Subjects: Library Science，Information Science >> Library Science submitted time 2025-06-28
Abstract： Facing the "15th Five Year Plan" and future development, public libraries should focus on solving three problems in combination with national strategic needs and their own characteristics: continuously strengthening the basic business construction of libraries, further attaching importance to innovative development design of libraries, and continuously strengthening the training of librarians’ abilities, so as to achieve high-quality development of public libraries during the "15th Five Year Plan" and future.
Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2025-06-27 Cooperative journals: 《中国全科医学》
Abstract： Background Heart failure（HF） is a major chronic condition that significantly impacts global health. Coronary heart disease（CHD） is the leading cause of HF. Developing risk prediction models for HF in patients with CHD is crucial for enabling healthcare professionals to identify high-risk populations and implement timely interventions. Objective To systematically evaluate risk prediction models for HF with CHD in Chinese patients，serving as a reference for the development，selection，and dissemination of relevant predictive models. Methods CNKI，Wanfang Data，VIP，SinoMed，PubMed，Embase，Web of Science and the Cochrane Library were searched for relevant studies on risk prediction models for HF with CHD in Chinese patients up to October 2024. Two reviewers independently screened the literature，extracted data，and assessed the risk of bias and applicability of the included studies using the Prediction Model Risk of Bias Assessment Tool （PROBAST）. Results A total of 27 studies were included，reporting 64 risk prediction models. The area under the receiver operating characteristic（ROC） curve（AUC） for these models ranged from 0.511 to 0.989，with 63 models achieving an AUC>0.7，indicating good predictive performance. However，PROBAST assessment revealed that all 27 studies had a high risk of bias and low applicability. Key predictive factors included age，left ventricular ejection fraction，history of diabetes，history of hypertension，NT-proBNP，and Gensini score. Conclusion The stability and external validity of existing risk prediction models for HF with CHD in Chinese patients require further validation through prospective，large-scale studies. Future model development should adhere strictly to PROBAST guidelines to ensure the design and implementation of high-quality，generalizable predictive models.
Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2025-06-27 Cooperative journals: 《中国全科医学》
Abstract： Background Currently，the landscape of cancer treatment has undergone significant transformations，with numerous cancer patients now surviving in a chronic disease paradigm over extended periods. Research indicates that a substantial number of cancer survivors succumb to non-tumor factors，with cardiovascular disease（CVD） being a prominent cause among them. Nevertheless，the potential CVD risks associated with cancer treatment are frequently overlooked，resulting in inadequate early intervention and protective measures.The estimated pulse wave velocity（ePWV） can reflect the degree of arterial stiffness and is an independent predictor of cardiovascular events. The simple calculation method provides feasibility for cardiovascular risk stratification in cancer patients. Objective To assess the influencing factors of ePWV for all-cause mortality and cardiovascular disease mortality in a cohort of cancer patients. Methods A retrospective cohort design was used. The cohort included 4 632 cancer patients who attended the National Health and Nutrition Examination Survey（NHANES） database from 1999 to 2018. Baseline data were collected，including age，gender，race，body mass index（BMI），chest circumference， baseline heart rate，total cholesterol（TC），high-density lipoprotein cholesterol（HDL-C），systolic blood pressure（SBP）， diastolic blood pressure（DBP），diabetes status，history of cardiovascular disease，smoking and drinking status. Follow-up to July 2023. With ePWV as the variable，the quartile method was used for grouping. All the subjects were divided into 4 groups，which were recorded as Q1，Q2，Q3 and Q4 groups. The baseline levels of the 4 groups were compared，and the Kaplan-Meier survival curves related to all-cause mortality and cardiovascular disease mortality of the patients were plotted. Cox proportional hazard regression model were used to explore the relationship of ePWV and mortality in cancer patients. The receiver operating characteristic（ROC） curve of the predictive