Performance Characterization of CR/PU Asphalt for Potential Application in Assembled Fast-Repairing Engineering

Conventional repairing methods for asphalt pavement have some inconveniences,such as insufficient strength,and are typically time-consuming.To address these issues,this study proposes a new technological method to design and prepare a high-performance assembled asphalt concrete block for fast repair of the potholes.A series of composite modified asphalt binders with 10%crumb rubber(CR)and different dosages(0%,1%,3%,5%)of polyurethane(PU)are examined to determine the optimized binder.Subsequently,the corresponding asphalt mixtures are prepared for further comparison and assessment of engineering properties,such as moistureinduced damage,high-temperature deformation,and low-temperature cracking characteristics.The test results show that PU can significantly improve the high-temperature performance and hardness of(crumb rubber modified asphalt)CRMA binder;3%PU contributes allowing the resistance of CRMA mixture to moisture-induced damage at higher levels,particularly under water whole immersion;as 3%PU is added,the high-temperature rutting deformation resistance of the CRMA mixture increases significantly,and the low-temperature anti-cracking properties are also improved slightly.Therefore,the innovatively designed high-quality assembled fast-repairing asphalt concrete block is recommended as an appropriate option for highway maintenance.

Numerical Simulation-Based Analysis of the Impact of Overloading on Segmentally Assembled Bridges

Segmentally assembled bridges are increasinglyfinding engineering applications in recent years due to their unique advantages,especially as urban viaducts.Vehicle loads are one of the most important variable loads acting on bridge structures.Accordingly,the influence of overloaded vehicles on existing assembled bridge structures is an urgent concern at present.This paper establishes thefinite element model of the segmentally assembled bridge based on ABAQUS software and analyzes the influence of vehicle overload on an assembled girder bridge struc-ture.First,afinite element model corresponding to the target bridge is established based on ABAQUS software,and the load is controlled to simulate vehicle movement in each area of the traveling zone at different times.Sec-ond,the key cross-sections of segmental girder bridges are monitored in real time based on the force character-istics of continuous girder bridges,and they are compared with the simulation results.Finally,a material damage ontology model is introduced,and the structural damage caused by different overloading rates is compared and analyzed.Results show that thefinite element modeling method is accurate by comparing with on-site measured data,and it is suitable for the numerical simulation of segmental girder bridges;Dynamic sensors installed at 1/4L,1/2L,and 3/4L of the segmental girder main beams could be used to identify the dynamic response of segmental girder bridges;The bottom plate of the segmental girder bridge is mostly damaged at the position where the length of the precast beam section changes and the midspan position.With the increase in load,damage in the direction of the bridge develops faster than that in the direction of the transverse bridge.Thefindings of this study can guide maintenance departments in the management and maintenance of bridges and vehicles.

Application Strategies of Modular Design in Assembled Teaching Buildings

As an efficient,environmentally friendly,energy-saving construction method,assembled buildings are now widely used in campus building construction.Modular design thinking is system-based design thinking,and its application to the design of an assembled teaching building project will comprehensively improve the rationality of the teaching building and component design.The paper focuses on the application of modular design thinking in assembled teaching building design,aiming to provide references for China’s architectural design units,giving full play to the advantages of modular design thinking in future teaching building design projects,and enhancing the level of design,for the construction of the teaching building and the basis of the technical guarantee.

Electrodeposited 3D hierarchical NiFe microflowers assembled from nanosheets robust for the selective electrooxidation of furfuryl alcohol

A robust and green strategy for the selective upgrading of biomass-derived platform chemicals towards highly valuable products is important for the sustainable development.Herein,the efficient electrocatalytic oxidation of biomass-derived furfuryl alcohol(FFA)into furoic acid(FurAc)catalyzed by the electrodeposited non-precious NiFe microflowers was successfully reached under the low temperature and ambient pressure.The 3D hierarchical NiFe microflowers assembled from ultrathin nanosheets were controllably synthesized by the electrodeposition method and uniformly grown on carbon fiber paper(CFP).Electrochemical analysis confirmed that NiFe nanosheets more preferred in the selective oxidation of FFA(FFAOR)than oxygen evolution reaction(OER).The linear sweep voltammetry(LSV)in FFAOR displayed a clear decrease towards lower potential,resulting in 30 mV reduction of overpotential at 20 mA cm^(-2) compared with that of OER.The optimal catalyst Ni_(1)Fe_(2) nanosheets exhibited the highest selectivity of FurAc(94.0%)and 81.4%conversion of FFA within 3 h.Besides,the influence of various reaction parameters on FFAOR was then explored in details.After that,the reaction pathway was investigated and rationally proposed.The outstanding performance for FFAOR can be ascribed to the unique structure of 3D flower-like NiFe nanosheets and oxygen vacancies,resulting in large exposure of active sites,faster electron transfer and enhanced adsorption of reactants.Our findings highlight a facile and convenient mean with a promising green future,which is promising for processing of various biomass-derived platform chemicals into value-added products.

