Table of Content

25 August 2019, Volume 47 Issue 8

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Architecture & Civil Engineering

Experimental Study on Punching Performance of Compound Concrete Slabs



WU Bo CHEN Yufei

2019, 47(8):  1-8.  doi:10.12141/j.issn.1000-565X.180613

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Punching behavior of eight compound concrete slabs was experimentally studied，and the influences of demolished concrete lumps，reinforcement ratio，thickness of slab and span of slab on the slab's punching perfor- mance were investigated． Validity of different design codes for predicting the punching shear capacity of the com- pound concrete slabs was discussed，and a correction coefficient was suggested． It finds that: (a) when the strength of demolished concrete is lower than that of fresh concrete，the initial stiffness of the compound concrete slab is almost the same as that of the conventional concrete slab，but the punching shear strength of the former is slightly smaller than the latter; (b) when the reinforcement ratio and span-to-thickness ratio keep unchanged， increasing the thickness of slab is more effective to enhance the slab's punching shear strength than reducing the span of slab; (c) it is very necessary to take the steel bars into account during the calculation of the slab's punching shear strength，when the span-to-thickness ratio is relatively small，the formulae for the punching shear capacity specified in current design codes need to be improved further; and (d) to make the predicted punching shear strength of the compound concrete slab has similar safety margin to conventional concrete slab，a reduction factor of 0. 95 is suggested to the former．

Mechanical Behaviors of Large-tonnage Complex Steel Spherical Hinged Support: Rotation Behavior Subjected to Axial Compressive Load



SHI Kairong PAN Wenzhi JIANG Zhengrong Lü Junfeng LUO Bin

2019, 47(8):  9-15.  doi:10.12141/j.issn.1000-565X.180650

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The steel spherical hinged support has the advantages of high loading capacity，reliable transfer of loads， flexible rotation with universal hinge，and allowance of large displacement and rotation angle． However，supports are in complex forced states subjected to various load combinations，which leads to the significant influence on inte- gral structural safety． Taking the large-tonnage complex steel spherical hinged support of T2 of Guangzhou Baiyun International Airport for example，the full-scale experiments and finite element simulation analysis were carried out and the rotation behavior of the support subjected to axial compressive load was studied． The rotation stiffness model of support subjected to axial compressive load was proposed for the refinement analysis of integral structure． The results show that the results of experiments and finite element simulations are similar，and the development tendency of stress and deformation of them is coincident． In addition，the actual rotational moment is less than that prescrip- tive by code and the rotation behavior is satisfied for the requirements of code and design．

Mechanical Properties of Scrap Tire Rubber Pads Based on Thermal Oxygen Aging



ZHANG Guangtai LU Dongliang WEI Feilai ZHANG Xiaoxu CAO Yinlong

2019, 47(8):  16-22.  doi:10.12141/j.issn.1000-565X.180561

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The 6-layer scrap tire rubber pads (STP) of 180mm ×180mm ×69mm were selected to study the aging performance of STP． Accelerated aging tests of specimens were carried out in a temperature-controlled weathering chamber at 100℃ for 77h，154h，231h，308h． By comparing the vertical ultimate strength，vertical compression stiffness，horizontal stiffness and horizontal energy dissipation capacity of STP before and after aging，the variation law of the vertical ultimate strength，vertical compression stiffness and horizontal energy dissipation capacity with aging time was analyzed． The results show that within the normal age of the buildings the mechanical properties of STP are stable and the seismic isolation is reliable．

Optimal Denoising Smooth Model of Underwater Drilling Blasting Seismic Wave Signal



SUN Miao WU Li ZHOU Yuchun MA Chenyang WANG Yufeng

2019, 47(8):  31-37.  doi:10.12141/j.issn.1000-565X.180601

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Monitoring environment，testing system and other factors will cause noise in the measured seismic wave signal during the monitoring of underwater drilling blasting seismic wave． In order to obtain the real blasting vibra- tion characteristics，the seismic wave signal of underwater drilling blasting was denoised． Firstly，the complementary ensemble empirical mode decomposition was used to decompose the noisy measured seismic wave signal，and the filtering algorithm was established based on the intrinsic mode function obtained from the decomposition． Then，the objective function considering the smoothness of the filtering algorithm and the standard deviation between the filte- ring algorithm and the measured signal was established． The model corresponding to the optimal solution of the objective function was the optimal denoising smooth model of the underwater drilling blasting seismic wave signal． Finally，the denoising ability of the model was analyzed by the denoising error ratio． The results show that the pro- posed optimal denoising smoothness model of seismic wave signal can be used in underwater drilling blasting signal denoising． The model can denoise the original signal while retaining the true components of the original signal．

