Combined effects of sulfate attack under drying–wetting cycles and loading on the fatigue behavior of concrete

Concrete structures often undergo both fatigue loading and environmental impacts during their useful lifetime. This study aims to explore the fatigue properties of concrete subjected to sulfate attacks under drying–wetting cycles and loading. The coupled influences of major cycle number and sodium sulfate solution on the residual deformation, elastic modulus, and damage variable were investigated by uniaxial cyclic loading tests. Moreover, the phase composition of concrete samples was examined by X-ray diffraction. Results indicate that the concrete residual deformation and damage variable could be classified into initial and stable stages, while the elastic modulus fluctuated within a certain range. The fatigue strength of concrete was found to increase with an increase in the major cycle number and sodium sulfate concentration in the early stages, whereas the fatigue performance of concrete decreased as the major cycle number and sodium sulfate concentration increased in the later stage. The degree of influence of major cycle number and sodium sulfate concentration on the fatigue properties of concrete differed in each stage. These findings can contribute to understand the variation pattern of concrete properties in complicated environments and provide an important reference for associated construction projects.

Recent Changes in Temperature and Precipitation of the Summer and Autumn Seasons over Fujian Province, China

Based on the observation data of daily temperature and precipitation in summer and autumn of 68 representative meteorological stations in Fujian Province from 1971 to 2018, using the climate Tendency Rate, Mann-Kendall trend test, Morlet wavelet analysis and other methods, this paper analyzes the variation trends of air temperature and annual precipitation and the wavelet periodic variation characteristics of annual precipitation time series in summer and autumn of Fujian Province over a period of approximately 48 years. The results show that over the approximately 48 years, the temperature and precipitation in summer and autumn in Fujian showed an obvious upward trend, which had a mutation around 2000, but the mutation time was different, and the precipitation was slightly earlier. The annual temperature and precipitation in summer and autumn experienced three oscillations on the 28a scale. In the 28a time scale of summer autumn seasonal oscillation, there are three negative centers and two positive centers. According to the characteristics of annual average temperature and annual precipitation in the first major cycle, the annual precipitation in summer and autumn will continue to increase in the future.

A Study on the Prosperity Index and Cycle Measurement of China Air Cargo Transport

The business cycle of the Air cargo in China is investigated in this paper. Both the composite indicator (CI) and the diffusion indicator (DI) are derived and the benchmark date is determined. The composite index is synthesized by 10 indicators using correlation analysis and the method of NBER. Then the spectral method is adopted in use of the CI to identify the the major cycle of air cargo in China. By the CI, there is a major cycle with the length of 3,6 years. The major cycle of air cargo in China keeps pace with the the global trade fluctuation. The cycle of air cargo of China is compared with the United States, and the railway cargo of China. The author finds out that the major cycle of the air cargo is basically consistent with the USA in the same period. Combined with the prosperity index, it illustrates that the growth of air cargo in China will reach a peak in around 2021-2022, considering the growth of global trade and the leading prosperity index.

The Origin and Propagation of the Antarctic Centennial Oscillation

The Antarctic Centennial Oscillation (ACO) is a paleoclimate temperature cycle that originates in the Southern Hemisphere, is the presumptive evolutionary precursor of the contemporary Antarctic Oscillation (AAO), and teleconnects to the Northern Hemisphere to influence global temperature. In this study we investigate the internal climate dynamics of the ACO over the last 21 millennia using stable water isotopes frozen in ice cores from 11 Antarctic drill sites as temperature proxies. Spectral and time series analyses reveal that ACOs occurred at all 11 sites over all time periods evaluated, suggesting that the ACO encompasses all of Antarctica. From the Last Glacial Maximum through the Last Glacial Termination (LGT), ACO cycles propagated on a multicentennial time scale from the East Antarctic coastline clockwise around Antarctica in the streamline of the Antarctic Circumpolar Current (ACC). The velocity of teleconnection (VT) is correlated with the geophysical characteristics of drill sites, including distance from the ocean and temperature. During the LGT, the VT to coastal sites doubled while the VT to inland sites decreased fourfold, correlated with increasing solar insolation at 65°N. These results implicate two interdependent mechanisms of teleconnection, oceanic and atmospheric, and suggest possible physical mechanisms for each. During the warmer Holocene, ACOs arrived synchronously at all drill sites examined, suggesting that the VT increased with temperature. Backward extrapolation of ACO propagation direction and velocity places its estimated geographic origin in the Southern Ocean east of Antarctica, in the region of the strongest sustained surface wind stress over any body of ocean water on Earth. ACO period is correlated with all major cycle parameters except cycle symmetry, consistent with a forced, undamped oscillation in which the driving energy affects all major cycle metrics. Cycle period and symmetry are not discernibly different for the ACO and AAO over the same time periods, suggesting that they are the same climate cycle. We postulate that the ACO/AAO is generated by relaxation oscillation of Westerly Wind velocity forced by the equator-to-pole temperature gradient and propagated regionally by identified air-sea-ice interactions.