value of ePWV for death in cancer patients was drawn，and the area under the ROC curve（AUC） was calculated. Results A total of 4 632 patients，with an average age of（60.7±1.01） years，were enrolled，comprising 2 426 females（52.37%） and 2 206 males（47.63%）. There were 1 158 cases（25.0 %） in Q1-Q4 groups. Significant differences were observed among the four groups in terms of age，gender，race，BMI，chest circumference，baseline heart rate，TC，HDL-C，SBP，DBP，diabetes history，cardiovascular disease history，smoking status，and alcohol consumption status（P<0.05）. During the follow-up period，830（17.9 %） of 4632 cancer patients died of all-cause and 376（8.1 %） died of cardiovascular disease.There were significant differences in all-cause mortality and cardiovascular disease mortality among the four groups（P<0.001）. Kaplan-Meier survival analysis revealed statistically significant differences in the survival curves related to all-cause mortality and CVD mortality among 4 groups（χ2 =587.11，P<0.001；χ2 =322.97，P<0.001）. The results of multivariate Cox regression analysis indicated that，compared with patients in Q1，those in Q2，Q3，and Q4 had an increased risk of all-cause mortality（Q2：HR=1.30，95%CI=1.23-1.38，P=0.045；Q3：HR=1.46，95%CI=1.01-2.13，P=0.047；Q4：HR=1.24，95%CI=1.04-1.49，P=0.017）. Additionally，patients in Q3 and Q4 exhibited an elevated risk of CVD mortality（Q3：HR=1.28，95%CI=1.05~1.56，P=0.013；Q4：HR=2.73，95%CI=1.67-4.48，P=0.026）；ROC curve showed that the AUC values of Q1，Q2，Q3 and Q4 quartile groups were 0.514，0.624，0.598 and 0.772，respectively. Conclusion For the first time，it was verified that elevated ePWV was positively correlated with the risk of all-cause and cardiovascular disease mortality in cancer patients. ePWV may be a predictor of the risk of death in this population.
Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2025-06-27 Cooperative journals: 《中国全科医学》
Abstract： Background Patients with interstitial lung disease（ILD）are prone to acute exacerbation（AE-ILD），with infection being a significant trigger. AE-ILD patients exhibit high mortality rates and poor prognoses，yet domestic research on this population remains limited. Objective To investigate the clinical predictive value of dynamic changes in peripheral blood lymphocyte count（LYM）for 28-day prognosis in AE-ILD patients with pulmonary infection and to establish a corresponding prognostic prediction model. Methods A retrospective cohort study included AE-ILD patients hospitalized in the Department of Respiratory Medicine at the Affiliated Hospital of Xuzhou Medical University from January 2022 to June 2024. Patients were stratified into survival（n=37）and non-survival（n=65）groups based on 28-day outcomes. Data collected included demographics（sex，age，diagnosis，ILD subtype，comorbidities），disease severity scores（APACHE II，SOFA），and laboratory parameters：white blood cell count（WBC），neutrophil count（NEU），lymphocyte count on days 1，3，and 5 （d1 LYM，d3 LYM，d5 LYM），hemoglobin（Hb），platelet count（PLT），procalcitonin（PCT），C-reactive protein （CRP），albumin（ALb），total bilirubin（T-bil），lactate dehydrogenase（LDH），creatinine（Scr），activated partial thromboplastin time（APTT），partial pressure of oxygen（PaO2），partial pressure of carbon dioxide（PaCO2），fraction of inspired oxygen（FiO2），PaO2/FiO2 ratio（P/F），and lactate（Lac）. Intergroup differences were analyzed，and statistically significant variables were identified. Receiver operating characteristic（ROC）curves evaluated prognostic predictive capacity. Univariate and multivariate Cox proportional hazards regression analyses were conducted using R software. Scores were assigned to each indicator based on the hazard ratio （HR）. A nomogram prediction model was constructed. After calculating the total score of each indicator, risk stratification was established. The ROC curve of the prediction model was drawn to evaluate its predictive value. The survival curves of 28-day prognosis of AE-ILD patients with different risk stratifications were plotted using R software, and the 28-day survival rates of patients in different groups were compared. Results The non-survival group exhibited higher than APACHE II scores，SOFA scores，PCT，CRP，and LDH（P<0.05）but lower than d3 LYM，d5 LYM，ALb，and P/F（P<0.05）. Dynamic LYM trends diverged：non-survivors showed progressive lymphopenia，while survivors demonstrated lymphocyte recovery. The results of the ROC curve showed that the AUCs of d3 LYM , d5 LYM , APACHE II score, and SOFA score in predicting the 28-day prognosis of patients with AE-ILD were 0.723, 0.764, 0.733, and 0.704, respectively. Multivariate Cox regression identified