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ZHANG Fuqing, YAO Ye, QU Haiyan, CUI Bo
2025,46(2):119-128, DOI: 10.7535/hbkd.2025yx02001
Abstract:
Aiming at the frosting problem of evaporators in cold storage leading to significant decrease in heat transfer efficiency and damage to the cold storage, based on the theory of heat and mass transfer, combined with actual cold storage data, a modified relationship for the air heat transfer coefficient applicable to the frosting state of cold storage was established，and a dynamic model of frosting on the surface of the cold storage evaporator was constructed. The accuracy of the model was verified by using the frosting experimental platform on the surface of the cold storage evaporator.The effects of different return air temperature, return air humidity, and wind speed conditions on the growth of frost layer and the heat transfer efficiency of the evaporator were discussed. The results show that the frosting process on the surface of the evaporator can be accelerated by increasing the return air humidity and wind speed, as well as reducing the return air temperature. High humidity (0.6 g/kg) and low temperature (-22 ℃) conditions will increase the growth rate of frost layer thickness and the decrease rate of heat transfer efficiency of the evaporator. In high wind speed (4.4 m/s) conditions, the surface temperature of the frost layer is increased, and the driving force for frosting is reduced. The established frost formation model for evaporators is comparatively close to actual operating conditions, which provides a solid model foundation and theoretical reference for defrosting control strategies in cold storage.
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JIA Guangfei, LIANG Hanwen, YANG Jinqiu, WU Zhe, HAN Yuxin
2025,46(2):129-140, DOI: 10.7535/hbkd.2025yx02002
Abstract:
Aiming at the problems of incomplete information contained in one-dimensional signals and overfitting of the DenseNet under variable working conditions, a rolling bearing fault diagnosis method based on continuous wavelet transform (CWT) time-frequency images and an improved densely connected convolutional network (IDenseNet) was proposed. Firstly, the one-dimensional vibration signal was converted into two-dimensional time-frequency images by CWT. Then, the DenseNet network was turned into IDenseNet, the ReLU activation function in the first convolutional block of DenseNet was replaced by the Swish activation function(which was smoother), and the style-based recalibration module (SRM) and the convolutional block attention module (CBAM) were introduced into the DenseNet network. The SRM focused on the weight of feature channels, while CBAM enhanced the feature expression ability from the two dimensions of channel and space. Finally, the two-dimensional time-frequency image was input into the IDenseNet model for feature extraction and fault diagnosis, and the fault diagnosis results were output through the Softmax layer of the model. The results show that the average fault recognition accuracy of the proposed method reaches 97.80% under constant and variable conditions, and the average fault recognition accuracy reaches 99.44% in the transfer learning model. The CWT-IDenseNet method can effectively improve the generalization ability of the model, which has significant advantages under constant and variable conditions, providing reference for improving the accuracy and reliability of rolling bearing fault diagnosis.
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2025,46(2):141-150, DOI: 10.7535/hbkd.2025yx02003
Abstract:
In response to the issue of fuzzy event argument boundaries in traditional Chinese medicine (TCM) event extraction, an event extraction model integrating local and global semantic features (EE-LGSF) was proposed, which combined convolutional neural networks, bidirectional long short-term memory networks, and attention mechanisms to enhance the effectiveness of TCM event extraction. Firstly, multi-dimensional local feature information of the text was extracted by combining convolutional neural networks with different filter window sizes, while the global feature information of the text was captured using bidirectional long short-term memory networks. Secondly, on this basis, dynamic interaction between local and global information was achieved through gating mechanisms to enhance the ability of model to identify argument boundaries. Furthermore, a fuzzy span attention mechanism was introduced to dynamically adjust the attention range, thereby optimizing the decision-making process for argument spans. Finally, label prediction was performed using conditional random fields. The results indicate that the proposed model improves the F1 score by 3.0 to 11.0 percentage points on the TCM medical records data-set, demonstrating superior performance in addressing TCM event extraction issues compared to related models. The proposed model effectively leverages both local and global semantic information of the text, enhances the flexibility of span learning and improves the capability of the model to identify argument boundaries, thereby achieving better performance in TCM event extraction. It has reference value for the inheritance and development of TCM knowledge.
