In-situ experimental investigation of the influence of structure characteristics on subway-induced building vibrations

Many types of buildings have been widely constructed in the vicinity of subway lines in China.Normal life and business activities are hampered by excessive subway-induced vibrations.This study aims to determine the influence of structure characteristics on structure-borne vibrations,generally based on experimental results.Vibration measurements were performed in four typical sites in Wuxi,China,involving over-track buildings,along-track buildings,frame structure buildings and a masonry building.Special structure designs like structure transfer floor were also included.Then,the captured data was analyzed in the time domain and the frequency domain.Furthermore,the influence of building location,structure type and structure layout was investigated.Finally,vibrations were evaluated with ISO and Chinese criteria and structure optimization for vibration attenuation was proposed.It is found that over-track buildings are more severely affected than along-track buildings.Higher frequency contents(20‒60 Hz)in over-track buildings and lower frequency contents(0‒10 Hz)in along-track buildings should be seriously considered in vibration control.Weaker structure member joints and lower material strength would be beneficial to over-track buildings while the inverse situation would be beneficial to along-track buildings.The application of structure transfer floor‒generally stiffer structure members and structure discontinuity‒is also beneficial.

Effect of structural characteristics distribution on strength demand and ductility reduction factor of MDOF systems considering soil-structure interaction

It is known that structural stiffness and strength distributions have an important role in the seismic response of buildings. The effect of using different code-specified lateral load patterns on the seismic performance of fixed-base buildings has been investigated by researchers during the past two decades. However, no investigation has yet been carried out for the case of soil-structure systems. In the present study, through intensive parametric analyses of 21,600 linear and nonlinear MDOF systems and considering five different shear strength and stiffness distribution patterns, including three code-specified patterns as well as uniform and concentric patterns subjected to a group of earthquakes recorded on alluvium and soft soils, the effect of structural characteristics distribution on the strength demand and ductility reduction factor of MDOF fixed-base and soil-structure systems are parametrically investigated. The results of this study show that depending on the level of inelasticity, soil flexibility and number of degrees-of-freedoms (DOFs), structural characteristics distribution can significantly affect the strength demand and ductility reduction factor of MDOF systems. It is also found that at high levels of inelasticity, the ductility reduction factor of low-rise MDOF soil-structure systems could be significantly less than that of fixed-base structures and the reduction is less pronounced as the number of stories increases.

Influences of Ti substitution on the structure and electrochemical properties of Mg_(1-x)Ti_xNi(x=0,0.1, 0.2, and 0.3) hydrogen storage alloys

MgNi-based hydrogen storage alloys Mg1–xTixNi （x = 0, 0.1, 0.2, and 0.3） were prepared by means of mechanical alloying. Mg in the alloy was partially substituted by Ti to improve the cycle stability of the alloys. The effects of the substitution of Ti for Mg on the microstructure and electrochemical performances of the alloys were investigated in detail. The results indicate that the substitution of Ti for Mg obviously decreases the discharge capacity, but it significantly improves their cycle stabilities. The microstructure of the alloys analyzed by X-ray diffraction （XRD） and scanning electron microscopy （SEM） shows that the alloys have a dominatingly amorphous structure. The substitution of Ti for Mg helps to improve the anti-oxidation/corrosion ability of the MgNi alloy but demolishes the electrochemical kinetics of hydrogenation/dehydrogenation. The Mg0.9Ti0.1Ni alloy electrode milled for 80 h exhibits the best integrative capability, which has the maximal discharge capacity of 331.66 mAh/g and the C30/Cmax of 63.65%.

Characteristic Functional Structure of Infinitesimal Symmetry Transformations for Nonholonomic System

It was proved that velocity-dependent infinitesima l symmetry transformations of nonholonomic systems have a characteristic functio nal structure, which could be formulated by means of an auxiliary symmetry tra nsformation function and is manifestly dependent upon constants of motion of th e system. An example was given to illustrate the applicability of the results.

Analysis of cut vertex in the control of complex networks

The control of complex networks is affected by their structural characteristic. As a type of key nodes in a network structure, cut vertexes are essential for network connectivity because their removal will disconnect the network. Despite their fundamental importance, the influence of the cut vertexes on network control is still uncertain. Here, we reveal the relationship between the cut vertexes and the driver nodes, and find that the driver nodes tend to avoid the cut vertexes.However, driving cut vertexes reduce the energy required for controlling complex networks, since cut vertexes are located near the middle of the control chains. By employing three different node failure strategies, we investigate the impact of cut vertexes failure on the energy required. The results show that cut vertex failures markedly increase the control energy because the cut vertexes are larger-degree nodes. Our results deepen the understanding of the structural characteristic in network control.

