Optimization of Green Space Plant Configuration in Residential Areas of Chongqing Central Business District Based on Green Plot Ratio—A Case Study of Xuhui City Residential Community

The current urban green space construction was guided by a two-dimensional index evaluation system, resulting in weak ecological benefits of green space. Green plot ratio (GPR), as a three-dimensional indicator, can characterize the ecological benefits of green areas and the ability of green areas to participate in the operation and regulation of urban ecosystems. As an important component of urban green space, the GPR index was added to the two-dimensional index evaluation system to optimize the green space, which can promote the development of low-carbon, healthy and ecological green space. Based on the research of 22 residential districts in the central city of Chongqing, the Leaf area index (LAI) index of common native garden plants in Chongqing was formed to improve the accuracy of green capacity index measurement in Chongqing. The study also took the residential community of Sunrise City in Banan District of Chongqing as an example, and carried out the optimization design practice from four types of residential community green areas: green areas next to houses, road green areas, concentrated green areas, and green areas attached to public service facilities.

Impact pressure of waves generated by landslides on bank slopes

Impulse waves that are generated by landslides in narrow reservoir areas threaten the stability of buildings and bank slopes.To discuss the action process and evolution law of the wave pressure on bank slopes,a three-dimensional physical model test that considers impulse waves generated by landslides was performed,and factors including landslide width,thickness,slope angles of the sliding surface,and bank slope angle were considered.Based on wave forms on the bank slopes,wave pressure curve characteristics,and peak value,the action process of wave pressure could be divided into the following stages:maximum pulsating pressure stage,wave impact stage(when waves break),and stationary pulsation stage.It was found that wave breaking is dependent on the value of the surf similarity parameterξ.The distribution pattern of impact pressure decays linearly on both sides of the maximum impact pressure point,and the attenuation degree decreases when it attains 40%of the maximum value.Thus,it is proposed that the prediction formula for the maximum effective impact pressure of the bank slope be related to the reciprocal of wave steepness,relative water depth,and slope rate.The prediction formula provides strong theoretical support for early safety warning and for predicting the bank slope under impulse waves generated by landslides.

Microplastics in sediment of the Three Gorges Reservoir:abundance and characteristics under different environmental conditions

Freshwater microplastic pollution is an urgent issue of global concern,and research on the distribution in reservoirs is lacking.We investigated the microplastic pollution levels in wet sediments collected from the Three Gorges Reservoir,the largest reservoir of China.Results show that microplastics were ubiquitous in the sediments of the Three Gorges Reservoir,and their abundance ranged from 59 to 276 pp/kg(plastic particles per kg,dry weight).Economic development and total population were important factors affecting the spatial heterogeneity of microplastic abundance,and the contribution of large cities along the reservoir to microplastic pollution should be paid with more attention.Fibrous microplastics were the most abundant type of microplastic particles in reservoir sediments,whereas polystyrene,polypropylene,and polyamide were the main types of polymers.The apparent spatial heterogeneity in morphology and color of microplastics is attributed to different anthropogenic or landbased pollution sources.Moreover,the accumulation of microplastics near the inlet of tributaries reflects the role of potential contributors of tributaries.More importantly,multiple bisphenols(BPs)and heavy metals detected at the microplastic surfaces indicate that microplastics can act as carriers of these pollutants in the environment in the same way as sediments did,which may alter the environmental fate and toxicity of these pollutants.Therefore,we conclude that the Three Gorges Reservoir had been contaminated with microplastics,which posed a stress risk for organisms who ingest them along with their associated pollutants(BPs,heavy metals).

