Search

The paper investigates the shear mechanic performance of transformed triangular corrugated steel plates (TT-CSPs) with top stringers applied in the trestle, incorporating a comprehensive analysis of how plate dimensions and corrugation density affect both elastic and inelastic buckling capacities. By proposing and validating formulas for the ultimate shear-bearing capacity through finite element analysis (FEA), this paper advances a capacity prediction approach that accounts for the finite rigidity of top stringers by introducing a reduction factor. The results reveal that corrugation density significantly impacts both elastic buckling load and ultimate strength, with plate width playing a more crucial role than height in determining capacity. Furthermore, the inclusion of top-stringer flexural rigidity is shown to notably enhance the shear-bearing capacity of TT-CSPs, providing a vital consideration for their strength design. [Display omitted] • Proposed formula for global elastic shear buckling load of transformed triangular corrugated steel plates (TT-CSP) • Proposed a comprehensive design method to predict shear-bearing capacity of TT-CSPs, considering top stringer constraints • Study the impact of corrugated plate and corrugation dimensions on elastic and inelastic buckling capacity of TT-CSPs • Reveal the contribution of top stringers to shear resistance of built-up TT-CSPs [ABSTRACT FROM AUTHOR]

Anti-phase boundary energy (APBE) is a vital contributing factor for the dislocation shearing mechanism which operates in Mg-RE alloys. To clarify the structure and composition dependence of APBE and provide the guidance for strength improvement of Mg alloys, the formation energy, misfit strain, and APBE of β series precipitates in Mg-Y-Nd system are investigated by first-principles calculations. The atomic occupations of ternary precipitates are determined based on misfit strains. The APBEs of β p ″ ′ phases are higher than that of β s ′ , and precipitates in Mg-Nd system possess higher APBEs than their counterparts in Mg-Y system. The higher APBEs enable larger strength increments of precipitates in Mg-Nd system than Mg-Y system when the amount of Y and Nd are the same. However, when both elements reach their solubility limit, the large amount of Y makes up the low APBE and achieves superior strength increment than the precipitates in Mg-Nd system. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In order to understand the strengthening mechanism and achieve the rational properties regulation of long-period stacking ordered phases (LPSO) contained Mg alloys, thermodynamic stability, transformation energies and elastic properties of LPSO in Mg–Zn–Y and Mg–Ni–Y systems are investigated via first-principles calculations. 14H-type LPSO (14H) is predicted to be the stable phase. Furthermore, the transformation energies from other LPSO to 14H are small, implying their appearance as metastable phases in Mg alloys. All LPSO phases contribute to the strength increment, especially for 14H that has the maximum effect, uncovering the availability of the property regulation through LPSO design. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The contact interaction between the core and external restraining members is a vital factor that affects the overall performance of buckling-restrained braces (BRBs) significantly. In this study, refined finite element (FE) model was employed to evaluate the contact force between the core and external restraining members and to investigate the BRB performance. Moreover, the influences of strength and stiffness of external restraining member, core length, and other geometric parameters on the BRB performance were also studied. On the basis of numerical results obtained in the study, the recommended values of core width-to-thickness ratio, core thickness and gap were proposed. By considering the core plasticity and the lateral restraint of external restraining member, some formulas for predicting the half-wave length of core buckling as well as contact force were also proposed while the core buckled in multi-wave form. These formulas were numerically verified and could be references in the design of BRB. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the behavior of steel plate shear walls (SPSWs) with pre-compression from adjacent frame columns which is produced in the construction process. Firstly, some parameters used in analytical finite element models, such as the stiffness of frame beams and columns and the magnitude of the loads are discussed. Then, numbers of numerical examples are analyzed and show that the influence of pre-compression varies with the dimension of SPSWs. Also, the distribution and transferring of axial forces between frame columns and SPSWs during loading are discussed. Finally, a reduction coefficient of shear-carrying capacity of SPSW due to pre-compression is proposed. [Copyright &y& Elsevier]

Abstract: New biodegradable poly(ester urethane)/soy protein isolate (PEU/SPI) hybrids were prepared by in situ polymerization. The chemical incorporation of the SPI into the backbone chain of the PEU was facilitated by the reaction of the amine functional groups of SPI with methylene diphenyl diisocyanate (MDI). X-ray diffraction results showed that the chemical incorporation of SPI into PEU significantly changed the molecular structure of the PEU. The PEU/SPI hybrids exhibited higher thermal decomposition temperature and significant increase in the modulus compared with that of pure PEU. Microscopic examination of the morphology of PEU/SPI hybrids confirmed very fine and homogeneous SPI dispersion in PEU. The hydrolytic degradation of the PEU in a phosphate buffer solution was accelerated by incorporation of SPI, which was confirmed by water absorption and scanning electron microscopy of the samples after up to 10 weeks immersion in the buffer solution. This study provides a facile and innovative method of controlling the biodegradation rate of pure PEU with the additional advantage of environmentally-benign biodegradation of the hybrid PEU/SPI polymer, making the concept potentially widely applicable. [Copyright &y& Elsevier]

