steel produced with cooling rates varying from 80.0 to 0.3℃/s were determined using a dilatometer, scanning electron microscope, Vickers hardness tester, and nanoindentation tester. The results showed that the hardness of martensite decreased at a rate of approximately 0.935 HV/s with carbon diffusion time (the cooldown time required to transition from Ar3, 635-100℃). The range of the residual stress caused by the hard particles decreased with decreasing cooling rate, from - 400-300 MPa (cooling rate 40℃/s) to - 200-100 MPa (cooling rate 0.5℃/s), proving that the TiC particles significantly contributed to the residual stress in the high-titanium steels.

关键词： Cooling rate Microstructure Hardness TiC particle Residual stress

Tunable fabrication of single-crystalline CsPbI_(3) nanobelts and their application as photodetectors

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International Journal of Minerals,Metallurgy and Materials 2021年第6期28卷 1030-1037页

作者： Tao Yang Ya-peng Zheng Kuo-Chih Chou Xin-mei Hou Collaborative innovation center of Steel technology University of Science and Technology BeijingBeijing 100083China

Lead halide perovskites have received increasing attention recently as a candidate material in various optoelectronic areas because of their high performance as light ***,we report the growth of CsPbI_(3) nanobelts via a solution process.A single-crystalline CsPbI_(3) nanobelt with uniform morphology can be achieved by controlling the amount of PbI_(2).A single-crystalline CsPbI_(3) nanobelt possesses a mean width,length,and thickness of 100 nm,5μm,and 20 nm,*** this work,photodetectors(PDs)based on individual CsPbI_(3) nanobelts are constructed and found to perform well with an external quantum efficiency and responsivity of 2.39×10^(5)% and 770 A/W,*** PDs also show a high detectivity of up to 3.12×10^(12) Jones,which is at par with that of Si *** PDs developed in this work exhibit great promise in various optoelectronic nanodevices.

关键词： photodetector cesium lead triiodide perovskite nanobelt detectivity

Untrusted Hardware Causes Double-Fetch Problems in the I/O Memory

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Journal of Computer Science & technology 2018年第3期33卷 587-602页

作者： Kai Lu Peng-Fei Wang Gen Li Xu Zhou College of Computer National University of Defense Technology Changsha 410073 China Science and technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha 410073 China Collaborative innovation center of High-Performance Computing National University of Defense Technology Changsha 410073 China

The double fetch problem occurs when the data is maliciously changed between two kernel reads of the supposedly same data, which can cause serious security problems in the kernel. Previous research focused on the double fetches between the kernel and user applications. In this paper, we present the first dedicated study of the double fetch problem between the kernel and peripheral devices （aka. the hardware double fetch）. Operating systems communicate with peripheral devices by reading from and writing to the device mapped I/O （input and output） memory. Owing to the lack of effective validation of the attached hardware, compromised hardware could flip the data between two reads of the same I/O memory address, causing a double fetch problem. We propose a static pattern-matching approach to identify the hardware double fetches from the Linux kernel. Our approach can analyze the entire kernel without relying on the corresponding hardware. The results are categorized and each category is analyzed using case studies to discuss the possibility of causing bugs. We also find four previously unknown double-fetch vulnerabilities, which have been confirmed and fixed after reporting them to the maintainers.

关键词： hardware double fetch double-fetch bug I/O memory peripheral device double-fetch vulnerability

DFTracker: detecting double-fetch bugs by multi-taint parallel tracking

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Frontiers of Computer Science 2019年第2期13卷 247-263页

作者： Pengfei WANG Kai LU Gen LI Xu ZHOU Science and technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha 410073 China College of Computer National University of Defense Technology Changsha 410073 China Collaborative innovation center of High Performance Computing National University of Defense Technology Changsha 410073 China

A race condition is a common trigger for concurrency bugs. As a special case, a race condition can also occur across the kernel and user space causing a doublefetch bug, which is a field that has received little research attention. In our work, we first analyzed real-world doublefetch bug cases and extracted two specific patterns for doublefetch bugs. Based on these patter ns, we proposed an approach of multi-taint parallel tracking to detect double-fetch bugs. We also implemented a prototype called DFTracker (doublefetch bug tracker), and we evaluated it with our test suite. Our experiments demonstrated that it could effectively find all the double-fetch bugs in the test suite including eight realworld cases with no false negatives and minor false positives. In addition, we tested it on Linux kernel and found a new double-fetch bug. The execution overhead is approximately 2x for single-file cases and approximately 9x for the whole kernel test, which is acceptable. To the best of the authors1 knowledge, this work is the first to introduce multi-taint parallel tracking to double-fetch bug detection—an innovative method that is specific to double-fetch bug features—and has better path coverage as well as lower runtime overhead than the widely used dynamic approaches.

关键词： multi-taint parallel tracking double fetch race condition between kernel and user time of check to time of use real-world case analysis Clang Static Analyzer