Finite Element Simulations on Failure Behaviors of Granular Materials with Microstructures Using a Micromechanics-Based Cosserat Elastoplastic Model

This paper presents a micromechanics-based Cosserat continuum model for microstructured granular materials.By utilizing this model,the macroscopic constitutive parameters of granular materials with different microstructures are expressed as sums of microstructural information.The microstructures under consideration can be classified into three categories:a medium-dense microstructure,a dense microstructure consisting of one-sized particles,and a dense microstructure consisting of two-sized particles.Subsequently,the Cosserat elastoplastic model,along with its finite element formulation,is derived using the extended Drucker-Prager yield criteria.To investigate failure behaviors,numerical simulations of granular materials with different microstructures are conducted using the ABAQUS User Element(UEL)interface.It demonstrates the capacity of the proposed model to simulate the phenomena of strain-softening and strain localization.The study investigates the influence of microscopic parameters,including contact stiffness parameters and characteristic length,on the failure behaviors of granularmaterials withmicrostructures.Additionally,the study examines themesh independence of the presented model and establishes its relationship with the characteristic length.A comparison is made between finite element simulations and discrete element simulations for a medium-dense microstructure,revealing a good agreement in results during the elastic stage.Somemacroscopic parameters describing plasticity are shown to be partially related to microscopic factors such as confining pressure and size of the representative volume element.

A New Vehicle Detection Framework Based on Feature-Guided in the Road Scene

Vehicle detection plays a crucial role in the field of autonomous driving technology.However,directly applying deep learning-based object detection algorithms to complex road scene images often leads to subpar performance and slow inference speeds in vehicle detection.Achieving a balance between accuracy and detection speed is crucial for real-time object detection in real-world road scenes.This paper proposes a high-precision and fast vehicle detector called the feature-guided bidirectional pyramid network(FBPN).Firstly,to tackle challenges like vehicle occlusion and significant background interference,the efficient feature filtering module(EFFM)is introduced into the deep network,which amplifies the disparities between the features of the vehicle and the background.Secondly,the proposed global attention localization module(GALM)in the model neck effectively perceives the detailed position information of the target,improving both the accuracy and inference speed of themodel.Finally,the detection accuracy of small-scale vehicles is further enhanced through the utilization of a four-layer feature pyramid structure.Experimental results show that FBPN achieves an average precision of 60.8% and 97.8% on the BDD100K and KITTI datasets,respectively,with inference speeds reaching 344.83 frames/s and 357.14 frames/s.FBPN demonstrates its effectiveness and superiority by striking a balance between detection accuracy and inference speed,outperforming several state-of-the-art methods.

Analysis of the Impact of Road Traffic Safety Facilities on Traffic Safety

The development of the national economy is closely tied to infrastructure construction.In recent years,China has seen a significant increase in the number and scale of road construction projects,aimed at facilitating the flow of goods and enabling convenient travel for the masses.However,this surge in road construction also raises concerns about road traffic safety.Road traffic safety facilities play a crucial role in warning and protecting against traffic accidents.To ensure their effective implementation,this paper analyzes the essence of road traffic facilities and their impact on traffic safety.By identifying challenges in the application of traffic safety facilities and adhering to safety facility application principles,suggestions are proposed to enhance traffic safety management.

Landscape Improvement Design of Mountainous Scenic Roads Under the Background of“All-for-one tourism”:A Case Study of Scenic Roads of Nanshan in Chongqing

"All-for-one tourism" emphasizes the transformation of tourism from the original single scenic spot service to "traveling on the road",and advocates the guiding destination service of integrating transportation and surrounding scenery sources.As the most abundant carrier of tourism environment,mountainous scenic spots are valued more by the development of natural tourism resources.In addition to the characteristics of scenic spots,how to use scenic roads to create a regional atmosphere has become a focus of tourism construction.Taking scenic roads of Nanshan in Chongqing as an example,this study analyzed the key points of road landscape upgrading under different construction levels,and put forward design strategies from the perspective of regional characteristics and regional cultural elements,so as to effectively enhance the regional landscape characteristics of the roads,with a view to providing reference for relevant planning and design.

Control Planning Strategy of Urban Ecological Space Under the Background of Stock Renewal:A Case Study of Beautiful Landscape Planning of Yongchuan District,Chongqing

Under the traditional mode of"incremental"development,urban development has bred urban problems such as lack of land resources,unbalanced distribution of public space,over development of land use,etc.The concept of"stock renewal"is that the construction and development of a city changes from"extensive"construction to"refined"urban construction and management mode.Taking Yongchuan District’s regulatory detailed planning as an example,based on the concept of stock renewal as the guiding ideology of urban control planning,this study made corresponding strategies for the control planning of Yongchuan District’s mountain,water system,green space system,etc.On the basis of the problems of mountain encroachment,water bank erosion,lack of green space and safeguard mechanism,the protection and utilization planning of mountain,water and green were put forward,and safeguard mechanism in the process of planning and implementation was established,so as to provide specific guidance for the construction of Yongchuan central urban area,with a view to providing reference for the preparation and implementation of relevant regulatory detailed planning.

