Influence of the column-to-beam flexural strength ratio on the failure mode of beam-column connections in RC frames

The column-to-beam flexural strength ratio(CBFSR)has been used in many seismic codes to achieve the strong column-weak beam(SCWB)failure mode in reinforced concrete(RC)frames,in which plastic hinges appear earlier in beams than in columns.However,seismic investigations show that the required limit of CBFSR in seismic codes usually cannot achieve the SCWB failure mode under strong earthquakes.This study investigates the failure modes of RC frames with different CBFSRs.Nine typical three-story RC frame models with different CBFSRs are designed in accordance with Chinese seismic codes.The seismic responses and failure modes of the frames are investigated through time-history analyses using 100 ground motion records.The results show that the required limit of the CBFSR that guarantees the SCWB failure mode depends on the beam-column connection type and the seismic intensity,and different types of beam-column connections exhibit different failure modes even though they are designed with the same CBFSR.Recommended CBFSRs are proposed for achieving the designed SCWB failure mode for different types of connections in RC frames under different seismic intensities.These results may provide some reference for further revisions of the SCWB design criterion in Chinese seismic codes.

Study on the Application of UHVDC Hierarchical Connection Mode to Multi-infeed HVDC System

随着我国特高压交直流技术的广泛应用，多馈入直流集中落入受端负荷中心将是未来我国电网发展所面临的重要问题。为从电网结构上有效解决多馈入直流系统的问题，提出一种特高压直流分层接入交流电网的方式。研究分层接入方式直流多馈入短路比计算方法的适用性，从理论上对比特高压直流不同接入方式下多馈入直流电网的系统特性，证明特高压直流分层接入方式有助于提高多馈入直流系统的电压支撑能力，引导潮流在1000kV与500kV层级间合理分布。结合国家电网规划，仿真验证了特高压直流分层接入方式的优势。

Experimental and Numerical Studies of Failure Modes and Load-Carrying Capacity of Through-Diaphragm Connections

Shear failure in panel zones and plastic hinges in steel beams are the two major failure modes of connections between concrete-filled steel tubular(CFST) columns and steel beams. To investigate the behavior of this type of connection in both modes,two through-diaphragm connections were tested under cyclic and monotonic loadings and the load-carrying capacity,ductility,and strength of degradation of connections were discussed. Using ABAQUS software,we developed nonlinear finite-element models(FEMs) to simulate the load-carrying capacity and failure modes of the connections under monotonic loading. The finite-element(FE) analysis and test results showed reasonable agreement for the through-diaphragm connections,which confirms the accuracy of FEMs in predicting the load-carrying capacity and failure modes of connections. Based on the validated FEM,a parametric study was then conducted to investigate the infl uence of the thicknesses of the tube and diaphragm on the load-carrying capacity and failure modes of these connections. The results indicate that the strength,stiff ness,and load-carrying capacity are infl uenced less by the thickness of the diaphragm,and more by the thickness of the steel tube. According to the FE analysis results,it can be found that the critical condition between the two failure modes is determined by the shear resistance and bending resistance.

Shaking test research on connection modes between block infill wall and frame beam

In order to achieve an optimal anti-seismic behavior,or rather stability,the out-of-plane stability of infill wall in frame has been researched with the shaking test of four sets of two-layer infill wall,in which four different connection modes of filled with inclined bricks on the top,disconnection,flexibility and semi-flexibility were adapted.The acceleration and displacement response of the specimens were analyzed under the seismic load.Also,some feasible connection modes were gained by comparing the response of infill walls.Finally,the calculation of earthquake of infill wall was held.The results showed that seismic responses of the infill walls whose connect with frame in form of flexibility and semi-flexibility modes are weaker than others obviously,and their integrality is better.Thus the conclusion could be drawn that out-of-plane stability of the specimens with connection modes of flexibility and semi-flexibility are better than those with the connection modes of filled with inclined bricks on the top and disconnection.The research results can provide evidence for establishing specifications and directing the construction and therefore help reduce the casualties and property loss caused by earthquake disasters.

Resting-state connectivity in the default mode network and insula during experimental low back pain

Functional magnetic resonance imaging studies have shown that the insular cortex has a signif- icant role in pain identification and information integration, while the default mode network is associated with cognitive and memory-related aspects of pain perception. However, changes in the functional connectivity between the defauk mode network and insula during pain remain unclear. This study used 3.0 T functional magnetic resonance imaging scans in 12 healthy sub- jects aged 24.8 ± 3.3 years to compare the differences in the functional activity and connectivity of the insula and default mode network between the baseline and pain condition induced by intramuscular injection of hypertonic saline. Compared with the baseline, the insula was more functionally connected with the medial prefrontal and lateral temporal cortices, whereas there was lower connectivity with the posterior cingulate cortex, precuneus and inferior parietal lobule in the pain condition. In addition, compared with baseline, the anterior cingulate cortex exhibited greater connectivity with the posterior insula, but lower connectivity with the anterior insula, during the pain condition. These data indicate that experimental low back pain led to dysfunction in the connectivity between the insula and default mode network resulting from an impairment of the regions of the brain related to cognition and emotion, suggesting the impor- tance of the interaction between these regions in pain processing.