Abstract: Multi-tube latticed steel columns without diagonal tubes and the ones with diagonal tubes are two common types of prismatic latticed columns used nowadays. Instability behavior of prismatic multi-tube latticed steel columns is studied in this paper. The focus on the problem is based on the derivation of shear stiffness for multi-tube latticed steel columns. Formulas are established to express the elastic buckling loads as well as the modified slenderness ratios, in which the effect of shear deformation is taken into account. Cases are analyzed via finite element method ANSYS to calculate the ultimate load-carrying capacity of the latticed columns for comparison with the design method in different design codes for compressive members. Formulas to estimate the design resistance for axial compressive prismatic multi-tube latticed steel columns are proposed and detailed design suggestions for the component steel tubes are presented as well. [Copyright &y& Elsevier]

Abstract: Novel biodegradable and biocompatible poly(ester-urethane)s were synthesized by in situ homogeneous solution polymerization of poly(ɛ-caprolactone) diol, dimethylolpropionic acid (DMPA), and methylene diphenyl diisocyanate in acetone followed by solvent exchange with water. The effects of the DMPA content and hard segment content on the properties of the polyurethanes were measured by DSC, TGA, and hydrolytic degradation measurements. The results showed that DMPA had a dramatic effect on the particle size; the particle size decreased rapidly with increasing DMPA content. The hydrolytic degradation test showed that the degradation rate was little affected by the DMPA content in the range investigated, but was observed to be influenced by the hard segment content. Cell toxicity analysis showed that the biodegradable poly(ester-urethane)s synthesized in this study did not exhibit any detectable toxicity to human umbilical vein endothelial cells and mouse embryonic stem cells. Both types of cells can effectively adhere to and spread on the surface of pure poly(ɛ-caprolactone) or poly(ester-urethane)s. The present study demonstrates the feasibility of a facile synthesis of biodegradable polyurethanes and of their aqueous dispersions with prescribed properties for biomedical applications. [Copyright &y& Elsevier]

This study proposes a new remote sensing technique to measure three-component (3C) dynamic displacement of three-dimensional (3D) structures. A sensing system with a UAV platform and contact-free sensors (e.g., optical and infrared (IR) cameras) is employed to provide a portable and convenient alternative to conventional approaches that require sensor installation on a structure. The original contributions of this study include (1) integrating both optical and IR cameras with a UAV platform to measure dynamic structural response, and (2) developing new data post-processing algorithms (based on target identification, Direct Linear Transformation, and active stereo vision) to simultaneously extract the 3C displacement of a 3D structure from optical and IR videos, which presents a unique advantage compared to the existing UAV-based displacement measurement techniques that allow the measurements in only one or two directions using optical cameras or laser sensors. The efficacy of the proposed technique is validated through laboratory experiments. [Display omitted] • 3D dynamic displacements are measured simultaneously. • Optical/infrared sensors and a UAV are integrated to a portable sensing system. • Algorithms using active stereo vision are developed to measure depth displacement. • High measurement accuracy is achieved with a fast-computational speed. [ABSTRACT FROM AUTHOR]