Strategies for Improving the Overall Environmental Quality of Rivers Based on “Renovation and Restoration” Concept: A Case Study of Landscape Planning of Linjiang River, Yongchuan District, Chongqing City

The concept of "renovation and restoration" marks the transformation from urban and rural planning and construction to intensive development mode and to quality improvement stage.The environmental imbalance problem of emphasizing development and neglecting ecology in the past has become the focus of the current urban quality improvement stage.Rivers are related to the origin,development and evolution of cities,affect the layout,transportation and environment of cities,and bear the culture,economy and characteristics of cities.Taking the Linjing River of Yongchuan in Chongqing as an example and taking the concept of "renovation and restoration" as the guidance of the design of the overall environmental quality improvement of the river,this study analyzed and summarized the problems to be solved in the improvement of the environmental quality of the river based on the four river environmental impact factors of water pollution,water resource supply and demand,ecological environment and shore water waterfront type and the strategies of optimizing the aquatic environment management,constructing the ecological landscape pattern,shaping the regional cultural landscape and combining the economic development along the river were put forward in order to improve the overall environmental quality of Linjiang River and provide reference for relevant planning and design.

Plant Furnishing Patterns in Residential Areas of Chongqing City, China

Suitable patterns for the plant furnishing in residential areas of Chongqing City were defined according to actual functional needs, and construction of landscape spaces was explored. Specific plant furnishing patterns were proposed respectively for 6 kinds of green spaces in residential areas: roadside green spaces, public green spaces, green spaces around residences, green spaces around public buildings, peripheral green spaces and vertical green spaces. Application cases in high-rise residential areas, multi-storey residential areas, and low-storey residential areas were taken to show feasibility of these plant furnishing patterns.

不同冲击荷载下高温-水冷却花岗岩能量耗散特征研究

研究地热钻井施工中高温岩石冷却后的能量耗散特性,对提高岩石破碎效率至关重要。通过对分离式霍普金森压杆(SHPB)系统在不同冲击载荷下的动态试验,研究了高温-水冷却花岗岩的能量耗散特性。花岗岩的加热范围为25℃至1000℃。此外,还通过电镜扫描(SEM)和压汞试验(MIP)获得了该花岗岩的微观形貌和孔隙分布。以400℃为界,孔隙分布变化趋势可分为两个阶段:在400℃之前,微孔和小孔占比超过75.00%;当T≥400℃时,中孔占比迅速增加。此外,动态峰值应力和峰值应变随入射能量的增加而增加,而动态弹性模量的变化趋势不明显。当加热温度从25℃增加到800℃时,耗散能占比呈上升趋势,而加热到1000℃的花岗岩的吸收能量下降。当应变率在100 s^(-1)-120 s^(-1)之间时,能量利用效率最高。

Distribution patterns of landslides triggered by the 2022 Ms 6.8 Luding earthquake,Sichuan,China

At 12:52 pm on September 5,2022,an Ms 6.8 earthquake occurred in Luding County,Sichuan Province,China.Based on high-resolution aerial photographs and satellite imageries obtained after the earthquake,as well as field investigation,a total of 8685 earthquake-triggered landslides(EQTLs)were interpreted.The landslides covered an area of 30.7km^(2),with a source area of 9.4 km^(2).These EQTLs were mainly distributed in areas with a seismic intensity of VIII and IX.Most of the landslides were small and medium in size,and their types included landslide,rockfall,and rock slump.Characteristic landslide distributions were found,EQTLs were distributed along the Xianshuihe fault,landslide area decreased gradually with an increased distance to the fault;EQTLs were distributed along the Daduhe River and roads;besides,landslide distribution was associated with ground deformation caused by the earthquake.EQTLs’characteristics indicated that,a large number of EQTLs were located near the foot of the slope;the full area of EQTLs and their source area followed a power function.This study concluded that Luding EQTLs were greater in number and area but relatively smaller in terms of affected area.Investigations on geo-hazards post-earthquake and risk assessment were proposed in the earthquake-stricken area to support the rehabilitation and reconstruction.