Response Spectrum Analysis of 7-story Assembled Frame Structure with Energy Dissipation System

Viscoelastic damper is an effective passive damping device,which can reduce the seismic response of the structure by increasing the damping and dissipating the vibration energy of structures.It has a wide application prospect in actual structural vibration control because of simple device and economical material.In view of the poor seismic behaviors of assembled frame structure connections,various energy dissipation devices are proposed to improve the seismic performance.The finite element numerical analysis method is adopted to analyze relevant energy dissipation structural parameters.The response spectrum of a 7-story assembled frame structure combined the ordinary steel support,ordinary viscoelastic damper,and viscoelastic damper with displacement amplification device is analyzed.The analysis results show that the mechanical behavior of assembled frame structure with ordinary steel supports are not significantly different from those without energy dissipation devices.The assembled frame structure with viscoelastic damper has better seismic performance and energy dissipation,especially for the viscoelastic damper with displacement amplification devices.The maximum value of inter-story displacement angle decreases by 32.24%;the maximum floor displacement decreases by 31.91%,and the base shear decreases by 13.62%compared with the assembled frame structures without energy dissipation devices.The results show that the seismic fortification ability of the structure is significantly improved,and the overall structure is more uniformly stressed.The damping structure with viscoelastic damper mainly reduces the dynamic response of the structure by increasing the damping coefficient,rather than by changing the natural vibration period of the structure.This paper provides an effective theoretical basis and reference for improving the energy dissipation system and the seismic performance of assembled frame structures.

Analysis of Soundproof Technology of Assembled Steel Structure Houses

The problem of noise has always been highlighted in assembled steel structure houses.Therefore,it is necessary to use effective soundproof measures where steel beams intersect with the reserved line pipe openings,doors,windows,elevator shafts,and other locations.In this paper,we will investigate the areas with subpar soundproof performance in an assembled steel structure residential project and propose suitable noise control measures to address this issue.

In vitro corrosion and antibacterial properties of layer-by-layer assembled GS/PSS coating on AZ31 magnesium alloys

To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate（GS） and poly（sodium 4-styrene sulfonate）（PSS）, were prepared via layer-by-layer（Lb L） assembly. The morphologies, chemical compositions and corrosion resistance of the obtained（PSS/GS）n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of（PSS/GS）n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.

Novel Kriging-Based Decomposed-Coordinated Approach for Estimating the Clearance Reliability of Assembled Structures

Turbine blisks are assembled using blades,disks and casings.They can endure complex loads at a high temperature,high pressure and high speed.The safe operation of assembled structures depends on the reliability of each component.Monte Carlo(MC)simulation is commonly used to analyze structural reliability,but this method needs to run thousands of computations.In order to assess the clearance reliability of assembled structures in an efficient and precise manner,the novel Kriging-based decomposed-coordinated(DC)(DCNK)approach is proposed by integrating the DC strategy,the Kriging model and the importance sampling-based Markov chain(MCIS)technique.In this method,the DC strategy is used to decompose a multi-objective problem into many single-objective problems.The relationships between these many single-objectives and the overall objective are then coordinated.The Kriging model is applied to establish the limit state functions of the single-objectives and multi-objective problems,while the MCIS method is used to assess the structural assembled clearance reliability.Moreover,a highly nonlinear complex compound function is first utilized to verify the DCNK model from a mathematical perspective.Then,the reliability of an aeroengine high-pressure turbine(HPT)blade-tip radial running clearance(BTRRC)is analyzed to validate the DCNK approach by considering thermo-structural interaction.The analytical results show that the reliability is 0.9976 when the allowance value of the BTTRC is 1.7650×10^(−3)m.Compared with different methodologies(including direct simulation,the classical Kriging model,and the weighted response surface method(WRSM)),the proposed method holds obvious advantages in computing time and precision,as well as simulation efficiency and precision.The efforts of this paper provide a useful approach to analyzing assembled clearance reliability and contribute to the development of structural reliability theory.

Application of virtual material in joint surface of complex assembled structures

In order to acquire the dynamic characteristics of joint surfaces of complex assembled structures, a novel parameter identification technique was adopted. Virtual materials were introduced to simulate the stiffness and damping features of the joint surfaces between two different structures. Properties of the virtual materials, including elasticity modulus, density, and Poisson ratio, were gradually modified. At last, FEM modal results of the assembled structures are consistent with the experimental ones. This proves the feasibility of the simulating method and paves a solid foundation of the further research of the dynamic simulation.