Comparison the Performances of Three Earthing Systems for Micro-Grid Protection during the Grid Connected Mode

This paper presents, tests and compares three earthing systems (TT, TN and IT) for Micro-Grid (MG) protection against various fault types during the connected mode. The main contribution of this work is including the models of all the micro sources which interfaced to the MG by power electronic inverters. Inverters in turns are provided with current limiters and this also included in the inverter models to exactly simulate the real situation in the MG during fault times. Results proved that the most suitable earthing system for MG protection during the connecting mode is the TN earthing system. That system leads to a suitable amount of fault current sufficient to activate over current protection relays. With using TN system, Touch voltages at the faulted bus and all other consumer’s buses are less than the safety limited value if current limiter is included with the transformer of the main grid which connects MG. For the two others earthing systems (TT and IT), fault current is small and nearly equal to the over load current which make over current protection relay can not differentiate between fault current and overload current. All models of micro sources, earthing systems, inverters, main grid and control schemes are built using Matlab?/Simulink? environment.

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.

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.

Experimental Study of Moso Bamboo to-Steel Connections with Embedded Grouting Materials

Moso bamboos have attracted excessive attention as a renewable green building material to the concept of sustainable development.In this paper,the 20 bolted Moso bamboo connection specimens with embedded steel plates and grouting materials were designed according to connection configurations with different bolt diameters and end distance of bolt holes,and their bearing capacities and failure modes were analyzed by static tension tests.According to the test results of all connectors,the failure modes of the specimens are divided into four categories,and the effects of bolt diameter and bolt hole end distance on the connection bearing capacity and failure mode are analyzed.The test results show that the deformation and failure process can be divided into four stages.The main influence factor of connector bearing capacity is bolt diameter.Connectors can be divided into four failure modes,and brittle failure can be avoided by adopting certain structural measures.Filling with grouting material can improve the bearing capacity of joints.Due to the large variability of bamboo,further experiments are needed.

Disrupted functional connectivity of default mode network and executive control network in patients with vascular cognitive impairment, no dementia

Objective： To investigate functional connectivity within default mode network （DMN） and ex-ecutive control network （ECN） in vascular cognitive im-pairment, no dementia （VCIND）. Methods： Twenty-eight VCIND patients and sixteen healthy controls were recruit-ed. A seed-based connectivity analysis was performed us-ing data from resting-state functional magnetic resonance imaging （fMRI）. Based on previous fndings, posteriorcingulate cortex （PCC） and dorsolateral prefrontal cortex （DLPFC） were chosen as regions of interest to study these networks.One-sample t-test and two-sample t-test were used for statistical analysis. Results： Compared with thecontrols, the VCIND group exhibited increased functional activity in such DMN regions as the left inferior temporal gyrus, parahippocampal gyrus, and medial frontal gyrus. The VCIND group had decreased functional connectivity of DMN at right superior frontal gyrus, left mid-cingu-late area, the medial part of left superior frontal gyrus, and bilateral medial frontal gyrus. The VCIND group also showed decreased functional connectivity of ECN pri-marilyat left inferior parietal gyrus, right angular gyrus, right middle occipital gyrus, and right middle frontal cor-tex. Conclusions： Increased functional connectivity with-in DMN and decreased functional connectivity within ECN suggested dysfunction of these two networks, which mightbe associated with the cognitive defcitsin patients with VCIND. These fndingsmay help usunderstandthe pathogenesis and clinical characteristics of VCIND.

Influence of Control Modes of Grid-Connected Solar Photovoltaic Generation on Grid Power Flow

Integration of Solar Photovoltaic (PV) generation into an existing distribution system has many impacts on the system, with the power flow being one of the major issues. This impact is not generic for any network, but it may manifest itself either positively or negatively, depending on the grid configuration, interface control modes, operation mode, and load profile. Grid-connected PV systems have three control options of the local voltage controller of the interface DC-AC converter. These control modes are Power Factor control, voltage control, and Droop Voltage control. This paper aims at evaluating and comparing the impacts of those control modes on the grid power flow. A set of evaluation criteria and indices is defined and mathematically formulated. Based on the requirements of the used program (Power Factory Dig Silent V14.1.3), a computation plan (algorithm) has been proposed. The algorithm has been applied to a typical weak network and a wide range of simulations has been carried out. Simulation results have been thoroughly discussed and important findings have been concluded.