Distributed Control Software for the Active Surface System of Tian-ma Radio Telescope

The Tian-ma Radio Telescope(TMRT) applies an Active Surface System(ASFS), which corrects for large-scale deformations due to gravity and thermal on the primary reflector. The centralized and automated management of the ASFS using software has become a challenge, for which we have developed the TMRT Active Surface System Control Software(TASCS). This paper describes the design and implementation of TASCS for device control,status monitoring, human-computer interaction, and data management functionalities. TASCS adopts the opensource Tango Controls framework and distributes middleware technology to realize real-time automated adjustment of the primary reflector through remote centralized control of a large number of actuators. At present, it has been successfully deployed on the TMRT and has played an important role in Event Horizon Telescope observations.

Effects of anti-pull ties on the bearing behaviors of shallow tunnel-type anchorages in soft rock

Tunnel-type anchorages(TTAs)installed in human gathering areas are characterized by a shallow burial depth,and in many instances,they utilize soft rock as the bearing stratum.However,the stability control measures and the principle of shallow TTAs in soft rock have not been fully studied.Hence,a structure suitable for improving the stability of shallow TTAs in soft rock strata,named the anti-pull tie(APT),was added to the floor of the back face.Physical tests and numerical models were established to study the influence of the APT on the load transfer of TTAs,the mechanical response of the surrounding rock,the stress distribution of the interface,and the failure model.The mechanical characteristics of APTs were also studied.The results show that the ultimate bearing capacity of TTAs with an APT is increased by approximately 11.8%,as compared to the TTAs without an APT.Also,the bearing capacity of TTAs increases approximately linearly with increasing height,width,length,and quantity of APTs,and decreases approximately linearly with increasing distance from the back face and slope angle of the tie slope.The normal squeezing between the tie slope and the surrounding rock increases the shear resistance of the interface and expands the range of the surrounding rock participating in bearing sharing.Both tension and compression zones exist in the APT during loading.The tension zone extends from the tie toe to the tie bottom along the tie slope.The range of the tie body tension zone constantly expands to the deep part of the APT with an increasing load.The peak tensile stress value is located at the tie toe.The distribution of compressive stress in the tie body is the largest at the tie top,followed by the tie slope,and then the tie bottom.

Dynamic damage evolution of bank slopes with serrated structural planes considering the deteriorated rock mass and frequent reservoirinduced earthquakes

To investigate the dynamic damage evolution characteristics of bank slopes with serrated structural planes,the shaking table model test and the numerical simulation were utilized.The main findings indicate that under continuous seismic loads,the deformation of the bank slope increased,particularly around the hydro-fluctuation belt,accompanying by the pore water pressure rising.The soil pressure increased and then decreased showed dynamic variation characteristics.As the undulation angle of the serrated structural planes increased(30°, 45°, and 60°),the failure modes were climbing,climbinggnawing,and gnawing respectively.The first-order natural frequency was used to calculate the damage degree(Dd)of the bank slope.During microseisms and small earthquakes,it was discovered that the evolution of Dd followed the“S”shape,which was fitted by a logic function.Additionally,the quadratic function was used to fit the Dd during moderately strong earthquakes.Through the numerical simulation,the variation characteristics of safety factors(Sf)for slopes with serrated structural planes and slopes with straight structural planes were compared.Under continuous seismic loads,the Sf of slopes with straight structural planes reduce stalely,whereas the Sf for slopes with serrated structural planes was greater than the former and the reduction rate was increasing.