Food Science & Technology

Effects of HPMC and GOD on the Quality of Frozen Dough and Baked Bread



ZHAO Qiangzhong DU Cui CAI Yongjian HUANG Lihua TANG Yuxuan DENG Xinlun ZHAO Mouming

2019, 47(8):  38-47.  doi:10.12141/j.issn.1000-565X.180445

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A certain amount of hydroxypropyl methyl cellulose (HPMC) or glucose oxidase (GOD) were added into original frozen dough to investigate the effects of HPMC and GOD on the quality of frozen dough and baked bread． The results show that with the increasing addition of HPMC or GOD，the elastic modulus of frozen dough and the specific volume，springiness，resilience and sensory scores of bread firstly rose and then fell，and the hard- ness and chewiness of bread firstly decreased and then increased，and the indicators achieved peak value when HPMC，GOD at 0. 06%，0. 015‰ respectively． During freezing storage，the variation amplitude of the quality of frozen dough and bread was smaller than control when added HPMC or GOD，and the amplitude of variation of HPMC was the least，indicating that HPMC or GOD addition could maintain the storage quality of frozen dough， and the effect of HPMC was more significant．

Extraction，Structure and Emulsifying Property of Alkaline-extracted Polysaccharide from Sugar Beet Pulp



YU Shujuan LIN Jiawei GUO Xiaoming AI Chao

2019, 47(8):  48-56.  doi:10.12141/j.issn.1000-565X.180490

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Sugar beet pulp is a main by-product of beet sugar industry． The comprehensive utilization of sugar beet pulp and its secondary pulp is critical to add value to the beet sugar industry． Five alkaline-extracted polysaccha- rides (AEP) were extracted from the remaining pulp of sugar beet pectin (SBP) by using an alkaline extractant (alkali dosage 1 ～4meq/g) at 90℃ for extraction duration of 1h． Effects of alkali dosage on the yield，structure and emulsify properties of AEP were investigated． The results show that，with the increase of alkali dosage，both the galacturonic acid and ferulic acid contents will decrease，whereas both the neutral sugar content and weight- average molar mass will increase． AEP2. 5 (extracted at alkali dosage 2. 5meq/g) has the highest yield (35. 6%) and its protein content is 20. 77%． Emulsifying performance of AEP is influenced by alkali dosage; AEP1. 0 and AEP2. 5 have superior emulsifying activities than the remainder，while AEP2. 0，AEP3. 0，AEP4. 0 and sugar beet pectin have comparable emulsifying activities． AEP fresh emulsion contains higher proportions of small droplets (volume average particle size d 4，3 ＜1μm) than SBP fresh emulsion． AEP2. 5 exhibited better emulsifying activity and stability than SBP as indicated by their different d 4，3 values (0. 847μm for AEP2. 5 versus 0. 958μm for SBP); d 4，3 increase to 0. 911μm and 1. 507μm for AEP2. 5 and SBP respectively after 7 days' storage at 55℃． At critical concentrations of 2. 50% and 1. 25%，AEP2. 5 and SBP，respectively，gave their optimum emulsifying perfor- mances with d 4，3 values of 0. 404μm and 0. 825μm．

Expression of Wheat Endoplasmic Reticulum Oxidoreductin 1 in Pichia pastoris



HU Songqing LI Wang CHEN Yu HOU Yi

2019, 47(8):  57-63,70.  doi:10.12141/j.issn.1000-565X.180567

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Wheat endoplasmic reticulum oxidoreductin 1 (wEro1) was expressed by Pichia pastoris recombinant to develop a healthy and natural novel biological flour improver． The wero1 gene was subcloned into the Pichia pastoris expression vector pPICZα A，and the secretory expression of wEro1 was realized in Pichia pastoris GS115． The yield of wEro1 reached (53. 24 ± 2. 11)U/mL after optimizing the induced expression conditions． The expressed products were purified by ammonium sulfate precipitation and anion exchange chromatography，and the enzymatic properties of wEro1 were investigated． The reasults show that wEro1 possesses thiol oxidizing activity catalyzing disulfide isomerase (PDI) with an optimum pH of 7. 5 and an optimum temperature of 30℃; the enzyme has good stability under low temperature and neutral pH conditions． Pichia pastoris recombinant wEro1 was added to flour to investigate its effect on flour processing quality． It was found that the ability of Pichia pastoris recombinant wEro1 to improve flour silty properties was stronger than that of E. coli recombinant wEro1．