Effect of spectral resolution on the measurement of monoaromatic hydrocarbons by DOAS

The excellent response characteristics and detection sensitivity with much lower operational cost and the capability to discriminate between the isomer of some monoaromatic hydrocarbons （MAHCs） make differential optical absorption spectroscopy （DOAS） a powerful tool to trace concentration variation of MAHCs. But due to the similarity in chemical structure, those MAHCs have the similar overlapped characteristic absorption structures, which make the selection of instrumental parameter critical to the accurate detection of MAHCs. Firstly, the spectral resolution used in DOAS system determines the nonlinear absorption of O2 and the mass dependence of characteristic absorption structure; thereby it determines the effect of elimination error of O2 absorption in the atmospheric spectra for the detection of MAHCs. Secondly, spectral resolution determines the differential absorption characteristics of twelve MAHCs representing major constituents in technical solvents used in the automobile industry and the interference of spectral overlapping. Thirdly, the spectral resolution determines the sensitivity, time resolution and linear range. So the spectral resolution range with the best ratio of signal to noise is used to determine the most suitable spectral resolution range, as well as the spectral resolution range that ensure the characteristic absorption structure of MAHCs and the minimization of O2 absorption interference. Finally, 0.15-0.16 nm （FWHM： full width at half maximum） is assumed to be closest to the optimum spectral resolution and it is confirmed by the results of practical measurement of MAHCs by DOAS.

The Characteristics and Pragmatic Strategies of English Euphemism

Some words may cause embarrassment in daily communication,and euphemism is a language type to avoid embarrassment.Euphemism is widely used in English expression.On the basis of exploring the characteristics of English euphemism in times,regionalism,register,and nationality,this paper discusses in detail the pragmatic functions of English euphemism from four dimensions,namely taboo,politeness,positivity,and concealment,in order to provide guidance for the proper use of English euphemism.

Study on the Distribution Law of Horizontal Seismic Forces between Slab-Column and Shear Wall

In slab column-shear wall structures,both the whole structure′s seismic behavior and failure mode are greatly influenced by the distribution of horizontal seismic forces between slab-column and shear wall.In this paper,a pushover analysis of topical slab column-shear wall structure was carried out,the seismic shear force that the slab-column and shear wall should undertake was worked out,the influences of plastic internal force redistribution and structure stiffness characteristic value on horizontal seismic distribution were studied and the calculation formula was given.The analysis results showed that with the yield of the shear walls,the story shear force was undertaken by slab-columns correspondingly increased while with the decrease of characteristic value of stiffness of a structure,and the horizontal seismic force was undertaken by slab-columns correspondingly decreased.According to the code,the design of horizontal force distribution may be cause insecurity problems,so it is necessary to give the distribution law of horizontal seismic forces in slab-column shear wall structures as the supplement to the corresponding regulation of the Code.

Dual Strengthened Control of Recrystallization Behavior on CVCDE Magnesium Alloy Containing Characteristic Structure

Various characteristic structures in typical magnesium alloys,including dislocation cells,substructures and twins,have an important influence on the dynamic recrystallization behavior,and the DRX(dynamic recrystallization)behavior is closely related to the grain refinement and texture weakening of the hot deformed structure.Therefore,this study reveals the influence of the above characteristic structures on the dynamic recrystallization behavior of magnesium alloys,which have great significance for regulating the high-performance hot deformed microstructure of magnesium alloys and optimizing the macro mechanical properties.In this study,continuous variable channel direct extrusion(CVCDE)magnesium alloy was prepared by CVCDE,and its macro mechanical properties including hardness and uniaxial tension were characterized.The thermoplastic deformation behavior and texture evolution of magnesium alloy with characteristic structure were analyzed by electron back-scattering diffraction technology.It is found that the dislocation recombination was realized by deformation mechanism(slip,climb and cross slip),the formation of grain substructure in coarse grains and the induction of recrystallization by twins promote the recrystallization behavior in hot deformed structures more adequate,which effectively improves the degree of microstructure refinement and deformation uniformity.

Effect of Ni/(La+Mg) Ratio on Structure and Electrochemical Performance of La-Mg-Ni Alloy System

As the alloy with the most suitable Ni/（La＋Mg） ratio has higher capacity and good cycle stability,the effects of Ni/（La＋Mg） ratios on the electrochemical performances of the La0.80Mg0.20Nix （x=3.5 to 5.0） alloys have been investigated to find the most suitable Ni/（La＋Mg） ratio. The results of XRD and SEM observations show that the phase composition of the alloys varies with different Ni/（La＋Mg） ratios. When Ni/（La＋Mg） is not more than 4.25,all the alloys contain LaNi5 and （La,Mg）2Ni7 phases,in addition,the LaMg and （La,Mg）Ni3 phases exist in the x=3.5 and 3.75 alloys,respectively. The LaMg2Ni9 phase exists in the x=4.25 alloy. There are the LaNi5 and LaMg2Ni9 phases in the x=4.5,4.75,and 5.0 alloys. The phase abundance and cell volume change with different Ni content. When the Ni/（La＋Mg） ratio is not more than 4.25,the alloys possess excellent activation capability,however,the activation capabilities of the alloys decrease with a further increase in the Ni/（La＋Mg） ratio. With increasing the Ni/（La＋Mg） ratio,the maximum discharge capacities,the medium voltages,and the cycle stabilities of the alloys first increase and then decrease. When the Ni/（La＋Mg） ratio is 3.75,the corresponding alloy has the maximum discharge capacity among all the alloys. However,the cycle stability of the Ni/（La＋Mg）=4.0 alloy is better than that of the others.