冷热交变花岗岩的力学与损伤特性研究

为研究冷热交变岩石的力学性能和损伤演变规律,对冷热交变后的花岗岩进行单轴压缩试验和巴西劈裂试验,利用声发射监测和电镜扫描技术分析花岗岩加载过程中的声发射信号特征和试样破坏后的微观形态特征。结果表明,在不同冷热交变次数下,花岗岩的抗压强度与抗拉强度都明显降低,且两者呈显著的线性关系。在单轴压缩条件下,花岗岩的破坏模式以轴向劈裂破坏和剪切破坏为主;在巴西劈裂条件下,随着热处理温度的升高,花岗岩的破坏表现为径向破坏、径向弧形破坏和沿弱结构平面的混合破坏。两种实验条件下试样破坏过程中的声发射计数变化与应力−应变曲线变化基本一致。归一化累积声发射计数可以较好地反映试样加载过程中的损伤演变特征。试样的初始损伤随着温度和冷热交变次数的增加而增加,导致花岗岩在加载过程中的损伤率持续增长。此外,基于力学参数定义了三个损伤变量,其中基于抗拉强度的损伤变量对冷热交变次数最为敏感。

Investigation of the interaction between NS-DBD plasma-induced vortexes and separated flow over a swept wing

The effect of nanosecond pulsed dielectric barrier discharge(NS-DBD) plasma flow separation control is closely related to the actuation frequency,because it involves the interaction between plasma-induced vortexes and separated flow.In order to study the mechanism of NS-DBD plasma flow separation control over a swept wing,especially the influence of the actuation frequency,at first,experimental studies of the actuation frequencies at 100 Hz are conducted to validate the numerical simulation method.Then,numerical studies of different actuation frequencies which are 50 Hz,100 Hz,160 Hz,200 Hz,500 Hz,and 1000 Hz,respectively are conducted.The interaction between the plasma-induced vortexes and the separated flow is analyzed.Results show that there is a range of the actuation frequency which includes the frequency(160 Hz) calculated by the average aerodynamic chord length to make the control effect good,but when the actuation frequencies are too low(50 Hz) or too high(1000 Hz),the control effect will get worse.The former is because plasmainduced vortexes disappear in a period within an actuation cycle;the latter is because plasma-induced vortexes cannot develop completely,resulting in a weak vortex intensity.

Research on the Dynamic Response of Submerged Floating Tunnels to Wave Currents and Traffic Load

Submerged floating tunnel(SFTs)are typically subjected to complex external environmental and internal loads such as wave currents and traffic load.In this study,this problem is investigated through a finite element method able to account for fluid-structure interaction.The obtained results show that increasing the number of vehicles per unit length enhances the transverse vibrational displacements of the SFT cross sections.Under ultimate traffic load condition,one-way and two-way syntropic distributions can promote the dynamic responses of SFTs whereas two-way reverse distributions have the opposite effect.

Impact of backwater on water surface profile in curved channels

Owing to extensive construction of dams, the impact of backwater on flow may lead to navigation or flood control issues in curved channels. To date, the impact of backwater on the water surface profile in curved channels remains unknown and requires investigation. In this study, experiments were conducted in a glass-walled recirculating flume with a length of 19.4 m, a width of 0.6 m, and a depth of 0.8 m, and the impact of backwater on the water surface profile in a 90° channel bend was investigated. The experimental results showed that the backwater degree had a significant impact on the transverse and longitudinal flow depth distributions in the bend. The transverse slope of the flow (Jr) increased linearly with an increase in the Froude number of the approach flow upstream of the bend. Jr increased with the longitudinal location parameter ξ when −0.2 < ξ < 0.5, and decreased with ξ when 0.5 < ξ < 1.2. Furthermore, the results showed that Jr asymptotically decreased to zero with an increase in the degree of backwater. An equation was formulated to estimate the transverse slope of the flow in a 90° bend in backwater zones.

TLE orbit determination using simplex method

Two-Line Element(TLE)datasets are the only orbital data source of Earth-orbiting space objects for many civil users for their research and applications.The datasets have uneven qualities that may affect the reliability of the propagated positions of space objects using a single TLE.The least squares approach to use multiple TLEs also suffers from the poor quality of some TLEs,and reliable error information cannot be available.This paper proposes a simplex algorithm to estimate an optimal TLE from multiple TLEs and obtain the uncertainty of each element.It is a derivative-free technique that can deal with various orbit types.Experiments have demonstrated that using the TLE estimated from the simplex method is more reliable,stable,and effective than those from the batch least squares method.As an application example,the optimal TLE and its uncertainty are used for predicting the fallen area,keeping the actual fallen site in the prediction areas.