- Current Issue
- Online First
- Most Downloaded
- Archive
-
ZHANG Yan, LI Siyu, LIU Chang, GAO Shihao, YU Ting
2026,47(2):119-126, DOI: 10.7535/hbkd.2026yx02001
Abstract:
In order to solve the problem that the traditional stress cone adopts the straight cone curve, which is easy to cause the uneven distribution of the electric field inside the cable intermediate joint, a quadratic cone curve stress cone was designed by using the number-shape combination method. Firstly, the 35 kV cable intermediate joint model was established. Secondly, the electric field distribution characteristics of the stress cone with the straight cone curve and the quadratic cone curve were compared and analyzed. Finally, the key structural parameters such as the winding insulation thickness, cone length, stress cone thickness and cone head curvature radius of the quadratic cone curve stress cone were designed. The results show that compared with the straight cone curve stress cone, the maximum electric field strength inside the joint of the quadratic cone curve stress cone can be reduced by 47.43% at most. When the stress cone winding insulation thickness, cone length, cone curvature radius and stress cone thickness are 10.94 mm, 50.48 mm, 2.3 mm and 3.3 mm, respectively, the maximum electric field strength inside the joint can be reduced to 3.32 kV/mm, and the maximum electric field strength of the cone surface can be reduced to 1.67 kV/mm. The parametric design of the quadratic cone curve stress cone can more effectively uniform the internal electric field of the joint, reduce the possibility of partial discharge, and improve the operation reliability of the joint. It has reference value for the optimal design of the cable intermediate joint stress cone.
-
ZHANG Yisen, XUE Qiang, LIU Qiang, ZHANG Heng, LIU Yuzhi
2026,47(2):127-136, DOI: 10.7535/hbkd.2026yx02002
Abstract:
In response to the problem that the proportion of power electronic devices in the new power system is increasing, leading to intensified nonlinear responses and a significant increase in harmonic components of single-phase grounding fault currents, and traditional arc suppression methods are difficult to effectively suppress the arc, this paper proposed an arc suppression method based on fractional order model predictive control(FOMPC). Firstly, the traditional inductors in the double-linked H-bridge were replaced with fractional-order inductors of different orders. Secondly, the corresponding order model predictive control method was adopted to compensate for the fault residual current based on the principle of minimizing the current tracking error, thereby achieving effective arc suppression. Finally, the performance of the method was verified through hardware-in-the-loop experiments. The results show that using the appropriate order FOMPC for arc suppression has superior performance in response speed and arc suppression effect. The integration of fractional calculus theory with active arc suppression inverters and its control can improve the response speed and reduce the fault current, providing a reference for fault suppression in power electronicized power grids.
-
Experimental and numerical simulation analysis of the effects of water level fluctuation on subgrade
WANG Tao, ZHANG Yunpeng, LI Mingyang, LI Ting, XU Peng, SU Yihao
2026,47(2):137-144, DOI: 10.7535/hbkd.2026yx02003
Abstract:
To address the limitation that current studies on subgrade seepage stability often simplify fills as homogeneous materials, this research investigated the effect of anisotropy in permeability by considering horizontal and vertical coefficients. Firstly, laboratory tests were conducted to examine the variation of horizontal and vertical permeability coefficients of fills with dry density. Subsequently, field tests were carried out to analyze the hydraulic response characteristics of river-side subgrade under fluctuating water levels. Finally, numerical simulations were performed to discuss the influence of permeability coefficient anisotropy on subgrade stability. The results indicate that the ratio of horizontal to vertical permeability coefficients of fill is closely correlated with dry density. During the initial stages of water level decline, significant changes in volumetric water content and pore water pressure are observed at monitoring points within the subgrade. Neglecting permeability coefficient anisotropy may lead to an underestimation of subgrade instability risks under declining water level conditions. Furthermore, higher rates of water level change coupled with more pronounced permeability coefficient anisotropy in the fill correspond to lower safety factors of the subgrade. The study result can enhance the rationality of the subgrade stability design under water level change conditions, which provides valuable insights for the design of road subgrades in flood detention and retention areas.