Landscape characteristic aesthetic structure： Construction of urban landscape characteristic time-spatial pattern based on aesthetic subjects

The paper presents means and models of city-landscape characteristic structure construction on the aspect of landscape aesthetics subjects, which is called the landscape characteristic aesthetic structure and in short as LCAS. In this paper, the steps of LCAS research are as follows： Describes the concepts of the landscape characteristic aesthetic structure （LCAS）, and expounds the LCAS properties： systematic quality, temporal and spatial quality, and virtual existence. Learns from typology research methods, discusses the elements and types needed in a landscape characteristic aesthetic system, and constructs research method for LCAS pattern. As for the temporal dimension, the dynamic evolution and interaction expressed in LCAS between the ＂tradition＂ and ＂modernity＂ landscapes conflict. As for the spatial dimension, this paper explores the LCAS patterns in macroscopic scope of city group, the middle scope of single cities and the microcosmic scope of urban spaces with questionnaires and examples research.

The Characteristic of Threading Dislocation in Different Structures GaN Films Grown by MOCVD

Three mechanisms to reduce threading dislocations(TDs) in GaN films as the epitaxial films grow thicker are suggested by SEM and

Structures,properties,and applications of zwitterionic polymers

Zwitterionic polymers have attracted research attention in recent years owing to their unique molecular struc-tures.In the same repeat unit,positive and negative charges are simultaneously located on a pair of cationic and anionic groups;therefore,zwitterionic polymers have a large dipole moment and numerous charged groups.Al-though the molecular chain of the zwitterionic polymer can be maintained in an electrically neutral state overall,the coexistence of the oppositely charged groups confers extremely high polarity and excellent hydrophilicity to the polymer.At the same time,the electricality of the polymer can be further regulated by the environmental pH and salt ions,which greatly broadens the scope of applications in different fields.This review introduces various structures of zwitterionic polymers and analyzes the reasons why zwitterionic polymers exhibit pH responsive-ness,anti-polyelectrolyte effects,and superior electrical conductivity.The application fields are also summarized by generalizing the research status of zwitterionic polymers,including applications in antifouling coatings,drug delivery,wastewater treatment,and sensors,etc.

Multiple characteristic structure fragments scans coupled to high-resolution mass spectrometry strategy for discovering unknown structural analogs of mycotoxins in food

The cereals and their products,which have been easily infected by fungi and contaminated with mycotoxins,are serious threat to both human and animals alike.And yet,detection of these unknown fungal infection and mycotoxins contaminates remains a great challenge.In this work,a holistic approach based on multiple characteristic structure fragments scans and high-resolution mass spectrometry(HRMS)was proposed for discovering unknown structural analogues of mycotoxins.The structural similarity of the same class of compounds provides a direction for the discovery and identification of unknown structural analogues of mycotoxins.The following steps were carried out:the fragmentation pathways of four types of mycotoxins were elucidated through comprehensive fragment analysis.By the combination of fragmentation pathways,the multiple characteristic structure fragments were screened out,with the common fragments were obtained by Veen diagram.Finally multiple characteristic structure fragments scans were carried out to find the unknown structural analogues of mycotoxins.The approach,first proposed by us,was proved to be effective in discovering and identifying 5 structural analogues of mycotoxins in real samples.It was proved to be a simple,fast and accurate method for early detection of fungal infection and mycotoxin contaminants,even for trace amounts of chemicals in complex matrix,and is of great significance to prevent hazardous substances infection from the food supply chains worldwide.

Research on the temperature characteristic of Love wave device with structure of multi-waveguides used for gas sensor

This paper aimed at extracting optimal structural parameters for Love wave device with structure of multi-waveguides to improve its temperature stability. The theoretical model dealing with the Love wave propagation in multi-waveguides was established first, the dispersion characteristic is depicted by the acoustic propagation theory of stratified media and boundary conditions. Combing with the dispersion characteristics and Tomar＇s method, the optimal structural parameters for the Love wave device with zero temperature coefficient were extracted, and confirmed by the following experimental results. Excellent temperature coefficient of the Love wave device with SU-8/SiO2 on ST-90°X quartz substrate was evaluated experimentally as only 2.16 ppm/℃, which agrees well with the calculated results. The optimized Love wave device is very promising in gas sensing application.

