Nonlinear characteristics of the vegetation change and its response to climate change in the karst region of southwest China

The vegetation is known to be sensitive to both climate change and anthropogenic disturbance. However, the relationship between changes in vegetation and climate is unclear in karst regions. The nonlinear characteristics of vegetation change and its possible relationships with driving factors in the karst region of southwest China are revealed, using methods of Ensemble Empirical Mode Decomposition, Mann-Kendall, and Partial Least Squares Regression. The results show that: (1) vegetation changes demonstrate an increasing trend with an abrupt change in 2002. Multiple time scales of 3, 6, 10, and 25-year are observed in vegetation variations, dominated by long-term trend and the short time scale of 3-year with variance contributions of 58.10% and 28.63%. (2) The relationship of climate indexes with vegetation changes shows r2 = 0.78 ( p < 0.01) based on the reconstruction of characteristic scales, indicating significant great relationship. In space, the area percentage with relationship of climate to vegetation is more than 50%, and the impact is much greater after the abrupt change of vegetation in 2002 ( r2 are 0.24–0.91 and 0.42–0.99, respectively). In addition, the correlation between vegetation change and ecological engineering is 0.15 ( p < 0.01). The results indicate that climate change is the main impact factor of vegetation change, ecological engineering has positive influences in improving vegetation condition, and methods of scales decomposition and abrupt detection could reveal some hidden information for better understanding ecosystems in karst regions.

Stability and synchronous characteristics of a two exciters vibration system considering material motion

Nowadays, two exciters vibration system played an indispensable role in a majority of machinery and devices, such as vibratory feeder, vibrating screen, vibration conveyer, vibrating crusher, and so on. The stability of the system and the synchronous characteristics of two exciters are affected by material motion. However, those effects of material on two exciters vibration system were studied very little. Based on the special background, a mechanical model that two exciters vibration system considering material motion is proposed. Firstly, the system's dynamic equations are solved by using Lagrange principle and Newton's second law. Then, the motion stability of the system when material with different mass move on the vibrating body is analyzed by [Formula: see text] mapping and numerical simulation methods, and the motion forms of the material are also studied. Meanwhile, the frequency responses of the vibrating body are analyzed. Finally, the influence of material on the phase difference of the two exciters is revealed. It can be concluded that with the mass ratio of the material to the vibrating body increasing, the system's motion evolves from stable periodic motion to chaotic state, the synchronization ability of two exciters decline, and the unpredictability of abrupt change about the phase difference increases. Further, the uncertainties of both the abrupt change of phase difference and the collision location affect each other and eventually lead to the instability of the system.

Liminality as an Autopoietic Process within Spatial Identity

Spatial identity surpasses geographical boundaries of a certain space, and denotes not only physical characteristics of space, but its meaning to people that use it, as well as their intercommunication, which produces new social and spatial meaning. Unless there is an abrupt change in social structure or formal/functional transformation of (un)built environment, we perceive spatial identity as something almost permanent. However, it is in a constant state of change, existing in a present state that relies on our past experiences and contains projections of our future, maintained through constant background processes of disorganization and concomitant organization – in other words, identity is in the state of (perpetual) liminality. Liminality is the product, as well as the initiator of autopoietic processes within identity, which leads to the main premise of this article – (spatial) identity is an autopoietic system. This is analyzed through three chosen aspects of place attachment: ritual, memory and architecture.

BIPOLAR PLATES FOR ELECTROLYZERS AND FUEL CELLS – HOW INNOVATION MANAGEMENT IS AS A BASIS FOR SUCCESS THESE COMPONENTS

An almost abrupt change in attitude towards applications in the field of renewable energies has emerged in recent months, both among decision-makers in politics and in companies. [1] In particular, the topic of hydrogen production by electrolysis plays an eminently important role. In water electrolysis, water is split into its constituent ¬parts hydrogen and oxygen using electrical energy. The resulting hydrogen is of interest to future energy systems for a number of reasons, including the fact that hydrogen can serve as a storage medium for electrical energy from renewable energy conversion systems such as photovoltaic or wind turbines.