Distribution of Ge Self-Assembled Quantum Dots on Six Ge1 - x Buffer Layers

The effect of buried misfit dislocation on the distribution of Ge self-assembled quantum dots (SAQDs) grown on a relaxed SiGe buffer layer was investigated. The strain field of arrays of buried dislocations in a relaxed SiGe buffer layer provided preferential nucleation sites for quantum dots. Burgers vector analysis using plan-view transmission electron microscopy (TEM) verified that the preferential nucleation sites of Ge SAQDs depended on the Burgers vector direction of corresponding dislocations. The measurement of the lateral distance between SAQDs and dislocations together with crosssection TEM observation clarified that the location of SAQDs was at the intersection of the dislocation slip plane and the top surface. The misfit strain should be an additional factor governing the uniformity in size, shape and distribution of Ge SAQDs.

Research on the influence of grouted sleeves and assembled seams on the deformation and bearing capacity of compression-flexure member

Grouted sleeves can effectively connect precast elements,but the effect of grouted sleeves for increased stiffness and assembled seam for weakening stiffness on the precast column’s mechanical properties is unclear.Based on the full-scale test results of precast columns connected with grouted sleeves and the correctness of the numerical models,the influence analysis of the individual and coupling action of the grouted sleeves and assembled seam on the deformation and bearing capacity of the precast column is carried out.The research results show that grouted sleeves significantly affect the deformation and peak bearing capacity of precast columns;when precast columns are subjected to the action of high axial pressure,grouted sleeves significantly affect the bearing capacity.However,the influence of assembled seams on the peaking capacity of the precast column is more obvious when it was tested under low axial compression.It is recommended that the connection position should be 2 times the height of the grouted sleeve from the bottom of the foundation.

Self Assembled Monolayer Films of C_（60） on O，O＇－Bis（2－aminoethyl）dithiophos Modified Copper

On the surface of O,O'-bis(2-aminoethyl) dithiophosphate modified copper C60forms self-assembled monolayer films (SAMs) through the chemical bond. The film was characterized by contact angle, X-ray photoelectron spectroscopy, electrochemisny, TOF Mass Spetropy.

Power-Dependent Luminescence of CdSe/ZnS Nanocrystal Assembled Layer-by-Layer on a Silver Nanorod Array

We investigate the power-dependent luminescence of CdSe/ZnS semiconductor quantum dots closely packed layer- by-layer in the proximity of a silver nanorod array cavity. It is found that the emission peak shifts significantly to the longer wavelengths as the excitation power increases, especially when the longitudinal surface plasmon resonance of the Ag nanorod array cavity is adjusted to be close to the emission wavelength. The equivalent gain varies with the coating layer of CdSe/ZnS semiconductor quantum dots and the excitation power is also studied to explain this interesting spectrum-shifting effect. These findings could find applications in the dynamic information processing of active plasmonic and photonic nanodevices.

A Theoretical Study of Light Absorption in Self Assembled Quantum Dots

Self assembled quantum dots have shown a great promise as a leading candidate for infrared detection at room temperature. In this paper, a theoretical model of the absorption coefficient of quantum dot devices is presented. Both of bound to bound absorption and bound to continuum absorption are taken into consideration in this model. This model is based on the effective mass theory and the Non Equilibrium Greens Function (NEGF) formalism. NEGF formalism is used to calculate the bound to continuum absorption coefficient. The results of the model have been compared with a published experimental work and a good agreement is obtained. Based on the presented model, the bound to bound absorption coefficient component is compared to the bound to continuum absorption coefficient component. In addition, the effects of the dot dimensions and electron filling on the bound to continuum absorption coefficient are also investigated. In general, increasing the dot filling increases the absorption and decreasing the dots dimensions will increase the absorption and move the absorption peak towards longer wavelengths.

Thruster direction controlling of assembled spacecraft based on gimbal suspension

The attitude control system design and its control effect are affected considerably by the mass-property parameters of the spacecraft. In the mission of on-orbit servicing, as fuel is expended, or the payloads are added or removed, the center of mass will be changed in certain axe; consequently, some thrusters＇ directions are deviated from the center of mass（CM） in certain plane. The CM of assembled spacecraft estimation and thruster direction control are studied. Firstly, the attitude dynamics of the assembled spacecraft is established based on the Newton-Euler method. Secondly, the estimation can be identified by the least recursive squares algorithm. Then, a scheme to control the thrusters＇ directions is proposed. By using the gimbal installed at the end of the boom, the angle of the thruster is controlled by driving the gimbal; therefore, thrusters can be directed to the CM again. Finally, numerical simulations are used to verify this scheme. Results of the numerical simulations clearly show that this control scheme is rational and feasible.