-
MA Zhilin, GUO Peng, WANG Qixin, ZHANG Zhiyao, LIAO Qiuhan, ZHU Dong, MA Yongjing, SUN Yijie
2026,47(2):145-157, DOI: 10.7535/hbkd.2026yx02004
Abstract:
To deal with the scheduling problem in rail vehicle assembly, where assembly line task allocation is complex and car body components require frequent cross-station transfers relying on trolleys, this study proposed an end-to-end hierarchical multi-agent deep reinforcement learning framework for scheduling optimization. Firstly, the allocation of assembly tasks across multiple assembly lines was modeled as a sequential decision problem. The high-level agent encoded the assembly task and line features using a Transformer and generated line assignment strategies with a Pointer Network. Secondly, the lower-level agents coordinated the selection of operations, station assignments, and dolly scheduling, and used Graph Attention Networks to extract relational features from heterogeneous nodes. Finally, multiple comparison experiments were conducted to validate the effectiveness of the proposed method. The results show that the method achieves optimal scheduling across different instance scales. The coordination of low-level agent strategies achieves an average maximum makespan gap of 11.36%, which outperforms the 15.00% achieved by the graph isomorphism network method, and the method provides high-quality scheduling with computation efficiency significantly higher than the Late Acceptance Hill Climbing algorithm. The proposed hierarchical collaborative scheduling framework achieves unified modeling and coordinated optimization of assembly task assignment and multi-resource scheduling, providing an efficient and adaptable intelligent optimization approach for rail vehicle assembly scheduling.
-
WANG Yunling, LYU Xinghao, CAO Yuntao, LI Yipeng, ZHANG Shuai, ZHANG Yuzhuo
2026,47(2):158-169, DOI: 10.7535/hbkd.2026yx02005
Abstract:
This study aims to develop an active sound generation system for electric vehicles to enhance the comfort and power sensation of the in-car sound during acceleration. A design method for in-car sound during acceleration is proposed, considering three aspects: the composition of engine orders, the distribution of spectral energy, and the enhancement of sound amplitude within typical speed ranges. Based on in-car sound surveys, subjective evaluations, and test results, the simulation analysis of engine order sounds was completed. An acoustic design scheme for the acceleration scenario was established for a certain A-class pure electric SUV model, and an active sound generation system based on the vehicle’s audio system was developed. The in-vehicle test results show that the active sound generation system increases the sound pressure level and loudness inside the vehicle, achieving a maximum reduction of 1.0 acum in the sharpness of the in-car sound. This active sound generation system can effectively improve the sound quality inside electric vehicles, providing reference for the subjective evaluation calibration and active control method research of in-car sound quality during the acceleration condition of electric vehicles.
-
ZHU Yuehong, YU Changlong, LI Jing, WANG Jufang
2026,47(2):170-181, DOI: 10.7535/hbkd.2026yx02006
Abstract:
In order to expand the theory of fractional q-difference equations, the existence of solutions to boundary value problems of a class of iterative functional higher-order fractional q-difference equations with integral boundary conditions on infinite intervals was studied. Firstly, the Green[DK]’s function of fractional difference equation boundary value problem was calculated and its properties were studied. Secondly, an appropriate Banach space and norm were introduced, and the integral operator was then constructed. Thirdly, the existence theorem of positive solution of the problem was obtained by using monotone iterative technique and upper and lower solution method. Finally, the effectiveness and practicability of the main results were verified by a concrete example. The results show that under certain growth conditions of the nonlinear term g, there exists at least one positive solution to the boundary value problem of iterative functional fractional quantum difference equations on infinite intervals. The research results enrich the solvability theory of fractional q-difference equations, reflect the influence of feedback iterative terms on the existence of solutions, and provide certain theoretical guidance for the application of iterative functional fractional q-difference equations in many fields such as control engineering, biomedicine, population theory, and social economy.
-
ZHAO Suqian, YANG Linguang, LIU Na, ZHANG Rixin, DING Yanhong
2026,47(2):182-190, DOI: 10.7535/hbkd.2026yx02007
Abstract:
In order to develop equivariant cobordism classification of manifolds with involutions whose fixed point sets are product of projective spaces, the equivariant cobordism classification of all manifolds with involutions (M,T) with fixed point set F=CP(2n)×HP(2m+1)(m≥n≥3) was studied. Firstly, the existence of bounding involutions with CP(2n)×HP(2m+1) as its fixed point set was proved; Secondly, according to the form of normal bundle over F, the results were discussed by dividing several cases, by constructing a suitable symmetric polynomial, according to Kosniowski-Stong theorem, the contradiction was obtained by calculating characteristic numbers, and non-existence of non-bounding involutions was proved, or that involutions exist and bordism was obtained by calculating characteristic numbers; Finally, bordism was obtained. The results show that every smooth closed manifold (M,T) with an involution T having fixed point set of form CP(2n)×HP(2m+1)(m≥n≥3) exists and bounds. The research results enrich the equivariant cobordism classification of involutions with fixed point set product of projective spaces, and provide theoretical reference for the further study involutions with fixed point set other special manifold.
