Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2024-08-16
Abstract： Lifestyle Medicine，which emerged in the 1980s，is an interdisciplinary discipline involving various fields such as medicine，nutrition，exercise science，epidemiology，psychology，etc. It serves as a crucial bridge between public health promotion and clinical treatment，and plays a significant role in preventing，treating，and rehabilitating various diseases. This paper presents a comprehensive review of the definition，connotation，origin，development，and evaluation tools for assessing the effectiveness of Lifestyle Medicine. The findings reveal that Lifestyle Medicine aligns remarkably well with the principle of traditional Chinese medicine（TCM） regarding disease prevention and treatment. Despite notable research advancements in chronic disease management in China，the field of lifestyle medicine is still at an early stage of development. However，there remains a lack of specific，quantified，and standardized guidelines for implementing lifestyle interventions as well as clinical protocols and evaluation systems. The localization of Lifestyle Medicine in China still needs to consider local conditions，while increasing national policy support to establish a national data monitoring system and decision support system. Emphasizing health equity and optimising resource allocation across different regions are also essential aspects to be considered. Furthermore，integrating the advantages of TCM，including of its characteristic therapies，simplicity and cost-effectiveness， will promote the application and dissemination of Lifestyle Medicine for preventing and managing chronic diseases，thereby enhancing overall population health.
Peer Review Status:
Awaiting Review
Subjects: Nursing >> Nursing submitted time 2024-08-15
Abstract：目的 探究超细化综合护理干预在肝内胆管癌术后化疗患者负性情绪中的应用效果。方法 选取我院2023年1月到2024年1月收治的182例肝内胆管癌术后化疗患者作为本次研究对象，采用随机数字表法将其分为对照组（n=91）和试验组（n=91），对照组进行常规护理，试验组在常规护理基础上加上超细化综合护理干预内容，从而比较两组患者干预前后负性情绪、疲乏程度、生活质量以及护理满意度。结果 两组患者经干预后焦虑（SAS）、抑郁（SDS）评分均有显著下降，且试验组SAS、SDS评分均低于对照组（PPPP<0.05）。结论 超细化综合护理干预实施能够帮助肝内胆管癌术后化疗患者改善负性情绪，提高战胜疾病信心，从而减轻癌因性疲乏，提高生存质量与生活质量，通过亲情式细化服务提高患者的满意度。
Peer Review Status:Awaiting Review
Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2024-08-15
Abstract： The prevalence of cardiovascular disease（CVD）in China is on the rise. It is estimated that there are 330 million people with CVD，including 13 million cases of stroke，11.39 million cases of coronary heart disease（CHD），8.9 million cases of heart failure（HF），5 million cases of pulmonary heart disease，4.87 million atrial fibrillation，2.5 million cases of rheumatic heart disease，2 million cases of congenital heart disease，45.3 million cases of peripheral arterial disease（PAD）， and 245 million cases of hypertension. In 2021，the total number of discharges of patients with cardiovascular and cerebrovascular diseases in China was 27 649 800，accounting for 15.36% of the total number of discharges（including all inpatient diseases） in the same period，including 14 872 300 CVDs，accounting for 8.26%，and 12 777 500 cerebrovascular diseases，accounting for 7.10%. The economic burden of CVD on residents and society still increases，and the inflection point of CVD prevention and treatment has not yet arrived.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-08-15
Abstract： [Background]: Molten salt reactor is one of the six internationally recognized and recommended fourth generation reactors , which is different from conventional solid-state nuclear fuel reactors. It is necessary to analyze the relationship between 7Li abundance and nuclear critical parameters in order to do a good job in core design management and nuclear safety supervision. [Purpose]: This study modeled a molten salt reactor with reference to engineering practice, and used software simulation calculations to analyze the impact of different 7Li abundance fuel salts on the reactivity of the molten salt reactor, and to analyze the changes in nuclear critical parameters. [Methods]: By iterative calculation, quickly and accurately find the 7Li abundance value at the critical state of the molten salt reactor core. [Results]: The final conclusion is that the reactivity of the molten salt reactor increases with the increase of fuel salt 7Li abundance, and the rate of change in reactivity of the molten salt reactor is also related to 7Li abundance. [Conclusions]: Based on the analysis results of this study, conduct in-depth exploration, summarize relevant management requirements from the perspective of laws and regulations, and propose key points for attention from the perspective of review and management.
