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Broadband transmitted wavefront measurement is a detection method that uses transmitted wavefronts at a few specific wavelengths though a function of Zernike coefficients and wavelength to predict other transmitted wavefronts at any wavelength within a certain range. This method is used when the designed wavelength of the interferometer and the detection wavelength are different. The function of the Zernike coefficients and wavelength can be expressed by the Conrady formula which can be used to describe a monotonic function curve or a function curve with an inflection point. Two methods, i.e., solving and fitting, can be used to determine the coefficients of the Conrady formula. Owing to the inevitable errors in the actual measurements, the fitting method is preferred to determine the coefficients of the Conrady formula. However, by analyzing the Conrady formula, it was found that the curve obtained by fitting the Conrady formula is a monotonic curve. This method cannot be used to obtain a curve with an inflection point or a slow-changing curve in the long waveband. In this paper, we propose an improved data fitting approach that transforms the Conrady formula into a polynomial formula to fit a given set of data for determining the Conrady formula coefficients. The correctness of the method was verified via simulations. Finally, the feasibility of the proposed method was verified by changing the light source and using the Fizeau interferometer to measure the transmitted wavefront of the doublet lens. To ascertain the feasibility of using visible light to predict the invisible light band, a near-infrared 1064 nm light source was added to the experimental set-up to broaden the range of the transmitted wavefront prediction waveband. Experimental results showed that the conversion polynomial fitting method can be used to obtain monotonic curves and the curve with an inflection point and a slow-changing curve in the long waveband, thereby mitigating the limitation of directly fitting the Conrady formula using a set of data points. Furthermore, using this method, we verified that the visible light can be used to predict the transmitted wavefront at any wavelength in the invisible light band. This observation is highly significant for the practical applications of the broadband transmitted wavefront measurement technique.

The sound absorption coefficient was evaluated for the acoustic performance of the pavement in many studies, which is an evaluation index generated by the non-contact interaction between the tyre a...

In the actual working condition, the cavitation phenomenon is inevitably accompanied by the collapse of a large number of bubbles, and will affect the performance of hydraulic machinery. Therefore, it is of great significance to study the process of multi-bubble collapse. The double bubble system is the most simplified one in multi-bubble system, and it is also the basis of studying multi-bubble. However, the existing bubble dynamic studies mainly focused on single bubble and its interaction with the wall. This paper studies the interaction between two bubbles with different sizes and the influence of the wall on the process of bubble collapse by the VOF method. We have already investigated the interaction between two bubbles with different sizes without a wall (in free water) in our previous study. In this paper, we find that if there is a wall nearby, these two bubbles move close to each other when collapsing, and both move close to the wall at the same time. Through the study of bubble collapse time in the single bubble and the double bubble system, we find that the existence of the wall will delay the collapse time of bubble. However, the existence of the wall can also increase the intensity of collapse and rebound process of the bubble. Through the study of the center displacement of the bubble, we find that the double bubble system can increase the displacement of both bubbles. The method used in this paper can be easily extended to the study of multi-bubble, which provides a feasible method for the simulation of multi-bubble collapse near the wall.

This investigation was carried out to study the effects of the type and amount of supplementary cementitious materials on mechanical properties and surface durability of Portland cement concrete (P...

The rotor of Permanent Magnet Synchronous Motors (PMSM) is an electromechanical coupled dynamics system. The asymmetrical magnetic field-induced mechanical vibration has important effect on the operation performance of the high speed and high power density PMSM. In this paper, an electromechanical coupled lateral/torsional dynamic model caused by electromagnetic excitation is derived based on a Lagrange–Maxwell approach. The stability of the equilibrium was analyzed using a linearized matrix of the system equation. A stability criteria of coupled torsional-lateral motions was provided, and the influences of the electromagnetic and mechanical parameters on mechanical vibration stability were investigated. Finally, the vibration damping of the electromechanical coupling parameters vibration was explored. These results we represent get us better to understand the nonlinear response of the eccentric PMSM rotor system and are beneficial to control and diagnose the eccentric.

Triazine-based organic polymers@SiO2 nanospheres were prepared and applied as an extraction coating onto stainless steel wires and the wires were filled into polyetheretherketone tube for in-tube solid-phase microextraction. Taking polycyclic aromatic hydrocarbons as targets, main factors affecting extraction performance of the tube were investigated through coupling to high performance liquid chromatography. Under the optimum conditions, an online analytical method for polycyclic aromatic hydrocarbons was established with large linear ranges (0.010-20 µg/L), low limits of detection (0.003-0.010 µg/L), high enrichment factors (533-2954), and good repeatability (relative standard deviations

Silk fibers were carbonized to develop a biomass carbon material as an adsorbent for solid-phase microextraction. The surface structure of the carbonized silk fibers was characterized by scanning electron microscopy, and the graphitization degree was determined by Raman spectrometry. After carbonization under high temperature, the orderliness and structural regularity of carbon atoms on silk fibers were promoted. Extraction tube packed with carbonized silk fibers was prepared for in-tube solid-phase microextraction. Coupled with high performance liquid chromatography, it exhibited good extraction performance for hydrophobic polycyclic aromatic hydrocarbons. Main parameters including sampling volume, sampling rate, methanol content in sample, and desorption time were systematically investigated. Under the optimum conditions, the analysis method was established and it exhibited wide linear range (0.016-20 μg/L) with good linearity (correlation coefficient ≥ 0.9947), low limits of detection (0.005-0.050 μg/L), and high enrichment factors (1189-2775). Relative standard deviations (n = 3) for intraday (≤3.3%) and interday (≤9.6%) tests indicated that the extraction material had satisfactory repeatability. Finally, the analytical method was successfully applied to detect trace polycyclic aromatic hydrocarbons in real water samples, demonstrating its satisfactory practicability.

