The collapse of surface goaf beneath highways can result in instability and damage to roadbeds. However, filling the goaf areas with foam concrete can significantly enhance the stability of the roadbeds while considerably reducing the costs of filling materials. This study analyzes the effects on destructive characteristics, mechanical properties, stress–strain curve features, and relevant metrics, while also observing the microstructure of basalt fiber-calcined gangue-silty clay foam concrete (BF-CCG-SCFC). The results indicate that the water–binder ratio significantly influences the cubic compressive strength, split tensile strength, and fluidity of BF-CCG-SCFC. Silty clay reduces the cubic compressive strength, split tensile strength, and fluidity of BF-CCG-SCFC. Conversely, an appropriate amount of calcined gangue and basalt fiber significantly increases the cubic compressive strength and split tensile strength, while decreasing fluidity. To satisfy the strength and fluidity requirements of the filler material in hollow areas, the optimal water–binder ratio for BF-CCG-SCFC is 0.55, the ideal mixing ratio of calcined gangue to silty clay is 2:2, and the basalt fiber content should be 1%. The study examines the influence of varying water–binder ratios, the combined proportions of calcined gangue and silty clay, and different basalt fiber contents on the elastic modulus, peak stress, and peak strain of BF-CCG-SCFC. Additionally, the water–binder ratio influences the matrix strength through the non-hydration reactions of doped particles, while gangue and clay induce a “gradient hydration effect” during the hydration process. The incorporation of basalt fibers enhances the mechanical interlocking between the fibers and the matrix.
A severe challenge resulting from the harsh climate and environment is the power supply to remote rail-side devices on the Tibetan plateau. Evolving renewable energy harvesting technologies offer a promising solution. This paper proposes and verifies a wind-solar energy harvester (WSEH) based on an airflow enhancement mechanism (AFEM) for powering rail-side devices. The proposed WSEH includes a vertical axis wind turbine (VAWT), flexible photovoltaic deflectors (FPVD), and energy conversion and storage devices. The AFEM is implemented based on the FPVD, which boosts the airflow energy blown to the VAWT due to the Venturi effect. The FPVD, based on an umbrella-like mechanism, unfolds as a PV panel for solar energy harvesting and folds as a deflector to boost the wind energy harvesting capacity for the VAWT. In CFD simulation, the maximum power coefficient of VAWT reaches 0.387, and the optimum gain effect of FPVD is 66.54%. The prototypes, including VAWT and FPVD, are tested in a wind tunnel to verify the practical effects demonstrated by no-load speed and load output of the VAWT. The case study indicates that the WSEH generates 1566.82 kWh of electrical energy per year, which is adequate for powering rail-side devices on the Tibetan Plateau.
A severe challenge resulting from the harsh climate and environment is the power supply to remote rail-side devices on the Tibetan plateau. Evolving renewable energy harvesting technologies offer a promising solution. This paper proposes and verifies a wind-solar energy harvester (WSEH) based on an airflow enhancement mechanism (AFEM) for powering rail-side devices. The proposed WSEH includes a vertical axis wind turbine (VAWT), flexible photovoltaic deflectors (FPVD), and energy conversion and storage devices. The AFEM is implemented based on the FPVD, which boosts the airflow energy blown to the VAWT due to the Venturi effect. The FPVD, based on an umbrella-like mechanism, unfolds as a PV panel for solar energy harvesting and folds as a deflector to boost the wind energy harvesting capacity for the VAWT. In CFD simulation, the maximum power coefficient of VAWT reaches 0.387, and the optimum gain effect of FPVD is 66.54%. The prototypes, including VAWT and FPVD, are tested in a wind tunnel to verify the practical effects demonstrated by the no-load speed and load output of the VAWT. The case study indicates that the WSEH generates 1566.82 kWh of electrical energy per year, which is adequate for powering rail-side devices on the Tibetan Plateau.
The development of solid rocket engine has a long history. However, modern rocket technology and space flight developed until the end of the nineteenth century and the beginning of the twentieth century, and hence the gradual emergence of solid rocket, liquid rocket and hybrid rocket. Today, with the development of solid rocket, all kinds of knowledge and technologies emerge in an endless stream. Therefore, this paper aims at reviewing the development history of rockets in different major countries and summarizing the current research and development status of solid rocket and looking forward to the future development of solid rockets. According to the related theories, even though different kinds of materials have deeply used in SRM, there is still some room to research and develop new materials for SRM.
Both hydrodynamic factors and social factors have large impacts on the loss of life caused by dam failure. Relatively large uncertainty intervals of the influencing factors lead to changes in the potential loss of life. Based on an analysis of the formation mechanism of loss of life, the influencing factors were identified. Combined with interval theory, a method for calculating loss of life and determining the impacts of the influencing factors on loss of life was proposed. The intervals of the exposure rate of the population at risk and the mortality of the exposed population, which are impacted by the major influencing factors such as the flood severity, warning time, understanding of dam failure, and building vulnerability, were recommended. Furthermore, a range of correction coefficients caused by the minor influencing factors, such as the dam failure time, rescue ability, and age distribution, was analyzed. The proposed method was validated by analyzing the losses of life in 21 flooded regions after 10 dam failure events and 2 flash river floods, in which the intervals of the estimated results all contained the actual loss of life. In addition, the ratios of the upper bounds to the corresponding lower bounds of the intervals were all less than 10, which is in accordance with the characteristic that the results of different existing methods vary within an order of magnitude. This is the first work that pays careful attention to the uncertainty intervals of loss of life estimates, and the proposed method effectively determined the severity of the potential loss of life caused by dam failure.
Wearable health monitoring devices can effectively capture human body information and are widely used in health monitoring, but battery life is an important bottleneck in its development. A full negative-work energy harvester based on the homo-phase transfer mechanism by analyzing human motion characteristics was proposed in this paper. The system was designed based on the homo-phase transfer mechanism, including a motion input module, gear acceleration module, energy conversion module, and electric energy storage module. The output performance in three human-level, downhill, and running states was tested, respectively. Finally, we have evaluated the feasibility of an energy harvester powering wearable health monitoring devices, and the harvester can generate 17.40 J/day power, which can satisfy the normal operation of a typical health monitoring device. This study has certain promoting significance for the development of a new generation of human health monitoring.
Despite the rapid development of risk analysis in dam engineering, there is a relative absence of research on the environmental impact of dam break. As a systematic theory, set pair analysis has a good effect in dealing with uncertainties, although the result is relatively rough and easy to distort. A connection degree of five grades and a generalized set of potential are introduced to improve traditional set pair analysis. Combined with the index system, the evaluation model of the environmental impact of dam break is established, which is based on generalized set pair analysis. Taking Sheheji Reservoir dam as an example, a comparison of evaluation results of fuzzy mathematics theory and generalized set pair analysis is made, which verifies the scientificity and practicability of the method proposed in this paper. The results show that the evaluation grade of the environmental impact of dam break at Sheheji Reservoir is serious, and appropriate management measures should be taken to reduce the risk.
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