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YANG Xinsheng, XIE Xiaolong, WEI Ming
2025,46(2):151-160, DOI: 10.7535/hbkd.2025yx02004
Abstract:
In order to address the problem that the existing susceptible-infected-recovered(SIR) model does not consider the impact of the topology of the airport network on the flight delay propagation, the topological characteristic index of the airport network was calculated based on the complex network theory.The comprehensive importance of each airport was evaluated by using the entropy weighted technique for order preference by similarity to ideal solution(TOPSIS) method, and all airports were divided into several classes, thus the improved SIR model for the flight delay propagation of airports in different classes was established and the propagation thresholds of the model were solved. Taking the Chinese airport network in 2023 as an example, all airports were classified into five categories, and an improved SIR model was used to simulate the flight delay propagation of airports under different initial conditions. The simulation results show that the improved SIR model is more suitable for simulating delay propagation.The higher the comprehensive importance of an airport, the wider the delay propagation range becomes, the faster the speed is, and the longer the recovery period lasts.The delay propagation ability of E-class airports is significantly improved, when flights from multiple airports are delayed.The topology of the airport network has an inhibitory effect on the delay propagation, and it is difficult for delays to spread to all the airports. The improved SIR model demonstrates the differential effects of airport importance on delay propagation and provides reference for the formulation of flight delay management strategies.
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WANG Jiahe, DOU Yujie, PANG Xingmei, LYU Lun
2025,46(2):161-166, DOI: 10.7535/hbkd.2025yx02005
Abstract:
In order to expand the basic theory of Dyck path and ternary tree, the bijection and counting problems between the 20-Dyck path and the ternary tree with n inliers were studied. Firstly, the bijection between the 20-Dyck path and the L-R-T sequence was established by constructing a novel combinatorial L-R-T sequence. Secondly, the transformation relationship between the L-R-T sequence and the ternary tree with n inliers was constructed by means of analysis and induction, thus providing a combined proof of its counting formula. Finally, the relationship between the peaks and valleys of the 20-Dyck Path and the L-R-T sequence and the ternary tree was studied. The results show that the bijection problem between two combined structures can be proved by the relationship with other structures. The research results enrich the related theories of Dyck path and ternary tree, and provide theoretical reference value for the application of these two structures in the field of combinatorics.
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2025,46(2):167-174, DOI: 10.7535/hbkd.2025yx02006
Abstract:
In order to expand the theory of fuzzy logic algebra, the fuzzy ideals and fuzzy congruences of co-residuated lattices and their interrelationships were studied. Firstly, by using Heyting algebra as the valuation domain, the concepts of fuzzy ideals and fuzzy congruences of co-residuated lattices were introduced, and their mutual induction methods were studied to prove a one-to-one correspondence between them. Secondly, the equivalent descriptions of fuzzy ideals and fuzzy congruence relationships were studied using cut set and strong cut set methods. The research shows that fuzzy ideals and the fuzzy congruences are two equivalent concepts and thus will play the same role in structure and classification problems. The research conclusion enriches the relevant theory of fuzzy logic algebraic algebras and can provide certain theoretical reference for further study of other algebraic systems.
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WANG Jufang, ZHANG Jinye, YU Changlong
2025,46(2):175-185, DOI: 10.7535/hbkd.2025yx02007
Abstract:
In order to enrich the basic theory of boundary value problems for fractional q-difference equations, the boundary value problems for a class of nonlinear fractional q-difference equations with p-Laplacian operator on infinite intervals were explored. Firstly, the Green function of the boundary value problem of linear fractional q-difference equation was calculated and its properties were studied. Secondly, the compactness criterion on infinite intervals was introduced and the integral operator on an abstract space was constructed. Thirdly, by selecting the initial value functions and using the monotone iterative technique, the existence of positive solutions for the boundary value problem were obtained. Finally, the validity of obtained results was verified through an example. The results show that when certain increasing condition is given to the nonlinear term f, the maximum and minimum positive solutions of the fractional q-difference equation can be obtained by establishing iterative sequences. The research results extend the existing relevant conclusions and provide theoretical reference for the further application of fractional q-difference equations in mathematics, physics and other fields.
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CAO Wei, XU Xiaoyang, ZHANG Xiangjing, XU Yuelong
2025,46(2):186-195, DOI: 10.7535/hbkd.2025yx02008
Abstract:
To enhance the sodium storage capacity, cycling stability and rate performance of hard carbon (HC) materials, high-temperature pyrolysis was employed to achieve doping of various heteroatoms (Zn, S, and Zn/S co-doping) into the HC materials. Using the continuous etching of the carbon framework by ZnS particles, which were formed during the pyrolysis of carbon precursors, abundant pore structures were generated to increase the number of active sites. During Zn/S co-doping process, the pyrolysis temperature was adjusted to 1 050 ℃ and the H-Zn/S-HC-1050 carbon material was obtained after acid treatment. The composition and microstructure of the material were characterized, and its electrochemical performance was tested. The results indicate that the reversible discharge specific capacity of H-Zn/S-HC-1050 carbon material was 276.26 mA·h/g at a current density of 50 mA/g, which was 15.46% higher than the original Zn/S-HC carbon material with a specific capacity of 239.26 mA·h/g; After 100 charge-discharge cycles at a current density of 100 mA/g, reversible specific capacity still maintains at 201.65 mA·h/g. The modified H-Zn/S-HC-1050 carbon material can fully leverage the synergistic effect of Zn/S co-doping through optimizing carbonization and reducing impurity attachment, which provides some reference for the development of high-performance hard carbon materials.
