Abstract:The downtime and potential safety hazards of wind turbines caused by high temperature have posed important technical bottlenecks that restrict the development of the current wind power industry. For the sake of fully understanding the thermal management of wind turbines，this article starts from the current development requirement of large-scale，intelligence and diversification for wind turbines. Then，the state-of-art wind turbine cooling technology is comprehensively reviewed from the view of the working principles，technical characteristics，and adaptation occasions of air and liquid cooling. On this basis，inspired by the high -efficiency cooling technology methods of existing electronic devices，the feasibility of applying the new cooling technology in the field of wind turbine thermal management is analyzed and discussed，and the future development direction of the new generation of wind turbine cooling technology is prospected. This review may provide materials for the development of new and high-efficiency cooling technologies for future wind turbines in our country，and can enlighten technological innovations in thermal management of new generation wind turbines.

Abstract:This paper selects the mainstream of the freight transportation，i.e.，small and medium freight enterprises to find a best way to platform transformation. An evolutionary game model is established and two transformation strategies，i.e. autonomous operation and joint operation are proposed. The results show that: ① When the extra benefits of group and group are more than their costs，both parties tend to adopt the autonomous operation transformation strategy and the joint operation. Moreover，the specific choice will be affected by the extra benefits and the allocation ratio. When the conditions are not met，both sides of the game can only adopt the autonomous operation strategy. ② The more the additional revenues，the higher the probability of joint operation transformation strategy will be chosen. ③ An optimal income allocation ratio can be found，which makes the both sides of the game choose the joint operation transformation strategy.

Abstract:In order to research the stress -strain constitutive relationship model of concrete confined by steel-frame polyethylene plastic composite pipe(SRPE) under uniaxial compression, the restraint effect of the SRPE pipe on the core concrete is equivalent to the linear superposition of the restraint effect of the outer HDPE pipe and the embedded steel mesh skeleton mid-latitude wire on the core concrete. By referring to the research idea of the classic Mander model, the effective lateral constraint stress of SRPE pipe on core concrete was calculated, and the calculation method for the ultimate compressive stress and strain of SRPE casing concrete is proposed by modifying the strength of confined concrete in the model to increase the coefficient k value, and the corresponding stress-strain relationship model is established. The results show that the calculated results of the model are relatively close to the experimental results, indicating that the proposed constitutive relationship model has a certain accuracy.

Abstract:Focusing on the foundation pit of an ultra -deep working well in Foshan City, numerical simulation methods are used to analyze the influence of different foundation pit sizes on the horizontal displacement, bending moment, surface settlement behind the wall, and pit bottom uplift of the diaphragm wall, and the reliability of numerical analysis is verified by on-site monitoring results. The influence of the size effect on the arch effect characteristics of the circular foundation pit is further studied. It is found that that the horizontal displacement, bending moment, surface settlement behind the wall, and pit bottom uplift of the diaphragm wall show an overall trend of increasing with the increase of the size of the foundation pit. When the diameter of the foundation pit is less than 65.9 m, it has a greater impact on various parameters. And when the diameter of the foundation pit is about 0.6~0.9 times of the excavation depth of the foundation pit, the circumferential stress of the retaining structure is greater than the radial stress, which has a good "arch effect"; when the diameter of the foundation pit exceeds this range, the hoop stress is smaller than the radial stress, and the "arch effect" is weakened. Through the study of the size of an ultra-deep circular foundation pit, it is expected to provide reference for related projects.

Abstract:In order to investigate the soil displacement and pile foundation deformation and internal force distribution characteristics under adjacent construction access load in Nanchang binary strata, as well as evaluate the influence of adjacent construction access load on the safety of existing bridge pile foundations, a series of numerical simulations are conducted via Plaxis 3D. The difference of calculation results between two soil constitutive models of Mohr-Coulomb(M-C) and small strain stiffness(HSS) is compared. Besides, the HSS model is used to analyze the additional deformation and internal force of the existing pile foundation adjacent to the working line under the construction access load, and its safety performance are evaluated. The results show that the influence area of the soil displacement calculated by the M-C model is too large, and the calculation result by the HSS model is much closer to the practical situation. Considering 6 mm as the allowable value of soil settlement, the influence width is 3.2 m beyond the centerline of the construction access. The deformation and internal force of the adjacent existing bridge pile foundation are within the safety range, meeting the safety requirements specified by the codes or standards.

