Multiscale Characteristics and Connection Mechanisms of Attraction Networks:A Trajectory Data Mining Approach Leveraging Geotagged Data

Urban tourism is considered a complex system,and multiscale exploration of the organizational patterns of attraction networks has become a topical issue in urban tourism,so exploring the multiscale characteristics and connection mechanisms of attraction networks is important for understanding the linkages between attractions and even the future destination planning.This paper uses geotagging data to compare the links between attractions in Beijing,China during four different periods:the pre-Olympic period(2004–2007),the Olympic Games and subsequent‘heat period’(2008–2013),the post-Olympic period(2014–2019),and the COVID-19(Corona Virus Disease 2019)pandemic period(2020–2021).The aim is to better understand the evolution and patterns of attraction networks at different scales in Beijing and to provide insights for tourism planning in the destination.The results show that the macro,meso-,and microscales network characteristics of attraction networks have inherent logical relationships that can explain the commonalities and differences in the development process of tourism networks.The macroscale attraction network degree Matthew effect is significant in the four different periods and exhibits a morphological monocentric structure,suggesting that new entrants are more likely to be associated with attractions that already have high value.The mesoscale links attractions according to the common purpose of tourists,and the results of the community segmentation of the attraction networks in the four different periods suggest that the functional polycentric structure describes their clustering effect,and the weak links between clusters result from attractions bound by incomplete information and distance,and the functional polycentric structure with a generally more efficient network of clusters.The pattern structure at the microscale reveals the topological transformation relationship of the regional collaboration pattern,and the attraction network structure in the four different periods has a very similar importance profile structure suggesting that the attraction network has the same construction rules and evolution mechanism,which aids in understanding the attraction network pattern at both macro and micro scales.Important approaches and practical implications for planners and managers are presented.

Insights into the dwarfing mechanism of pear(Pyrus betulaefolia) based on anatomical and structural analysis using X-ray scanning

The lack of a suitable rootstock to control scion growth has limited the development of high-density plantations in pear production, which is partly attributed to poor understanding of the dwarfing mechanism. In the present study, the rootstock of the dwarf-type pear (Pyrus betulaefolia)PY-9’ was identified and used as the material for anatomical analysis.PY-9’ grew to half the tree height of the normal cultivar Zhengdu’, along with fewer internodes and shorter length. Significant differences in growth rate betweenPY-9’ andZhengdu’ were detected at approximately 30 days after full bloom, which corresponded with the time of the greatest difference in water potential between the dwarf and normal cultivar.PY-9’ showed a higher photosynthetic rate thanZhengdu’. Anatomical analysis showed thatPY-9’ had higher area ratios of both phloem and xylem and more developed vascular tissues thanZhengdu’. The three-dimensional reconstructed skeleton of the xylem from X-ray computed tomography scanning revealed greater intervessel connectivity inZhengdu’ than inPY-9’, which could contribute to the more vigorous growth ofZhengdu’. This study thus provides the first comparison of the microstructural properties of xylem elements between a dwarfing-type and vigorous-type pear rootstock, providing new insights into the dwarfing mechanism in pear and facilitating breeding of dwarf pear rootstocks to increase crop productivity.

Effects of connection types and elevated temperature on the impact behaviour of restrained beam in portal steel frame

Based on the background of structural protection and Disaster Reduction Engineering, the dynamic behaviour and failure mechanism of restrained beams in portal steel frames in localised fire are investigated via experimental measurement and numerical simulation techniques. Comprehensive parametric studies are carried out to discuss the influence of end connection types, temperature, impact velocity,impact mass and span-to-depth ratio(SDR) on the dynamic response of the beams. The characteristics of deformation, internal force and energy distribution about the restrained beams and its joints are investigated. A temperature dependent criterion for evaluating the frame joint performance is proposed to measure the degree of performance degradation and impact resistance of the joint. The dynamic displacement amplification factor in different temperature environments are proposed for the different beam end constraint types and SDRs. Results of the experimental and numerical analysis show that the welded connection(WC) of three typical joint types is the strongest, and the extended endplate connection(EEC) is the weakest in terms of the impact resistance performance. With regard to the failure mode of the joint, the failure positions of the WC and the welded-bolted connection are located in the inner web of the column. Meanwhile, the EEC is located in the connection position between the beam and the endplate. Three different internal force stages and two obvious critical temperature boundaries of the restrained beams emerge with the increase in temperature, and they have significant characteristics in terms of deformation trend, internal force transfer and energy distribution. During the impact, a phenomenon known as “compression arch action” develops into “catenary action” with the increase in deflection in the frame beam mechanism.