P/F（HR=2.01，95%CI=1.08-3.75）、PCT（HR=2.14，95%CI=1.02-4.49）、Hb（HR=2.34，95%CI=1.22-4.48）、d5 LYM（HR=2.40，95%CI=1.01-5.70）as independent predictors of 28-day mortality. The nomogram model was constructed based on d5 LYM，P/F，PCT and Hb. The AUC value of this model for predicting 28-day mortality in AE-ILD patients was 0.853（95%CI=0.781-0.925），with the optimal cut-off value being 2. The sensitivity and specificity were 88.24% and 82.35%，respectively. According to the results of the optimal risk stratification, 0-2 is classified as the low-risk group, and 3-6 is classified as the high-risk group. There were significant differences on the 28-day survival rates between the two groups of patients（χ2 =51, P<0.001）. Conclusion Lymphopenia is associated with increased 28-day mortality in AE-ILD patients with pulmonary infection. The nomogram model incorporating LYM-d5，P/F，PCT，and Hb provides a clinically practical tool for risk stratification and prognostic assessment.
Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2025-06-26 Cooperative journals: 《中国全科医学》
Abstract： Background Blood stasis syndrome is a significant concurrent syndrome in primary Sjögren's syndrome （pSS）. However，the quantitative characteristics and clinical correlations remain insufficiently explored. Objective To investigate the quantitative characteristics of blood stasis syndrome in pSS patients and the association with glandular secretory function，imaging features，serum indicators，and the risk of systemic involvement. Methods This study adopted a prospective cohort design，enrolling 171 patients with suspected pSS who were treated at Yueyang Hospital of Integrated Traditional Chinese and Western Medicine，Shanghai University of Traditional Chinese Medicine，from July 2022 to January 2024. Based on the 2016 ACR/EULAR classification criteria，patients were divided into a pSS group（130 cases） and non-pSS group（41 cases）. General information was collected，including gender，age，clinical manifestations，presence of other autoimmune diseases， other medical history，and medication history. Clinical indicators included unstimulated salivary flow rate，visual analog scale（VAS） score for dry mouth，salivary gland ultrasound（SGUS），and labial gland biopsy results. Laboratory indicators included antinuclear antibodies（ANA），anti-SSA/Ro antibodies，IgG，erythrocyte sedimentation rate（ESR），rheumatoid factor，C3/C4，and systemic involvement. Blood stasis syndrome scores were calculated using the International Diagnostic Guidelines for blood stasis syndrome. Differences in general information，clinical indicators，and blood stasis syndrome scores between the two groups were compared. Pearson or Spearman correlation analyses were used to evaluate the correlations between blood stasis scores and clinical indicators. The distribution of high-frequency blood stasis syndrome scores was also analyzed. Results The rates of positive blood stasis syndrome，blood stasis syndrome scores，VAS scores for dry mouth，total SGUS grades for bilateral glands，positive rates of labial gland biopsy，positive rates of anti-SSA/Ro antibodies，ANA titers，ESR，and IgG levels of pSS group were higher than non-pSS group，and the unstimulated salivary flow rate was lower than non-pSS group，with a statistically significant difference（P<0.05）. Correlation analysis revealed that blood stasis scores in the pSS group were positively correlated with VAS scores for dry mouth（r=0.520，P<0.05） and total SGUS grades for bilateral glands（rs=0.492，P<0.05），negatively correlated with unstimulated salivary flow rate（r=-0.491，P<0.05）. The rate of systemic involvement in the moderate to severe blood stasis group was higher than the mild group（P<0.05）. Analysis of high-frequency blood stasis items showed that purple-dark tongue or sublingual venous engorgement，fixed pain，limb numbness/joint deformity，and pathological masses had higher positive rates in the blood stasis syndrome differentiation of pSS patients. In salivary gland ultrasound grading，the blood stasis scores in the grade 3 groups for both parotid and submandibular glands were higher than those in the lower-grade groups，with statistically significant differences（P<0.05）. Conclusion Blood stasis syndrome is prevalent in pSS patients，and its severity is closely associated with glandular dysfunction，abnormalities in SGUS imaging，and the risk of systemic involvement. SGUS can serve as an objective assessment tool for blood stasis syndrome，supporting the TCM theory of blood stasis leading to dryness，and providing a theoretical basis and clinical reference for the personalized diagnosis and treatment of pSS.