Structural and functional connectivity in traumatic brain injury

Traumatic brain injury survivors often experience cognitive deficits and neuropsychiatric symptoms.However,the neurobiological mechanisms underlying specific impairments are not fully understood.Advances in neuroimaging techniques（such as diffusion tensor imaging and functional MRI）have given us new insights on structural and functional connectivity patterns of the human brain in both health and disease.The connectome derived from connectivity maps reflects the entire constellation of distributed brain networks.Using these powerful neuroimaging approaches,changes at the microstructural level can be detected through regional and global properties of neuronal networks.Here we will review recent developments in the study of brain network abnormalities in traumatic brain injury,mainly focusing on structural and functional connectivity.Some connectomic studies have provided interesting insights into the neurological dysfunction that occurs following traumatic brain injury.These techniques could eventually be helpful in developing imaging biomarkers of cognitive and neurobehavioral sequelae,as well as predicting outcome and prognosis.

Age-related changes in resting-state functional connectivity in older adults

Age-related changes in the brain connectivity of healthy older adults have been widely studied in recent years,with some differences in the obtained results.Most of these studies showed decreases in general functional connectivity,but they also found increases in some particular regions and areas.Frequently,these studies compared young individuals with older subjects,but few studies compared different age groups only in older populations.The purpose of this study is to analyze whole-brain functional connectivity in healthy older adult groups and its network characteristics through functional segregation.A total of 114 individuals,48 to 89 years old,were scanned using resting-state functional magnetic resonance imaging in a resting state paradigm and were divided into six different age groups(<60,60–64,65–69,70–74,75–79,≥80 years old).A partial correlation analysis,a pooled correlation analysis and a study of 3-cycle regions with prominent connectivity were conducted.Our results showed progressive diminution in the functional connectivity among different age groups and this was particularly pronounced between 75 and 79 years old.The oldest group(≥80 years old)showed a slight increase in functional connectivity compared to the other groups.This occurred possibly because of compensatory mechanism in brain functioning.This study provides information on the brain functional characteristics of every age group,with more specific information on the functional progressive decline,and supplies methodological tools to study functional connectivity characteristics.Approval for the study was obtained from the ethics committee of the Comision de Bioetica de la Universidad de Barcelona(approval No.PSI2012-38257)on June 5,2012,and from the ethics committee of the Barcelona’s Hospital Clinic(approval No.2009-5306 and 2011-6604)on October 22,2009 and April 7,2011 respectively.

Abnormal characterization of dynamic functional connectivity in Alzheimer’s disease

Numerous studies have shown abnormal brain functional connectivity in individuals with Alzheimer’s disease(AD)or amnestic mild cognitive impairment(aMCI).However,most studies examined traditional resting state functional connections,ignoring the instantaneous connection mode of the whole brain.In this case-control study,we used a new method called dynamic functional connectivity(DFC)to look for abnormalities in patients with AD and aMCI.We calculated dynamic functional connectivity strength from functional magnetic resonance imaging data for each participant,and then used a support vector machine to classify AD patients and normal controls.Finally,we highlighted brain regions and brain networks that made the largest contributions to the classification.We found differences in dynamic function connectivity strength in the left precuneus,default mode network,and dorsal attention network among normal controls,aMCI patients,and AD patients.These abnormalities are potential imaging markers for the early diagnosis of AD.

Differential aberrant connectivity of precuneus and anterior insula may underpin the diagnosis of schizophrenia and mood disorders

BACKGROUND Over the past decade,resting-state functional magnetic resonance imaging(rsfMRI)has concentrated on brain networks such as the default mode network(DMN),the salience network(SN),and the central executive network(CEN),allowing for a better understanding of cognitive deficits observed in mental disorders,as well as other characteristic psychopathological phenomena such as thought and behavior disorganization.AIM To investigate differential patterns of effective connectivity across distributed brain networks involved in schizophrenia(SCH)and mood disorders.METHODS The sample comprised 58 patients with either paranoid syndrome in the context of SCH(n=26)or depressive syndrome(Ds)(n=32),in the context of major depressive disorder or bipolar disorder.The methods used include rs-fMRI and subsequent dynamic causal modeling to determine the direction and strength of connections to and from various nodes in the DMN,SN and CEN.RESULTS A significant excitatory connection from the dorsal anterior cingulate cortex to the anterior insula(aI)was observed in the SCH patient group,whereas inhibitory connections from the precuneus to the ventrolateral prefrontal cortex and from the aI to the precuneus were observed in the Ds group.CONCLUSION The results delineate specific patterns associated with SCH and Ds and offer a better explanation of the underlying mechanisms of these disorders,and inform differential diagnosis and precise treatment targeting.