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SHAO Jiangtao, QI Junyu, HAN Zexu, GUO Xueling, QI Yike, WANG Yingze
2025,46(2):196-206, DOI: 10.7535/hbkd.2025yx02009
Abstract:
The pathogenesis of inflammatory diseases involves complex cellular cascades within tissues, where macrophages play a pivotal role. These cells exhibit remarkable phenotypic plasticity and can polarize into M1 or M2 types depending on the stage of inflammation to adapt to the microenvironment. Environmental adaptability changes prompt macrophages to undergo metabolic reprogramming, providing necessary energy support for cells to effectively participate in anti-inflammatory responses and regulate inflammatory processes. However, research on metabolic reprogramming in anti-inflammatory therapy remains insufficient. This review systematically described the mechanism of macrophages in inflammation process and the latest research progress on metabolic reprogramming. It pointed out the challenges faced by metabolic reprogramming in treating inflammatory diseases and suggests that future research on macrophage metabolic reprogramming should focus on the following areas: 1) exploring the mechanism by which metabolic reprogramming products affect the production of inflammatory cytokines by macrophages; 2) conducting an in-depth analysis of the molecular mechanism of metabolic reprogramming in regulating macrophages; 3) exploring the effects of individual differences on the regulation of macrophage metabolic pathways and customizing individualized treatment plans based on these differences.
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ZHU Liguang, GUO Chaofei, GUO Zhihong, HAN Baochen, WANG Xianhui, XIE Tianwei, ZHAO Hairui, CHENG Lin
2025,46(2):207-214, DOI: 10.7535/hbkd.2025yx02010
Abstract:
To improve the lubrication performance and heat transfer control capability of continuous casting mold flux, the effects of K2O on its properties were systematically investigated by using a rotary viscometer, infrared emissivity technique (IET), infrared spectrometer, Raman spectrometer, and X-ray diffractometer (XRD). The results indicate that when the K2O content increases from 0 to 6 wt.%, the viscosity of the mold flux (at 1 300 ℃) initially decreases and then increases, and reaching its minimum value at 2 wt.% K2O, along with the lowest transition temperature. Microstructural analysis reveals that the proportions of simple structural units (Q0 and Q1) in the molten slag firstly increase and then decrease, while complex structural units (Al-O-Al and Si-O-Al) exhibit the opposite trend. This leads to an initial reduction followed by an increase in the overall structural complexity and polymerization degree of the slag. Furthermore, increasing K2O content promotes the precipitation of the Bredigite phase (Ca7Mg(SiO4)4) while suppressing the formation of the Cuspidine phase (Ca4Si2F2O7), resulting in a gradual decline in the heat flux density of the mold flux. Comprehensive analysis demonstrates that the optimal K2O content of 2 wt.% significantly enhances both lubrication performance and heat transfer regulation of the mold flux, which provides theoretical reference for optimizing continuous casting processes.
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SU Jizhi, TONG Zhenyu, LI Yong, YU Haifeng, ZHANG Haoxuan, PAN Zuanfeng
2025,46(2):215-224, DOI: 10.7535/hbkd.2025yx02011
Abstract:
Aiming at the problem that the damaged parts in replaceable beam cannot be disassembled and replaced due to excessive residual displacement after strong earthquakes, a new self-centering coupling beams (SCCB) based on shape memory alloy (SMA) rod was proposed. Firstly, a new self-centering friction damper was designed and tested to study its mechanical properties. Secondly, the low cycle reciprocating loading test was carried out on the same SCCB specimen to explore the effect of loading rate on its hysteresis performance. Finally, a finite element model of SCCB was established and parameterized. The results show that the hysteretic properties of SCCB show a typical "flag type" . When the friction force is 10 kN, the loading rate increases from 1 mm/min to 10 mm/min, and the hysteretic area decreases by 34.45%; Increasing the diameter of SMA rod can improve the stiffness, bearing capacity and energy consumption of SCCB, and reduce the residual displacement; Increasing the pretension of SMA rod can improve the stiffness and bearing capacity, which has little influence on energy consumption. SCCB can effectively improve the adaptability of structures to residual displacement after strong earthquakes, providing reference for the design of replaceable beams.