A 100-day feeding trial was conducted to investigate the effects of dietary lipid on growth performance and lipid deposition as well as the regulation mechanism in abalone Haliotis discus hannai Ino. Abalones (initial weight: 10.98 ± 0.05 g) were fed with graded levels of dietary lipid (1.57%, 2.34%, 3.17%, 3.82%, 4.63%, 5.56%, 6.17% and 6.72%). Results showed that weight gain rate (WGR) and increment in shell length of abalone were highest in 3.82% dietary lipid level. Based on the quadratic regression analysis for WGR, the optimal dietary lipid level for abalone was estimated to be 3.87%. Concentrations of the total triacylglycerol, low-density lipoprotein cholesterol and non-esterified fatty acids in serum as well as lipid contents in hepatopancreas and muscle were positively related to dietary lipid levels. Compared to the group with 3.82% of dietary lipid, higher (6.72%) and lower (1.57%) dietary lipid down regulated the expression of genes involved in fatty acids transport and lipolysis in hepatopancreas and muscle, which might be related to AMP-activated protein kinase α2 (AMPKα2)/peroxisome proliferator-activated receptor α (PPARα) signaling. Higher dietary lipid (6.72%) down regulated, while lower dietary lipid (1.57%) up-regulated the expressions of genes involved in de - novo lipogenesis in hepatopancreas. Both higher (6.72%) and lower (1.57%) dietary lipid down regulated these genes' expression in muscle. It was found that c-Jun N-terminal kinases (JNK)/mammalian target of rapamycin (mTOR)/sterol regulatory element-binding protein 1c (SREBP-1c) signaling participate in the regulation of de - novo lipogenesis. In conclusion, lipid deposition in abalone was affected by dietary lipid levels through AMPKα2/PPARα and JNK/mTOR/SREBP-1c pathway. • The optimal dietary lipid level for abalone was estimated to be 3.87%. • Dietary lipids increased the lipid deposition in abalone. • 6.72% or 1.57% dietary lipid regulated lipolysis through (ATGL, HSL)/AMPKα2/PPARα pathway. • 6.72% or 1.57% dietary lipid regulated lipogenesis through JNK/mTOR/SREBP-1c pathway. [ABSTRACT FROM AUTHOR]

Nitrous acid (HONO) is the primary source of hydroxyl radical (OH) during daytime and significantly contribute to the formation of secondary organic compounds (SOA) and atmospheric oxidizing capacity. One month simultaneous observations at ship channel site (SCS) and background site (BGS) in Shanghai, China were conducted to aim at estimating the HONO concentration from ship direct emission and analyzing the nocturnal budget of HONO during non-clean period in SCS. The HONO average concentrations at both BGS and SCS during non-clean period were 0.37 ± 0.42 ppbv and 0.91 ± 0.78 ppbv, respectively. The diurnal variation of HONO from ship direct emission presented a double-peak trend with a maximum value 0.38 ± 0.18 ppbv at 07:00 in the morning. The proportion of HONO emission from ships was in a range of 43%~74% in the daytime, while, the proportions were 42%~63% and 14%~28% at night in clean and non-clean periods, respectively. HONO nocturnal conversion frequencies from NO 2 were 0.29%/h at both sites in non-clean period, during which the deposition velocities of HONO were 0.21–1.4 cm/s and 0.34–1.4 cm/s at BGS and SCS, respectively. • HONO emission from ships is identified and measured by long-path DOAS. • Difficult-calculate and unknown HONO source substituted by background site observation. • Proportion of ship direct HONO emission was estimated on different cases. • The NO 2 -to-HONO conversion frequencies on ship channel site and background site were equal. [ABSTRACT FROM AUTHOR]

• UAV is used to collect images for bridge condition assessment and heath monitoring. • Human-in-the-loop machine learning is used to segment elements from a point-cloud. • Damage detection from images is automated. • Damage growth is measured using images taken at different times/angles. • Damage location and extent are recovered by projecting 2D images to 3D point-cloud. Recently, the rapid development of commercial unmanned aerial vehicles (UAVs) has made collecting images of bridge conditions trivial. Measuring the damage extent, growth, and location from the collected big image set, however, can be cumbersome. This paper proposes a streamlined bridge inspection system that offers advanced data analytics tools to automatically : (1) identify type, extent, growth, and 3D location of defects using computer vision techniques; (2) generate a 3D point-cloud model and segment structural elements using human-in-the-loop machine learning; and (3) establish a georeferenced element-wise as-built bridge information model to document and visualize damage information. This system allows bridge managers to better leverage UAV technologies in bridge inspection and conveniently monitor the health of a bridge through quantifying and visualizing the progression of damage for each structural element. The efficacy of the system is demonstrated using two bridges. [ABSTRACT FROM AUTHOR]