-
LIU Xiaorui, LI Duan, MA Kunru, LIU Chang, YUE Yunkai, ZHANG Liang
2026,47(2):191-199, DOI: 10.7535/hbkd.2026yx02008
Abstract:
Energy efficiency optimization control technology for air compressor stations has attracted significant attention due to its critical role in industrial energy conservation and consumption reduction. The current research status of key technologies for energy efficiency control in air compressor stations was summarized. Firstly, the basic composition and workflow of air compressor station systems were introduced, clarifying their importance as core energy supply units. Secondly, the focus was placed on three core areas: energy-saving optimization of air compressors, technologies for efficient and stable exhaust, and development in dryer technology. The key technologies and research progress in these areas were reviewed, covering representative methods and achievements in intelligent control algorithms, optimization of components and structures, and coordinated control strategies. Finally, three key system-level challenges in air compressor stations were identified: inadequate load-balancing strategies for multiple units, difficulties in matching control strategies with dynamic equipment states, and insufficient coordination among critical equipment. Accordingly, future research priorities are outlined as follows: 1) developing intelligent load distribution based on dynamic efficiency matching; 2) constructing an adaptive control framework deeply coupled with the actual operating conditions of equipment; 3) establishing cross-equipment data interaction and coordinated control mechanisms.
-
2026,47(2):200-208, DOI: 10.7535/hbkd.2026yx02009
Abstract:
To address the problem of excessive randomness introduced by the mechanical exchange of gene fragments in traditional crossover operators, which leads to the generation of invalid refactoring operations, this paper proposed a refactoring recommendation method called RefCross based on an adaptive crossover operator. Firstly, the submitted Java projects were parsed using source code analysis tools to construct a code structure model to extract code metrics. Then the fitness function was designed and the fitness value was calculated based on the extracted code metrics to guide the optimization direction of the crossover operator. Finally, the parent classification mechanism based on feature matching was constructed, and the crossover strategy was formulated. By combining with common gene retention, adaptive selection of differential genes, and the elite gene reinforcement strategy, the offspring refactoring sequences that balanced high-quality feature inheritance and diversity in the solution space was generated, thereby reducing the probability of generating ineffective refactoring operations. The results show that RefCross outperforms existing methods in precision, recall, and F1 score metrics on six open-source projects, achieving an average F1 score of 77.82%, representing a baseline improvement of 9.10 percentage points. This method effectively enhances the effectiveness and accuracy of refactoring recommendations, providing strong support for automated refactoring decisions.
-
XUE Ting, WANG Zhenzhou, MENG Zhiyong, ZHANG Xiuqing, YANG Lin, DENG Biao
2026,47(2):209-219, DOI: 10.7535/hbkd.2026yx02010
Abstract:
To address the low accuracy and efficiency of apple maturity detection under large-scale, lighting, and occlusion conditions, an improved FPB-DETR detection model based on RT-DETR was proposed. Firstly, a frequency-adaptive dilated convolution (FADC) module was introduced into the backbone network to precisely focus on subtle color gradients, immature spots, and texture stripes on apple surfaces by resolving the conflict between effective receptive field and feature bandwidth, as well as overcoming the limitations of fixed dilation rates. Secondly, a polaformer-attention-based intra-scale feature interaction（Pola-AIFI) module was designed to mitigate the issues of negative value neglect and excessive information entropy, suppressing interference from target apples under varying environmental conditions. Finally, a bi-directional feature pyramid network（BIFPN) structure was introduced during the multi-scale fusion stage to optimize feature fusion efficiency and key information focusing capability, reducing ambiguity interference in maturity feature transmission. The results show that the precision, recall rate and average accuracy of the FPB-DETR model proposed in this study are 92.5%, 92.7% and 96.8%, respectively, which increases by 2.0%, 1.7% and 1.8%, respectively compared with the original model, and are superior to those of Faster R-CNN, YOLOv5m, YOLOv8m, YOLOv11m and YOLOv12m object detection models, significantly enhancing the detection capability of the model; The average detection time of the model is 31 ms, which meets the real-time detection requirements for apple maturity. This study realizes better detection effect by combining feature extraction, attention mechanism and multi-scale fusion, providing reference for the optimization design of intelligent harvesting robots.
-
DONG Lihua, XIE Ruixue, CHEN Qiang, XU Dongbing, XU Zhice, YU Hongwei
2026,47(2):220-228, DOI: 10.7535/hbkd.2026yx02011
Abstract:
To address the unresolved issues of molecular configuration and thermal stability mechanism of bismuth subnitrate, mid-infrared (MIR) spectroscopy, one-dimensional variable temperature mid-infrared (1D VT-MIR) spectroscopy (303~573 K) and two-dimensional mid-infrared (2D-MIR) spectroscopy were used to analyze the temperature-dependent characteristics of its molecular vibrations. The results show that the molecular structure of bismuth subnitrate mainly includes four infrared absorption modes: asymmetric telescopic vibration mode of NO3 functional group asymmetrical stretching vibration mode (νasNO3-bismuth subnitrate), NO3 functional group symmetrical stretching vibration mode (νsNO3-bismuth subnitrate), NO3 functional group out-of-plane bending vibration mode (rNO3-bismuth subnitrate) and NO3 functional group in-plane bending vibration mode (βNO3-bismuth subnitrate). In the temperature range of 303~573 K, the absorption intensity and frequency corresponding to the main functional groups of its molecular structure change significantly, and the 2D-MIR spectroscopy can effectively capture the information of the change of the absorption peaks of the main functional groups. This study clarifies the molecular structure characteristics and thermal denaturation law of bismuth subnitrate, and confirms that tertiary mid-infrared spectroscopy technology can be effectively applied to the molecular structure and thermal denaturation of bismuth subnitrate, which provides technical support and data reference for the related research of this type of inorganic fine chemicals.