Peer Review Status:Awaiting Review
Subjects: Library Science，Information Science >> Library Science submitted time 2024-08-15
Abstract： With the advent of the Internet+ era, academic exchanges have seen new trends. Informal exchanges have been flourishing, communication based on virtual communities is more popular, and academic information has been continuously improved in the process of communication. Library is an important position to construct academic exchange platform and provide academic exchange service. This paper proposes that through collecting user data and introducing user portrait technology, more personalized academic resources and exchange services can be provided, and an academic exchange service framework including data level, portrait level, personalized service level and feedback level can be formed, so as to optimize the service pertinently.
Peer Review Status:Awaiting Review
Subjects: Medicine, Pharmacy >> Pharmacology submitted time 2024-08-15
Abstract： [Objective] Exploring the problems on the patent information registration platform for listed drugs in China and proposing strategies that generic drug companies need to adopt.
[Methods] Through data-mining，this paper conducts a comprehensive analysis and case comparison about Drug Patent Declaration II on China’s Drug Patent Registration
[Results] Recommend 10 chemical generic drug varieties for selection.
[Limitations] Comparative Study of Drug Patent Link Data in China and Overseas Countries.
[Conclusions] The lack of an error correction mechanism for ex officio review on the Chinese drug patent information registration platform is a major flaw in China’s drug patent linkage system.
Peer Review Status:Awaiting Review
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2024-08-14 Cooperative journals: 《干旱区科学》
Abstract： Wind erosion is a geomorphic process in arid and semi-arid areas and has substantial implications for regional climate and desertification. In the Columbia Plateau of northwestern United States, the emissions from fine particles of loessial soils often contribute to the exceedance of inhalable particulate matter (PM) with an aerodynamic diameter of 10 μm or less (PM10) according to the air quality standards. However, little is known about the threshold friction velocity (TFV) for particles of different sizes that comprise these soils. In this study, soil samples of two representative soil types (Warden sandy loam and Ritzville silt loam) collected from the Columbia Plateau were sieved to seven particle size fractions, and an experiment was then conducted to determine the relationship between TFV and particle size fraction. The results revealed that soil particle size significantly affected the initiation of soil movement and TFV; TFV ranged 0.304–0.844 and 0.249–0.739 m/s for different particle size fractions of Ritzville silt loam and Warden sandy loam, respectively. PM10 and total suspended particulates (TSP) emissions from a bed of 63–90 μm soil particles were markedly higher for Warden sandy loam than for Ritzville silt loam. Together with the lower TFV of Warden sandy loam, dust emissions from fine particles (<100 μm in diameter) of Warden sandy loam thus may be a main contributor to dust in the region's atmosphere, since the PM10 emissions from the soil erosion surfaces and its ensuing suspension within the atmosphere constitute an essential process of soil erosion in the Columbia Plateau. Developing and implementing strategic land management practices on sandy loam soils is therefore necessary to control dust emissions in the Columbia Plateau.
Subjects: Biology >> Ecology submitted time 2024-08-14 Cooperative journals: 《干旱区科学》
Abstract： Soil erosion caused by unsustainable grazing is a major driver of grassland ecosystem degradation in many semi-arid hilly areas in China. Thus, grazing exclusion is considered as an effective method for solving this issue in such areas. However, some ecological and economic problems, such as slow grassland rejuvenation and limited economic conditions, have become obstacles for the sustainable utilization of grassland ecosystem. Accordingly, we hypothesized that the conflict between grassland use and soil conservation may be balanced by a reasonable grazing intensity. In this study, a two-year grazing fence experiment with five grazing intensity gradients was conducted in a typical grassland of the Loess Plateau in China to evaluate the responses of vegetation characteristics and soil and water losses to grazing intensity. The five grazing intensity gradients were 2.2, 3.0, 4.2, 6.7, and 16.7 goats/hm2, which were represented by G1–G5, respectively, and no grazing was used as control. The results showed that a reasonable grazing intensity was conducive to the sustainable utilization of grassland resources. Vegetation biomass under G1–G4 grazing intensity significantly increased by 51.9%, 42.1%, 36.9%, and 36.7%, respectively, compared with control. In addition, vegetation coverage increased by 19.6% under G1 grazing intensity. Species diversity showed a single peak trend with increasing grazing intensity. The Shannon-Wiener diversity index under G1–G4 grazing intensities significantly increased by 22.8%, 22.5%, 13.3%, and 8.3%, respectively, compared with control. Furthermore, grazing increased the risk of soil erosion. Compared with control, runoff yields under G1–G5 grazing intensities increased by 1.4, 2.6, 2.8, 4.3, and 3.9 times, respectively, and sediment yields under G1–G5 grazing intensities were 3.0, 13.0, 20.8, 34.3, and 37.7 times greater, respectively, than those under control. This result was mainly attributed to a visible decrease in litter biomass after grazing, which decreased by 50.5%, 72.6%, 79.0%, 80.0%, and 76.9%, respectively, under G1–G5 grazing intensities. By weighing the grassland productivity and soil conservation function, we found that both two aims were achieved at a low grazing intensity of less than 3.5 goats/hm2. Therefore, it is recommended that grassland should be moderately utilized with grazing intensity below 3.5 goats/hm2 in semi-arid hilly areas to achieve the dual goals of ecological and economic benefits. The results provide a scientific basis for grassland utilization and health management in semi-arid hilly areas from the perspective of determining reasonable grazing intensity to maintain both grassland production and soil conservation functions.