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CHEN Xinpeng, WANG Chaoyi, LU Feng, LI Linlong, ZHAO Feilong, XIONG Cheng, LUO Chongjun, MA Kaimeng
2025,46(2):225-236, DOI: 10.7535/hbkd.2025yx02012
Abstract:
In order to study the pressure-reducing capacity of the tunnel drainage system in the water-rich areas, a three-dimensional fluid solid coupling numerical model was established using FLAC3D software based on the Fenghuang No.2 tunnel of the Hezhou Bama Expressway (Laibin to Du′an section). A new comprehensive evaluation method for the pressure-reducing capacity of drainage system was proposed to investigate the influence of three factors including the distance between circumferential drainage blind pipes, the ratio of permeability coefficient between surrounding rock and initial support, and the height of water head on the pressure-reducing capacity. The results show that the circumferential blind pipe has a significant reducing effect on the water pressure of the lining arch ring. The water pressure at the lining arch and side wall is relatively high, only lower than that of the inverted arch. When the distance of the blind pipes is 3~5 m, the water pressure at the top of the lining along the longitudinal direction of the tunnel exhibits an "M" shaped variation trend. However, when the distance of the blind pipes exceeds 5 m, the pressure reduction effect of the blind pipes begins to significantly decrease, and the variation characteristic of water pressure along the longitudinal direction of the tunnel changes to a "flat-topped mountain" shape. The pressure-reducing capacity of drainage system was evaluated by comprehensive stress index and pressure reduction coefficient, obtaining a prediction formula for the system pressure-reducing capacity. The maximum prediction error is 8.25%, indicating a high level of accuracy. The impact of the three factors on the pressure-reducing capacity is in the following order: the distance between circumferential blind pipes > the ratio of permeability coefficient between surrounding rock and initial support > the height of water head. The larger the ratio of surrounding rock to initial support permeability coefficient is, the lower the pressure-reducing efficiency of the drainage system is. It is necessary to reduce the distance between blind pipes or reinforcing the surrounding rock with grouting to increase the pressure-reducing efficiency of the drainage system. Taking into account multiple factors and the variation pattern of pressure-reducing capacity, construction period, and cost, it is suggested to set the distance between circumferential blind pipes at 5 m for this project. The proposed comprehensive evaluation method for the pressure-reducing capacity of the drainage system demonstrates good applicability, providing significant reference for the design and construction of the waterproof and drainage system of the water-rich tunnel.
Volume 46,2025 Issue 2
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Mechanical, Electronics and Information Science
Mathematics
Chemistry and Chemical Industry
Food Science and Biological Science
Material Science
Civil and Architectural Engineering
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WANG Jianxia, LIU Menglin, XU Yunfeng, ZHANG Yan
2021,42(1):48-59, DOI: 10.7535/hbkd.2021yx01007
Abstract:
Most of the real-life networks are heterogeneous networks that contain multiple types of nodes and edges, and heterogeneous networks integrate more information and contain richer semantic information than homogeneous networks. Heterogeneous network representation learning to have powerful modeling capabilities, enables to solve the heterogeneity of heterogeneous networks effectively, and to embed the rich structure information and semantic information of heterogeneous networks into low-dimensional node representations to facilitate downstream task applications. Through sorting out and classifying the current heterogeneous network representation learning methods at home and abroad, reviewed the current research status of heterogeneous network representation learning methods, compared the characteristics of each category model , introduced the related applications of heterogeneous network representation learning, and summarized and prospected the development trend of heterogeneous network representation learning methods. It is proposed that in-depth discussion can be carried out in the following aspects in future: First, avoid predefined meta-paths and fully release the automatic learning capabilities of the model; Second, design heterogeneous network representation learning method suitable for dynamic and large-scale networks.
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2021,42(1):67-74, DOI: 10.7535/hbkd.2021yx01009
Abstract:
As the side effects of antibiotics are becoming increasingly prominent and the number of approvals is declining year by year, it is urgent to develop other active substances that are similar in functions and not easy to develop drug resistance. Antimicrobial peptides (AMPs) have broad-spectrum antibacterial activities, thermal stability and unique mechanism of action. They can not only play the role of anti-bacterial infection in vivo and promote apoptosis of cancer cells, but also be used as chemotherapeutic agents against virus and antibacterial materials for hospital settings. In this paper, developments related to antimicrobial mechanisms and activities of antimicrobial peptides against drug-resistant bacteria, anticancer and antiviral infection in the field of medicine are systematically reviewed. The problems of stability, hemolytic and toxicity of antimicrobial peptides are elucidated and the development prospects of AMPs in medicine are provided. Further research on AMPs can be carried out in the following aspects in the future. 1) Antibacterial mechanism in vivo are studied to promote the development and application of antimicrobial peptides；2）Structures of AMPs are optimized by replacing and modifying amino acid residues and hybrid peptides are synthesized to improve their activities, reduce side effects and prevent drug resistance; 3）Application of delivery systems for AMPs or combination of AMPs with green natural extracts is investigated to improve their antibacterial activity and bioavailability.