Subjects: Physics >> Nuclear Physics submitted time 2025-06-25
Xiang, Dr. Jiabing
Wang, Mr. Yanxin
Yang, Mr. Yuhang
Zhao, Prof. Wei
Li, Dr. Baolei
Sun, Dr. Bao-Hua
Abstract： In this paper, we propose a novel design for a stationary CT system, termed the Alternating Source-Detector Array stationary CT (ASDA-sCT). The ASDA-sCT system comprises an array of miniature carbon nanotube X-ray sources and a detector array strategically positioned in the gaps between sources. To minimize projection loss caused by ray path obstruction, the X-ray sources are distributed within a short-scan trajectory that takes advantage of the fan-beam symmetry. After interpolation-based restoration of the discontinuities, CT images can be directly reconstructed using the filtered backprojection (FBP) algorithm with Parker’s weighting function. We further investigate the influence of the number of X-ray sources on the reconstruction quality of the ASDA-sCT system and determine the optimal source number for different X-ray exit window sizes. However, the limited number of sources and the interpolation errors introduced during sinogram restoration remain critical barriers to achieving high-quality image reconstruction. To tackle these issues, we propose a tailored triple-stage dual-domain cascade neural network (TSDDC-Net), which incorporates prior knowledge to correct interpolation errors in the sinogram and compensate for the missing projection views. In the projection domain, we introduce a novel multi-scale deformable convolution module (DFInception) that enhances feature extraction and improves the accuracy of sinogram refinement. In the image domain, a dual-encoder architecture is employed to independently extract features from the initial CT image reconstructed from raw interpolated projections and from the refined CT image reconstructed using the corrected sinogram. Ultimately, the well-designed deep learning model significantly enhances the quality of the reconstructed images. Experiments conducted on the Shepp-Logan phantom and abdominal CT datasets demonstrate the promising potential of the ASDA-sCT system for practical applications.
Peer Review Status:
Awaiting Review
Subjects: Linguistics and Applied Linguistics >> Linguistics and Applied Linguistics submitted time 2025-06-25
Abstract：
Individuals with autism spectrum disorders (ASD) exhibit social communication deficits as a core characteristic. In recent years, researchers have increasingly focused on their atypical conversational performance, a key aspect of social interaction. This article reviews two dimensions of conversational differences in individuals with ASD: conversational skills and conversation alignment, including the use of filled pause and backchannels, prosodic alignment, resonance, and intersubjective engagement. The article also highlights the need for future research to explore why individuals with ASD display these atypical conversational behaviors. To address this question, the authors propose two potential research directions: (1) developing conversational ability indicators to compare ASD and typically developing (TD) populations, and (2) constructing cognitive computational models of conversational performance to examine differences in cognitive mechanisms between the two groups.
Peer Review Status:Awaiting Review
Subjects: Library Science，Information Science >> Library Science submitted time 2025-06-25
Abstract： In the context of rapid advancements in Large Language Models (LLMs), how to effectively integrate these models with local library resources has become a critical issue in the development of smart libraries. This paper, drawing on the Retrieval-Augmented Generation (RAG) approach, explores how the Coze platform can be employed to build an intelligent question-answering service that leverages local domain knowledge without incurring high costs or complex technical requirements. By introducing the practices in the “Law Library Assistant” project at the Law Library of Xiamen University, the paper discusses the core processes of knowledge base construction, AI agent configuration and testing, multi-platform deployment, and post-launch maintenance—all based on the Coze platform. The results demonstrate that Coze’s intuitive visual interface lowers the barriers to system setup and maintenance, providing a viable solution for libraries to deliver efficient and reliable AI-powered services amidst the new wave of artificial intelligence.
