Table of Content

28 February 2022, Volume 50 Issue 1

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Prediction Model of Ground Vibration Velocity in Blasting Demolition of Wide Buildings and Structures

SUN Jinshan, YAN Jiaxin, JIANG Yuefei, ZHANG Zhen, LIU Tong

2022, 50(1):  5-10.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.001

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The seismic wave will be induced in the blasting demolition projects of buildings and structures when the collapsed reinforced concrete structure impacts the ground at high speed. The prediction of vibration velocity of seismic waves is essential to analyze the influence of demolition projects on the environment and design control measures. Based on the plastic deformation characteristics of soil under the intense impact， momentum conservation theory，and dimensional analysis method，we established a collapse vibration prediction model with a wide contact surface. Some actual cases verified the validity of the calculation model. It shows that the calculation accuracy of the model can meet the needs of engineering design，and it is easy to use.

Preparation and Electrochemical Performance of V₂O₅ Nanoparticles Based on Hydrothermal Method

LIU Wanneng，YE Haoran，NI Hang，TIAN Yu，ZHU Xiaolong，ZHENG Guang

2022, 50(1):  11-18.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.002

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V₂O₅ is a metal oxide electrode material with a layered structure and high theoretical specific capacitance. By changing the preparation method，crystal V₂O₅ micro-/nanomaterials with different morphologies can be prepared. To further improve the electrochemical performance of the V₂O₅ electrode material，this paper used V₂O₅ powder as the raw material to prepare the V₂O₅ precursor on the carbon cloth using the hydrothermal method. After annealing at 300 ℃ ，the V₂O₅ nanoparticles with an average diameter of 80 nm were prepared. The effect of different V₂O₅ powder addition and annealing temperature on the morphology of the product was discussed. The electrochemical performance of the annealed V₂O₅ nanoparticle carbon cloth electrode was tested. The results showed that the electrode had good electrochemical activity and cycle reversibility. When the current density was 1 A/g，the specific capacitance was 678. 6 F/g. It has better rate performance and lowers internal resistance. It can be applied as a supercapacitor electrode material.

Preparation and Gas-sensing Performance of CuO/ZnO Composite Nanostructures

WEI Xuechun，CHEN Xingjia，DU Rui，NIU Xiaojuan，TU Yafang，FU Qiuming

2022, 50(1):  19-26.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.003

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We fabricated CuO/ZnO composite nanostructures using an easy one-step hydrothermal method. Samples with different CuO contents were grown by changing the concentration of Cu ions in the reaction solution. The structure and morphology of the samples were tested by scanning electron microscope， X-ray diffraction， and other techniques. We tested the responses of the samples to ethanol gas by an intelligent gas sensing analyzer. The results indicated that the sensitivity of CuO/ZnO composite nanostructures to ethanol gas was significantly enhanced compared with pure ZnO. When the molar ratio of copper ion to zinc ion in the reaction solution was 3 to 5，the gas-sensing performance of the synthesized sample reached the best，and its sensitivity to 100 ×10^-6 ethanol was 55. 3 at the optimum working temperature of 200 ℃. The increased gas sensitivity can be ascribed to the higher specific surface area and p-n junction formation.

Respective Relational Expression of Three Differential Operators on Riemannian Manifolds Under the Conformal Riemannian Metric

TIAN Daping，WANG Min

2022, 50(1):  27-32.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.004

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Divergence operators， gradient operators and Laplacian operators are critical differential operators in differential geometry and play an essential role in other branches of mathematics. In this paper，from the perspective of Riemannian geometry，according to the definitions of the divergence operator， gradient operator， Laplacian operator and the conformal Riemannian metric on Riemannian manifolds，in the local coordinate system of Riemannian manifolds，we derive the relational expressions of the divergence operator，gradient operator and Laplacian operator under the conformal Riemannian metric respectively through direct calculations.

Study on Properties and Determination Methods of Subharmonic Functions

JIN Qingfei

2022, 50(1):  33-37.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.005

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Harmonic functions are essential in the theoretical research of partial differential equations，especially in elliptic partial differential equations. The subharmonic function is a generalization of the harmonic function. In this paper，we make a deep study of subharmonic functions. Furthermore，we give and prove two critical properties and two determination methods of subharmonic functions.

Study on Toughening of PET/MMT Composites

CHEN Xiuyu，CHEN Guofen

2022, 50(1):  38-46.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.006

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With PET/MMT composite system as the substrate，using polyethylene grafted maleic anhydride（PE-g-MAH），maleic anhydride grafted polyethylene octene elastomer（POE-g-MAH），and polypropylene grafted maleic anhydride （PP-g-MAH） as the toughening agent，melt blending them with a twin-screw extruder. We studied the effects of different toughening agents on the composite system′s mechanical properties，compatibility， and melt crystallization behavior. The results showed that adding the toughening agent into PET/MMT composite system had an excellent toughening effect. When the amount of POE-g-MAH added was 30%，the notched impact strength was 2.4 times that without the toughening agent. Infrared characterization showed that toughening modification could improve the compatibility of PET/MMT. XRD results showed that the toughening agent had no effect on the PET/MMT composite crystal structure，and its mechanical properties and processing properties could be improved by melt toughening. DSC results showed that the addition of tougheners could reduce the cold crystallization temperature of PET/MMT blends. SEM results showed that adding tougheners could increase the bonding force between the interfaces，which effectively improved the compatibility of the PET/MMT blend system.