Nano-molybdenum trioxide was prepared from nano-molybdenum disulfide by simple firing in muffle furnace. Nano-molybdenum trioxide was used as the extraction coating on the stainless steel wire. Four wires were filled in a polyetheretherketone tube to get an extraction tube. The tube was connected to the six-port valve of a high performance liquid chromatograph, and the online analysis system was constructed. Extraction selectivity of the tube for different types of compounds, including polycyclic aromatic hydrocarbons, plasticizers, estrogens, anilines and neonicotinoids, was studied. Good enrichment ability for polycyclic aromatic hydrocarbons, but the extraction efficiency of others was not satisfactory. Using eight polycyclic aromatic hydrocarbons as the targets, an analytical method was established after optimizing main factors such as sampling volume, sampling rate, methanol content, and desorption time. The established method exhibited wide linear range to 0.016-20.00 μg/L and low limits of detection to 0.005 μg/L, and the enrichment factors can be up to 2443. The method was applied to the detection of trace polycyclic aromatic hydrocarbons in tap water and river water, and a good recovery was obtained. The tube showed good durability and chemical stability, and it still remained good extraction effect after more than 140 run.

Four new luminescent metal–organic frameworks (LMOFs), {[Zn(L)]·CH3CN}n (1), [Zn2(L)2]n (2), [Zn(L) (H2O)]n (3) and {[Zn(L) (H2O)]·DMA}n (4), were assembled employing 6-(3-pyridyl)isophthalic acid (H2L) with Zn(II) ions, revealing versatile frameworks as well as various types of coordination modes of H2L. Single-crystal X-ray diffraction analyses reveal that complexes 1 and 4 exhibit a 3D dense-packing structure with a bi-nodal 3,6-connected net and an uninodal 3-connected net, respectively; while complexes 2 and 3 show 2D layered structures with a bi-nodal 3,6-connected net and an uninodal 3-connected net, respectively. Further, the solid-state luminescence properties of the complexes were measured at room temperature. The results manifest that 1 shows high selectivity and sensitivity for Cr(VI)-containing anions with detection limits of 43.77 ppm for CrO42− and 64.77 ppm for Cr2O72−. In addition, the luminescence of 1 can be quenched efficiently by trace amounts of antibiotics (dimetridazole, DTZ; sulfadiazine, SDZ; nitrofurazone, NZF; nitrofurantoin, NFT; furazolidone, FZD; chloramphenicols, INN). Complex 1 is responsive to antibiotics with detection limits of 1.35 ppm for DTZ, 1892.27 ppm for SDZ, 0.62 ppm for NZF, 0.78 ppm for NTF, FZD for 6.87 ppm.

Potholes are common distresses on poor quality or heavily trafficked asphalt pavements. Timely and durable maintenance is required to reduce the impacts on traffic, especially in winter and rainy conditions. Conventional coating materials for repair either require complex preparation or are of poor durability. This paper introduces a new polyurethane modified coating material to be used in pothole repairs, and compares it with the other two coating materials which are widely used in pothole maintenance, i.e., emulsified asphalt and cutback asphalt. Laboratory tests concerning workability, bonding performance and durability, and field surveys of three pothole patches installed in different environments were conducted. The results showed that the curing time and workability performance of the polyurethane modified coating were stronger than that of the control materials in low temperatures. Shear strength and pullout strength were greater at different test temperatures and moisture levels. The use of the polyurethane modified coating enhanced the ability of pothole patches to resist freezing-thawing cycles, dishing and shoving, when compared with the emulsified asphalt and cutback asphalt. The polyurethane modified coating had good pavement performance in field as well. Therefore, it is concluded that the polyurethane modified coating is a suitable choice for timely asphalt pavement potholes maintenance in cold and wet conditions.

Micro-surfacing is an available choice for pavement preventive maintenance. This paper introduced a new micro-surfacing using developed Waterborne Epoxy Resin (WER) modified emulsified asphalt to overcome the common distress, such as abrasion, rutting, ravelling and poor durability. The skid resistance, bonding, rutting and wear performances of different formulations of the proposed micro-surfacing materials were compared with Styrene Butadiene Rubber (SBR) modified micro-surfacing by load wheel tests, wet track abrasion tests, skid resistance tests, load wheel tracking tests, cantabro tests and accelerated loading tests. Results indicated that WER could improve the early pavement performance of micro-surfacing significantly, especially their bonding and rutting resistance. WER also produced improved durability performance. The damage in the critical condition of water immersion, freeze–thaw and heavy traffic was alleviated greatly by the use of WER. Therefore, it can be concluded that WER modified emulsified asphalt is a good binder for micro-surfacing.