Volume 47,2026 Issue 2
National Young Scholar/Local Science Foundation
Mathematics
Mechanical, Electronics and Information Science
Chemistry and Chemical Industry
-
DOI:
Abstract:
undefined
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
2021,42(2):180-194, DOI: 10.7535/hbkd.2021yx02011
Abstract:
As one of the important supporting technologies for the construction of CPS(cyber-physical space),the digital twin has been applied in many fields,such as aerospace,intelligent manufacturing,smart city,smart medical care,smart education,etc.However, some problems in the practice process has also appeared: the generalization of the concept of digital twin leads to the misunderstanding,which results in the inconsistency of production,teaching,research and application goals,and the practice results are not recognized by the target users; The lack of general and effective methods in concrete implementation leads to the limitation of the results,which results in the lack of universal practical cases and difficulty in forming recognized typical cases.To solve these problems,it is necessary to restrict the concept boundary of digital twin and extend the boundary of digital twin method,so as to form a new boundary of digital twin,promote the formation of consensus,increase implementation methods and promote its better development. 河北科技大学学报 2021年 第2期 刘〓青，等：数字孪生的新边界 Conceptually,physical entity is a collection of materials with various properties,which is characterized by complexity,authenticity and immediacy,and can dynamically evolve with the change of external conditions according to objective laws.In the study of mapping physical entities to digital twins,it is easy to expand the scope of concept to include simulation (the simulation of dynamic evolution process),data (external conditions),and even physical entities (objects).As a result,the concept of digital twin will lose its core and it is difficult to from a consensus.In terms of methods,based on the detailed investigation and analysis of related applications in multi-scenarios,the existing research on digital twin often goes beyond the perception process of physical entities,and directly relies on the models or modelconstruction methods in the original professional fields.While this method has made some progress,its limitations have already been revealed.Firstly,the existing models are mostly focused on subdivision fields,which can not be used universally among fields.Secondly,there are few existing models that reflect the characteristics of high fidelity,multi-scale and multi-physical fields of the digital twin model,and even less information flow corresponding to the whole life cycle.Direct application can not guarantee the effective realization of digital twin; Thirdly,entering the modeling process directly from the height of existing cognition may cause huge costs.For example,the ADT program,a world recognized typical case of US military,was constructed in ten years and with huge investment in manpower and material resources,which further hinders the industry from entering the practice of digital twin.In order to meet these challenges,in terms of conceptual boundary,this paper proposed that the digital twin should return to the essence of its digital model,and effectively restrict the model as the center,so as to promote the understanding of all parties involved in production,teaching and research to reach an agreement.As for the extension of method boundary,this paper put forward a multi-sensory oriented digital twin model construction method,that is,according to the general process of human understanding of the physical world,firstly obtained perceptual knowledge of features through various perception methods,and then further formed rational knowledge through various cognitive processes,from shallow to deep,from easy to difficult,from simple to complex.At first,the digital twin initial model of physical entity was established by multi-sensory methods,such as visual perception,auditory perception,tactile perception and dynamic perception,gustatory/taste perception,and combination with control data reflecting the change of conditions,thus focusing on the complexity and authenticity of physical entity at the beginning of the model establishment,fully embodying the characteristics of the digital twin model,and effectively enhancing the practicability and universality of the model. Then,the initial model was gradually matched with the existing cognitive knowledge framework,and the control data returned from the physical entity was used for continuous iteration.In this way,information of various property changes,real-time/near-real-time reactions,various objective laws and behavioral logic affecting the physical entity under specific external conditions can be gradually added to the digital twin model according to the actual needs of the research field,thus effectively controled the scale and cost of the model and gradually realized the information flow in the whole life cycle. Third,the optimized digital twin model was further used in theoretical and practical research,such as simulation,planning,optimization,decision-making,etc.,so as to promote the development of various studies.The application prospect of the multi-sensory oriented digital twin model in computer image scanning,cultural heritage protection,medical treatment,education and some special fields was prospected.
-
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.
-
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.
-
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.
-
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.