Analytical Investigation into the Rotational Performance of Glulam Bolted Beam-Column Connections under Coupled Bending Moment and Shear Force

Considering the glulam beam-column connection form and the number of bolts,monotonic loading test and finite element analysis was carried out on 9 connection specimens in 3 groups to study the rotational performance and failure mode of the connection.The test results revealed that compared with U-shaped connectors,T-shaped connectors can effectively improve the ductility of connections,and the increase in the number of bolts can reduce the initial stiffness and ductility of connections.By theoretical analysis,formulas for calculating the initial stiffness and ultimate moment of connections were deduced.Subsequently,the moment-rotation theoretical model of connections was established based on the formulas,which were validated according to the test data and simulation results.The proposed model can not only improve the current theoretical system of heavy-duty glulam beam-column structure but also provide a theoretical basis for calculating the mechanical properties of the glulam beam-column connection.

Mechanical characteristic and failure mechanism of joint with composite sucker rod

Composite sucker rods are widely used in oil fields because of light weight,high strength,and corrosion resistance.Bonded technology becomes the primary connection method of composites.However,the joints with composite sucker rods are prone to debone and fracture.The connected characteristics are less considered,so the failure mechanism of the joint is still unclear.Based on the cohesive zone model(CZM)and the Johnson-Cook constitutive model,a novel full-scale numerical model of the joint with composite sucker rod was established,and verified by pull-out experiments.The mechanical properties and slip characteristics of the joint were studied,and the damaged procession of the joint was explored.The results showed that:a)the numerical model was in good agreement with the experimental results,and the error is within 5%;b)the von Mises stress,shear stress,and interface stress distributed symmetrically along the circumferential path increased gradually from the fixed end to the loading end;c)the first-bonded interface near the loading end was damaged at first,followed by debonding of the second-bonded interface,leading to the complete shear fracture of the epoxy,and resulted in the debonding of the joint with composite sucker rod,which can provide a theoretical basis for the structural design and optimization of the joint.

Mechanical and Acoustic Performance Test of New Designed Metal Noise Barrier Unit Plate with No Riveted Connection

The modern transportation system is increasingly developed during recent years.It is an effective solution to set the noise barriers to reduce the traffic noise pollution caused by different kinds of transportation systems.Many deficiencies on concrete noise barriers and metal noise barriers with rivet structure can be eliminated by a new kind of noise barrier with no-riveted structure.The mechanical performance examination and acoustic performance test are conducted on the new-designed noise barrier with no-riveted structure.The results indicate that the maximum stress is 1.74 MPa and the maximum deformation is 1.04 mm with load acting on the unit plate.The noise reduction coefficient of this kind of no-riveted noise barrier unit plate is 0.75 and its noise insulation is 40 dB,which were conform to or superior to the standard requirements.Therefore,this new designed noise barrier meets the field application requirements of mechanical and acoustic performance,which demonstrates the noise barriers can be widely promoted.

Mechanical Properties of Moso Bamboo Connections with External Clamp Steel Plates

The Moso bamboo,a renewable green building material used in various new green buildings,have received exten-sive attention with the promotion of the concept of green buildings.To explore the mechanical properties of Moso bamboo connections with external clamp steel plates,the 16 specimens were designed by changing the bolt diameters and the end distances of the bolt holes.Their static tension tests were conducted to investigate bearing capacities and failure modes of different connection configurations.Based on test results,three failure modes of these connections were obtained,including the shear failure of bolt shank,bearing failure of bolt hole and punch-ing shear failure of the Moso bamboo.The influence of bolt diameters and end distances of bolt holes on bearing capacities of the connections was quantitatively analyzed.Based on a simplified mechanical model,the analytical models were deduced for the bolt shear failure and the bearing failure of bolt holes.The results showed that the predictive values are in substantial agreement with the experimental results.Finally,the design and manufacturing suggestions are recommended for this Moso bamboo connections.