Peer Review Status:Awaiting Review
Subjects: Mechanics >> Biomechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： Objective To explore the effects of plyometric training on lower extremity biomechanics and explosive power of college male basketball players, so as to provide theoretical basis for optimizing special basketball training. Methods A total of 18 male college basketball players were selected and randomly divided into an experimental group (receiving plyometric training) and a control group (receiving traditional resistance training), with 9 players in each group. Before and after training, the two groups of athletes were tested and analyzed for their lower limb explosive force dynamics indicators (including muscle RMS value, contribution rate, joint torque, and stiffness), kinematic indicators (ankle joint, knee joint, hip joint motion angle and angular velocity), and training indicators (jumping performance and mobility performance). Results After plyometric training, there was a significant difference (P<0.01) in the RMS values of the rectus femoris, medial head of the gastrocnemius muscle, and lateral head of the gastrocnemius muscle in the experimental group compared to traditional resistance training in terms of activation of the main muscles in the lower limbs. The RMS value of the long head of the biceps femoris muscle was significantly lower than that of the control group (P<0.05), and the contribution rate decreased by about 3.72%. At the joint stiffness level, the experimental group showed a significant increase in lower limb stiffness (P<0.05), with an increment of 6.4 BW/m; the maximum angle and maximum angular velocity during the ankle joint support period were significantly increased (P<0.05). The experimental group showed outstanding explosive power performance compared to the control group, with significant improvements in standing long jump, standing two foot takeoff and single foot takeoff during run-up (P<0.05). In terms of mobility performance, the T-shaped turn back run and V-shaped dribbling turn back layup scores improved by 1.09 s and 2.68 s, respectively, with significant differences (P<0.05). However, there was no significant difference between the 10 yard sprint running groups (P>0.05). Conclusion This study proves that compared to traditional resistance training, plyometric training can improve the lower limb explosive power of male college basketball players. Therefore, it deserves wide popularization in basketball specific training.
Subjects: Mechanics >> Biomechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： Objective Based on the muscular skeletal-finite element (MS-FE) model, we investigated the stress and strain distribution characteristics of anterior cruciate ligament (ACL) in the left leg at the moment of the volleyball player's dunking and landing. Methods The knee FEM of the volleyball player was established based on MRI and CT, and the marker point and ground reaction force of the volleyball player (male, 23 years old, 88 kg, 1.95 m, dominant side: right side) were synchronously collected by the motion trapping system and the 3D force measuring table. The knee joint moments were calculated by the musculoskeletal model in OpenSim, and the joint moments were used as inputs to the finite element model to output ACL stresses and strains. Results The results of simulation analysis showed that at the moment when the volleyball player completed the dunking action and landed on the ground, the equivalent stress endured by the ACL reached 27.7 MPa, and from the viewpoint of stress distribution directionality, the maximum principal stress of the ACL was 8.2 MPa at this time; in terms of strain response, the equivalent strain of the ACL reached 5.4%, which reflected that it had a larger integrated deformation in all directions; the maximum principal strain was 5.0%, which further confirms that the ligament produced a significant elongation effect along the fibre direction; and the maximum shear strain was 7.6%, indicating that the ACL also experienced a large lateral deformation during the landing stage. Conclusion The validated finite element model developed in this study can be used to better calculate the risk and prevention strategies of ACL injury in volleyball players landing on one leg after dunking the ball. This study can also be widely used in cartilage degradation etiology, optimization of rehabilitation training and simulation of knee surgery, which can provide effective methods for the clinical treatment of athletes and patients with ACL injuries.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2025-06-25