Subjects: Biology >> Ecology submitted time 2024-08-14 Cooperative journals: 《干旱区科学》
Abstract： Atmospheric deposition of nitrogen (N) plays a significant role in shaping the structure and functioning of various terrestrial ecosystems worldwide. However, the magnitude of N deposition on grassland ecosystems in Central Asia still remains highly uncertain. In this study, a multi-data approach was adopted to analyze the distribution and amplitude of N deposition effects in Central Asia from 1979 to 2014 using a process-based denitrification decomposition (DNDC) model. Results showed that total vegetation carbon (C) in Central Asia was 0.35 (±0.09) Pg C/a and the averaged water stress index (WSI) was 0.20 (±0.02) for the whole area. Increasing N deposition led to an increase in the vegetation C of 65.56 (±83.03) Tg C and slightly decreased water stress in Central Asia. Findings of this study will expand both our understanding and predictive capacity of C characteristics under future increases in N deposition, and also serve as a valuable reference for decision-making regarding water resources management and climate change mitigation in arid and semi-arid areas globally.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2024-08-14 Cooperative journals: 《干旱区科学》
Abstract： The characteristics of drought in Xinjiang Uygur Autonomous Region (Xinjiang), China have changed due to changes in the spatiotemporal patterns of temperature and precipitation, however, the effects of temperature and precipitation—the two most important factors influencing drought—have not yet been thoroughly explored in this region. In this study, we first calculated the standard precipitation evapotranspiration index (SPEI) in Xinjiang from 1980 to 2020 based on the monthly precipitation and monthly average temperature. Then the spatiotemporal characteristics of temperature, precipitation, and drought in Xinjiang from 1980 to 2020 were analyzed using the Theil–Sen median trend analysis method and Mann–Kendall test. A series of SPEI-based scenario-setting experiments by combining the observed and detrended climatic factors were utilized to quantify the effects of individual climatic factor (i.e., temperature and precipitation). The results revealed that both temperature and precipitation had experienced increasing trends at most meteorological stations in Xinjiang from 1980 to 2020, especially the spring temperature and winter precipitation. Due to the influence of temperature, trends of intensifying drought have been observed at spring, summer, autumn, and annual scales. In addition, the drought trends in southern Xinjiang were more notable than those in northern Xinjiang. From 1980 to 2020, temperature trends exacerbated drought trends, but precipitation trends alleviated drought trends in Xinjiang. Most meteorological stations in Xinjiang exhibited temperature-dominated drought trend except in winter; in winter, most stations exhibited precipitation-dominated wetting trend. The findings of this study highlight the importance of the impact of temperature on drought in Xinjiang and deepen the understanding of the factors influencing drought.