Polydopamine was coated onto cotton fibers as the adsorbent to improve the extraction efficiency. Polydopamine-coated cotton fibers were placed into a polyetheretherketone tube for in-tube solid-phase microextraction. To develop an online analysis system, the extraction tube was connected with high-performance liquid chromatography. The tube was evaluated with five estrogenic analytes, and the extraction and desorption conditions were optimized to get high extraction efficiency. Under the optimum conditions, the enrichment factors of five analytes were 143-1745. An online analysis method was established, it had large linear ranges (0.10-40 and 0.16-40 μg/L), low limits of detection (0.03, 0.05 μg/L) and satisfactory repeatability (≤3.2%). The analysis method was applied to detect targets in the real samples like as hot water in new plastic cup and tap water. The relative recoveries spiked at 1 and 5 μg/L in these samples were investigated and the results were in the range of 83.7-109%.

The deterioration of asphalt binders rheological behaviors in different aging stages were investigated by using self-developed indoor aging equipment SAT (simple aging test), and the corresponding ...

An optimised design of pavement considering the noise reduction performance is desired to reduce the tyre/pavement noise. A cost-effective and user-friendly laboratory test method for measuring the...

Tire–pavement friction plays a key role in traffic safety. With the development of auto vehicle industry, most of the new vehicles are equipped with Anti Braking System (ABS). Therefore, a predicti...

Silica aerogel with high surface area was prepared by an acid–base two-step catalytic sol–gel method under ambient pressure drying. It was coated onto stainless steel wires as an extraction phase, then three wires were placed into a polyetheretherketone tube for forming an in-tube solid-phase microextraction device. Combined with high performance liquid chromatography, the extraction device was assessed and it exhibited better extraction ability for polycyclic aromatic hydrocarbons than for estrogens and phthalates. Eight polycyclic aromatic hydrocarbons were selected as model analytes, and four main factors including sampling volume, sampling rate, organic solvent content in the sample and desorption time were investigated to achieve high sensitivity. After that, an on-line analysis method was established with low limits of detection (0.005–0.050 μg L−1), low limits of quantitation (0.017–0.165 μg L−1), wide linear range (0.017–15 μg L−1), good correlation coefficients (0.9990–0.9998) and high enrichment factors (576–2245). Relative standard deviations of the intra-day test and inter-day test were separately less than 2.0% (n = 3) and 3.6% (n = 3), demonstrating the stable performance of the extraction device. During the investigation of durability and chemical stability, relative standard deviations less than 7.8% (n = 3) indicated that the extraction device had satisfactory reusability under harsh conditions. Finally, the analytical method was successfully applied to the detection of polycyclic aromatic hydrocarbons in real water samples.

Low-speed skid resistance tests provide useful information not available from the normal high-speed skid resistance testing of road pavements. There are known limitations of the two commonly used m...

There are a lot of review papers of sample pretreatment, but the comprehensive review on pipette-tip solid-phase extraction (PT-SPE) is lacking. This review (133 references) is mainly devoted to the development of different types of micro- and nanosorbent-based PT-SPE, including silica materials, carbon materials, organic polymers, molecularly imprinted polymers, and metal-organic frameworks. Each section mainly introduces and discusses the preparation methods, advantages and limitations of adsorbents, and their applications to environmental, biological, and food samples. This review also demonstrates the advantages of PT-SPE like convenience, speed, less organic solvent, and low cost. Finally, the future application and development trend of PT-SPE are prospected.

Using poly(ionic liquid) (PIL) and tetraethyl orthosilicate (TEOS) as the co-precursors, PIL-hybridized silica aerogel was prepared via sol-gel method for solid-phase microextraction (SPME). The ratio between PIL and TEOS was regulated to achieve the best extraction effect. The aerogel was coated onto the surface of stainless steel wire to get SPME fiber. Coupled to gas chromatography-flame ionization detector (GC-FID), the fiber was separately evaluated by the determination of alkanes, polycyclic aromatic hydrocarbons (PAHs), as well as BTEX (benzene, toluene, ethylbenzene, and xylenes) in immersion mode. The extraction performance of PAHs was attributed to π stacking and hydrophobic effect. After optimization of main extraction and desorption conditions, the SPME-GC-FID method was established towards eight PAHs, and it provided low detection limits (0.005 μg L−1, 0.010 μg L−1) and wide linear ranges (0.016–20.00 μg L−1, 0.033–20.00 μg L−1) with good linear coefficients (0.9991–0.9998). The method was applied to detect trace PAHs in real water samples, with relative recoveries of 86.2–119.2%. Furthermore, PIL-hybridized silica aerogel exhibits some superiorities like higher sensitivity, shorter extraction time, and better repeatability over other extraction coatings. The present work not only extends the range of aerogel materials but also promoted their further applications in sample preparation.

The objective of this paper is to evaluate the effect of different aging times on the performance of styrene-butadiene-styrene (SBS) copolymer–modified asphalt. Two kinds of SBS-modified as...