Abstract： [Background]: In the field of nuclear thermal propulsion reactor engineering, real-time prediction of complex multi-physics temperature fields remains a critical challenge. [Purpose]: To address this issue, this study proposes a latent space neural operator (L-DeepONet)-based approach for real-time prediction of temperature fields in nuclear thermal propulsion reactors. [Methods]: A lightweight "encoder-operator learning-decoder" framework is constructed by coupling an autoencoder (AE) with a deep operator network (DeepONet). First, high-dimensional temperature fields are compressed into a 100-dimensional latent space using AE. Subsequently, DeepONet is trained in the low-dimensional space to learn coolant dynamic evolution patterns. Finally, high-fidelity reconstruction of predictions is achieved through the decoder. [Results]: Validation using OpenFOAM-generated coolant temperature field datasets demonstrates that the method achieves average relative errors below 1% for fuel temperature fields in both 40-second iterative predictions and 100-second long-term predictions, with errors for coolant and cladding below 0.5%. The training time of 79.23-192.83 seconds represents a two-order-of-magnitude acceleration compared to traditional CFD simulations, enabling real-time single-step long-term prediction with error distributions concentrated in gradient-sensitive regions. [Conclusions]: This work innovatively introduces latent space operator learning into multi-physics modeling of nuclear thermal propulsion reactors and achieves real-time prediction. The framework provides insights for real-time simulation and decision-making under extreme operating conditions, and can be extended to neutronics-thermomechanical coupling scenarios, offering new pathways for digital twin applications in advanced nuclear systems.
Subjects: Mechanics >> Biomechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： Objective To investigate the effects of high-definition transcranial direct current stimulation (HD-tDCS) on balance function, muscle strength and proprioception in patients with chronic ankle instability (CAI). Methods In this double-blinded sham-controlled study, 26 patients with CAI were enrolled and randomly completed two trials with a 20-minute session of tDCS targeting the sensorimotor cortex or a sham stimulation. The interval between two interventions was at least one week. Dynamic balance (Y balance), static balance, maximum muscle strength of plantar flexion/dorsiflexion of ankle joint and proprioception were completed before and after each intervention. Two-way ANOVA with repeated measures was used to analyze the effects of each variable on the above indicators. Results Twenty-five subjects completed all tests, and the overall accuracy of the stimulus was 43.1%. Two-way ANOVA showed that there was a significant interaction effect on the composite score of Y balance (F=6.279, P=0.016, =0.112). In addition, there were significant interaction effects on the left-right range of the pressure center of static balance (F=4.73, P=0.035, =0.088) and the average left-right velocity (F=4.98, P=0.030, =0.092) as well. There was no significant interaction effect on maximum muscle strength and proprioception. Further analysis showed that the composite score of Y balance increased significantly by 1.5% (P<0.001) after true stimulation; The range and velocity of the pressure center in the left and right directions decreased by 13.7% and 14.8% (P<0.001, P<0.001). The maximum voluntary contraction of the ankle plantar flexion increased by 5% (P=0.022). Conclusion The use of HD-tDCS to regulate the excitability of the sensorimotor cortex can effectively improve the ankle muscle strength, dynamic posture control ability and static balance ability of the population with CAI, which helps to reduce the symptoms of ankle instability and the risk of re-injury in this population.
Subjects: Mechanics >> Hydromechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： Linear elliptical shale shaker and translational elliptical shale shaker are two development forms of drilling fluid shale shaker. It is valuable and significant to study the screening efficiency of the two forms under different working parameters for actual production and selection. Based on the discrete element method, this paper uses EDEM calculation and analysis software to simulate the screening efficiency of drilling fluid shale shaker under linear array and elliptical array, study the movement parameters and movement times of various particles under two forms, and calculate the parameters of screen penetration and screen mouth desieving. It is found that under the same vibration parameters, the linear vibration mode is better than the elliptical vibration mode in dealing with impervious particles, while the translational elliptical vibration mode is better than the linear vibration mode in avoiding particle cluster formation. The greater the particle adhesion is, the more times the particles make parabolic movements on the screen, and the formation of particle clusters reduces the particle migration speed, leading to the reduction of the screen treatment efficiency of impervious particles in the unit time. In practice, the formation of particle clusters should be avoided as much as possible. In the vibration frequency range of 25~30 Hz, the influence of adhesion on particle velocity increases rapidly, thus reducing the exit screening rate.