Abstract:Based on the theoretical foundation of lower bound limit analysis method, corresponding equilibrium equation is derived by using complete stress field of slope which has been built based on perfectly pin connected truss assumption. Catastrophe model of slope failure is constructed based on mutation feature of slope failure. System model property and slope failure mechanism are analyzed, and the lower bound solution of slope failure is achieved. Ultimate load of a slope example is analyzed, and comparison between the solution acquired by the proposed method and the classical plastic theory and comparison between the solution acquired by the proposed method and the finite element method are adopted to illustrate the feasibility of the proposed method. The key difficult problem of slope lower limit analysis is solved by using the catastrophe theory. The executive idea of this research may provide a new optional approach to solve lower bound theoretical solution of ultimate bearing capacity of slope.

Abstract:The ceramic waste materials were processed into ceramic powder and the hydration performance of ceramic powder-cement composite binders under different curing conditions were studied by observing the micromorphology, measuring the chemically combined water content and the alkalinity of pore solution. It was shown that at the same curing conditions, the greater the adding rate of ceramic powder is, the more the chemically combined water content along with the alkalinity of pore solution of the hardened cement paste decreases; when the adding rate of ceramic powder is less than 20%, the earlier high temperature curing can increase the alkalinity of pore solution and has a great impact on the overall hydration degree; the earlier high temperature curing promotes the earlier hydration rate of ceramic powder-cement composite binders, which makes the micro-structure of the hardened cement paste at the prophase of hydration more compact, but it has an inhibitory effect on the improvement of the hydration degree of the later hardened paste. The results provide an experimental basis for further research on the hydration performance of ceramic powder-cement composite binders under early high temperature curing conditions.

Abstract:In order to more reliably improve the non-intrusive load decomposition ability of residents, the whole identification process is divided into two processes: load event identification and state identification. A MK change point detection algorithm based on dual sliding windows and a weighted dual-parameter hidden Markov model are respectively proposed for load event recognition and state recognition. In the state recognition, the appearance probability of each internal state of each device in each time period is brought into the algorithm as a weight. Through data verification and comparative experiments, it is shown that the NILM algorithm mentioned can more effectively identify the residents’ load.

Abstract:The crew scheduling of railway freight transportation is the work basis for freight locomotives operation. It is still made manually by the schedulers based on their experience in China, leading to some problems such as low efficiency of scheduling preparation, unbalanced work time of crew and waste of crew resources. In response to these problems, in this paper, a model for railway freight locomotive crew scheduling is established, with the aim of minimizing the crew idle transition time, the crew scheduling preparation process and the locomotive management regulations considered. To solve the model, the traversal searching algorithm based on “first come first serve” principle and genetic algorithm are designed. Finally, the example of two freight workshops in a locomotive depot is selected to verify that the proposed model and algorithm can effectively solve the problem. Compared with the original manual experience plan, the number of freight locomotive crew is reduced by 22.5% and 17.5%, and the efficiency of railway freight locomotive crew scheduling has been improved.

Abstract:Stereo matching algorithm plays an important role in binocular vision. Census stereo matching algorithm based on nonparametric transformation has been widely used in recent years, but in the process of obtaining disparity map, Census stereo matching algorithm relies too much on the gray value of the central pixel. In view of the insufficient matching accuracy caused by the traditional Census algorithm relying too much on the center pixel, this paper proposes a Census stereo matching algorithm based on cross based aggregation. In order to improve the accuracy of parallax image, this algorithm finds the pixels around the reference pixels which are similar to their colors through the cross based aggregation, and uses the pixels in the cross based aggregation to optimize the generation value of the reference pixels. The experimental results show that the cross-based Census stereo matching algorithm improves the parallax accuracy of the image, and under the condition of ensuring the matching accuracy, the cost aggregation time of the algorithm is greatly reduced compared with the four path cost aggregation Census algorithm.