• Deduce theoretical formula for elastic bending buckling load of transformed triangular corrugated steel plates (TT-CSP). • Study the impact of corrugated plate and corrugation dimensions on elastic and inelastic buckling capacity of TT-CSPs. • Reveal the contribution of top stringers to bending resistance of the built-up TT-CSPs. • Proposed a comprehensive design method to predict bending-bearing capacity of TT-CSPs with top stringer. This study investigates the bending-bearing capacity and design method of Transformed Triangular Corrugated Steel Plates (TT-CSPs) with top stringers adopted in trestles subjected to possible pure bending. Elastic buckling load and ultimate strength are derived through theoretical deduction and numerical analysis. Exploration focuses on the impact of boundary conditions, aspect ratio, corrugation density, and top stringers on buckling behavior and ultimate strength. This paper advances a design approach for the bending-bearing capacity of TT-CSPs with top stringers. Findings indicate that the vertical boundaries of TT-CSPs cannot meet the plane assumption and are close to being free-warping. Higher corrugation densities increase structural stiffness and uniformity, while TT-CSP height variations significantly affect stability. Top stringers behave as lateral constraints and undergo significant bending stresses, with their various buckling modes influencing the bending-bearing stability capacity of TT-CSPs. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Multi-AXis-Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements were performed to remote sensing the aerosol vertical profiles in suburb area of Shanghai, China from April to December 2017. The retrieval of aerosol extinction was based on the optimal estimation method combing the measured oxygen dimer O 4 absorption with simulation of forward radiative transfer model. It suggests that the employment of O 4 correction factor (CF O4) for daily aerosol retrieval should be adjusted, which includes three typical cases that a fixed CF O4 , no usage of CF O4 and different CF O4 in the morning and afternoon. In cases of using CF O4 , elevation angle dependent CF O 4 (α) were further proposed. Moreover, the retrieval results can be improved if the local sounding data of atmospheric temperature and pressure profiles were introduced into the forward radiative transfer model without utilizing additional CF O4. Afterwards, the retrieved Aerosol Optical Depth (AOD) and the surface Aerosol Extinction Coefficient (AEC) was in a good agreement with the AOD obtained from sun photometer observations and in-suit PM 2.5 concentrations, with a correlation coefficient R of 0.866 and 0.833, respectively. Besides, the vertical AEC profiles retrieved by MAX-DOAS were also validated well by the co-located lidar measurement. It can be found that the particles were mainly distributed below 1 km, and the maximum AEC usually appeared in the lowest 300 m and decreased with the altitudes. The averaged AEC within 1 km varied from 0.20 to 0.75 km−1, 0.25 to 1.08 km−1, 0.55 to 2.45 km−1 and 0.70 to 2.75 km−1 under different air quality of Grade II, III, IV and V. The sounding meteorological parameters and backward trajectories of air masses were integrated to diagnose the influencing factor of AEC at different altitudes, which illustrated that the AEC levels at lowest layer were impacted by the long distance transportation of air pollutants from north-northwest and regional local air pollution nearby during the winter time. The study shows that ground-based MAX-DOAS observation is powerful remote sensing technique to provide better understanding of aerosol properties at both ground surface and higher altitudes. Highlights • Aerosol vertical distribution were obtained by MAX-DOAS measurements in Shanghai. • O 4 correction factor (CF O4) need to be adjusted in the aerosol retrieval scheme. • Using local temperature and pressure profiles can improve the aerosol retrieval. • MAX-DOAS remote sensing are well validated by other auxiliary datasets. • High aerosol extinction usually occurred at the lowest layer below 0.3 km in winter. [ABSTRACT FROM AUTHOR]

To investigate on the daytime OH and its implication to fine particle, the long-path differential optical absorption spectroscopy (LP-DOAS) system was employed to observe the main OH precursors of O 3 , HCHO and HONO, as well as NO 2 and NO 3 radical from April to August 2013 over Shanghai, China. The main OH production paths from HONO, HCHO and O 3 were estimated to be occupied around 57.6%, 30.5% and 11.9% during daytime. The daytime OH radical concentration under steady-state was averaged at 1.02 × 10 7 molec cm −3 , which was significantly impacted by the photolytic processes. The relationship between photolysis frequency j(O 1 D) and OH radical suggests that heavy fine particle loads can make the photolytic reactions less efficiently and decrease the OH production and concentration. Utilizing CO as the indicator, the part of PM 2.5 mass related to primary emitted sources was found less impacted by the OH levels. The contribution of secondary organic aerosol with metrics of O 3 was enhanced with the increases of the OH levels, while secondary inorganic part of PM 2.5 was favor of the condition that smaller OH concentrations that 5 × 10 5 –5 × 10 6 molec cm −3 . Meantime, a simplified multivariate model was employed to evaluate the influences of OH levels on different parts of fine particles related to different emission and sources. Normalized by solar radiation, this part of OH unrelated to radiation was found to be inversely related to the PM 2.5 , which indicates the self-cleansing capability of the atmosphere. [ABSTRACT FROM AUTHOR]