Subjects: Mechanics >> Hydromechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： In order to investigate the applicability of mesh, which is the key basis for CFD (computational fluid dynamics) simulation, for gas dispersion prediction under chemical industrial parks (CIPs), full-scale numerical simulation was developed based on a tracer gas (SF6) field leakage experiment. Four types of mesh of tetrahedral, polyhedral, hybrid tetrahedral/hexahedral (hexcore), hybrid polyhedral/hexahedral (poly-hexcore) was selected, and then compared from grid generation characteristics (cell count, minimum orthogonal quality, maximum aspect ratio), simulation performance (calculation precision, accuracy and time). The results showed that from the mesh generation characteristics, the number of polyhedral grids (0.6~1.5 million) was minimized, followed by poly-hexcore mesh (0.8~3.3 million); poly-hexcore mesh (0.44) and polyhedral grid had the better mesh orthogonal quality (0.41) than tetrahedron (0.04) and hexcore (0.02), and the aspect ratio of the poly-hexcore mesh was the lowest. From the simulation perspective, the poly-hexcore type of mesh was the highest with all equations reaching 10-4. In terms of accuracy, poly-hexcore mesh had minimum simulation error and maximum correlation (0.98) with observed concentration. Meanwhile, the simulation efficiency of poly-hexcore mesh (27 min) was significantly higher than that of polyhedral mesh (47 min) and hexcore mesh (112 min). In addition, in terms of flow characteristics, the plume width of polyhedral mesh was larger than that of hybrid girds, and the average plume concentration of hexcore mesh was the highest.
Subjects: Mechanics >> Hydromechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： The cuboid frame artificial reefs can be used to change the flow field and provide a favorable habitat for a variety of marine life. In tropical waters such as offshore Hainan Island, artificial reefs can also provide an attachment base for coral restoration. In this paper, ADV was used to measure the flow velocity of the representative measuring points of the cuboid frame artificial reef model, and PIV was further used to measure the typical flow field characteristics around the reef model. Based on RANS equations and RNG k－ε turbulence model, the hydrodynamic field of a single cuboid frame artificial reef was numerically calculated under different incoming flow velocities and angles of incident flow, which was verified by experimental results. On this basis, the flow field effects of multiple reefs under different layout modes were calculated and analyzed. The results show that within a certain range, the volume of upwelling and back eddy of a single reef increases as the velocity of incoming stream increases, and the flow field effect is best when the angle of incident flow is 45°. The best field effect of two reefs is obtained at the spacing of 2.5 times of the length of the longitudinal reef and 1.5 times of the length of the transverse reef. When multiple reefs are arranged along a straight line, the staggered arrangement of each row of reefs has a larger volume of upwelling and back eddy, and the flow field effect is better.
Subjects: Mechanics >> Other Disciplines of Mechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： The calculation of cable force of grouted cable needs to consider the added mass of grouting and its influence on cable vibration, but there is still no effective calculation method at present. On the basis of cable force test of grouted prestressed cable, the theoretical calculation method of cable force was studied. First, the grouted prestressed cable was simplified as the axial tensional beam with uniformly distributed mass and two hinged ends, and the vibration differential equation of cable was established according to elastic distributed mass and two different vibration directions of cable. Then the computation expression for the mortar's vibration frequency was fitted by the parameters of cable length, grouting rate, linear density of the added mass, slenderness ratio, and the sectional flexural stiffness of mortar after regression analysis of the test data. The linear relationship between the calculated frequency and the measured one was also obtained. Finally, force calculation process of the cable force for the grouted cable was presented. Results show that the largest error between calculation and test cables is 5.4%, indicating that the method can be used in cable force calculation of grouted prestressed cable.