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MA Jing, WANG Ruiyang, WEN Ning
2021,42(1):75-81, DOI: 10.7535/hbkd.2021yx01010
Abstract:
In order to improve the oxidation resistance of 304 stainless steel, SiO2 thin film was prepared on the surface of stainless steel by sol-gel method with tetraethyl orthosilicate (TEOS) as raw material. The effect of film layers on the high temperature oxidation resistance of stainless steel at 900 ℃ was studied by means of oxidation kinetics, XRD, SEM and EDS. The results show that the adhesion of SiO2 film to stainless steel matrix is good, which promotes the selective oxidation on the stainless steel surface and the formation of protective Cr2O3 and NiCr2O4 oxide layers. The high temperature oxidation resistance of stainless steel is improved remarkably. The oxidation resistance of the sample coated with three layers of SiO2 film proforms the best, and the oxidation weight gain and oxidation spalling of the sample are only 58.1% and 41.4% of the uncoated sample after 100 hours of cyclic oxidation at 900 ℃. The high temperature oxidation resistance of stainless steel is effectively improved through SiO2 film coating, which is another attempt of surface treatment method applied to high temperature environment, and provides reference for other thin films prepared by sol-gel method.
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SUI Bingdong, ZHANG Pai, WANG Xiaojun
2021,42(1):22-29, DOI: 10.7535/hbkd.2021yx01004
Abstract:
In order to solve the problems of low recognition accuracy and easily affected by illumination conditions in the gesture recognition, an improved YOLOv3 gesture recognition algorithm was proposed. Firstly, a smaller detection scale was added to the original three detection scales to improve the detection ability of small targets; secondly, DIoU was used instead of the original mean square error loss function as the coordinate error loss function, the improved focal loss function was used as the confidence loss function of the boundary frame, and the cross entropy was used as the loss function of the target classification loss function. The results show that when the improved YOLOv3 gesture recognition algorithm is applied to gesture detection, the map index reaches 90.38%, which is 6.62% higher than that before the improvement, and FPS is nearly twice as high as before. After the new model is trained by the improved YOLOv3 method, the gesture recognition accuracy is higher, the detection speed is faster, the overall recognition efficiency is greatly improved, the loss weights of simple samples and difficult samples are balanced, and the training quality and generalization ability of the model are effectively improved.
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ZHANG Chunhui, WANG Laigui, ZHAO Quansheng, LI Weilong
2015,36(1):90-99, DOI: 10.7535/hbkd.2015yx01016
Abstract:
How to quantitatively evaluate the permeability change of coalbed subjected to liquid nitrogen cooling is a key issue of enhanced-permeability technology of coalbed. To analyze the evolution process of permeability of coupled coal deformation, failure and liquid introgen cooling, the coal is supposed as elastic, brittle and plastic material. Its deformation process includes elastic deformation stage, brittle strength degradation stage and residual plastic flow stage. Combined with strength degradation index, dilatancy index of the element and Mohr-Column strength criterion, the element scale constitutive model with the effects of confining pressure on peak-post mechanical behaviors is built. Based on the deformation process of coal rock, there exist two stages of permeability evolution of the element including decrease of permeability due to elastic contraction and increase due to coal rock element's failure. The relationships between the permeability and elastic deformation, shear failure and tension failure for coal are studied. The permeability will be influenced by the change of pore space due to elastic contraction or tension of element. Conjugate shear zones appear during the shear failure of the element, in which the flow follows so-called cubic law between smooth parallel plates. The calculation formulas of the permeability and the aperture of the fractures are given out based on the volumetric strain. When tension failure criterion is satisfied with the rock element fails and two orthogonal fractures appear. The calculation formulas of the permeability and the width of the fractures are given out based on the volumetric strain. Further, combined with the thermal conduction theory the permeability evolution model of coupled coal deformation, failure and liquid nitrogen cooling is presented. Then Fish function method in FLAC is employed to perform the model. The permeability's evolution process for coal bed cryogenically stimulated by flowing liquid nitrogen through gas production well in Wangyingzi mine, Liaoning province, is simulated and the results include: 1) When liquid nitrogen(LN2) is injected into a rock at warm reservoir temperature, heat from the rock will quickly transfer to the liquid nitrogen resulting in rapid cooling and contraction of coal bed. The nearer the position is to bore hole, the bigger the shrinkage deformation and thermal stress and coal fail when tension stress sufficiently built up. In this paper the tension failure band after 10 days' LN2 cooling is 0.65 m. 2) In tension failure area the cracks from cooling stimulation lead to the significant growth of permeability. The maximum permeability for element is 1.97×105 times more than that before cooling. 3) Apart from the bore hole, the thermal tensile stress leads to the growth of permeability at a rate of 1%~14%, far less than that in the tension failure area. 4) With increasing time the failure area gradually slowly grows up. It indicates that the longer cooling time does not mean better effects. 5) The cooling fracturing area is found to have a 1.0 m band. In practical engineering the pressure in hole bore and phase transition of water also influences the deformation and failure of coal, which leads to much more failure zone of cooling. 6) The evolution process of permeability of coupled coal deformation, failure and liquid introgen cooling can be better reflected by the model in this paper. This study is hoped to provide a simple but reasonable description of the permeability evolution of rocks subject to liquid nitrogen cooling.
