Experimental Study of Breakage of Particles under Compression

Granular materials are used widely and can be seen in natural and industrial applications such as sand bags or pharmaceutical pills. During their manufacturing, processing, transport and use, granular materials are subjected to various kinds of loadings. If the amplitude of the loading is above the strength threshold, particles constituting granular materials may fracture. It is very important to understand the failure of particles under these loading conditions to prevent or control their failure during all stages of their manufacturing and use. Better characterization of the fracture behavior of particles composed of different materials and sizes will allow more precise application and better maintenance of granular materials in commercial usage. The effects of size and material properties on the deformation and fracture behavior of granular particles are studied by investigating particles from three different size ranges for three different materials. The mechanical behavior is characterized by force-displacement and stress-strain plots under quasi-static compression (strain rate = 10-2s-1). Along with the deformation behavior, the strengths of particles are also recorded and Weibull distribution is fitted to the fracture stresses. It was observed that the smaller particles break at lower forces but actually withstand higher stress at fracture. The calculated Weibull moduli for different size range and materials show that the flaw population from the manufacturing process is different for different sizes and materials. This study shows that size and material properties alter the fracture stresses. Future experiment can be performed for the same particles under dynamic compression to better understand effects of strain rate on the fracture of particles

Mechanical Properties of Recycled Aggregate Concrete Modified by Nano-particles

In this study, different nano-particles were used to modify recycled aggregates concrete (RAC) containing recycled clay brick aggregates (RCBAs) to improve the RAC properties. Two stages of experimental works were performed. In the first stage, various nano-particle mixtures produced by different mixing methods, i.e. the use of surfactant and ultrasonication, were examined by optical microscope to evaluate the dispersion of the nano-particles in water liquid. The nano-particles modified cement mortar specimens were further evaluated by flexural tensile test to check how these mixing methods affect the properties of the nano-particle modified cement mortar. In the second experimental stage, the effects of four replacement ratios of recycled aggregates, three type of nano-particles, two mixing methods of RAC, additional surfactant and ultrasonication process used in the mix of nano-particle liquid, and the dosages of the nano-particles on the workability, compressive and split tensile properties of the nano-particle modified RAC were investigated

Baichuan 2: Open Large-scale Language Models

Large language models (LLMs) have demonstrated remarkable performance on a variety of natural language tasks based on just a few examples of natural language instructions, reducing the need for extensive feature engineering. However, most powerful LLMs are closed-source or limited in their capability for languages other than English. In this technical report, we present Baichuan 2, a series of large-scale multilingual language models containing 7 billion and 13 billion parameters, trained from scratch, on 2.6 trillion tokens. Baichuan 2 matches or outperforms other open-source models of similar size on public benchmarks like MMLU, CMMLU, GSM8K, and HumanEval. Furthermore, Baichuan 2 excels in vertical domains such as medicine and law. We will release all pre-training model checkpoints to benefit the research community in better understanding the training dynamics of Baichuan 2.Comment: Baichuan 2 technical report. Github: https://github.com/baichuan-inc/Baichuan

Editorial for the Special Issue on Safety and Reliability of Power Electronics Components and Systems

Efficiency and power density have been widely concerned with the development of power electronics, while the safety and reliability issues are attracting more and more attention in a few years due to the increasingly stringent safety requirements, e.g., in electric vehicle, consumer electronics, and aerospace industries. To understand the failure mechanisms and the safe operation area of components/systems in practical applications, comprehensive testing methods considering the operating conditions are becoming essential. Besides accelerated aging tests, multi-physics modeling, physics-of-failure analyses, degradation modeling, electro-thermal simulation, and lifetime assessment contribute to a better understanding of the failure roots in components and systems and the design of a safer system. Moreover, designing condition monitoring and health status estimation tools, fault diagnosis, fault tolerance, and active thermal management techniques help to realize the predictive maintenance of power electronic components and systems. Finally, emerging artificial intelligence (AI) and machine learning (ML) techniques are getting a lot of attention in aging data processing, remaining useful life estimation, etc. Correspondingly, we organized this Special Issue on Safety and Reliability of Power Electronics Components and Systems to collect emerging research achievements within the scope of safety and reliability of power electronics components and systems and circuits

RETRACTED: Forecasting Solar Cycle 25 Using an Optimized Long Short-term Memory Mode Based on F10.7 and Sunspot Area Data

In this paper, an optimized long short-term memory model is proposed to deal with the smoothed monthly F _10.7 and nonsmoothed monthly sunspot area (SSA) data, aiming to forecast the peak amplitude of both solar activities and the occurring time for Solar Cycle 25 (SC-25), as well as to obtain the maximum amplitude of sunspot number (SSN) and the reaching time according to the relationships between them. The “reforecast” process in the model uses the latest forecast results obtained from the previous forecast as the input for the next forecasting calculation. The forecasting errors between the forecast and observed peak amplitude of F _10.7 for SC-23 and SC-24 are 2.87% and 1.09%, respectively. The results of this evaluation indicator of SSA for SC-21 to SC-24 were 8.85%, 4.49%, 2.88%, and 4.57%, respectively, and the errors for the occurring time were all within 6 months. The forecast peak amplitude of F _10.7 and SSA for SC-25 is 156.3 and 2562.5 respectively, and the maximum values of SSN are calculated as 147.9 and 213 based on F _10.7 and SSA respectively, which implies that SC-25 will be stronger than SC-24, and that SC-25 will reach its peak at the beginning of 2025

First-principle study on the electronic structure and optical property of new diluted magnetic semiconductor (Y0.75Sr0.25) (Cu0.75Mn0.25)SO

In this research, we investigated the electronic structure and optical property of new diluted magnetic semiconductor (Y0.75Sr0.25) (Cu0.75Mn0.25)SO with decoupled charge and spin doping by first-principle calculation. We also compared (Y0.75Sr0.25) (Cu0.75Mn0.25)SO with pure YCuSO, and found that (Y0.75Sr0.25) (Cu0.75Mn0.25)SO is still a direct semiconductor with a band gap 1.20eV. The important difference from YCuSO is that the DOS of (Y0.75Sr0.25) (Cu0.75Mn0.25)SO presents asymmetry around fermi surface, leading to obvious spin order and ferror-magnetism due to the p-d hybridization through Mn 3d and S 3p. In case of the optical properties (including reflectivity coefficient, absorption coefficient, the imaginary part and real part of complex dielectric constant), the intensity of all peaks for both pure and doped YCuSO tends to zero above 15.5eV. However, the value of all the peaks for (Y0.75Sr0.25) (Cu0.75Mn0.25)SO reduces to some extent due to the Sr and Mn dopant. In addition, the position of all the peaks for (Y0.75Sr0.25) (Cu0.75Mn0.25)SO have a “red shift”, probably originating from the impurity states generated by the p-d hybridization through Mn 3d and S 3p. This will be beneficial for searching new 1111 phase DMS