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Evaluation of granule structure and strength properties of green packed beds in iron ore sintering using high-resolution X-ray tomography and uniaxial compression testing

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Particuology 2021年第4期19卷 157-166页

作者： Mingxi zhou hao zhou State Key Laboratory of Clean Energy Utilization Institute for Thermal Power EngineeringZhejiang UniversityHangzhou 310027China

The strength properties of green sinter beds,including the Young’s modulus and maximum bed strain,were evaluated using uniaxial compression *** green-sinter-bed samples were scanned using X-ray computed tomography(XCT),and the geometry characteristics of the granules were quantified by XCT image *** orthogonal array method was applied to determine the concomitant effects of the moisture,hydrated lime,and concentrate contents on the bed strength *** bed strain was observed when the granules had a thin adhering layer and increased interlock contacts,which had a great capacity to resist the applied load *** optimal combination for decreasing the bed maximum strain was 5.8%moisture,2%hydrated lime,and 0%*** moisture and concentrate contents were the most significant factors determining the green bed *** the moisture and concentrate contents produced granules with a thicker and more deformable adhering layer,resulting in a more compact *** addition of hydrated lime inhibited rearrangement,deformation,and fracture of the granules in green sinter bed during compression.

关键词： Packed bed strength Iron ore sintering X-ray computed tomography Uniaxial compression test Granule properties

Effects of Tabular Stratified CO_(2)/O_(2)Jets on Dynamic and NO_(x)Emission Characteristics of a Model Gas Turbine Combustor

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Journal of Thermal Science 2021年第4期30卷 1160-1173页

作者： TAO Chengfei zhou hao Institute for Thermal Power Engineering Zhejiang UniversityState Key Laboratory of Clean Energy UtilizationHangzhou 310027China

The effects of tabular stratified CO_(2)/O_(2)jet in cross flow on thermoacoustic instability and NO_(x)emission were experimentally *** explore the dependence of injection positions on flame stability,two factors were taken:the injection height and the injection direction of CO_(2)/O_(2)*** show that the injection positions seriously affect the control *** optimum acoustic amplitude-damped ratio of thermoacoustic instability can reach 76.61%with the first layer of horizontal *** sound pressure amplitude declined from 56 Pa to 13.1 *** concentration-damped ratio of NO_(x)emission can achieve 66.67%with the first layer of vertical *** concentration of NO_(x)emission declined from 50.4 mg/m^(3)to 16.8mg/m^(3)as the jet in cross flow rate *** oxygen ratio of stratified CO_(2)/O_(2)jets can produce lower NO_(x)emission but higher combustion *** descending gradient of NO_(x)emissions is different among different injection *** shifting of the sound pressure and flame CH*chemiluminescence *** oscillation frequency declined as the flow rate of CO_(2)/O_(2)jets *** unsteady long and compact flame was dispersed after CO_(2)/O_(2)*** macrostructure of flame was characterized as flatter and short under jet in cross *** variation curves of the flame length and top view area are similar to the shape of half saddle *** research proved the optimal control of thermoacoustic instability and NO_(x)emissions with a passive method,which could be conducive to the realization of clean and secure combustion in industrial lean premixed combustors.

关键词： CO_(2)/O_(2) combustion instability jet in cross flow NO_(x)emission tabular injector

Hydrothermal preparation of Nb-doped NaTaO_(3) with enhanced photocatalytic activity for removal of organic dye

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Chinese Journal of Chemical Engineering 2022年第6期35卷 142-149页

作者： hao zhou Qi Yin State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou 310027China

The construction of efficient photocatalysts has received much attention in wastewater *** this study,Nb-doped NaTaO_(3) was prepared with different doping ratio by a facile hydrothermal *** prepared catalysts were analyzed by X-ray diffraction,scanning electron microscopy,Brunauer-EmmettTeller(BET)theory,ultraviolet–visible diffuse reflectance *** the synthesized catalysts were employed to degrade a model pollutant,methylene blue(MB),under a 250 W mercury *** characterization tests confirm that Nb was successfully doped into the crystal structure of NaTaO_(3) and the modified NaNb_(x)Ta_(1)·xO_(3)(x is the doping ratio;x=0.25,0.5,0.75)samples were formed,which were in regular cubic shapes just like pure NaTaO_(3).The synthesized NaNb_(x)Ta_(1)·xO_(3)(x=0.25,0.5,0.75)had improved specific surface area and narrowed band gaps compared with pure NaTaO_(3).In photocatalytic degradation experiments,NaNb0.75Ta0.25O_(3) presented the best photocatalytic activity ascribed to the narrow band gap and the high surface area,degradating 95.7%of MB after 180 min of reaction,which was even twice the ability of pure NaTaO_(3).Besides,the effects of possible inorganic anions and cations in wastewater on photocatalytic degradation were *** spin resonance(ESR)tests and capture experiments were also conducted and a possible photocatalytic mechanism was *** work provides a direction for constructing superior NaTaO_(3)-based photocatalysts to be widely utilized in environmental protection.