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XIE Yinghua, LIU Zhaoxia, ZHANG Meimei, ZHANG Dongmei
2021,42(1):60-66, DOI: 10.7535/hbkd.2021yx01008
Abstract:
In order to avoid the irritation of metformin hydrochloride to the stomach and realize its release in the intestine, with metformin hydrochloride as the main drug and chitosan/sodium alginate as the composite support, the optimal formulation and preparation technology of metformin hydrochloride loaded pH-sensitive hydrogel microspheres were selected, and the pH-sensitivity and in vitro drug release characteristics were investigated. The formulation and process were optimized by single factor test and orthogonal test. The morphology was characterized by SEM. The entrapment efficiency and drug-loaded amount were determined by UV. The release degree was studied by rotating basket method. The results show that the optimized prescription is as following: chitosan and sodium alginate with a total concentration of 2%(mass-volume ratio), mass ratio of sodium alginate to chitosan =1∶1, mass ratio of drug to sodium alginate=2∶5, and 3.5% CaCl2(mass-volume ratio). The cumulative release rate is less than 4% in artificial gastric juice within 6 h, and up to 96.4% in artificial intestinal juice within 6 h. The formulation and process are stable and reliable, and the hydrogel microspheres have high mechanical strength, good biodegradability and stability. So it is a new metformin hydrochloride delivery system.
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CHEN Qi, ZHANG Renhui, HE Zhongyi, XIONG Liping
2021,42(1):1-7, DOI: 10.7535/hbkd.2021yx01001
Abstract:
In order to explore the lubrication performance of alcohols under high loads and high speeds conditions, especially the relationship between carbon-chain length and hydroxyl number and lubrication performance, the effects of carbon-chain length and hydroxyl number on the lubrication performance were well studied. The tribological properties of a series of alcohols were investigated by a four-ball tribological machine, and the effects of the carbon-chain length and the hydroxyl number on their lubricating properties were investigated by means of viscometer, transmission electron microscopy (TEM) and Raman. Experiments show that with the increasing of the carbon-chain length, the run-in period and the time for achieving stable friction coefficient were shorted, and the wear was reduced; with the increasing of the hydroxyl number, the wear decreased with no obvious run-in period and consistent fluctuation of friction coefficient for ethylene glycol and continuous decrease of friction coefficient for glycerol. It is found that friction-induced graphene is superior to amorphous carbon in effectively promoting the tribosystem to achieve the stable friction coefficient and shorten run-in period, which provides reference for the application of alcohols in the field of mechanical equipment.
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2021,42(1):8-14, DOI: 10.7535/hbkd.2021yx01002
Abstract:
In order to improve the positioning ability of ultra wideband network in non-cooperative indoor environment, the theory of centreless positioning algorithm was used to solve and analyze the output distance information of ultra-wideband ranging, and the relative positioning results were obtained. The positioning results of the system were compared with the results of the photoelectric calibration system, and the accuracy was evaluated. The results show that, compared with the traditional ultra-wideband positioning model, the combination of ultra-wideband ranging and centreless positioning algorithm can realize the centreless positioning and the relative positions among nodes, and finally determine the relative positions among nodes. The combination of UWB ranging and centreless positioning algorithm has good stability and accuracy in relative positioning, and can be widely used in various indoor and outdoor scenes.
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Research on impulse interference suppression method based on short time fractional Fourier transform
WANG Xiaojun, XUE Linbo, WANG Yanpeng
2021,42(1):15-21, DOI: 10.7535/hbkd.2021yx01003
Abstract:
In order to solve the problem that the impulse interference near the service frequency band of aviation radio navigation affects the receiver, and further improve the anti-jamming ability of GNSS system, a impulse interference suppression method based on STFRFT (short time fractional Fourier transform) was proposed. The optimal rotation order of the received signal was determined, and STFRFT was applied to the signal to obtain the two-dimensional distribution of time-frequency surface through coordinate rotation. Under the optimal order, the adaptive time-varying filter was used to separate the interference and the signal, so as to suppress the interference. The simulation results show that the adaptive filtering algorithm based on STFRFT has the best effect of eliminating interference compared with several traditional methods, and retains more useful signals while suppressing impulse interference. By combining STFRFT and adaptive time-varying filtering technology, the ability of suppressing impulse interference is improved, which provides some reference for the impulse anti-jamming technology of aviation radio navigation service.