Dynamic interwell connectivity analysis of multi-layer waterflooding reservoirs based on an improved graph neural network

The analysis of interwell connectivity plays an important role in the formulation of oilfield development plans and the description of residual oil distribution. In fact, sandstone reservoirs in China's onshore oilfields generally have the characteristics of thin and many layers, so multi-layer joint production is usually adopted. It remains a challenge to ensure the accuracy of splitting and dynamic connectivity in each layer of the injection-production wells with limited field data. The three-dimensional well pattern of multi-layer reservoir and the relationship between injection-production wells can be equivalent to a directional heterogeneous graph. In this paper, an improved graph neural network is proposed to construct an interacting process mimics the real interwell flow regularity. In detail, this method is used to split injection and production rates by combining permeability, porosity and effective thickness, and to invert the dynamic connectivity in each layer of the injection-production wells by attention mechanism.Based on the material balance and physical information, the overall connectivity from the injection wells,through the water injection layers to the production layers and the output of final production wells is established. Meanwhile, the change of well pattern caused by perforation, plugging and switching of wells at different times is achieved by updated graph structure in spatial and temporal ways. The effectiveness of the method is verified by a combination of reservoir numerical simulation examples and field example. The method corresponds to the actual situation of the reservoir, has wide adaptability and low cost, has good practical value, and provides a reference for adjusting the injection-production relationship of the reservoir and the development of the remaining oil.

Mechanical Experimental Study on Tensile Bolted Connections of Cross-laminated Timber

In order to explore a kind of high-strength,earthquake-resistant,eco-nomical and suitable connection,4 groups of cross-laminated timber wall-to-floor and wall-to-wall bolted connections were tested under monotonic and cyclic load-ing.The defommation characteristics and failure modes of the cross-laminated tim-ber wall-to-floor and wall-to-wall bolted connections were exploited.Load-slip curves,bearing capacity,yielding point,stiffness and ductility of each group of specimens were analyzed.The test results indicate that the loading process of cross-laminated timber bolted connections under tension can be categorized as five stages,namely the elastic stage,the slip stage,the embedding stage,the yield-ing stage and the ultimate stage.The ultimate tensile capacity of cross-laminated timber bolted wall-to-floor connections is 2.67 times that of the wall-to-wall bolted connections.Compared with cross-laminated timber self-tapping screwed connections,the ultimate tensile capacity of the cross-laminated timber wall-to-floor bolted connections is 2.70 times that of the self-tapping screwed connec-tions,and the ultimate tensile capacity of the cross-laminated timber wall-to-wall bolted connections is 3.83 times that of the self-tapping screwed connections.The crosslaminated timber bolted connections have larger yielding displacement and wider plastic range,and they are more energy dissipative and more ductile.Furthermore,the cost of the cross-laminated timber wall-to-floor bolted connec-tions is 46%that of the self-tapping screwed connections,while the cost of cross-laminated wall-to-wall bolted connections is 53%that of the self-screwed connections.

METAMORPHIC MECHANISMSAND THEIR CONFIGURATION MODELS

The concept of metamorphic mechanisms is presented, configuration models and configuration transformations relating to a set of new matrix operations are discussed and proposed. The configuration of a metamorphic mechanism reflects the connectivity change in the mechanism during motions which results in mobility change and presents the characteristics of the mechanism which is discussed in various applications particularly in decorative artifacts. The characteristics is further investigated with mobility analysis.

Seismic Behavior of Diaphragm-Through Connections of Concrete-Filled Square Steel Tubular Columns and H-Shaped Steel Beams

Based on the introductions of a type of diaphragm-through connection between concrete-filled square steel tubular columns (CFSSTCs) and H-shaped steel beams,a finite element model of the connection is developed and used to investigate the seismic behavior of the connection.The results of the finite element model are validated by a set of cyclic loading tests.The cyclic loading tests and the finite element analyses indicate that the failure mode of the suggested connections is plastic hinge at the beam with inelastic rotation angle exceeding 0.04 rad.The suggested connections have sufficient strength,plastic deformation and energy dissipation capacity to be used in composite moment frames as beam-to-column rigid connections.