In this paper, the ultra-thin layer (UTL) is defined as the dense framework structure mixture made of asphalt binder, fine aggregate with nominal maximum aggregate size (NMAS) not greater than 13.2 mm and possible additives (mineral or organic), thickness of 2&ndash, 4 cm. The study aims to investigate comprehensive performance of UTL asphalt mixture. The method of impact freeze thaw split test and the index of impact freeze&ndash, thawing damage degree (IFTDD) are proposed to reflect the durability. The indoor tire-rolling-down test system and accelerated abrasion machine are used to simulate the tire-pavement interaction and test road noise and skid resistance, respectively. Though evaluating the influencing factors (pavement thickness, gradation, asphalt binder type, and the content of KS additive) on durability, the optimum parameters with excellent durability are recommended. Combined with the test of noise and skid resistance, the factors affecting the surface function are analyzed. Moreover, the prediction mathematical model of skid resistance and the long-term safety benefit value Eeff are put forward. Results indicate that pavement thickness is the most significant factor effecting on durability, and gradation is the most significant factor affecting noise. Compared with KS additive, gradation has a greater influence on skid resistance index of Texture Depth (TD), whereas, KS additive is the most significant factor affecting British Pendulum Number (BPN). Furthermore, with the addition of asphalt rubber (AR), IFTDD and noise are reduced by 29.17% and 1.6 dB, and BPN and TD increase by 0.7 and 0.03 mm, remarkably. Compared with different asphalt types, the noise of UTL asphalt rubber mixture with 13.2 mm NMAS (UTL13 AR) is the lowest. Additionally, when KS content increases by 0.6%, the noise increases by 3 dB. Furthermore, on the basis of the calculation results of Eeff, UTL13 AR mixture with 0.5% KS has the best long-term benefit of pavement safety and is recommended for field project.

Transmitted wavefronts are usually measured by a laser interferometer of the corresponding design wavelength. The Zernike coefficient can be used to describe the transmitted wavefront of a circular aperture. However, it has some limitations in optical systems with non-circular apertures. In this paper, a method, based on discrete points, for measuring transmitted wavefronts in a broad bandwidth is presented. Simulations of monochromatic, achromatic and apochromatic systems verify the method. The system with off-axis field of view is also analyzed. The Conrady dispersion formula and apochromatic characteristic formula (ACF) are used to represent the relationship between the optical path difference (OPD) at each discrete point of the transmitted wavefront and the wavelength. We also experimentally verify this method by measuring the wavefront of the optical system with a square aperture. The results demonstrate that the method can be used to measure the non-circular wavefront in a broad bandwidth.

To enhance the extraction performance, a mesoporous silica was modified with ordered mesoporous carbon for solid-phase microextraction. Three stainless-steel wires coated with the mesoporous material were placed in a polyetheretherketone tube for getting an extraction tube. The tube was coupled to high-performance liquid chromatography with diode array detector, and the online analysis system was constructed. Then its extraction performance was evaluated using hydrophobic polycyclic aromatic hydrocarbons, phthalates, and hydrophilic neonicotinoids. The best selectivity was presented for polycyclic aromatic hydrocarbons. Several main conditions were optimized such as sampling volume, sampling rate, methanol concentration in the sample, and desorption time, a rapid and sensitive analytical method was established toward polycyclic aromatic hydrocarbons. The analytical method exhibited wide linear range from 0.017 to 15 µg/L with acceptable correlation coefficients more than 0.9990, limits of detection in 0.005-0.020 µg/L, limits of quantification ranging from 0.017 to 0.066 µg/L as well as large enrichment factors of 377-2314. It was successfully applied to detect trace polycyclic aromatic hydrocarbons in some real water samples including tap water, snow water, and domestic sewage.

Patching is one of the most common maintenance methods for potholes in roads. In order to improve the performance of cold-patching asphalt mixtures, an emulsified asphalt modified with waterborne epoxy resin was developed. Two waterborne epoxy resins and two curing agents were selected. The optimal experimental contents of the curing agents were obtained by measuring the compressive strength of the waterborne epoxy mortar (WEM) under different curing agent contents and curing period. The difference between the two waterborne epoxy resins was obtained by the flexural strength and stress&ndash, strain curves, which were measured by the modified bending test on the WEM. The evaluation method of the initial strength and forming strength of the waterborne epoxy emulsified asphalt mixture (WEEAM) was proposed by the experimental study of the compaction molding method and curing conditions. The high temperature performance, low temperature performance, and moisture susceptibility of the mixture were verified by comparing various kinds of WEEAM. The results show that using WEEAM as a road repair material has great advantages in improving pavement performance and road service levels.

A mesoporous silica was functionalized by carbon nanotubes to enhance the extraction performance. The mesoporous material was coated on stainless steel wires, and three wires were inserted inside of a polyetheretherketone tube for in-tube solid-phase microextraction. The tube was coupled to high-performance liquid chromatography with diode array detection to obtain online analytical system, then its extraction performance was evaluated using eight polycyclic aromatic hydrocarbons as the targets. In order to good sensitivity and accuracy, four conditions were optimized such as sampling volume, sampling rate, methanol content in the sample, and desorption time. Under the optimum conditions, an online analytical method was established and exhibited low limits of detection from 0.005 to 0.050 µg/L, wide linear range of 0.016-20.00 µg/L with acceptable correlation coefficients in 0.9921-0.9999, as well as large enrichment factors in the range of 311-2412. The method was successfully applied to determine trace polycyclic aromatic hydrocarbons in some real water samples including, two kinds of bottled water, tap water, and river water, a few polycyclic aromatic hydrocarbons were detected but none quantified in these samples.