Reversal Effect of Sertraline on Multidrug Resistance of Staphylococcus aureus



MENG Hecheng XIE Shenghai LI Lili CHEN Miaorui

2019, 47(8):  64-70.  doi:10.12141/j.issn.1000-565X.180097

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Multidrug-resistant Staphylococcus aureus (S. aureus) were taken as object to investigate the reversal effect of sertraline on multi-drug resistance of S. aureus and its reversal mechanism through the determination of minimum inhibitory concentration，growth rate，time-kill curves under the combination of non-antibiotics sertraline and different antibiotics，as well as transcriptional level of the drug resistance gene mecA and the efflux pump gene norA by real-time PCR． The results indicate that when the sertraline concentration is higher than 1 μg/mL，the growths of S. aureus are inhibited; when sertraline (1/2 MIC) is combined with tetracycline，it has a bactericidal effect on S. aureus． Sertraline combined with tetracycline，ciprofloxacin，and clindamycin，it has synergistic or additive inhibitory effect on S. aureus，which could increase the sensitivity of three antibiotics by more than 75%． Low concentration of sertraline could significantly reduce the expression of the efflux pump gene norA and mecA gene in SCCmec gene cassettes of S. aureus． The results show that sertraline can regulate the multi-drug resistance of S. aureus by inhibiting the expression of resistance genes such as norA and mecA，and reverse the resistance of S. aureus to various antibiotics when it is combined with antibiotics．

Computer Science & Technology

Music Auto-tagging Algorithm Based on Deep Analysis on Labels



WANG Zhenyu ZHANG Rui GAO Yuxuan XIAO Yongle

2019, 47(8):  71-76.  doi:10.12141/j.issn.1000-565X.180273

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Deep neural network algorithms have made breakthroughs in automatic labeling tasks，but it is still hard to solve the noise data problem in real music dataset． A music auto-tagging algorithm based on deep analysis on labels (DAL) which captures the potential relationship between audio features and music tags was proposed． The algorithm first extracts the audio features through a multi-level convolutional network，and then learn the vector repre- sentation of music tags to reduce the adverse effects of noise data． The experimental results show that the proposed algorithm can achieve higher mean area under receiver operating characteristic curve (AUROCC) and outperform other auto-tagging methods．

Distributed Low-rank Tensor Subspace Clustering Algorithm



LIU Xiaolan PAN Gan YI Miao LI Zhipeng

2019, 47(8):  77-83,95.  doi:10.12141/j.issn.1000-565X.180398

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Subspace clustering algorithm based on low-rank representation (LRR) cannot handle large-scale data effectively，and distributed low-rank subspace clustering algorithm (DFC-LRR) cannot handle the high-dimensional data directly． To solve this issue，a distributed low-rank subspace clustering algorithm based on tensor and distribu- ted computing was proposed． The proposed method firstly considered high-dimensional data as tensor and extended LRR subspace clustering algorithm to high-dimensional data by introducing tensorial multiplication into self repre- sentation of data． Then the low-rank coefficient tensor was obtained through the distributed parallel computing，and get the sparse similarity matrix by sparing every lateral slices of the coefficient tensor． Experimental results on the Extended Yale B，COIL20 and UCSD datasets show that the proposed algorithm outperforms DFC-LRR in clustering accuracy，and distributed computing can reduce the running time obviously．

Subtopic Detection Algorithm Based on Hierarchical Clustering



DAI Xiang HUANG Xifeng TANG Rui JIANG Mengting CHEN Xingshu WANG Haizhou LUO Liang

