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The objective of this study is to investigate the potential risks posed by snowdrifts, a prevalent cause of natural disasters in northern China, on railway subgrades, and to assess their risk level. As a wind-driven process of snow migration and redeposition, snowdrifts pose a significant threat to the safety of transportation infrastructures. This study focuses on the Afu Railway in Xinjiang, situated on the northern slopes of the Eastern Tianshan Mountains, where it experiences periodic snowdrifts. We employed a combination of the Analytic Hierarchy Process (AHP) and fuzzy comprehensive evaluation (FCE) to construct an integrated evaluation system for assessing the risk of snowdrift to railway subgrades. The results indicate that subgrade design parameters and regional snowfield conditions are two key metrics affecting the extent of snowdrift disasters, with topography, vegetation coverage, and wind speed also exerting certain impacts. The evaluation method of this study aligns with the results of on-site observations, verifying its accuracy and practicality, thereby providing a solid risk assessment framework for snowdrifts along the railway. The scientific and systematic hazard assessment method of railway subgrades developed in this research provides basic data and theoretical support for future research, and provides a scientific basis for relevant departments to formulate countermeasures, so as to improve the safety and reliability of railway operations. [ABSTRACT FROM AUTHOR]

Landslides represent the most destructive and prevalent geological hazards along mountainous highways, severely imperiling the construction and maintenance of road infrastructure. To mitigate risks associated with high slopes during construction, a systematic evaluation of landslide susceptibility is imperative. This study introduces an assessment method developed over three years of engineering practice, integrating ten parameters that are intricately linked to construction scale, geological conditions, and engineering design. The method innovatively employs the Index Complexity Algorithm (ICA) to ascertain the weight distribution of the parameters, thereby diminishing the impact of subjective biases in qualitative assessments and enhancing the objectivity and precision of the evaluation. Utilizing the slope in China as a case study, the paper meticulously demonstrates the application of the assessment method. A comprehensive evaluation of the slope's geological context, construction scale, and design rationality by the ICA algorithm yields a quantified risk score for the slope's potential hazards. The findings indicate that the slope is classified as high risk (Grade III) during highway construction, necessitating the implementation of risk mitigation measures such as prestressed anchor cables and grouting anchorage. Beyond offering a novel methodological approach to landslide risk assessment, the method significantly contributes to the sustainable construction and operation of mountainous highways. Anticipated refinements in the assessment process and the parameter are poised to augment the method's efficacy in slope engineering safety management, thereby bolstering the long-term stability and environmental sustainability of mountain highways. [ABSTRACT FROM AUTHOR]

This letter presents a wideband antenna for high-precision Global Navigation Satellite System (GNSS) applications. The antenna consists of a pair of improved orthogonal dipoles that are fed by a feed network with Composite Right/Left-Handed Transmission Lines (CRLH-TLs), a polygonal patch, and a reflector. By using improved orthogonal dipole, the beamwidth of the antenna is broadened. The CRLH-TLs is adopted in feed network to obtain outputs with stable phase difference. Experiment results indicate that the antenna has a less than 10-dB return-loss bandwidth in the range of 1.1 to 1.7 GHz, a 3-dB axial-ratio bandwidth from 1.2 to 1.6 GHz, and a larger than 6.37 dBi gain in the whole operating band. The measured results show that the proposed antenna has stable performance in the whole operating band, which means that it is a suitable antenna used for GNSS applications.

In subsurface irrigation systems in desert areas, the wetting front transport pattern allows the determination of irrigation flow and timing. In this study, an indoor subsurface irrigation experiment on aeolian sandy soil is designed, and the vertical and horizontal wetting front movement distances under different irrigation flows are obtained. The dimensional analysis method was used to perform a dimensional analysis on the experimental data. An empirical setting front distance estimation model, which only considers three parameters, saturated hydraulic conductivity Ks, irrigation flow Q, and total irrigation volume V, was proposed. The model's accuracy was statistically evaluated with the observed data and verified by a numerical simulation using HYDRUS-2D/3D. The mean absolute error (MAE) and root mean square error (RMSE) of the proposed model in the horizontal and downward directions were 0.80 and 0.95 cm, respectively, with a percentage bias (PBIAS) of −3.47 ≤ ±10 and a Nash–Sutcliffe efficiency (NSE) of 0.98, which is close to 1. Thus, this model can contribute to the selection of the appropriate depth and spacing of subsurface laterals. [ABSTRACT FROM AUTHOR]

Wind power is widely used in industry, meteorology, shipping and so on. Accurate measurement of wind parameters is the key to improve the efficiency of wind power application. But at present, wind parameters are largely measured by different devices based on time difference method, which is easily influnced by enviromental noise. Beam-forming algorithm can improve the ability to resist environmental noise and the accuracy of hardware itself. Therefore, the beam-forming algorithm can be used to measure wind parameters in the high noise environment. However, the efficiency of the algorithm depends on how to search for spectral peak. In this paper, a three-dimensional wind measurement method with chaotic-sequence improved genetic-particle swarm optimization algorithm is proposed to improve the waveform searching efficiency of beamforming algorithm. It first searches for rough target wind parameters globally, and then searches for precise target wind parameters locally. Through simulation verification, the proposed algorithm can measure the wind parameters after 0.087s under the condition of system error of 50dB and environmental noise of 20dB, the accuracy of wind speed is 0.5%, the accuracy of wind direction is 1%, and the accuracy of pitch angle is 0.5%. Compared with the wind measurement by traversal method, the proposed algorithm can improve the wind measurement efficiency by about 20 times, and has similar or even better measurement results.. And by comparing with other algorithms, the advantages of this algorithm are verified. [ABSTRACT FROM AUTHOR]

A circular polarized square fractal patch antenna with square slot and via is proposed, which can be applied to global navigation satellite systems. Two pairs of square ring slot with different sizes are placed diagonally for antenna circularly polarized radiation. By changing the square patch into a fractal structure and adding defective ground structure, miniaturization can be achieved while the bandwidth is further expanded. The total antenna size is 0.3λo × 0.3λo × 0.03λo (λo is the free‐space wavelength at 1.575 GHz). The final measurement results show that the maximum gain is 3.26 dBic, the 3 dB axial ratio (AR) bandwidth is 1.57–1.6 GHz and the impedance bandwidth (S11 < −10 dB) is more than 60 MHz at the resonant frequency of 1.575 GHz. [ABSTRACT FROM AUTHOR]

Three new system reliability models are presented.

Due to complicated structures and discontinuities in surrounding rock mass, existing empirical failure criteria cannot meet the requirements of engineering practice such as tunnels. To improve estimation accuracy on the strength of rock mass with joints, a modified chart of the Geological Strength Index using Hoek-Brown criteria was further tested to estimate rock mass strength [Lin et al. (2014) Bull Eng Geol Environ 4(73):1245-1258], and, in this paper, new strength estimation equations for jointed rock mass were then modified based on a large dataset obtained from Chinese projects. Here, standard drilling time is first introduced and described in this study, and then used as a parameter to estimate rock strength. Different empirical formulas based on joint density, rock mass classification, Hoek-Brown criteria, and elastic wave velocity are thus used to estimate rock mass strength by using data from the Jiubao tunnel. The results estimated based on different empirical formulas were similar, indicating that the modified assessment method presented in this paper can be used to estimate rock mass strength under certain circumstances. Cross-correlation of different empirical methods provides significant confidence in predicted rock mass strength calculations. [ABSTRACT FROM AUTHOR]