Avoiding sealing failure of flanged connection for tubes made of dissimilar materials subjected to elevated temperature

Carbonic composite materials and ceramics appear to be excellent structural materials for parts subjected to very high temperatures in molten salt reactors(MSRs), in which the reactor core outlet temperature is normally above 700℃. Because of the high temperature,there are major challenges in the sealing of flanged connections for tubes made of alloys and nonmetallic materials. In this study, an improved method for sealing bolted flange connections for tubes made of dissimilar materials at high temperature is analyzed. The study focuses on the compensation mechanism for the difference in thermal expansion between the bolts and the flanges. An angle is introduced for the sealing surface in the flanged connection to provide effective sealing. The arctangent of the angle is the ratio of the thickness between the theoretical core of the sealing surface and the outside end face of the flange to the distances between the axis of the flanged joint and the theoretical core of the sealing surface of the flange; the sealing surface of the flange, which is made of the same material as the fastening assemblies, faces the fastening assemblies. To ensure effective sealing, the frictional coefficient between the two sealing surfaces should not exceed the tangent of the angle. This result does not agree well with the solution given by previous researchers. Further, in the modified flanged connection, the compression of each bolt in the clamped condition is increased to maintain the compaction force unchanged without increasing the number of bolts on the flanged joint.

Reliability of power connections

Despite the use of various preventive maintenance measures, there are still a number of problem areas that can ad- versely affect system reliability. Also, economical constraints have pushed the designs of power connections closer to the limits allowed by the existing standards. The major parameters influencing the reliability and life of Al-Al and Al-Cu connections are identified. The effectiveness of various palliative measures is determined and the misconceptions about their effectiveness are dealt in detail.

MU-GAN:Facial Attribute Editing Based on Multi-Attention Mechanism

Facial attribute editing has mainly two objectives:1)translating image from a source domain to a target one,and 2)only changing the facial regions related to a target attribute and preserving the attribute-excluding details.In this work,we propose a multi-attention U-Net-based generative adversarial network(MU-GAN).First,we replace a classic convolutional encoder-decoder with a symmetric U-Net-like structure in a generator,and then apply an additive attention mechanism to build attention-based U-Net connections for adaptively transferring encoder representations to complement a decoder with attribute-excluding detail and enhance attribute editing ability.Second,a self-attention(SA)mechanism is incorporated into convolutional layers for modeling long-range and multi-level dependencies across image regions.Experimental results indicate that our method is capable of balancing attribute editing ability and details preservation ability,and can decouple the correlation among attributes.It outperforms the state-of-the-art methods in terms of attribute manipulation accuracy and image quality.Our code is available at https://github.com/SuSir1996/MU-GAN.

Mechanical Behavior of Light Trusses Made of Poplar Laminated Veneer Lumber and Connected with Bolts and Tooth Plates

Poplar Laminated Veneer Lumber(Poplar LVL)is a new type of engineering materials with high strength,good reliability and small variability.Poplar LVL is manufactured from the fast-growing poplar,which is widely used in packaging,furniture and others,however,is rarely adopted in construction.In order to explore the feasibility of poplar LVL trusses in construction of roof,four 4.5-m-span Fink-and-Howe trusses were designed and assembled,which were made of poplar LVL with bolted-and tooth-plated connections.Vertical static loading on the upper chord joints of a truss was imposed by self-balancing test device.The mechanical properties of trusses were examined.The ultimate load,deformation character and failure mode of each truss were measured,observed and analyzed.Furthermore,four types of analytical models with different joint connection assumptions were used to estimate the ultimate load and deflection.The results showed that the poplar LVL trusses were basically in elastic stage before the design load was reached,showing good working performance under the action of design load.The bearing capacity of the trusses of bolted connections was greater than that of the tooth-plated connections.As for the same joint connection type,the bearing capacity of Fink trusses exceeded that of Howe trusses.The poplar LVL light trusses of both types of connections showed good structural performance,which could be reasonably used for building roof systems.

Intelligent Modularized Reconfigurable Mechanisms for Robots:Development and Experiment

With the development of intelligent flexible manufacturing,traditional industrial manipulators with a single configuration are difficult to meet a variety of tasks.Reconfigurable robots have developed rapidly which could change their configurations and end effectors for different tasks.The reconfigurable connecting mechanism(RCM)is a core component of reconfigurable robots.In this paper,two types of intelligent modularized RCMs with light weight,high payload,and large pose(position and attitude)error tolerance are developed.One is driven by shape memory alloy(SMA)and recovery spring.It is locked by steel balls and key.The other is driven by electromagnetic coil and locked by permanent magnet and key.The locking principle,mechanical system and control system of the two RCMs are detailed introduced.Both of them meet the requirements of high precision and high payload in the industrial field.Finally,the developed RCMs are respectively integrated to a practical robot and experimented.The experiment results verified the performance of the two RCMs.