Application and Detection Method of Neohesperidin Dihydrochalcone in the Field of Food and Medicine

ZHANG Liang，HU Siqian，XIE Xinchun，HUANG Dongyun，HUANG Bing，WANG Yazhen

2022, 50(1):  47-54.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.007

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As a food additive，neohesperidin dihydrochalcone（NHDC）has the functions of sweetening and flavoring to modify food flavor. In the medicine aspect，NHDC possesses the efficacy of protecting the liver，lowering blood sugar and blood lipids，improving intestinal probiotic flora，anti-inflammatory，antioxidant，et al. Both in the process of food processing and production and in pharmaceutical application research，the control of NHDC content is a necessity. Therefore，the determination of NHDC is one of the most important issues for workers in related fields currently. The conventional detection methods for NHDC include high-performance liquid chromatography， high-performance liquid chromatographymass spectrometry，capillary electrophoresis，electrochemical method，et al. This paper reviewed the research progress and standard analytical methods for the determination of NHDC in the field of food and medicine in the past ten years.

Factors Affecting Patients′ Choice of Peritoneal Dialysis：A Singlecenter Descriptive Study

LI Tianyu，CHEN Wenli，LIU Changxuan

2022, 50(1):  55-64.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.008

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Objective This study investigates the peritoneal dialysis（PD）patients who chose Wuhan Central Hospital for the designated hospital to understand the factors affecting patients′ choice of PD as the initial dialysis method and provides feasible suggestions and measures for further promotion of PD in the current and other regions. Methods We selected PD patients who chose Wuhan Central Hospital as the designated hospital，PD as the initial dialysis method， and had no hemodialysis （HD） contraindications. Then we sent out questionnaires to patients to collect the factors that affect patients to choose PD as the initial dialysis method，the patient′s pre-dialysis education，and family support. The questionnaire was issued on November 1，2020，and the deadline for the collection was November 30，2020. Results We distributed 100 questionnaires and recovered 92 valid questionnaires. Statistical results of all influencing factors of the initial selection of PD：64 people agreed that PD spent less（69. 6%），71 people（77. 1%） agreed that PD had a good effect，75 people （81. 5%） agreed that PD did not require frequent trips to the hospital，76 people （82. 6%） agreed that the schedule of PD treatment and life was more flexible，76 people （82. 6%） agreed PD did not require too much extra care and reduce the burden on their families，85 people（92. 4%）agreed that the PD operation was easy to handle，54 people （58. 7%） thoroughly listened to doctors′ opinions. Pre-dialysis education： 80 people （87. 0%） agreed that they knew the disease and its prognosis before entering the dialysis treatment，and 72 people （78. 3%） had anticipation of the dialysis treatment and were preparing in the future，76 people （82. 6%） or their family members had understood the characteristics of the two dialysis treatment methods before dialysis. Family support：61 people（66. 3%）highly supported，29 people（31. 5%）moderately supported，and 2 people （2. 2%）poorly supported. Conclusion Driving PD as the first choice for dialysis treatment could ensure the treatment effect， reduce treatment costs， improve the life quality of patients， and save more patients with limited resources. In the actual process of PD promotion，getting the approval and support of specialists，publicizing and promoting PD through medical staff are the most effective measures. Simultaneously，in the process，the economics of PD treatment，the good results of the treatment，the benefits to work and life，the lighter family burden，and the easy-to-learn operation could effectively guide patients and their families to choose PD and obtain patients family support. Finally，by early and regular physical health testing and health education，providing patients with more ways to understand PD-related knowledge，a well-designed pre-dialysis education plan could enhance patients′ self-management ability，eliminate patients′ doubts，overcome fears，and encourage patients to choose PD.

Meta-analysis of the Efficacy of Cinacalcet Combined with Low-dose Calcitriol in the Treatment of Secondary Hyperparathyroidism in Maintenance Hemodialysis Patients