关键词： Photocatalytic degradation Methylene blue NaTaO_(3)

Effect of CO_(2) Opposing Multiple Jets on Thermoacoustic Instability and NO_(x) Emissions in a Lean-Premixed Model Combustor

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Journal of Thermal Science 2024年第1期33卷 207-221页

作者： zhou hao HU Liubin Institute for Thermal Power Engineering State Key Laboratory of Clean Energy UtilizationZhejiang UniversityHangzhou 310027China

This paper experimentally studied the effect of CO_(2) opposing multiple jets on the thermoacoustic instability and NO_(x) emissions in a lean-premixed model *** feasibility was verified from three variables:the CO_(2) jet flow rate,hole numbers,and hole diameters of the *** indicate that the control effect of thermoacoustic instability and NO_x emissions show a reverse trend with the increase of open area ratio on the whole,and the optimal jet flow rate range is 1-4 L/min with CO_(2) opposing multiple *** this flow rate range,the amplitude and frequency of the dynamic pressure and heat release signals CH~* basically decrease as the CO_(2) flow rate increases,which avoids high-frequency and high-amplitude thermoacoustic *** amplitude-damped ratio of dynamic pressure and CH*can reach as high as 98.75% and 93.64% with an optimal open area ratio of 3.72%.NO_(x) emissions also decrease as the jet flow rate increases,and the maximum suppression ratio can reach 68.14%.Besides,the flame shape changes from a steep inverted "V" to a more flat "M",and the flame length will become shorter with CO_(2) opposing multiple *** research achieved the synchronous control of thermoacoustic instability and NO_(x) emissions,which could be a design reference for constructing a safer and cleaner combustor.

关键词： thermoacoustic instability lean-premixed model combustor CO_(2)opposing multiple jets open area ratio NO_(x)emissions

Physiological-physical feature fusion for automatic voice spoofing detection

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Frontiers of Computer Science 2023年第2期17卷 157-166页

作者： Junxiao XUE hao zhou Research Institute of Artificial Intelligence Zhejiang LabHangzhou 311121China School of Cyber Science and Engineering Zhengzhou UniversityZhengzhou 450002China Henan Key Laboratory of Cyberspace Situation Awareness Zhengzhou 450000China

Biometric speech recognition systems are often subject to various spoofing attacks,the most common of which are speech synthesis and speech conversion *** spoofing attacks can cause the biometric speech recognition system to incorrectly accept these spoofing attacks,which can compromise the security of this *** have made many efforts to address this problem,and the existing studies have used the physical features of speech to identify spoofing ***,recent studies have shown that speech contains a large number of physiological features related to the human *** example,we can determine the speaker's gender,age,mouth shape,and other information by *** by the above researches,we propose a spoofing attack recognition method based on physiological-physical features *** method involves feature extraction,a densely connected convolutional neural network with squeeze and excitation block(SE-DenseNet),and feature fusion *** first extract physiological features in audio from a pretrained convolutional *** we use SE-DenseNet to extract physical *** a dense connection pattern has high parameter efficiency,and squeeze and excitation blocks can enhance the transmission of the ***,we integrate the two features into the classification network to identify the spoofing *** results on the ASVspoof 2019 data set show that our model is effective for voice spoofing *** the logical access scenario,our model improves the tandem decision cost function and equal error rate scores by 5%and 7%,respectively,compared to existing methods.

关键词： spoofing attacks SE-DenseNet physiological feature

Mitigation of Combustion Instability and NO_(x)Emissions by Microjets in Lean Premixed Flames with Different Swirl Numbers

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Journal of Thermal Science 2023年第4期32卷 1697-1709页

作者： zhou hao HU Liubin Zhejiang University Institute for Thermal Power EngineeringState Key Laboratory of Clean Energy UtilizationHangzhou310027China

Swirl combustion serves as a helpful flame stabilization method,which also affects the combustion and emission *** article experimentally investigated the effects of CO_(2)microjets on combustion instability and NO_(x)emissions in lean premixed flames with different swirl *** microjets’control feasibility was examined from three variables of CO_(2)jet flow rate,thermal power,and swirl *** indicate that microjets can mitigate the combustion instability and NO_(x)emissions in lean premixed burners with different swirl numbers and thermal ***,the damping effect of microjets in low swirl intensity is better than that in high swirl *** damping ratio of pressure amplitude can reach the maximum of 98%,and NO_(x)emissions can realize the maximum reduction of 10.1×10^(−6)at the swirl angle of 30°.Besides,the flame macrostructure switches from an inverted cone shape to a petal shape,and the flame length reduction at low swirl intensity is higher than that of high swirl *** research clarified the control differences of mitigation of combustion instability and NO_(x)emissions by microjets in lean premixed flames with different swirl numbers,contributing to the optimization of microjets control and the construction of high-performance burners.