Design of Assembled PCB Imaging System Based on Laser Triangulation

With the increasing miniaturisation and integration of electronic products and the increase of heat, it is necessary to design and introduce heat sinks and install fans. The volume of electronic components, especially the height, is very important for the structural and thermal design of electronic devices. This paper presents a design scheme of an online height measurement device based on laser triangulation and commercial charge coupled device(CCD). It analyzes the principles of electronic component height measurement, and expounds the composition and working principle of the laser measurement system. In addition, the commonly used methods to determine the center position are compared and analysed. These methods include circle fitting, gray centroid and extension method or Gaussian fitting. These methods usually lead to different results. The experimental results show that the fitting speed of the gray centroid is faster. The 3 D model of components is given through measurement, and the error factors affecting measurement are analysed.

“Integrated”Solution and Engineering Application of Assembled Cable-Stayed Pedestrian Landscape Overbridge

The construction of modern cities emphasizes the nature and harmony among the“people”,“things”and“environment”,reflecting the harmony and unity of the formal beauty,functional beauty and surrounding environment of architecture.Based on the introduction of the design concept of the assembled pedestrian overbridge,through the Jianhua Building Materials Group’s first“pre-fabricated low-rise tower-stayed pedestrian landscape overbridge”project in China,this paper proposes a solution that can improve the landscape design of the overbridge and reduce the construction complexity of the overbridge,the assembly product supply and the construction process“integration”under the premise of ensuring the safety and stability of the pedestrian overbridge,whose prefabricated production and assembly construction,shortening the construction period,reducing energy consumption,reducing pollution,and obtaining good social comprehensive benefits.

In vitro corrosion resistance and antibacterial properties of layer-by-layer assembled chitosan/poly-L-glutamic acid coating on AZ31 magnesium alloys

Surface functionalization of magnesium(Mg)alloys is desired to obtain the surfaces with both improved corrosion resistance and antibacterial property.A corrosion-resistant and antimicrobial coating was prepared on Mg alloy surface by layer-by-layer(LbL)assembly of chitosan(CHI)and poly-L-glutamic acid(PGA)by electrostatic attraction.The functionalized surfaces of the Mg alloys were characterized by field-emission scanning electron microscopy(FE-SEM),Fourier transform infrared(FT-IR)spectroscopy and electrochemical tests.The bactericidal activity of the samples against Staphylococcus aureus was assessed by the zone of plate-counting method.The obtained coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance.

In vitro corrosion resistance,antibacterial activity and cytocompatibility of a layer-by-layer assembled DNA coating on magnesium alloy

A chitosan/deoxyribonucleic acid(CHI/DNA)_(5)coating was constructed by layer-by-layer(LbL)assembly dip coating method with Mg(OH)_(2)coating as an inner protective layer on AZ31 alloy.X-ray diffractometry,X-ray photoelectron spectrometry,Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were utilized to represent the chemical compositions and surface morphologies of the coatings.Electrochemical tests and hydrogen evolution measurements were implemented to confirm the good corrosion resistance of the composite coating in artificial body fluid.Antimicrobial activity of the composite coatings was tested via the plate-counting method,and the cytotoxicity of the samples was appraised by MTT assay and Live/dead staining.A double action was put into effect for the composite coating,which the inner Mg(OH)2 coating plays the part of physical barrier,and the outer(CHI/DNA)5 coating is employed as an inducer to fabricate a biocompatible Ca-P corrosion product coating during immersion,making up for its thin thickness.Otherwise,the composite coating is also beneficial for the growth of bone,resulting from the biomineralization effect of the outer polyelectrolyte multilayer.The good antibacterial property of the(CHI/DNA)5/Mg(OH)2 coating is ascribed to the contact-killing strength of CHI.Thus,the obtained(CHI/DNA)5/Mg(OH)2 coating has a wide application prospect in the field of Mg-based bone implantation.

Thermal analysis of an LED module with a novelly assembled heat pipe heat sink

This work aims to improve the thermal performance of a light emitting diode(LED) module by employing a novelly assembled heat pipe heat sink. The heat pipe was embedded into the heat sink by a phase change expansion assembly(PCEA) process, which was developed by both finite element(FE) analysis and experiments. Heat transfer performance and optical performance of the LED modules were experimentally investigated and discussed. Compared to the LED module with a traditionally assembled heat pipe heat sink, the LED module employing the PCEA process exhibits about 20% decrease in the thermal resistance from the MCPCB to the heat pipe. The junction temperature is 4% lower and the luminous flux is 2% higher. The improvement in the thermal and optical performance is important to the high power LED applications.