CHENG Jinhua，WANG Min，HU Jintao，WU Yang，LI Hua，SHANG Weifeng

2022, 50(1):  65-71.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.009

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Objective To systematically evaluate the efficacy of cinacalcet combined with low-dose calcitriol in treating maintenance hemodialysis patients with secondary hyperparathyroidism. Methods We searched PubMed，Wanfang，and CNKI databases to collect clinical research results on comparing the efficacy of cinacalcet combined with lowdose calcitriol and cinacalcet in the treatment of SHPT in hemodialysis patients. The search period was from establishing the database to November 1，2020. The Rev Man 5.1 software was used for meta-analysis. Results Finally， 10 studies were included in the metaanalysis，involving 726 patients. Meta-analysis results showed that：compared with the cinacalcet group， cinacalcet combined with low-dose calcitriol group decreased iPTH［MD = -89. 41，95%CI（ -120. 36，-58. 46），P < 0. 000 01］，increased serum calcium ［MD = 0. 37， 95%CI（0. 28，0. 46）， P < 0. 000 01］， decreased serum phosphorus ［MD = -0. 24，95%CI（ -0. 33，-0. 15），P < 0. 000 01］，decreased alkaline phosphatase ［MD = -32. 35，95%CI（-41. 52，-23. 18），P < 0. 000 01］，reduced the volume of parathyroid glands［MD = -0. 31，95%CI（-0. 39，-0. 23），P < 0. 000 01］ and reduced the incidence of adverse reactions ［OR = 0. 20，95%CI（0. 09，0. 44），P < 0. 000 1］. Conclusion The clinical efficacy of cinacalcet combined with lowdose calcitriol in the treatment of SHPT is better than that in the cinacalcet group in hemodialysis patients，and the incidence of adverse reactions is lower.

Analysis of Clinicopathological Features and Diagnostic Trap of 48 Cases of Gastrointestinal Stromal Tumor

HUANG Xuan，LI Yan，CHEN Qiongxia，CHEN Ying，ZHEN Hongyan

2022, 50(1):  72-78.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.010

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Objective To investigate the clinicopathological features and differential diagnosis of gastrointestinal stromal tumor （GIST）. Methods 48 cases of GIST were examined by routine HE and immunohistochemical staining and followed up. At the same time， we analyzed the clinicopathological characteristics combined with relevant literature reviews. Results Morphological manifestations of these lesions were diverse. Smooth muscle tumor cells were uniform，mild，braided，and bundled；tumor cells could also have an epithelioid appearance； some tumor cells had a pseudochrysanthemum-shaped mass structure and palisade structure. There was active cell proliferation，including giant multinucleolate and myxoid stroma cells. Vimentin，CD117，Dog-1，and CD34 were all positive in tumor cells. S-100 and SMA were positive in some cases. The Ki-67 increment index increased with tumor grade，which was 2% ～ 25%. p53 was positively expressed in the middle and high levels of lesions. The expression of ER- α36 was strongly positive in tumor cells and localized in the cell membrane/plasma. Follow-up was established in the whole group，10 cases were lost to follow-up，and 11 patients died. Conclusion The GIST is a kind of stromal tumor with different malignant potential. The combined detection of CD117 and Dog-1 can assist the diagnosis and differential diagnosis of GIST. The expression of ER-α36，a new subtype of estrogen receptor-α is highly expressed in GIST，which provides a new research direction for the pathogenesis and treatment of this disease.

Obstacle Avoidance Strategy of Autonomous Unmanned Watercraft on the Surface Using Heuristic Search Algorithm

YU Linwen，YE Xi，QIAN Tonghui

2022, 50(1):  79-86.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.011

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Aiming at the global optimization problem of the static path planning of the autonomous unmanned watercraft on the surface，we propose a global path planning method based on an improved heuristic function to enhance the accuracy of the global path planning algorithm. The grid method is used to model the known environmental topographic map. This paper designs a new heuristic function based on the A^* algorithm. It optimizes the path by changing the gain coefficient of the navigation controller. Because the drifting effect of water surface obstacles will affect the path planning of the autonomous unmanned watercraft on the surface，the drift increment caused by the drifting effect of the water surface obstacle is simulated by setting different obstacle shapes and sizes. The MATLAB simulation platform is used for many experimental tests，and the test results prove the actual reliability of the improved obstacle avoidance strategy algorithm.

Printed Circuit Board Defect Detection Algorithm Based on Improved Faster RCNN

CHEN Xueshi，SU Tong，QI Weimin

2022, 50(1):  87-96.  doi:10.16389/j.cnki.cn42-1737/n.2022.01.012

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There are many electronic components on PCB，the distance between them is small，and the circuit routing color is relatively similar. The traditional method based on machine vision detection has some problems，such as slow detection speed，false detection rate，fewer types of defects that can be detected. Based on this，we propose a defect detection method of printed circuit board based on improved Faster RCNN，which can detect six kinds of defects on printed circuit board：leakage，notch，open circuit，short circuit，burr，and residual copper at the same time. Firstly，the basic detection framework is Faster RCNN，and the basic improvement measures are pyramid feature network（FPN），multiscale training，anchor box，and clustering. Secondly，we replace the smoothL1 loss function in the original algorithm with the improved loss function（DIoU）as boundary box location regression loss function. Finally，we calculate the mean precision（mAP）of the model under various experimental conditions and compare the results of different algorithms. The experimental results show that the mAP of the original Faster RCNN is 73. 7%，and the mAP of the improved Faster RCNN is 95. 1%. Compared with the original algorithm，the mAP of the printed circuit board defect detection model increases by 21. 4%，which has obvious advantages over other algorithms.