2019, 47(8):  84-95.  doi:10.12141/j.issn.1000-565X.180203

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The topics generated by the topic model have the problem of semantic difference when using the latent Dirichlet allocation (LDA) to detect topic． The LDA model will generate generic topics with broad meanings，and the parameter K is set by human experience． These problems will lead to a mixed topic situation with multiple sub- topics in the modeling results． To solve the problems above，a subtopic detection algorithm was carried out by using a kind of document feature word sequence based on the hierarchical clustering algorithm． The algorithm was applied to solve the problems that the LDA model classification result is too coarse and low value of public opinion monito- ring caused by the generalization of hot topic detection results． Firstly，the LDA model's results were optimized by filtering two kinds of matrixs，i. e． ，the topic-word distribution and the document-word distribution． Then the over- lapping topics were detected and merged，and the generic topics and mixed topics were detected by using the densi- ty between documents． Finally，the hierarchical clustering algorithm was used to find the subtopics under a topic． The experimental results show that the detection of subtopics in this method can reflect the characteristics of hot topics at a deeper level，which is convenient for public opinion monitoring analysis． Compared with Single-Pass algo- rithm and K-means algorithm，the results obtained by this method are more effective． The selection strategy of K is robust to subtopic detection algorithms based on hierarchical clustering．

Incentive Mechanism of Crowdsensing Based on Loss Aversion



LIU Jiaqi GAO Mu

2019, 47(8):  96-104.  doi:10.12141/j.issn.1000-565X.180534

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At present，the incentive mechanism of crowdsensing is mostly based on traditional economics，while the study of behavioral economics shows that users do not always pursue the maximization of their economic utility because of loss aversion，and the incentive mechanism based on traditional economics can not fully and effectively motivate users． Therefore，an incentive mechanism based on loss aversion (LA-RAIM) was designed． This mecha- nism sets reward factor based on user's loss aversion． By giving users additional rewards during the incentive time， users feel that they will lose if they do not participate in the system，so as to motivate more users to participate． Compared with the classical RVA-IM，the simulation results show that LA-RAIM can not only increase the number of participants，but improve the platform utility and user average utility．

Unstable Data Partition Recognition Algorithm for Unstructured Cloud Data Management System



ZHENG Meiguang YANG Jiao CHANG Chenglong HU Zhigang

2019, 47(8):  105-112.  doi:10.12141/j.issn.1000-565X.180497

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In the context of big data，data nodes in unstructured cloud data management systems need to process ever-expanding raw data，index data and intermediate data． “Data expansion”will significantly increase the time and energy consumption of cloud data management systems． In order to reduce the data transmission overhead caused by the frequent movement of data in unstructured data management system，an algorithm for identifying unstable data partitions was proposed． Firstly，for the unstructured data management system，the cloud model of data partition was conducted in the storage system by introducing the cloud model theory，and unstable data partitions were identified． Then the relevant algorithm was called to re-layout unstable data partitions． Experimental results show that the unstable data partition identification algorithm can effectively identify unstable data partitions and relayout them，and significantly reduce data transmission overhead．

Materials Science & Technology

Structure and Property Analysis of Fluorescent Films with CMC/Tb-Eu



YE Jun FU Zichang XIONG Jian

2019, 47(8):  113-119.  doi:10.12141/j.issn.1000-565X.180621

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The carboxymethyl cellulose (CMC) composite fluorescent films with CMC/Tb-Eu (CTE) were pre- pared by casting method，and the rheological properties of CTE suspensions were studied． The structure and pro- perties of composite films were characterized by Fourier transform infrared spectroscopy (FTIR)，atomic force microscopy (AFM)，fluorescence spectroscopy (FL) and mechanical tests． The rheological results show that the CTE suspensions with mass fraction from 2% to 6% maintain the rheological characteristics of shear thinning of CMC solution． FTIR shows that process during the film formation does not change the chemical structure of CTE particles． That is，Tb³⁺  or Eu³⁺ undergoes coordination and ion exchange reaction with CMC． When the excitation wavelength is 374nm，the composite films emit a characteristic fluorescence spectrum of Tb³⁺ and Eu³⁺ ，wherein the emission peak fluorescence intensity at 543nm is the largest，which is ⁵ D₄ →⁷F₅  emission of Tb³⁺ ． When the CTE content is 0. 2g，the fluorescence intensity of the film is the strongest． The mechanical properties show that the increase of CTE content can simultaneously increase the tensile modulus and tensile strength of the film，and there is no significant difference in the elongation at break． The maximum tensile modulus of the film is 4. 179GPa and the maximum tensile strength is 78. 76MPa．