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YIN Yanan, ZHEN Ran, WU Xiaojing, ZHANG Chunyue, WU Xueli
2021,42(1):38-47, DOI: 10.7535/hbkd.2021yx01006
Abstract:
In order to solve the problem that ant colony algorithm is easy to fall into local optimum in UAV route planning, an improved ant colony algorithm was proposed. The upper and lower limits of pheromone volatilization factor and pheromone were set to prevent ants from falling into local optimum because pheromone on short path was too high or pheromone on long path was too low. At the same time, under the influence of multiple heuristic factors, the overall length of the path was taken as an adaptive heuristic function factor to determine the state transition probability. When the path length was large, the adaptive heuristic function factor was small, which reduced the probability of choosing the path by the ant colony. The experimental results show that the improved algorithm reduces the path length by 6.4% and the variance of the optimal path length by 85.78%, which increases the consideration of environmental integrity, shortens the path length, reduces the number of iterations, and jumps out of the local optimum. In the case of increasing environmental complexity, the algorithm can effectively choose a better path and provide a theoretical basis for UAV route planning after introducing the adaptive heuristic function factor.
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LI Chunhua, QIN Yunfan, LIU Yukun
2021,42(1):30-37, DOI: 10.7535/hbkd.2021yx01005
Abstract:
Aiming at the problem of poor precision performance of traditional Bayesian model saliency detection algorithm, a Bayesian model saliency detection algorithm based on improved convex hull was proposed. Firstly, the foreground of the image was extracted by the manifold ranking algorithm, which was used as the prior probability in Bayesian model. Secondly, Harris corner detection algorithm based on color enhancement was used to detect the feature points of the image in three color spaces of RGB, HSV and CIELab; the convex hulls in RGB, HSV and CIELab spaces were constructed respectively; and the intersection of convex hulls were obtained. Thirdly, the saliency region map was calculated by Bayesian model according to the prior probability and the observed likelihood probability obtained by combining convex hulls and color histograms. Finally, the proposed algorithm was tested in two public data sets MSRA and ECSSD. The experimental results show that the proposed algorithm can suppress the background noise effectively and detect the salient areas completely. The test results of F-measure value in MSRA and ECSSD databases are 0.87 and 0.71 respectively, and the accuracy-recall rate curve is higher than that of traditional classical algorithms in complex image databases. The proposed algorithm improves the detection effect of the traditional classical algorithm and the accuracy of saliency map detection.
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MENG Zhian, LU Suling, YAN Huajun, HAN Pengbiao, HU Xilei, WANG Tonghui, WANG Hao
2021,42(1):82-90, DOI: 10.7535/hbkd.2021yx01011
Abstract:
In order to solve the problems of backward production technology, long processing cycle and low material utilization rate in traditional U-shaped steel tie rods, an integrated steel tie rod forming process was proposed. Taking the preform forming of 35 steel tie rod U-shaped head as the research object, a three-pass heating upsetting method was designed. The DEFORM-3D finite element software was used to analyze the simulation results of the temperature field and stress field after upsetting under different process conditions. The hot forming process parameters with better forming effect were discussed, and the feasibility of forming was verified through experiments. The results show that the optimum hot forming process parameters of each pass are as follows: the initial forging temperature of the first pass is 1 150 ℃, while the punch speed is 20 mm/s; the initial forging temperature of the second pass is 1 150 ℃, while the punch speed is 30 mm /s; the initial forging temperature of the third pass is 1 100 ℃, while the punch speed is 20 mm/s. Under the hot forming process parameters, the forming forces of each pass are 1 520, 2 090, 5 290 kN, and the expansion forces of each pass are 5 870, 6 710, 8 830 kN, respectively. After upsetting, the metal streamline distribution is reasonable, there is no crossover and folding phenomenon, and the forming effect is good. The equivalent stress distribution inside the part is relatively uniform while preparing the preform in the three-pass hot upsetting method, which can form a good quality part. It provides a certain reference for the upsetting aggregate process design and equipment selection of the U-shaped head perform of 35 steel tie rod.