H6 Non-isolated Full Bridge Grid-connected PV Inverters With Low Leakage Currents

为满足非隔离光伏并网发电系统对共模漏电流的限制，提出一种六开关逆变器拓朴（H6拓扑）。所提出的H6拓扑在功率传输模态时，进网电流半个工频周期流过3支开关管，而另半个工频周期流过2支开关管，故相对于H5拓扑，降低了通态损耗，有利于热应力均衡，且仍满足续流阶段光伏电池输出端与电网脱离的要求。详细分析拓扑的工作原理，并推论给出H6非隔离光伏并网逆变器的其它3种拓扑结构；比较分析了H5拓扑、Heric拓扑和H6拓扑的损耗和成本。通过1kW通用样机平台对比验证了上述3种拓扑的效率和共模特性。实验结果表明，H6拓扑的变换效率高于H5拓扑、但略低于Heric拓扑，共模特性优于Heric拓扑、但略劣于H5拓扑。

MODEM与ISDN两种网络接入方式的对比

对比两种网络接入方式 (MODEM方式和ISDN方式 )技术上的特性及其存在的差异 ,并通过测试说明ISDN方式比MODEM方式更先进 ,更具优越性。

Lobster Fishery Connectivity and Management In Indonesia Waters

The distribution of lobsters in Indonesian waters is very wide,even lobster species in Indonesia are also scattered in the tropical waters of the western Pacific Ocean,the Indian Ocean,Africa to Japanese waters.Indonesian waters are divided into 11(eleven)Fishery Management Zone(FMZ).Lobsters in Indonesia may come from various water areas,both national and regional water zones,and they’re called the sink population.Its spread is influenced by the movement of the current.Lobster seed is nurtured by nature through ocean currents from Australia,East Indonesia,Japan,then back to Australia.Lobsters have a complex life cycle,where adult lobsters inhabit coral reefs as a place to lay eggs,then hatch into planktonic larvae,and grow up in open seas and carry out diurnal and ontogenetic vertical migrations before returning to nurseries in shallow coastal areas and reefs,coral,as well as habitat by the type of species.Literature research had used at least two methodologies to estimate the distribution and connection sensitivity matrices of marine organism larvae.The two most common approaches are using genetic markers and numerical biophysical modeling.Thus,this research uses molecular genetic techniques to explain the ge­netic structure of lobster populations using a biophysical model approach that can explain the genetic structure of lobsters,as well as the distribution based on regional oceanographic synthesis data and lobster biology known in Indonesian waters.This model has four components,namely:1)a ben­thic module based on a Geographical Information System(GIS)which is a lobster habitat in the spawning and recruitment process,2)a physical oceanography module containing daily velocity in the form of a three-di­mensional hydrodynamic model,3)a larva biology module that describes larval life history characteristics,and 4)a Lagrangian Stochastic module that tracks the individual trajectories of larvae.

A tour-based analysis of travel mode choice accounting for regional transit service

The aim of this work is to explore the impact of regional transit service on tour-based commuter travel behavior by using the Bayesian hierarchical multinomial logit model, accounting for the spatial heterogeneity of the people living in the same area.With two indicators, accessibility and connectivity measured at the zone level, the regional transit service is captured and then related to the travel mode choice behavior. The sample data are selected from Washington-Baltimore Household Travel Survey in 2007,including all the trips from home to workplace in morning hours in Baltimore city. Traditional multinomial logit model using Bayesian approach is also estimated. A comparison of the two different models shows that ignoring the spatial context can lead to a misspecification of the effects of the regional transit service on travel behavior. The results reveal that improving transit service at regional level can be effective in reducing auto use for commuters after controlling for socio-demographics and travel-related factors.This work provides insights for interpreting tour-based commuter travel behavior by using recently developed methodological approaches. The results of this work will be helpful for engineers, urban planners, and transit operators to decide the needs to improve regional transit service and spatial location efficiently.

大规模可再生能源发电友好并网与运行调控技术研究综述

“双碳”目标下大规模可再生能源系统的友好并网与稳定运行问题被广泛关注,但受精确的发电不确定性建模技术与科学的并网调控策略制约.为解决这一问题,从可再生能源发电预测与不确定性建模、可再生能源系统并网运营模式、可再生能源系统并网控制方法三个方面进行梳理和总结,讨论了不同时间尺度下发电不确定性预测技术、针对多场景运行需求的不确定性建模技术;从可再生能源-储能系统、可再生能源集群-独立储能系统、多能源互补系统三个角度分析总结了目前并网运营模式;在此基础上,分析总结了跟网型与构网型两种并网控制策略.最后展望了高比例可再生能源系统在未来电网形态演变中的发展方向,以期为新型电力系统中可再生能源与电网协同发展的研究和技术应用提供借鉴.