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Parallel factor analysis (PARAFAC) coupled with support-vector machine (SVM) was carried out to identify and discriminate between the fluorescence spectroscopies of coconut water brands.

PARAFAC was applied to reduce three-dimensional data of excitation emission matrix (EEM) to two-dimensional data. SVM was applied to discriminate between six commercial coconut water brands in this study. The three largest variation data from fluorescence spectroscopy were extracted using the PARAFAC method as the input data of SVM classifiers.

The discrimination results of the six commercial coconut water brands were achieved by three SVM methods (Ga-SVM, PSO-SVM and Grid-SVM). The best classification accuracies were 100.00%, 96.43% and 94.64% for the training set, test set and CV accuracy.

The above results indicate that fluorescence spectroscopy combined with PARAFAC and SVM methods proved to be a simple and rapid detection method for coconut water and perhaps other beverages.

As the service time of bridges increases, the degradation of bending capacity, the lack of safety reserves and the decrease in bridge reliability are common in early built bridges. Due to the defective lateral hinge joints, hollow slab bridges are prone to cracking of hinge joint between plates, transverse connection failure and stress of single plates under the action of long-term overload and repeated load. These phenomena seriously affect the bending capacity of the hollow slab bridge. This paper aims to describe a new method of simply supported hollow slab bridge reinforcement called polyurethane–cement (PUC) composite flexural reinforcement.

This paper first studies the preparation and tensile and compressive properties of PUC composite materials. Then, relying on the actual bridge strengthening project, the 5 × 20 m prestressed concrete simply supported hollow slab was reinforced with PUC composites with a thickness of 3 cm within 18 m of the beam bottom. Finally, the load test was used to compare the performance of the bridge before and after the strengthening.

Results showed that PUC has high compressive and tensile strengths of 72 and 46 MPa. The static test revealed that the measured values and verification coefficients of the measured points were reduced compared with those before strengthening, the deflection and strain were reduced by more than 15%, the measured section stiffness was improved by approximately 20%. After the strengthening, the lateral connection of the bridge, the strength and rigidity of the structure and the structural integrity and safety reserves were all significantly improved. The application of PUC to the flexural strengthening of the bridge structure has a significant effect.

As a new type of material, PUC composite is light, remarkable and has good performance. When used in the bending strengthening of bridge structures, this material can improve the strength, rigidity, safety reserve and bending capacity of bridges, thus demonstrating its good engineering application prospect.

The purpose of this paper is to analyze the liquid sloshing behaviors in two-dimensional tanks with various porous baffles under the external excitation.

Adopting the finite element method (FEM) and control variable method to study the impacts of the height, length, number, location, shape, porous-effect parameter of the porous baffle, the external load frequency and the shape of the tank on the liquid sloshing response.

The amplitude of the free surface can be reduced effectively when the baffle opening is appropriate. The anti-sway ability of the system increases in pace with the baffle’s height growing. Under the same conditions, the shapes of the baffles have an important effect on improving the anti-sway ability of the system.

As there exist the differences of the velocity potential between each side of the porous baffle, which means that there are two different velocity potentials at a point on the porous baffle, the conventional finite element modeling technologies are not suitable to be applied here. To deal with this problem, the points on the porous baffle are regarded as two nodes with the same coordinate to model and calculate.

In order not to affect the highway and railway traffic under the bridge during the construction process, bridges adopting swivel construction method are increasingly used at areas where the traffic is heavy. Previous studies are mostly conducted by assuming that the bridge is under its own stability conditions, without considering the impact of construction error, changes of external condition and wind-induced vibration on the stability of the bridge, which poses serious challenges to the bridge construction process. This paper aims to analyze the extent to which static load and fluctuating wind effect influence structural stability and to test the credibility of the structure.

A finite element calculation method is used to analyze a T-shaped rigid frame swivel bridge. A full bridge model was built, and a local model of the turntable structure established; the two are then combined means of node coupling. Subsequently, the three sensitivity indexes – deflection rate, stress change rate and the change rate of spherical hinges – are used to evaluate in what way the bridge stability is influenced under various factors.

It is found that the stability of the swivel bridge is quite sensitive to unilateral overweight, steel beam tension and wind-induced vibration effects but less sensitive to the change of bulk density. Also found is that the change of elastic modulus exerts some effects on deflection but has negligible effects on other stability indexes. Furthermore, the transverse unbalanced torque on the bridge generated by wind-induced vibration is an important factor in determining the size of the turntable, indicating that it is not just controlled by the weight of the bridge.

All factors affecting the stability of swivel construction are analyzed, and solutions to reduce the influence are proposed. The influence of wind-induced vibration effects on swivel construction is analyzed for the first time. It is pointed out that wind-induced vibration effects have great influence on the structure, and its influence could not be neglected.

Polyurethane concrete has a high strength-to-weight ratio in the short term, and the strength-to-weight ratio stage during the maintenance period is critical. Freeze-thaw cycles have a noticeable damaging effect on the durability of polyurethane concrete. The engineering specification of polyurethane concrete with incomplete hydration reaction must be studied, as well as the development of internal structure during curing. In this paper, the polyurethane concrete tests were set up under eight distinct maintenance settings based on the climate features of the northern area and the service environment. The test results were evaluated to determine the effect of the number of early freeze-thaw cycles and the time node of early freeze-thaw cycles on the mechanical characteristics of polyurethane concrete, which revealed that the time node of freeze-thaw damage impacted the freeze-thaw resistance of polyurethane concrete susceptible to early freeze-thaw damage.