Abstract: During the analysis of data from the full scale monitoring of the dynamic response of tall buildings, it has been observed that under certain conditions the fundamental natural frequencies of the structure can coalesce for moderate wind excitation. Together with this phenomenon, the dependency of damping on the amplitude of the response was also noted. Recently, a detailed description of this amplitude dependency has been made possible by a new generation of concept-based damping models, developed following the boom in the collection of full scale data from the monitoring of tall buildings. In light of this new knowledge, this paper investigates the possibility that the amplitude dependency of damping could be at the root of the frequency coalescing phenomenon. To this end, a concept-based probabilistic damping model is coupled with a reduced order two-degrees-of-freedom system that reproduces the two coalescing modes of a building. For this system, the analytical time-invariant conditions under which the frequency coalescence can occur are firstly identified. Then, the inherent variability of the amplitude dependent damping, described by the concept-based model, is considered as a means for instantaneously satisfying the aforementioned conditions. By exciting the reduced system through experimentally determined wind loads, the direct observation of the phenomenon—through time–frequency wavelet analysis—is achieved. [Copyright &y& Elsevier]

Formaldehyde (HCHO) provides a proxy to reveal the isoprene and biogenic volatile organic compounds emission which plays important roles in atmospheric chemical process and climate change. The ground-based observation with zenith-sky DOAS is carried out in order to validate the HCHO columns from OMI. It has a good correlation of 0.71678 between the HCHO columns from two sources. Then we use the OMI HCHO columns from January 2006 to December 2015 to indicate the interannual variation and spatial distribution in Xishuangbanna. The HCHO concentration peaks appeared in March or April for each year significantly corresponding to the intensive fire counts at the same time, which illustrate that the high HCHO columns are strongly influenced by the biomass burning in spring. Temperature and precipitation are also the important influence factors in the seasonal variation when there is nearly no biomass burning. The spatial patterns over the past ten years strengthen the deduction from the temporal variation and show the relationship with land cover and land use, elevation and population density. It is concluded that the biogenic activity plays a role in controlling the background level of HCHO in Xishuangbanna, while biomass burning is the main driving force of high HCHO concentration. And forests are greater contributor to HCHO rather than rubber trees which cover over 20% of the land in the region. Moreover, uncertainties from HCHO slant column retrieval and AMFs calculation are discussed in detail. [ABSTRACT FROM AUTHOR]

In the nocturnal boundary layer, nitrate radical (NO 3) has an important contribution to atmospheric chemistry through oxidation of nitrogen oxides and hydrocarbons. Vertical distributions of NO 2 , O 3 and NO 3 were measured by four differential optical absorption spectroscopy instruments at meteorological tower in Beijing from June 1 to July 22, 2019. The results show the mean diurnal variations of NO 2 , O 3 , and NO 3 display a single peak (up to 65.0 ppbv, 196.8 ppbv and 317.5 pptv, respectively) in time. O 3 and NO 3 mixing ratios generally increased against heights, which is opposite to NO 2 , suggesting the contribution of O 3 to NO 3 production at higher altitude. According to the correlation coefficients between NO 3 production rates (P NO3) and NO 2 or O 3 levels, P NO3 was sensitive to NO 2 mixing ratio at higher altitude but to O 3 near the ground. Averaged NO 3 lifetimes (τ NO3) of lowest, middle, upper and highest layer intervals were 104, 118, 164 and 213 s, respectively, which indicates τ NO3 increase against height and explains why NO 3 mixing ratios are larger at higher altitude to some extent. Main control factors of NO 3 removal changed from gas-phase reactions to N 2 O 5 hydrolysis with height increase. When relative humidity (RH) exceeded 70% or PM 2.5 level exceeded 50 μg·m−3, τ NO3 was almost less than 300 s with mixing ratio lower than 70 pptv. The clear negative dependence of τ NO3 on RH and PM 2.5 reveals the influencing factors on indirect loss. Under polluted conditions, vertical profiles of NO 2 , O 3 and NO 3 varied drastically. Stable atmosphere (low nocturnal boundary layer height and thermal inversion), RH level and RH gradient are the main reason for the evident difference in NO 3 gradient. Vertically increased NO 3 radicals may imply the formation of nitrate aerosols and further increase the nitrate content in high- altitude particulate matter. Unlabelled Image • Vertically increased NO 3 radical in the nocturnal boundary layer. • NO 3 removal mainly from gas-phase reactions to N 2 O 5 hydrolysis with height increase. • Stable atmosphere, low RH and negative RH gradient facilitate large NO 3 gradient. [ABSTRACT FROM AUTHOR]