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LIU Qing, LIU Bin, WANG Guan, ZHANG Chen, LIANG Zhixing, ZHANG Peng
2019,40(1):68-78, DOI: 10.7535/hbkd.2019yx01011
Abstract:
In recent years, the research on Digital Twin is in the ascendant. As a new paradigm or concept, it shows great potential. However, the connotation and scope of the Digital Twin concept is still uncertain, especially the Digital Twin Model definition is not clear.According to the pattern category, the Digital Twin Model can be divided into general model and special model, in which the special model is still the focus of current research, and the research content is mainly embodied in the use of Digital Twin method to model specific projects. It also includes concept for developing specialized models. These specific projects in addition to the traditional manufacturing related to parts measurement and quality control, manufacturing, design and work processes, as well as system management, but also in the field of biomedical applications and applications for petroleum engineering and so on. There are many tools and techniques for developing special models, such as general industrial software, special industrial software, simulation platform and self-developed secondary development tools, etc.The research object of the Digital Twin general model is not specific to a specific project, but how to represent the controlled elements of the model as a group of common objects and the relationships between these objects. This provides a consistent approach to the management and communication of controlled elements between different environments. The research on the general model is mainly divided into the conceptual research and the model implementation method; the research heat of the two directions is almost the same. Conceptual research ranges from product lifecycle management to system behavior description, such as general system behavior and system reconfiguration, and to product configuration management, to specific workflow, such as design methods, manufacturing systems and manufacturing processes. The research content is relatively divergent, and there is no particularly prominent hot spot. The research of Digital Twin general model implementation is mainly reflected in the modeling language construction, the model development methods exploration, the specific tools usage, the Meta-model concept implantation and the model algorithm exploration.Digital Twin Model is one of the core areas of Digital Twin research. Its future research focuses on how to integrate the external features and intrinsic properties from different Digital Twin artifacts into a model with interoperability, interactivity and scalability for more efficiently realizing the information flow between the physical world and the digital world, thus achieving the universal Digital Twin application, and then supporting the CPS (Cyber Physical Space) and CPPS (Cyber Physical Production System) construction. To this end, the next problem in the Digital Twin Model needing to be solved first is how to dock the standard reference architecture, such as the RAMI4.0 (Reference Architecture Model Industrial 4.0) proposed by Germany and the IMSA (Intelligent Manufacturing System Architecture) by China, etc. Secondly, the Digital Twin Model needs a unified method to describe and it also needs consistent conclusions, in order to standardize the models established by independent development, thus improving the interoperability and scalability of the model. Otherwise, the performance of the model will decrease significantly as the system scales raise. Thirdly, the research on China's Digital Twin Model requires the support of domestic professional industrial software and modeling software, so that the Chinese scholars can carry out in-depth research that is more in line with national conditions.
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QIN Si-liang, WANG Qing-guo, QU Zhao-ming, LEI Yi-san
2012,33(4):309-312, DOI: 10.7535/hbkd.2012yx04007
Abstract:
The permittivity of carbon fibers in different composites is calculated and discussed by using M-G equations, Bruggeman equations and generalized M-G equation. Results show that for high draw ratio fibers, all the three equations can calculate out the permittivity with the same numerical level and variation trend. Generalized M-G equation and M-G equation have a similar result but Bruggeman''s result is smaller. All three equations become invalidation when fibers'' concentration reaches its percolation threshold, which means that all three equations are useful at low concentration.
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WEN Juan, LI Fu, DING Junjun, LI Gang
2015,36(1):1-8, DOI: 10.7535/hbkd.2015yx01001
Abstract:
Urban rail transit vehicles have been more and more attractive to people as a kind of fast, comfortable, energy-saving, environmental protection and safe transportation. But because of the vehicle noise and vibration, urban rail vehicles also face severe challenges. The research of resilient wheels has been continuously developed and improved. Based on the review of development background and structure sorts of resilient wheels, the advantages of resilient wheels are described, and the research status of noise and vibration reducing, infinite element strength analysis, vehicle dynamic analysis and the wheel-rail wear of resilient wheels are discussed. Taking the low-floor LRVs (light rail vehicles) in domestic and overseas as example, the development and application of the resilient wheels in city rail transit is described, and the application prospects of the resilient wheels in LRVs in domestic and the future research direction of elastic wheel are discussed.
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CUI Hai-ting, ZHANG Gai, JIANG Jing-zhi
2012,33(5):453-458, DOI: 10.7535/hbkd.2012yx05016
Abstract:
By using the solidification/melting model of FLUENT software, the melting and solidification process of the aluminum-silicon alloy in a cylinder heat storage with double wall were simulated numerically. Considering the third kind of boundary condition, the dynamic temperature field distribution and the position of the phase interface change moving with time are obtained. And the melting and solidification duration time is also calculated. The results have important reference value for the numerical simulation of the phase change problem and the design of phase change energy storage device.
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2008,29(4):299-304, DOI: 10.7535/hbkd.2008yx04010
Abstract:
Based on the developed rehabilitation manipulator, study on the control system is carried out, such as embedded system platform with the ARM microprocessor S3C2410as its core, motor control module and data acquisition module based on serial peripheral interface (SPI) bus, control software and graphical user interfaces (GUI) etc. According to the mechanical system, a sensor system is also designed to realize the function of acquisition of rehabilitation dada during rehabilitation motion. The test proves the feasibility of the system which can be used in clinic in future.