Subjects: Mechanics >> Other Disciplines of Mechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： In order to ensure the safe and stable operation of engineering structures under long-period wind speed, the influence of the extreme value of non-stationary non-Gaussian wind speed on engineering structures should not be ignored. In this paper, the field measured wind speed is taken as the research object. According to whether the time-varying mean or the time-varying root mean square is excluded from the wind speed sample, we set four wind speed working conditions. And the extreme value of non-stationary non-Gaussian wind speed of the four wind speed working conditions is obtained by combining the stationary transformation method and Sadek-Simiu method. The research results indicate that the wind speed extreme value obtained by excluding the time-varying mean value kept basically unchanged with the original wind speed, while the wind speed extreme value obtained by removing the time-varying root mean square generally increased by more than 30%。In conclusion, the time-varying root mean square of the field measured wind speed can improve the calculation results of the non-stationary non-Gaussian wind speed extreme value. This method provides a new strategy for the further development of engineering applications.
Subjects: Mechanics >> Other Disciplines of Mechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： In order to improve the accuracy of damage identification, this paper introduces the concept of reciprocal variable and proposes a truss damage identification method combining reciprocal variable and generalized flexibility matrix. This method only needs low order modal parameters. In this paper, a control equation based on incomplete modes is introduced, and an iterative strategy based on non-negative least square method is used to solve the damage identification problem. In each cycle, the non-negative least square method is used to determine the damage location and degree of the structure. By excluding the non-damaged elements, a new coefficient matrix is reconstructed, and the new coefficient matrix and the original right-hand term are used to solve the next cycle until the convergence accuracy requirements are met. Numerical simulation results show that compared with the original recognition method based on generalized flexibility matrix, the recognition effect of the method combining reciprocal variable with generalized flexibility matrix is better. In the case of noise and incomplete measured mode shapes, the method combining the incomplete mode shape control equation with the iterative strategy can maintain certain identification accuracy.
Subjects: Mechanics >> Other Disciplines of Mechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： Based on the absolute nodal coordinate formulation (ANCF), the free vibration characteristics of functionally graded thin elliptic cylindrical shells are investigated. Using the third-order Bézier curve fitting technique, the circumferential tangent vector and circumferential length of ANCF-rectangular-shell element are calculated, which avoids the elliptic integral calculation and increases the fitting accuracy. Based on the kinetic energy expression and the functional relationship between Green's strain tensor and absolute displacement, the generalized mass matrix, generalized elastic force column matrix and generalized stiffness matrix of functionally graded thin elliptic cylindrical shell are derived. The nonlinear dynamical differential equations are established based on D'Alembert principle. At the equilibrium position of the system, the linear differential equations of motion for the functionally graded thin elliptic cylindrical shell are established by introducing the small variation quantity of the generalized coordinates. Through numerical calculation, this paper analyzes the effects of different gradient indexes, eccentricity of elliptical section and length-radius ratio on the natural frequencies of functionally graded thin elliptic cylindrical shells with simply supported ends. The results show that the elastic modulus ratio, density ratio and gradient index of materials have obvious influences on the natural frequency; the natural frequencies of shell made of stainless steel-alumina (circumferential wave number is 1~3) decrease with the increase of length-radius ratio; the natural frequency corresponding to the circumferential wave number of 1 increases with the increase of eccentricity, and length-radius ratio is the main factor affecting the change of natural frequency.
Subjects: Mechanics >> Other Disciplines of Mechanics submitted time 2025-06-25 Cooperative journals: 《应用力学学报》
Abstract： The influence of vehicle bridge coupling response under vehicle jumping impact with different parameters was studied. The variable cross-section beam was divided into finite micro segments and the vibration equation of the bridge was obtained through force analysis. The 1/4 vehicle model was selected and the vibration equation of the vehicle was established by using the D'Alembert principle. Then the vehicle bridge coupled vibration equation was obtained and solved with the Newmark-β method. The results show that the stiffness of suspension and tire system has no significant effect on the displacement response of the bridge under vehicle jumping impact without considering the geometric nonlinearity. It is not that the faster the vehicle speed is, the more obvious the vehicle bridge coupling displacement response is. The vehicle weight has a significant effect on the vehicle bridge coupling response. The displacement response is more intense as the vehicle becomes heavier.
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