Subjects: Biology >> Ecology submitted time 2024-08-14 Cooperative journals: 《干旱区科学》
Abstract： The Three-River Source Region (TRSR) in China holds a vital position and exhibits an irreplaceable strategic importance in ecological preservation at the national level. On the basis of an in-depth study of the vegetation evolution in the TRSR from 2000 to 2022, we conducted a detailed analysis of the feedback mechanism of vegetation growth to climate change and human activity for different vegetation types. During the growing season, the spatiotemporal variations of normalized difference vegetation index (NDVI) for different vegetation types in the TRSR were analyzed using the Moderate Resolution Imaging Spectroradiometer (MODIS)-NDVI data and meteorological data from 2000 to 2022. In addition, the response characteristics of vegetation to temperature, precipitation, and human activity were assessed using trend analysis, partial correlation analysis, and residual analysis. Results indicated that, after in-depth research, from 2000 to 2022, the TRSR's average NDVI during the growing season was 0.3482. The preliminary ranking of the average NDVI for different vegetation types was as follows: shrubland (0.5762)>forest (0.5443)>meadow (0.4219)>highland vegetation (0.2223)>steppe (0.2159). The NDVI during the growing season exhibited a fluctuating growth trend, with an average growth rate of 0.0018/10a (P<0.01). Notably, forests displayed a significant development trend throughout the growing season, possessing the fastest rate of change in NDVI (0.0028/10a). Moreover, the upward trends in NDVI for forests and steppes exhibited extensive spatial distributions, with significant increases accounting for 95.23% and 93.80%, respectively. The sensitivity to precipitation was significantly enhanced in other vegetation types other than highland vegetation. By contrast, steppes, meadows, and highland vegetation demonstrated relatively high vulnerability to temperature fluctuations. A further detailed analysis revealed that climate change had a significant positive impact on the TRSR from 2000 to 2022, particularly in its northwestern areas, accounting for 85.05% of the total area. Meanwhile, human activity played a notable positive role in the southwestern and southeastern areas of the TRSR, covering 62.65% of the total area. Therefore, climate change had a significantly higher impact on NDVI during the growing season in the TRSR than human activity.
Subjects: Biology >> Ecology submitted time 2024-08-14 Cooperative journals: 《干旱区科学》
Abstract： The Mongolian Plateau in East Asia is one of the largest contingent arid and semi-arid areas of the world. Under the impacts of climate change and human activities, desertification is becoming increasingly severe on the Mongolian Plateau. Understanding the vegetation dynamics in this region can better characterize its ecological changes. In this study, based on Moderate Resolution Imaging Spectroradiometer (MODIS) images, we calculated the kernel normalized difference vegetation index (kNDVI) on the Mongolian Plateau from 2000 to 2023, and analyzed the changes in kNDVI using the Theil-Sen median trend analysis and Mann-Kendall significance test. We further investigated the impact of climate change on kNDVI change using partial correlation analysis and composite correlation analysis, and quantified the effects of climate change and human activities on kNDVI change by residual analysis. The results showed that kNDVI on the Mongolian Plateau was increasing overall, and the vegetation recovery area in the southern region was significantly larger than that in the northern region. About 50.99% of the plateau showed dominant climate-driven effects of temperature, precipitation, and wind speed on kNDVI change. Residual analysis showed that climate change and human activities together contributed to 94.79% of the areas with vegetation improvement. Appropriate human activities promoted the recovery of local vegetation, and climate change inhibited vegetation growth in the northern part of the Mongolian Plateau. This study provides scientific data for understanding the regional ecological environment status and future changes and developing effective ecological protection measures on the Mongolian Plateau.
Subjects: Biology >> Ecology submitted time 2024-08-14 Cooperative journals: 《干旱区科学》
Abstract： Understanding the response of vegetation variation to climate change and human activities is critical for addressing future conflicts between humans and the environment, and maintaining ecosystem stability. Here, we aimed to identify the determining factors of vegetation variation and explore the sensitivity of vegetation to temperature (SVT) and the sensitivity of vegetation to precipitation (SVP) in the Shiyang River Basin (SYRB) of China during 2001–2022. The climate data from climatic research unit (CRU), vegetation index data from Moderate Resolution Imaging Spectroradiometer (MODIS), and land use data from Landsat images were used to analyze the spatial-temporal changes in vegetation indices, climate, and land use in the SYRB and its sub-basins (i.e., upstream, midstream, and downstream basins) during 2001–2022. Linear regression analysis and correlation analysis were used to explore the SVT and SVP, revealing the driving factors of vegetation variation. Significant increasing trends (P<0.05) were detected for the enhanced vegetation index (EVI) and normalized difference vegetation index (NDVI) in the SYRB during 2001–2022, with most regions (84%) experiencing significant variation in vegetation, and land use change was determined as the dominant factor of vegetation variation. Non-significant decreasing trends were detected in the SVT and SVP of the SYRB during 2001–2022. There were spatial differences in vegetation variation, SVT, and SVP. Although NDVI and EVI exhibited increasing trends in the upstream, midstream, and downstream basins, the change slope in the downstream basin was lower than those in the upstream and midstream basins, the SVT in the upstream basin was higher than those in the midstream and downstream basins, and the SVP in the downstream basin was lower than those in the upstream and midstream basins. Temperature and precipitation changes controlled vegetation variation in the upstream and midstream basins while human activities (land use change) dominated vegetation variation in the downstream basin. We concluded that there is a spatial heterogeneity in the response of vegetation variation to climate change and human activities across different sub-basins of the SYRB. These findings can enhance our understanding of the relationship among vegetation variation, climate change, and human activities, and provide a reference for addressing future conflicts between humans and the environment in the arid inland river basins.