Epidemic Spread in Networks Induced by Deactivation Mechanism

We have studied the topology and epidemic spreading behaviors on the networks in which deactivation mechanism and long-rang connection are coexisted. By means of numerical simulation, we find that the clustering coefficient C and the Pearson correlation coefficient r decrease with increasing long-range connection μ and the topological state of the network changes into that of BA model at the end （when μ = 1）. For the Susceptible-Infect-Susceptible model of epidemics, the epidemic threshold can reach maximum value at μ = 0.4 and presents two different variable states around μ= 0.4.

Water-cut rising mechanism and optimized water injection technology for deepwater turbidite sandstone oilfield: A case study of AKPO Oilfield in Niger Delta Basin, West Africa

Through the analysis of the reservoir connection relationship and the water-cut rising rules after water breakthrough in the highly volatile oil AKPO oilfield, a new model of water-cut rising was established, and the timing and strategy of water injection were put forward. The water-cut rising shapes of producers after water breakthrough can be divided into three types, and their water-cut rising mechanism is mainly controlled by reservoir connectivity. For the producers which directly connect with injectors in the single-phase sand body of the single-phase channel or lobe with good reservoir connectivity, the water-cut rising curve is "sub-convex". For the producers which connect with injectors through sand bodies developed in multi-phases with good inner sand connectivity but poorer physical property and connectivity at the overlapping parts of sands, the response to water injection is slow and the water-cut rising curve is "sub-concave". For the producers which connect with injectors through multi-phase sand bodies with reservoir physical properties, connectivity in between the former two and characteristics of both direct connection and overlapping connection, the response to water injection is slightly slower and the water-cut rising curve is "sub-S". Based on ratio relationship of oil and water relative permeability, a new model of water cut rising was established. Through the fitting analysis of actual production data, the optimal timing and corresponding technology for water injection after water breakthrough were put forward. Composite channel and lobe reservoirs can adopt water injection strategies concentrating on improving the vertical sweep efficiency and areal sweep efficiency respectively. This technology has worked well in the AKPO oilfield and can guide the development of similar oilfields.

职场正念的人际影响及作用机制

职场正念在人际领域的益处日渐凸显,有必要厘清其在概念发展和人际作用方面的新趋势,为组织塑造积极的职场环境提供启发。研究揭示目前存在两种不同的职场正念概念发展趋势:结果导向和过程导向,前者关注职场背景下概念与测量的统一趋势以探索有益的结果集合,后者侧重挖掘正念嵌入人际互动的过程机制;职场正念通过4种关联机制对质量和功能相关的人际结果产生影响:(1)在互动中通过开放的注意力捕捉信息以协调相互依赖工作的知识关联;(2)降低与内外部情绪体验相关的自我推断并强化与他人之间归属、支持和关怀的情感关联;(3)在互动中促进资源积累与抑制资源流失的资源关联;(4)导航资源流动方向与影响价值交换意愿的交换关联;资源和交换关联机制可辅助促进知识和情感关联机制。未来需更深入地探讨职场正念在数字化和AI技术、远程办公及职场多样化、公平与包容性文化和污名化管理等挑战性工作领域的人际作用。

联络通道施工盾构机接收对已建盾构隧道影响试验研究

联络通道机械法施工中盾构机接收对已建盾构隧道受荷变形影响机制暂不明确问题,通过设计1∶10的缩尺模型试验,开展了联络通道机械法施工中盾构机接收对已建盾构隧道影响试验研究。试验结果分析表明:联络通道机械法施工时,盾构机开挖面附加水平土压力将导致接收端已建盾构隧道对侧的土压力在中部有显著的增大,而两端则减小,即导致顶推对侧发生了水平被动土拱现象;在中间附加水平土压力作用下,隧道在中间发生了显著的竖椭圆变形,而在两端则发生了一定的横椭圆变形;隧道中间发生竖椭圆变形对上下地层形成挤压,在竖向上同样形成了被动土拱现象;隧道纵向挠曲变形时出现了一定的反弯现象。盾构隧道作为地层中的管状结构物,在地层中纵向变形分析时需要考虑横断面变形的影响。