Influences of Shrinkage,Creep,and Temperature on the Load Distributions in Reinforced Concrete Buildings During Construction

Site measurements have shown that slab loads re-distribute, between the slabs during the concrete curing, while the external Ioadings and structural geometry remain the same. Some have assumed that this is caused by concrete shrinkage and creep, but there have been no studies on how these factors exactly influence the load distributions and to what degree these influences exist. This paper analyzes the influences of concrete shrinkage, creep, and temperature on the load re-distributions among slabs. Although these factors may all lead to load re-distribution, the results show that the influence of concrete shrinkage can be neglected. Simulations indicate that shrinkage only reduces slab loads by a maximum of 1.1%. Creep, however, may reduce the maximum slab load by from 3% to 16% for common construction schemes. More importantly, temperature variations between day and night can cause load fluctuation as large as 31.6%. This analysis can, therefore, assist site engineers to more accurately estimate slab loads for construction planning.

Load Distribution Assessment of Reinforced Concrete Buildings During Construction with Structural Characteristic Parameter Approach

High-rise reinforced concrete buildings are in great demand in developing countries with rapid urbanization. Construction engineers are facing more and more safety control challenges. One major issue is the understanding of the load distributions, especially the maximum slab load, of structures under construction, which is time dependent. Previous methods were mainly targeted to specific examples, providing specific solutions without addressing the fundamental issues of finding general solutions for load distributions in reinforced concrete buildings with different geometrical and material characteristics during construction. The concept of a structural characteristic parameter is used here to parametedze the main geometrical and material characteristics of concrete structures for generalized assessments of load distributions during construction. The maximum slab load for 20 different construction shoring/reshoring schemes is presented. The results indicate that the traditional simplified method may underestimate or overestimate the maximum slab load, depending mainly on the shoring/reshoring schemes. The structural characteristic parameter approach was specifically developed to assist construction engineers to estimate load distributions to assure safe construction procedures.

Characterization of( Nb,Ti,Mo) C Precipitates in an Ultrahigh Strength Martensitic Steel

A study on ultrahigh strength steel plate subjected to novel thermo-mechanical control process was presented. The mechanical properties examination showed that the investigated steel exhibited excellent combination of ultra-high strength（ 2 200 MPa） and toughness（ 26 J）. The microstructure of the experimental steel was observed by scanning electron microscope and transmission electron microscope. Desired martensitic lath with width of about 180- 250 nm was obtained. Nanostructured carbide precipitates with sizes of 20-50 nm,which contained Nb,Ti and Mo,were observed in the lath martensitic microstructure,and confirmed to be MC-type carbides with B1 structure by means of selected area electron diffraction.The compositional characteristics revealed by energy dispersive X-ray spectrometer mapping implied that the carbide forming elements Nb,Ti and Mo distributed in the precipitates evenly. Three-dimensional atom probe tomography reconstruction further indicated that Mo incorporated into the precipitates without enrichment in the carbide-matrix interface and probably substituted for Nb and Ti to form the（ Nb,Ti,Mo） C carbides.

Structural characteristics of cement-stabilized soil bases with 3D finite element method

Cement-stabilized soil bases have been widely used in expressways due to its high strength,appropriate stiffness,good water resistance,and frost resistance.So far,the structural characteristics and mechanical behaviors of cement-stabilized soil bases were not investigated so much.In this paper,the 3D elastic-plastic finite element method(FEM)was used to analyze the mechanical behaviors and structural characteristics of cementstabilized soil bases from construction to operation.The pavement filling and the traffic loading processes were simulated,and a contact model was used to simulate the contact behavior between each layer of the pavement.Considering the construction process,the structural characteristics and mechanical behaviors of cementstabilized soil bases were studied under asphalt-concrete pavement conditions.Furthermore,the general rules of deformations and stresses in cement-stabilized soil bases under different conditions were discussed,and some suggestions were put forward for the design and construction of cement-stabilized soil bases.

Latest Advances in Climate Change Detection Techniques

In recent years,the global warming and its influences on people and social economy have received increasing attention from international communities.Determining the current trend of global temperature variation has become one of the critical issues in climate change research.Obviously,it is rather important to develop new climate change detection technology in order to identify new characteristics of the global warming.This review introduces the latest advances and past achievements on the climate change detection technology in China with emphases on new detection methods in the following five aspects：（1） abrupt climate change detection,（2） signal separation and extraction from observed data,（3） intrinsic complexity of the climate system,（4） recognition of the dynamical characteristics of the climate system,and（5） definitions and detection of extreme events.At last,some cruxes and key problems in the current climate change detection technology research are briefly discussed.