Abstract:Combined with the vehicle-track coupling dynamic sub-model of the modern tram, multi-point contact sub-model of wheel and rail and Archard material grinding wear sub-model, a predictive analysis model of wheel wear was established. The accuracy of the model in this paper is verified by comparing with the results of relevant references. It is used to calculate and analyze the influence of the widened gauge on the wheel wear of a modern tram when it passes through a curved track with a small radius. The results show that: under the same line condition, the abrasion of independent wheel rim is greater than that of non-independent wheel； the difference value is 0.94 mm at most, and the results for two kinds of wheel tread are close to each other. For the line with small curve radius, the wheel rim wear is relatively small when the gauge width is 10-15 mm, while the wheel rim wear is relatively uniform when the gauge width is 15 mm. The research results can provide useful reference for modern tram vehicle maintenance.

Abstract:In view of the inconsistency and incompatibility in the calculation results of the EMU assignment, the undertaking of the EMU maintenance workload of the EMU depot(station), and the scale of the maintenance facilities in the newly built high-speed railway hub, this article proposes, Three methods for measuring the size of the EMUs in the hub using the full turnaround time and daily train-kilometer method as indicators. Focusing on the daily EMU-kilometres and full turnaround time as the main indicators to calculate the size of the EMUs in the hub，it explores the overhaul workload of the EMU depot(station) and the method for calculating the scale of overhaul facilities. The research results show that the calculation results using the daily train-kilometer index of EMUs have a large margin, and it is necessary to rationally adjust the average daily shape-kilometer indicators of the EMUs in the hub based on the main technical standards of the railway in the hub, passenger flow, and driving plan. However, the calculation method is more convenient and suitable for long-term railway hub planning investment and EMU vehicle production scale control. The calculation results using the full turnaround time index of EMUs are more scientific and reasonable, which can effectively improve the utilization rate and operation rate of EMUs. At the same time, it can effectively reduce the waste of maintenance resources and the investment in engineering construction in terms of operation and maintenance.

Abstract:Ballastless track is widely used in high-speed railway in China. Because of its good quality and small amplitude of irregularity, it is difficult to distinguish line sections when using the current track quality index (TQI) to evaluate track smoothness, which is not conducive to the fine management of ballastless track. Therefore, a new method for calculating TQI value based on the combination of amplification factor and different weight combinations is proposed. Taking the irregularity detection data from Shanghai-Hangzhou high-speed railway uplink as an example, the weight of each single component in TQI is allocated by using the coefficient of variation, and the single component value is graded according to the management standard by using the amplification coefficient. By comparing the new TQI value with the original TQI value, the calculation results of the new TQI value are divided into four intervals, TQI≤600, 600＜TQI≤700, 700＜TQI≤800, TQI＞800, in order to better evaluate and manage the smoothness of high-speed railway ballastless track.

Abstract:In order to explore the double effects of the input of tech-finance on the technological innovation performance of high-tech industry, this paper selects the panel data of tech-finance input and innovation performance of high-tech industry in 31 provinces and cities in China from 2010 to 2018. It adopts the random effects model and dynamic panel system GMM model for empirical research to discuss the direct and indirect effects of tech-finance on technological innovation of high-tech industry. The result shows that the government fiscal expenditure on science and technology, loan of science and technology, science and technology and human resources have direct effects on technological innovation. In addition, government fiscal expenditure on science indirectly promotes the high-tech industry to carry out technological innovation by improving the business conditions of enterprises.

Abstract:By studying the structural characteristics of linear crossed polyomino chain X_n and crossed polyomino cylinder chain G_n, the Laplacian spectra of X_n and G_n are calculated by the Laplacian eigenvalues of the composite graph, and the analytic expressions of Kirchhoff index, degree-Kirchhoff index and the number of spanning trees of X_n and G_n are derived. And we show that when n tends to be infinity, the Kirchhoff index of crossed polyomino cylinder chain G_n is one-half of the Kirchhoff index of the linear crossed polyomino chain X_n.