关键词： combustion instability swirl numbers thermal power CO_(2)microjets NO_(x)emissions lean premixed flame

Comparison study of two criteria for identification of structural dynamic stability

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Science China(Technological Sciences) 2019年第5期62卷 856-867页

作者： zhou hao LI Jie School of Civil Engineering Tongji University State Key Laboratory of Disaster Reduction in Civil Engineering

Dynamic stability analyses of structures are becoming increasing prevalent in applications for tall buildings and space structure designs. This paper presents an effective energy criterion for identifying the dynamic stability of generalized structures through the modification of an earlier developed energy criterion for hardening structures. Two time-varying effective energy indices are introduced to account for the dynamic stability of both the hardening and deteriorating structures; one for the description of structural properties, i.e., the structural effective intrinsic energy, and the other for the measurement of the input energy, i.e., the valid external work. It is shown that a structure's stability can survive provided the effective intrinsic energy is always less than the valid external work during a dynamic excitation. The first passage of the effective intrinsic energy over the valid external work indicates the dynamic instability of the structure. A comparison study is carried out regarding the validity and applicability between the energy and effective energy criteria as applied to the dynamic stability analysis of three different structures.

关键词： identification criterion dynamic stability effective intrinsic energy valid external work deteriorating structure

Mitochondrial quality control mechanisms as molecular targets in cardiac ischemia-reperfusion injury

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Acta Pharmaceutica Sinica B 2020年第10期10卷 1866-1879页

作者： Jin Wang hao zhou Department of Cardiology Chinese PLA General HospitalMedical School of Chinese PLABeijing 100853China

Mitochondrial damage is a critical contributor to cardiac ischemia/reperfusion(I/R)*** quality control(MQC)mechanisms,a series of adaptive responses that preserve mitochondrial structure and function,ensure cardiomyocyte survival and cardiac function after I/R *** includes mitochondrial fission,mitochondrial fusion,mitophagy and mitochondria-dependent cell *** interplay among these responses is linked to pathological changes such as redox imbalance,calcium overload,energy metabolism disorder,signal transduction arrest,the mitochondrial unfolded protein response and endoplasmic reticulum *** mitochondrial fission is an early marker of mitochondrial damage and cardiomyocyte *** mitochondrial fusion has been observed in stressed cardiomyocytes and correlates with mitochondrial dysfunction and cardiac *** allows autophagosomes to selectively degrade poorly structured mitochondria,thus maintaining mitochondrial network ***,abnormal mitophagy is maladaptive and has been linked to cell *** mitochondria serve as the fuel source of the heart by continuously producing adenosine triphosphate,they also stimulate cardiomyocyte death by inducing apoptosis or necroptosis in the reperfused ***,defects in MQC may determine the fate of *** this review,we summarize the regulatory mechanisms and pathological effects of MQC in myocardial I/R injury,highlighting potential targets for the clinical management of reperfusion.

关键词： Mitochondrial quality control Mitochondrial fission Fusion Mitophagy Mitochondrial death Cardiomyocyte I/R injury Apoptosis Necroptosis

Experimental study on crushing strength and Young's modulus of granules in iron ore sintering using Taguchi method

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Particuology 2020年第6期18卷 175-185页

作者： Mingxi zhou hao zhou Jianuo Xu Jianxiong Xu State Key Laboratory of Clean Energy Utilization Institute for Thermal Power EngineeringZhejiang UniversityHangzhou 310027China

The contributions of three operating parameters(moisture content,hydrated lime addition,magnetite concentrate substitution)to the crushing strength and Young's modulus of granules in each stage of iron ore sintering were studied by applying the Taguchi *** results indicated that the strength properties of the iron ore granules were greatly affected by its structure,which is composed of inner nuclei and an outer adhering *** granules with a thick adhering layer showed a clear changing trend in strength with increasing temperature,whereas those with a thin adhering layer showed additional fluctuations as their force-displacement responses were greatly determined by the *** granules with a thick adhering layer were gen erally more deformable and easier to break than that those with the thin adhering layer in most *** signal-to-noise ratio and variance analysis indicated that moisture was the dominant parameter affecting the strength properties of the iron ore granules,as this factor controls the primary granule structure and material *** the progress of sintering,the contribution of moisture to the quality characteristics gradually decreased(from〜80%to 50%),whereas the contributions of hydrated lime and magnetite concentrate increased correspondingly(from〜5%to 20%).

关键词： Iron ore granule Crushing strength Young's modulus Taguchi method