Rheological Properties and Fluidity of Alkali-activated Fly Ash-slag Grouting Material



YIN Suhong GUAN Haiyu HU Jie HUANG Haoliang YU Qijun

2019, 47(8):  120-128,135.  doi:10.12141/j.issn.1000-565X.180028

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The rheological properties and fluidity of alkali-activated fly ash-slag grouting materials were studied by Brookfield R/S plus rheometer and Marsh cone． The effects of sodium silicate modulus and concentration and slag content on slurry were discussed． The correlation between rheological properties and Marsh fluidity was explored by grey relational analysis method． The research shows that the Marsh cone with an 10 mm inner diameter is suitable for the fluidity test of the alkali-activated fly ash-slag grouting material． The alkali-activated fly ash-slag grouting material is shear thicking slurry withing reological property index greater than 1． When the sodium silicate modulus is 1. 7，the sodium silicate concentration is 18%，and the slag content is 10%，it has good working performance． The correlation between Marsh fluidity of the slurry and the yield stress and plastic viscosity of the slurry is greater than 0. 8，and the correlation is good． The rheological property at the 20 s^-1 shear rate is the best correlated with the Marsh fluidity． The Marsh cone method can be used to detect the fluidity of the slurry．

Preparation and Humidity Sensitive Performance of Nanocellulose/Carbon Nanotube Composite Films



ZHU Penghui CHEN Gang OU Huajie JIANG Chenying CHE Mingyang

2019, 47(8):  129-135.  doi:10.12141/j.issn.1000-565X.180043

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Nanocellulose (NFC) was firstly prepared by means of TEMPO oxidation method． NFC was used as a dispersant for dispersing carbon nanotubes (CNT) in water，and a stable and well-dispersed NFC/CNT suspension was prepared through ultrasonication and centrifugation treatment． Then the concentration of the centrifugally trea- ted NFC/CNT dispersion was measured by Lambert-Beer's law，and the dispersion effect of NFC/CNT was further characterized by atomic force microscope and Zeta potential． Finally，flexible NFC/CNT composite films were pre- pared with the obtained NFC/CNT dispersion by vacuum filtration method． Scanning electron microscopy analysis showed that the prepared films had a multi-layered ordered structure，and NFC and CNT were intertwined to form a network structure． Raman spectroscopy further indicates that hydrogen bonding exists between NFC and CNT in the composite film． The results of the humidity sensitive performance of the obtained NFC/CNT composite films show that CNT content has an important effect on the humidity sensitivity of the films． When the CNT content is 5%，the sensitivity value reaches 64% under 95% relative humidity，and the linearity fitting coefficient is 0. 982，indicating excellent humidity sensitive performance．

Johnson-Cook Constitutive Model and Failure Parameters of 2A97 Al-Li Alloy



REN Jibin WANG Cunxian ZHANG Xinyue SUO Tao LI Yulong TANG Zhongbin

2019, 47(8):  136-144.  doi:10.12141/j.issn.1000-565X.180554

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The finite element simulations of explosion and high-speed collision often involve the process of large deformation and fracture of materials． The 2A97 Aluminum-Lithium (Al-Li) alloy was selected to investigate the Johnson-Cook (J-C) failure model，and the new experimental and numerical framework for determining of revised J-C failure parameters was conducted． The specimens with different notch sizes were designed，and the strain distri- bution and stress triaxialities of the notch samples were studied by using the finite element simulation． Results show that the maximum strain of the notch samples was concentrated at the notch surface，and the variations of stress tri- axialities at the notch surface during the loading process were obtained． Based on the results，the fine speckle was made，and the failure strains of the quasi-static and dynamic loading samples under 293K －573K were obtained by 2D digital image correlation (DIC) measurement method． Thus，the revised stress triaxialities，strain rate and temperature were accurately corresponded to the failure strains，which helps to obtain the accurate J-C failure parameters． In addition，the fracture of Al-Li alloy specimen was observed by SEM，and the microcosmic mechanism of effect of stress triaxiality on the failure strain of Al-Li alloy was investigated． Results show that the micropores produced in the deformation process no longer accumulate into dimples with the increase of stress triaxiality．