Subjects: Geosciences >> Hydrology submitted time 2024-08-14 Cooperative journals: 《干旱区科学》
Abstract： Since the 1950s, numerous soil and water conservation measures have been implemented to control severe soil erosion in the Liuhe River Basin (LRB), China. While these measures have protected the upstream soil and water ecological environment, they have led to a sharp reduction in the downstream flow and the deterioration of the river ecological environment. Therefore, it is important to evaluate the impact of soil and water conservation measures on hydrological processes to assess long-term runoff changes. Using the Soil and Water Assessment Tool (SWAT) models and sensitivity analyses based on the Budyko hypothesis, this study quantitatively evaluated the effects of climate change, direct water withdrawal, and soil and water conservation measures on runoff in the LRB during different periods, including different responses to runoff discharge, hydrological regime, and flood processes. The runoff series were divided into a baseline period (1956–1969) and two altered periods, i.e., period 1 (1970–1999) and period 2 (2000–2020). Human activities were the main cause of the decrease in runoff during the altered periods, contributing 86.03% (–29.61 mm), while the contribution of climate change was only 13.70% (–4.70 mm). The impact of climate change manifests as a decrease in flood volume caused by a reduction in precipitation during the flood season. Analysis of two flood cases indicated a 66.00%–84.00% reduction in basin runoff capacity due to soil and water conservation measures in the upstream area. Soil and water conservation measures reduced the peak flow and total flood volume in the upstream runoff area by 77.98% and 55.16%, respectively, even with nearly double the precipitation. The runoff coefficient in the reservoir area without soil and water conservation measures was 4.0 times that in the conservation area. These results contribute to the re-evaluation of soil and water conservation hydrological effects and provide important guidance for water resource planning and water conservation policy formulation in the LRB.
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2024-08-13
Abstract： The traditional uniformity coefficient Cu cannot reflect the uniformity of gap-graded granular mixtures. This paper proposes a new index Cmu to quantify the uniformity of granular mixtures based on the study on their small-strain stiffness G0. The samples of granular mixtures with different fines content (FC) and particle size ratio (PSR) are prepared. The G0 values are determined by quasistatic drained triaxial tests on these samples. The Cmu values are calculated from the obtained G0 values and can be expressed as a function of FC and PSR. The rationality of the proposed Cmu is verified. The Cmu can be used to predict the G0 of granular mixtures when the mechanical coordination number (CNm), shear modulus of particles (Gp), confining stress (σ0) and Cmu are given.
Peer Review Status:Awaiting Review
Subjects: Mechanics >> Biomechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract：
Objective This study aimed to analyze and compare the athlete's center of mass(COM)velocity,COM height,ground reaction force(GRF),and lower limb joint moment of different levels of athletes during pole vault run-up and takeoff,so as to explore the technical characteristics of the transition between run-up and takeoff,which provides reference and help for the training and competition of pole vault.Methods A large-scale three-dimensional(3D)motion capture system(200 Hz)and three force platforms(2 000 Hz)were used to collect the kinematics and ground reaction force data of male elite pole vaulters,and five first-class athletes,four master athletes and three international master athletes were analyzed.Mann-Whitney U test was utilized for biomechanical parameters between every two groups within international master athletes,master athletes,and first-class athletes.Wilcoxon signed ranks test was used between every two corresponding biomechanical parameters of the second-to-last step,the last step,and takeoff.Results The athletes' COM velocity,COM height,GRF,and lower limb joint moment showed significant differences between the different level groups of pole vaulters,and the biomechanical parameters of the second-to-last step,the last step,and the takeoff also displayed significant differences.Conclusion Based on the data of this study,the male pole vaulters showed biomechanical characteristics that varied with their levels.The COM velocity and GRF of the international master athletes indicate their higher sports competence.The differences between the biomechanical parameters of the second-to-last step,the last step,and takeoff,including COM velocity,COM height and GRF,might display the technical characteristics of pole vault movement transition,which indicate the kinematic and kinetic transition characteristics of pole vault from run-up to takeoff.