The phase of an interferogram carries the desired information for various applications such as 3-D profilometry. It can be obtained with a wavelength tuning interferometer by acquiring a series of interferograms while changing the laser wavelength. The phase achieved by the interferometer, however, has severe error due to the laser output power change, which is produced inherently from changing the laser wavelength. To eliminate such phase error, we propose a real-time closed-loop feedback control system to keep the laser output power stable during the wavelength tuning. The control system integrates a photodetector, a data acquisition card, and an electro-optic amplitude modulator with our software to achieve the purpose. The experimental result of the system can steadily output a desired intensity value and the measurement speed is up to 600 KHz. Both its control principles as well as its experimental validation are depicted in this letter.

Interlayer of pavement overlays or bridge deck pavement using waterborne epoxy resin emulsified asphalt (WEREA) is proposed for the purpose of preventing pavement from shoving at bridge deck. This study consists of theoretical analysis on cohesion and simulation failure tests of cohesion and waterproof. The results show that the cohesion performance is affected by temperature and the choice of curing agent, and the shear strength performance is related to interlayer contact texture. The components and network microstructure of WEREA enhance the cohesion property of interlayer and improve the material viscoelasticity, and as a result it improves the shear strength and pullout strength performance. In addition, WEREA also has a strong waterproof performance on the bridge deck pavement as tack coat.

Rutting has been one of the primary concerns for highway engineers in China. Granulated polymer anti-rutting additive may be an effective way to solve this problem. However, it is difficult to find...

Although microstructure is closely related to performance and is even considered decisively influential, this paper addresses the poorly understood morphology characteristics of styrene-butadiene-s...

The quantification of styrene-butadiene-styrene (SBS) in modified asphalt is essential to evaluate the performance of modified asphalt. In this work, Fourier transform infrared (FTIR) spectroscopy ...

Recycled asphalt mixture has been widely used in all grades of asphalt pavement in the world, but its unstable fatigue performance limits the addition of reclaimed asphalt pavement (RAP) materials. According to the characteristics of the two hot recycled methods commonly used in China, nine kinds of fine aggregate matrix (FAM) were produced in the laboratory. Based on the torsion bar fixture of dynamic shear rheometer (DSR), linear viscoelastic (LVE) test, strain sweep, frequency sweep and time sweep test were carried out on FAM. The results showed that aging time and the increase of RAP content would have a negative effect on the fatigue performance of FAM, and the effect of aging time was more significant. Both time sweep test and strain sweep test could predict the fatigue properties of FAM, but strain sweep test could save more time. Therefore, it was suggested that strain sweep test could be used as a prediction method of fatigue properties of FAM.

In order to develop an online detection method for polycyclic aromatic hydrocarbons (PAHs) in honey, graphene oxide-functionalized mesoporous silica was prepared and introduced as the coating in the field of in-tube solid-phase microextraction. An extraction tube was coupled to high performance liquid chromatography with diode array detector, and the online analytical system was constructed. After the main extraction and desorption conditions were optimized, a sensitive and online method based on matrix-matched calibration was established towards trace PAHs in honey. The method exhibited wide linear range from 0.8 ng g−1 to 250 ng g−1 and low detection limit of 0.25 ng g−1, and the enrichment effect reached 2719. The proposed method was validated and successfully applied to the analysis of six honey samples. The extraction tube showed good durability and acceptable chemical stability during the experiment.

As bitumen from different manufacturers exhibit different properties, which may impact on the performance of asphalt pavement, currently it is necessary to implement appropriate methods in order to classify or identify the source of bitumen. In this work, 15 bitumen samples from three different manufacturers were collected and analysed by attenuated total reflectance Fourier transform infrared (ATR-FTIR). The spectrum data were analysed by data pretreatment and principal component analysis (PCA). The PCA score plot reveals that the bitumen samples were successfully solved in three distinct regions, and each cluster comprised bitumen from the same manufacturer. Furthermore, the regression model was obtained by PCA and validated by detecting testing bitumen samples, which exhibited high correct identification rates. The results suggested that PCA-assisted ATR-FTIR spectroscopy could be a promising rapid and accurate method for classifying and identifying the source of bitumen, and would be capable of furthe...

Chip-sprinkling cement concrete (CSCC) pavement can provide satisfactory friction and has potential for noise attenuation due to its exposed surface texture, making abrasion resistance significant. The abrasion resistance of CSCC pavement was evaluated using the Cantabro test method, with smooth surface concrete as the control group. This method uses a Los Angeles Abrasion Machine without steel balls. Using the same method, the abrasion durability of CSCC was also assessed using different concentrations of sodium chloride solutions. The effects of different water/cement ratios and chip-sprinkling parameters were analyzed. The latter variables included aggregate particle size, aggregate spreading area ratio, and aggregate pressing depth ratio. Data indicate that the abrasion losses of CSCC specimens change quickly at first, but later they change more gradually. Aggregate particle sizes of 9.5–13.2 mm may be better when just considering the effect of aggregate particle size on the abrasion resistance. Abrasion losses of CSCC specimens multiply with increasing aggregate spreading area ratios and decrease with the rising aggregate pressing depth ratios. On the whole, abrasion resistance of CSCC is superior to the smooth surface concrete in the control group.