The evaluation of energy saving performance for the modular design centrifugal chiller

The modular concept design and operation of a centrifugal chiller offers the potential of increased cycle efficiency both at full load and off load conditions compared to the single compressor chiller. Modular chiller design is that a smaller, individual chiller can be connected with another, to make a larger capacity system. In the case of a tandem chiller, there would be faced to the higher initial cost or bigger foot print than a single compressor chiller at the same capacity because manufacturing cost, weight and size will be decreased according to increase of the refrigeration capacity. Therefore, it is obvious that a modular chiller have to be improved its efficiency first by both the operation algorithm and major cycle components. Eventually, the efficiency of the modular chiller achieves up to 6% at the full load condition after added series counter flow effect as much as 3% and more 3% added by improved aerodynamic design for impeller. Moreover, maximize off design potential through the capacity combination algorithm as the way of uneven loading makes 24% improved based on AHRI 550/590.

Awheel Along Europe’s Rivers: Geoarchaeological Trails for Cycling Geotourists

This review study presents an overview of the potential for the development of geoarchaeological trails for leisure cyclists in Europe. It initially defines and discusses the underpinning key concepts and then examines the nature and main needs of leisure cyclists. It considers and recognises appropriate geo-interpretative themes, of geological/geomorphological and archaeological/historical interest, to employ in developing the trails. Noting that river valleys have long been natural route-ways for human expansion into Europe (as exemplified by the ‘Stone Age’ and the Roman Empire), and that many of today’s major cycle trails are beside rivers with loess deposits, a geoarchaeological geotourism strategy is considered in relation to them. Case studies of specific sites, from central southern England, the Middle Danube and Middle Rhine valleys, outline the current provision and the basis of the proposed trails. Finally, a common relatively low-cost, mixed media, geo-interpretative and promotional approach could generate the impetus to further develop the strategy is suggested.

Occupy and the Temporal Politics of Prefigurative Democracy

This article sheds new light on the Occupy movement by foregrounding its temporal dimensions, particularly in relation to a previous major cycle of transnational contention, the alter-globalization movement (AGM). The discussion engages three temporal considerations in particular: 1) the centrality of instantaneous digital media to both movements’ rapid rise and diffusion 2) the pervasiveness – especially within Occupy – of the temporal ethos of prefigurative politics, and 3) the sustainability and longer term legacy of the Occupy cycle, from the temporal vantage point of the year 2016, i.e. five years since the movement’s rise and prompt demise, and fifteen years since the peak of the AGM. The article’s conclusion insists on the importance of a long term vision when it comes to evaluating the outcomes of collective action.

The 2012 Phenomenon Comes of Age

This essay is an update on the “2012 phenomenon” first discussed in my article in Nova Religio 9, no. 3 (February 2006), which was the first academic assessment of the movement. Since then, this international movement has developed with remarkable speed, focusing intense and still-growing speculation on the completion of a major cycle in the Mayan Long Count calendar on 21 December 2012. Various factors have accelerated the 2012 phenomenon's recent growth, including the decipherment of two ancient Mayan hieroglyphic texts that explicitly refer to the 2012 date, and the release of the Hollywood film 2012. The topic now draws serious academic analysis, and has led to far greater involvement in the 2012 phenomenon by the Maya themselves, including publication of the first books on the subject by Maya authors. This article reassesses the movement as it approaches its culmination on 21 December 2012, and presents indigenous perspectives acquired through conversations with Maya spiritual guides and elders in Guatemala and Mexico.