Subjects: Mechanics >> Biomechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract：
It is necessary to accurately identify the mechanical properties of skin tissue for diagnosis,evaluation and treatment of skin tissue diseases by means of mechanical modeling.Therefore,this paper proposes a skin tissue constitutive parameter identification method using adaptive simulated annealing optimization algorithm combined with approximation model technology.First,the finite element method was used to simulate the skin uniaxial tensile test,and the numerical mechanical response data of skin tissue were obtained under different parameter combinations.In order to improve the computational efficiency of parameter identification,response surface model,Kriging model,and ellipsoidal neural network were constructed to replace the repeated simulation calculation process,and the fitting accuracy of the three approximation models was verified by the determination coefficient R2.Finally,an adaptive simulated annealing optimization algorithm was used to identify the constitutive parameters that best matched the uniaxial tensile test results of skin tissue of common pig belly through inversion with the objective of minimizing the root mean square error of the test curve and the numerical calculation curve: C10=0.140 1 MPa,k1=24.51 MPa,k2=0.496 1,κ=0.317 1,and φ=13.86°.The results show that the ellipsoidal neural network model is more suitable for fitting the nonlinear relationship between skin constitutive model parameters and stress-strain response.The comparison between the identified numerical and experimental curves shows that the adaptive simulated annealing algorithm combined with the approximation model is a fast and reliable method to identify the anisotropic hyperelastic constitutive parameters of skin tissue.
Subjects: Mechanics >> Hydromechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract： During the thermal exploitation of enhanced geothermal system(EGS),reservoir permeability varies dynamically under the influence of stress.In order to reveal the coupling mechanism between the permeability of fractured rock matrix and stress field and its influence on the performance of heat mining,a thermo-hydro-mechanical(THM)coupling model of dual mediums including matrix and fracture was established based on the THM coupling theory,and the THM field of the reservoir is analyzed when the matrix and fracture permeability change with the stress.The results show that under the combined action of thermal stress and water pressure,the matrix permeability decreases gradually,and the fracture permeability increases exponentially.Hence,the rate of recovery heat is mainly determined by the dynamic changes of the fracture permeability.However,the predicted fracture permeability is 41.8% higher than the actual permeability if the dynamic changes of the matrix permeability is ignored during the simulation.As a result,the predicted heat breakthrough time is advanced,which would underestimate the system running life of nearly two years.Therefore,it is significant to evaluate the service life of EGS system to consider the coupling effect of fracture and matrix permeability and stress simultaneously.
Subjects: Mechanics >> Hydromechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract：
Based on the SST k-ω turbulence model,the surface wind pressure of nine high-rise buildings,such as balconies,different concave and convex shapes and different grid types,is analyzed in detail.The wind pressure distribution characteristics of the building surface under different facade forms are clarified,and the mechanism of the facade form's influence on the surface wind pressure of the high-rise buildings is revealed in combination with the flow field information around the high-rise buildings.The results show that the maximum value of windward wind pressure coefficient increases and the maximum value of negative value of leeward wind pressure coefficient decreases with the addition of balcony on the facade.And balcony density has some influence to these.At the same time,the balcony will cause the flow to separate at the top of the balcony on the top floor of the building and form a local negative pressure on the top of the windward surface of the high-rise building.Compared with the smooth facade,the concave and convex facades will lead to an increase in the wind pressure difference between the windward surface and the leeward surface of the high-rise building.The phenomenon of pressure mutation will occur in the area near the top of the building,and a large negative value will appear at the corner of the wall.The addition of vertical grilles will also increase the pressure difference between the windward and leeward surfaces of high-rise buildings,while the lateral and rectangular grilles have a relatively small impact on structural wind loads.
Subjects: Mechanics >> Hydromechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract：
In order to explore the breakage mechanism and crack expansion pattern of concrete under jet impact,a numerical model of abrasive water jet impacting concrete was constructed based on smooth particle hydrodynamics(SPH)method.The relationship of stress propagation and breakage mode inside concrete,abrasive volume fraction and porosity of concrete with crack length,failure particle number,pit depth and pit diameter was investigated.It is indicated that cracks have strong hindering effect on stresses,and the superposition of reflections with boundary stress waves cause stress concentration in some regional,forming the central microcracks and internal broken blocks.The crack length increased by nearly 2.30 times,the number of failed particles by 3.38 times,and the pit depth value by 4.00 times,with abrasive volume fraction of 20% compared to 0%,indicating that the addition of abrasives to the jet substantially increased the breakage effect.The greater porosity of concrete is,the more diffuse cracks distribute,the larger of damage area,the greater of damage degree,and the greater fractal dimension are,indicating that porosity reduces the concrete compressive strength and that materials with large porosity are more prone to breakage.
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