Pavement skid resistance plays a key role in traffic safety. Meanwhile, tire-pavement noise is a major source of traffic noise in urban areas. Current asphalt mixture design methods, however, mostl...

A combination between an ionic liquid and melamine-formaldehyde aerogel on the carbon fibers was developed for in-tube solid-phase microextraction of estrogens with high efficiency. The sorbent has a high enrichment capability for several estrogens. Scanning electron microscopy showed that the aerogel on the carbon fibers has a porous three-dimensional network structure. Several important parameters such as sampling volume, sampling rate, the concentration of organic solvent in sample, pH value of sample as well as desorption time were optimized towards estrogen targets. Comparing with melamine-formaldehyde aerogel coating, the coating gave higher extraction efficiency. Comparing with melamine-formaldehyde aerogel coating, the new coating displays higher extraction efficiency. An online analytical method of estrogens was established, by the combination between in-tube solid-phase microextraction and high performance liquid chromatography with diode array detector. Analytical figures of merit include low limits of detection (

Recently, there has been an increasing interest in the applications of recycled mixtures with a high reclaimed asphalt pavement (RAP) content. However, many government departments are hesitant about the applications of that due to being worried about the durability of its pavement, and few findings has been reported in terms of the percentage of fine reclaimed asphalt pavement (FRAP, 0~5 mm) in recycled mixtures. In this paper, 25% or more RAP by the weight of aggregates is defined as high RAP and high FRAP refers to 10% or more FRAP by the weight of aggregates. This paper examines the laboratory performances of mixtures with high RAP (30%, 40%, and 50%) and FRAP (10%, 15%, and 20%). Performance evaluations have been conducted by conventional tests, including the low-temperature bending test, fatigue test, and the moisture susceptibility test. The results show that with the increasing RAP and FARP contents, 41% (30-R-10) to 63% (50-R-15) of virgin asphalt can be saved, both the low-temperature and fatigue performance decrease, and the moisture performance firstly increases and then decreases. The results of analysis of variance (ANOVA) in terms of low-temperature and moisture performance show that RAP contents in recycled mixtures have a significant effect on the performance, while the effect of FRAP contents on the performance of recycled mixtures is insignificant.

As a global-optimized and naturally inspired algorithm, particle swarm optimization (PSO) is characterized by its high quality and easy application in practical optimization problems. However, PSO has some obvious drawbacks, such as early convergence and slow convergence speed. Therefore, we introduced some appropriate improvements to PSO and proposed a novel chaotic PSO variant with arctangent acceleration coefficient (CPSO-AT). A total of 10 numerical optimization functions were employed to test the performance of the proposed CPSO-AT algorithm. Extensive contrast experiments were conducted to verify the effectiveness of the proposed methodology. The experimental results showed that the proposed CPSO-AT algorithm converges quickly and has better stability in numerical optimization problems compared with other PSO variants and other kinds of well-known optimal algorithms.

Intensity inhomogeneity often occurs in a large number of images, offering a great challenge in image segmentation. The local intensity clustering (LIC) is a region-based method for image segmentation, with the bias field demonstrating good performance in the intensity homogeneity region. However, due to the characteristic of the smoothing and slow change in the bias field, LIC model fails to obtain good results for images with complex background. To solve this problem, this paper proposes a multiplication optimization level set image segmentation algorithm. First, the bias field is represented by a set of multiplication smooth basis functions, with the iterative solution of the bias field converted to search for the optimal coefficients for the basis functions, to reduce the complexity of background. Minimization of this objective function are deduced theoretically to provide the evolution function. Compared with LIC model, our algorithm can simultaneously segment images and correct the bias field. The effectiveness of the algorithm is verified by experiments on synthetic images and medical images.

Cotton fiber is an environmentally friendly and natural material with a certain extraction capacity, while its enrichment ability is poor. In order to improve the extraction efficiency of cotton fibers, it was carbonized to form a layer of amorphous carbon as the sorbent by a simple carbonization method. Carbonized cotton fibers were filled into a polyetheretherketone tube for in-tube solid-phase microextraction. The carbonization time was investigated to obtain high extraction efficiency. Coupled to high-performance liquid chromatography, the extraction tube was evaluated with polycyclic aromatic hydrocarbons, estrogens and phthalates, and it exhibited best extraction efficiency for polycyclic aromatic hydrocarbons. Under the optimum conditions, an online analysis method for several polycyclic aromatic hydrocarbons was established with large linear ranges (0.016-0.20 μg/L), low limits of detection (0.005-0.020 μg/L), and high enrichment factors (948-2874). Analysis method was successfully applied to the detection of targets in the real samples and shown satisfactory durability and chemical stability. Moreover, the relative recoveries ranged from 82 to 119.2%, which demonstrated the applicability of carbonized cotton fibers in sample preparation. Compared with other reported methods, the proposed method provided shorter extraction time, higher enrichment factors, comparable limits of detection, and recoveries.