Challenges of Managing Information Security during the Pandemic

The COVID-19 pandemic of 2019 surprised information security practitioners in the organizations due to the change imposed on employees’ work routines. Employees were asked to work from home, and therefore changes were necessary to reduce information security risks actively. The abrupt change of work environments brought many challenges to the practitioners, which caused them to make decisions regarding organizational information security. This article aims to uncover those challenges through an ethnography study within an organization during the fourteen months of teleworking. On an overarching level, we found four challenges to be of concern: technical security, regulations and policies, employee awareness of security issues, and, finally, preparedness for the new work environment of teleworking. We believe that the challenges brought by the analysis will inspire discussions about the future of research and practice regarding information security management in case of disasters.

Variability and trend analysis of precipitation during 1961-2015 in Southwest Guizhou Autonomous Prefecture (SGAP), China

Information on variability and trends of precipitation over a region is useful in the agricultural production management. The linear regression analysis, 5-year moving average, accumulated anomaly and Mann-Kendall trend detection were used to assess the variability and trends in precipitation over Southwest Guizhou Autonomous Prefecture (SGAP) region of China. The results revealed that the annual precipitation showed an increasing trend at Wangmo and Xingren and decreasing trends at Anlong, Ceheng, Pu’an, Qinglong, Xingyiand Zhenfeng stations. The UF(k) and UB(k) curves of each region have intersections, except in Ceheng and Xingren, and this indicated that the precipitation has seen a abrupt change in six stations. The results of this study will provide theoretical guidance for agricultural water management in Southwest Guizhou Autonomous Prefecture of China.

Lithofacies Architecture and Distribution Patterns of Lacustrine Mixed Fine-Grained Rocks —a Case Study of Permian Lucaogou Formation in Jimsar Sag, NW China

As the controlling effect of complex lithofacies of lacustrine mixed fine-grained rocks on the shale oil sweet spot remains unclear, core, outcrop, general logging, nuclear magnetic resonance (NMR) logging, testing, and production data were used to study the types, combination pattern, and genesis of lithofacies architectures of lacustrine mixed fine-grained rocks in the study area by lithofacies hierarchy analysis, X-ray fluorescence (XRF) logging, UAV, and 3D geological modeling. The research shows that: 1) According to lithology and sedimentary structure, the mixed fine-grained rocks can be divided into 13 lithofacies types of different origins in 5 sub-categories and 2 categories. 2) UAV photography was combined with a traditional field survey to characterize the 3D spatial distribution of lithofacies architecture of the Lucaogou Formation on the outcrop, and it is found that the lithofacies architecture patterns of mixed fine-grained rocks include three types: gradual change type, abrupt change type, and special type. The gradual change type with higher sand development degree and symmetrical lithofacies architecture has a high quality reservoir with dissolution pores, and is mixed beach-bar sand in the mixed zone. It is high in development degree and often appears as several similar cycles stacking over each other. The abrupt change type can be subdivided into two sub-types, asymmetric and smaller in reservoir thickness. It is very high in development degree and often comes in several similar cycles. The special type belongs to thick clastic rock relatively independent in the mixed fine-grained rocks with a high development degree of sand. The sand is a higher quality reservoir with properties of tight reservoir. It often appears as stacking of single cycle sand. 3) The different lithofacies architectures in the mixed fine-grained rocks have significant differences in distribution. The gradual change type is mainly composed of mudstone, dolomitic siltstone, and sandy dolomite, dolomitic siltstone, and mudstone, and appears in lenticular shape overlapping with each other on the plane. The abrupt change type is made up of felsic siltstone, dolomitic siltstone, sandy dolomite, and mudstone, and appears as isolated thin layers on the plane. The special type is mainly composed of mudstone and felsic siltstone, and mudstone, and turns up as lenses of different sizes on the plane.