The early-age freeze-thaw damage polyurethane concrete was experimentally studied by controlling the time node of the freeze-thaw cycle and the curing environment. The test considered the time node, frequency of freeze-thaw damage of polyurethane concrete and the influence of subsequent curing environment and observed the mass change, relative dynamic elastic modulus, relative durability index, compressive strength and apparent damage of polyurethane concrete. The early mechanical properties of polyurethane concrete were studied by analyzing the change of numerical value. The microscopic mechanism of strength formation of polyurethane concrete was analyzed by XRD, FTIR and SEM image.

The closer the time of freeze-thaw damage was to the specimen hardening, the worse the mechanical properties and structure were, according to SEM photographs. For specimens with serial number of 12-groups, its compressive strength is only 82.39% of that of the standard group, even if the curing process continues after 20 times thawing, which increased early environment exacerbate strength loss in polyurethane concrete and also reduced freeze-thaw resistance. The findings of the tests reveal that curing can restore the freeze-thaw resistance of damaged polyurethane concrete. Curing in water has a better recovery impact than curing in air; the mechanical properties can be restored by sufficient re-curing time and good re-curing conditions.

By studying the freeze-thaw cycle test and test results of polyurethane concrete in different curing time nodes, the relationship between the mechanical properties of polyurethane concrete and the time node, number of freeze-thaw cycles, and subsequent maintenance environment was explored. Considering the special mechanism of strength formation of polyurethane concrete, the polyurethane concrete damaged by freeze-thaw has the ability to continue to form strength under subsequent maintenance. This experimental study can provide an analytical basis for the strength formation and reconditioning of polyurethane concrete structures subjected to freeze-thaw environments during the curing time under extreme natural conditions in fall and winter in actual projects.

Field robots can surmount or avoid some obstacles when operating on rough ground. However, cable-climbing robots can only surmount obstacles because their moving path is completely restricted along the cables. This paper aims to analyse the dynamic obstacle-surmounting models for the driving and driven wheels of the climbing mechanism, and design a mechanical structure for a bilateral-wheeled cable-climbing robot to improve the obstacle crossing capability.

A mechanical structure of the bilateral-wheeled cable-climbing robot is designed in this paper. Then, the kinematic and dynamic obstacle-surmounting of the driven and driving wheels are investigated through static-dynamic analysis and Lagrangian mechanical analysis, respectively. The climbing and obstacle-surmounting experiments are carried out to improve the obstacle crossing capability. The required motion curve, speed and driving moment of the robot during obstacle-surmounting are generated from the experiments results.

The presented method offers a solution for dynamic obstacle-surmounting analysis of a bilateral-wheeled cable-climbing robot. The simulation, laboratory testing and field experimental results prove that the climbing capability of the robot is near-constant on cables with diameters between 60 and 205 mm.

The dynamic analysis method presented in this paper is found to be applicable to rod structures with large obstacles and improved the stability of the robot at high altitude. Simulations and experiments are also conducted for performance evaluation.

The purpose of this paper is to analyze the rationale, strategies and significance of Chinese investment in the USA and its impact on US–China relations.

Through empirical analysis, this preliminary study examines the rationale, strategies and impact of Chinese investment in the USA.

Chinese investment has promoted economic growth in both countries, but it faces several challenges including security concerns and cultural clashes.

This paper is one of the first, comprehensive studies of the topic.

The purpose of this paper is to carry out a comprehensive review for state-of-the-art works in disruption risk management of express logistics mainly supported by air-transportation. The authors aim to suggest some new research directions and insights for express logistics practitioners to develop more robust planning in air-transportation.

The authors mainly confined the research to papers published over the last two decades. The search process was conducted in two dimensions: horizontal and vertical. In the horizontal dimension, attention was paid to the evolution of disruption management across the timeline. In the vertical dimension, different foci and strategies of disruption management are employed to distinguish each article. Three keywords were used in the full text query: “Disruption management”, “Air transportation”, and “Airline Operations” in all database searches listed above. Duplications due to database overlap, articles other than those from academic journals, and papers in languages other than English were discarded.

A total of 98 articles were studied. The authors categorized the papers into two broad categories: Reactive Recovery, and Proactive Planning. In addition, based on the problem characteristics and their application scenarios, a total of 11 sub-categories in reactive recovery and nine sub-categories in proactive planning were further identified. From the analysis, the authors identified some new categories in the air-transportation recovery. In addition, by analyzing the papers in robust planning, according to the problem characteristics and the state-of-the-art research in recovery problems, the authors proposed four new research directions to enhance the reliability and robustness of air-transportation express logistics.

This study provided a comprehensive and feasible taxonomy of disruption risk management. The classification scheme was based on the problem characteristics and the application scenarios, rather than the algorithms. One advantage of this scheme is that it enables an in-depth classification of the problem, that is, sub-categories of each class can be revealed, which provides a much wider and clearer horizon to the scientific progress in this area. This helps researchers to reveal the problem’s nature and to identify the future directions more systematically. The suggestions for future research directions also point out some critical research gaps and opportunities.

This study summarized various reasons which account for the disruption in air-transportation. In addition, the authors suggested various considerations for express logistics practitioners to enhance logistics network reliability and efficiency.

There are various classification schemes in the literature to categorize disruption management. Using different algorithms (e.g. exact algorithm, heuristics, meta-heuristics) and distinct characteristics of the problem elements (e.g. aircraft, crew, passengers, etc.) are the most common schemes in previous efforts to produce a disruption management classification scheme. However, the authors herein attempted to focus on the problem nature and the application perspective of disruption management. The classification scheme is hence novel and significant.