Polypropylene hollow fibers as the adsorbent were directly filled into a polyetheretherketone tube for in-tube solid-phase microextraction. The surface properties of hollow fibers were characterized by a scanning electron microscope. Combined with high performance liquid chromatography, the extraction tube showed good extraction performance for five environmental estrogen hormones. To achieve high analytical sensitivity, four important factors containing sampling volume, sampling rate, content of organic solvent in sample, and desorption time were investigated. Under the optimum conditions, an online analysis method was established with wide linear range (0.03-20 µg/L), good correlation coefficients (≥0.9998), low limits of detection (0.01-0.05 µg/L), low limits of quantitation (0.03-0.16 µg/L), and high enrichment factors (1087-2738). Relative standard deviations (n = 3) for intraday (≤3.6%) and interday (≤5.1%) tests proved the stable extraction performance of the material. Durability and chemical stability of the extraction tube were also investigated, relative standard deviations of all analytes were less than 5.8% (n = 3), demonstrating the satisfactory stability. Finally, the method was successfully applied to detect estrogens in real samples.

The control of spin electromagnetic (EM) waves is of great significance in optical communications. Although geometric metasurfaces have shown unprecedented capability to manipulate the wavefronts of spin EM waves, it is still challenging to independently manipulate each spin state and intensity distribution, which inevitably degrades metasurface-based devices for further applications. Here we propose and experimentally demonstrate an approach to designing spin-decoupled metalenses based on pure geometric phase, i.e., geometric metasurfaces with predesigned phase modulation possessing functionalities of both convex lenses and concave lenses. Under the illumination of left-/right-handed circularly polarized (LCP or RCP) terahertz (THz) waves, these metalenses can generate transversely/longitudinally distributed RCP/LCP multiple focal points. Since the helicity-dependent multiple focal points are locked to the polarization state of incident THz waves, the relative intensity between two orthogonal components can be controlled with different weights of LCP and RCP THz waves, leading to the intensity-tunable functionality. This robust approach for simultaneously manipulating orthogonal spin states and energy distributions of spin EM waves will open a new avenue for designing multifunctional devices and integrated communication systems.

Some novel methods are introduced to improve thermal storage stability and pavement performance of crumb rubber modified binder. In this paper, the objective was to investigate the effects of compound activation on the molecular structure and physical properties of crumb rubber, as well as rheological properties and thermal storage stability of crumb rubber modified binders. Two activation methods, with and without diesel pre-swelling, and six microwave radiation intensities were designed in this study. Fourier transform infrared spectroscopy (FTIR) test, swelling equilibrium test and dynamic mechanical thermal analyzer (DMA) test were performed to evaluate the characteristic functional groups and physical properties of crumb rubbers before and after activation. Additionally, rheological properties test at various service temperatures and thermal storage stability test were carried out on the crumb rubber modified binders. The results show that certain microwave radiation intensity would break the C-S and C=S bonds and reduces the cross-linking density of crumb rubber. Activation mode was the main factor affecting high temperature stability, fatigue life and low temperature relaxation property rather than microwave radiation intensity compared with control one. In addition, thermal storage stabilities of activated crumb rubber modified binders were better than control one. The more radiation intensity, the improvement effect of thermal storage stability is. Synthesizes each kind of property, diesel pre-swelling and microwave radiation intensity of 1.2 kJ/g was a preferable combination in this study.

Aerogels have attracted more and more attention in many fields due to the unique properties, including large surface area, high porosity, excellent adsorption, and low thermal conductivity. Based on the specific advantages, an organic aerogel was developed as the coating for solid-phase microextraction (SPME) in this work. Melamine-formaldehyde-resorcinol aerogel was in situ prepared on the surface of basalt fibers through the copolymerization reaction, the fibers were placed into a polyetheretherketone tube to achieve SPME tube. Coupled to high performance liquid chromatography (HPLC), the tube was investigated and exhibited good extraction selectivity towards polycyclic aromatic hydrocarbons (PAHs) by π-π stacking and hydrophobic interactions. Under the optimal conditions, an online in-tube SPME-HPLC method was established with satisfactory enrichment factors (1128–2016), wide linear ranges (0.03–30 μg L−1 and 0.15–30 μg L−1), low limits of detection (0.01–0.05 μg L−1) and acceptable repeatability (RSD ≤ 3.9%, n = 5). The method was successfully applied to the determination of several PAH targets in real samples.

Biochar materials have been focused on enormous attention in the fields of capacitance, catalysis, adsorption due to its renewability, abundant in content and widespread distribution. In this work, corncob biochar materials were prepared under different carbonized temperature and characterized by scanning electron microscopy and Raman spectroscopy for surface morphology and graphitization degree. Then the materials were separately attached onto stainless steel wires as the coatings for solid-phase microextraction (SPME). Four wires with the same coating were placed into a polyetheretherketone tube to develop several extraction tubes. Coupled to high performance liquid chromatography (HPLC) with diode array detector (DAD), the tubes were evaluated using several polycyclic aromatic hydrocarbons (PAHs) as model analytes. According to the comparison of extraction efficiency, the best tube was selected. To achieve high sensitivity, both main extraction and desorption processes were optimized. Under the optimum conditions, an in-tube SPME-HPLC-DAD method for PAHs was established with low limits of detection (0.003–0.030 ng mL−1), wide linear ranges (0.010–15 ng mL−1, 0.017–15 ng mL−1, 0.033–15 ng mL−1 and 0.099–15 ng mL−1), high enrichment factors (1864–2615) and acceptable repeatability (relative standard deviations (RSDs, n = 3) less than 2.9% and 6.7% for intra-day and inter-day tests). Furthermore, the accuracy of the method was investigated via analyzing trace PAHs in real water samples and good recoveries (81.7%-116.8%) were obtained. In addition, the extraction tube exhibited satisfactory durability and chemical stability (RSDs ≤ 8.0%, n = 3) and acceptable reproducibility (RSD ≤ 7.8%, n = 3).

The objective of this study is to evaluate the long-term aging effect on the rheological properties of the modified PG 76-22/PG 76-16 binders produced from ground tire rubber (GTR) with various polymers after a long-term aging process. The tests included the investigation of G*sinδ, phase angle, amplitude sweep, frequency sweep, creep and creep recovery and stress relaxation in terms of three base binders and five polymers. The test results indicated that both base binder and polymer type affect the fatigue resistance, creep and creep recovery, viscoelastic property, and relaxation characteristic of each modified binder. In addition, terminally blended GTR binder has better fatigue resistance than laboratory blended GTR binder after a long-term aging procedure in this study. It seems that binders modified with polyphosphoric acid combined with 7% GTR exhibit more elastic properties and better rheological properties than other modified binders regardless of binder sources.

In this paper, we describe a coupled nonlinear electromechanical torsional vibration model of a high-speed permanent magnet synchronous motor driven system based on the Lagrange–Maxwell theory. The chaotic state is induced by external excitation forces. A multitime delay feedback control scheme is derived to suppress chaos in such vibrations. An analytical criterion condition for chaos is deduced by Melnikov’s method. Detailed numerical studies, including bifurcation diagram, phase portrait, and a Poincaré map, confirm the analytical prediction. It is revealed that the chaotic motion can be effectively suppressed by reducing or increasing the feedback parameters of the multitime delay feedback control scheme.

In order to overcome the shortcomings of the durability of hydrophobic emulsified asphalt coating due to attenuation of skid resistance performance and insufficient wear resistance, Waterborne epoxy resin (WER) was used as a modifier to prepare WER modified hydrophobic emulsified asphalt (WERHEA), which was used for the micro-surfacing mixture. The wet track abrasion test and load wheel test were used to determine the optimal asphalt dosage range of the micro-surfacing mixture of the two kinds of aggregates. The hydrophobic and anti-icing properties of the WERHEA micro-surfacing mixture were verified. In addition, the wear resistance performance, interlayer bonding performance, skid resistance performance and the attenuation of skid resistance performance after accelerated wear test was considered. The results show that when the content of WER is 12%, the oil stone ratio of granite micro-surfacing mixture is 7.5–8.6%, and that of basalt micro-surfacing mixture is 7.4–8.4%; the wear resistance of the micro-surfacing mixture is significantly improved, and the wear resistance of basalt is better than that of granite; 46% increase in shear strength and 105.7% increase in pull strength; The British pendulum number (BPN) and the Texture depth (TD) reached the peak, and then there was a downward trend. Considering that the increase in WER content may cause the mixture to segregate and reduce the skid resistance performance. After the accelerated abrasion test, its skid resistance performance is still the best with 12% WER. Therefore, the optimal amount of WER is 12%.

Hydrated lime is known to be an effective moisture damage additive, and it can also reduce the chemical ageing of the bitumen and stiffen the mastic. However, the optimum content and fineness of hydrated lime used in asphalt have been rarely studied. In order to determine the effect of lime content and fineness on hydrated lime modified asphalt and select the optimum lime content and fineness, XD90 asphalt, granite and 200 mesh, 300 mesh and 400 mesh lime with different lime content were chosen as experimental materials. At first, according to surface free energy method, the adhesion work W a was chosen as the main index to evaluate the adhesion between asphalt and granite, and the asphalt surface free energy components after hydrated lime modification were tested. After that, basic technical properties of hydrated lime modified asphalt were studied to refine lime content and fineness. Finally, multiple stress creep and recovery and linear amplitude sweep tests were carried out respectively to study rheological properties of hydrated lime modified asphalt. The results showed that the asphalt adhesiveness increased with the increase of lime fineness, and the optimum lime content for asphalt adhesiveness was around 10%. Moreover, hydrated lime could raise the asphalt viscosity and stiffen asphalt. To make ductility meet the specification requirements, the lime content should be controlled below 10%. When lime content was around 3%–10%, hydrated lime modified asphalt had relatively good rheological properties compared with base asphalt. Meanwhile, the high temperature performance together with the ability to resist permanent deformation was improved apparently. In conclusion, taking into account the adhesion, rheology and basic properties of hydrated lime modified asphalt, the optimum lime content and fineness could be finally determined.

The wavelength-tuned Fizeau interferometer achieves the desired phase for interferograms based on the use of a phase-shifting technique. It can then use it to measure the surface and thickness of a parallel transparent object. However, phase errors occur owing to the inherent changes of the power of the tunable laser diode induced upon laser wavelength changes. To improve the measurement accuracy, we propose an optical power, real-time feedback control system, and a synchronous calibration scheme. The significance of the proposed method relies on the fact that the laser intensity variation can be detected quickly and compensated by adjusting the bias voltage. To verify the effectiveness of the proposed system, we incorporated it into the optical system of the wavelength-tuned, phase-shifting interferometer for experimentation. The control principles and the experimental validation of the proposed system are described in this letter.