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To reduce the time required to complete the regeneration process of erasure codes, we propose a Tree-structured Parallel Regeneration (TPR) scheme for multiple data losses in distributed storage systems. Under the scheme, two algorithms are proposed for the construction of multiple regeneration trees, namely the edge-disjoint algorithm and edge-sharing algorithm. The edge-disjoint algorithm constructs multiple independent trees, and is simple and appropriate for environments where newcomers and their providers are distributed over a large area and have few intersections. The edge-sharing algorithm constructs multiple trees that compete to utilize the bandwidth, and make a better utilization of the bandwidth, although it needs to measure the available bandwidth and deal with the bandwidth changes; it is therefore difficult to implement in practical systems. The parallel regeneration for multiple data losses of TPR primarily includes two optimizations: firstly, transferring the data through the bandwidth optimized-paths in a pipeline manner; secondly, executing data regeneration over multiple trees in parallel. To evaluate the proposal, we implement an event-based simulator and make a detailed comparison with some popular regeneration methods. The quantitative comparison results show that the use of TPR employing either the edge-disjoint algorithm or edge-sharing algorithm reduces the regeneration time significantly.

Abstract:Four samples of plagioclase and biotite from the Shaxi porphyry in the lower part of the Yangtze metallogenic belt were analyzed for age determination with the 40Ar/39Ar method. The results yield reproducible ages of 126 Ma to 135 Ma with a high level of confidence according to the agreement between isochron and plateau ages. The four Ar‐Ar ages are relatively consistent within the analytical error. These ages are also consistent with, but more precise than, previous K‐Ar and Rb‐Sr ages and thus provide better constraints on the time of porphyry formation and associated Cu‐Au mineralization along the middle to lower part of the Yangtze metallogenic belt. The ages of 126 to 135 Ma are interpreted to represent the intrusive time of the Shaxi porphyry, so that the Cu‐Au mineralization should have occurred later due to the post‐magmatic hydrothermal event.

Abstract: Spelean stalagmite dating using thermal ionization mass spectrometry (TIMS) on the basis of U-Th disequilibrium has contributed greatly to paleoclimatology, paleo-environment, paleo-oceanology, archaeology as well as modern volcano-magmatism studies. Results of our studies on stalagmite chronology are also reported in this paper.

Abstract:This paper presents a study of the major and trace element compositions of fresh mantle‐derived spinel lherzolite and harzburgite inclusions from Cenozoic alkaline basalt in Mount Lianshan and Mount Panshi, Liuhe County, Jiangsu Province. An estimation is made of the contents of the major elements and some of the trace elements in the primitive mantle source region of the area, from which the authors have obtained MgO/Al2O3= 7.86. The contents of MgO and Al2O3are also obtained as 37.58% and 4.78% respectively based on the correlation of MgO‐Al2O3. Then, the contents of various elements in the primitive mantle are calculated using their regression equations with MgO, and the compositon of the primitive mantle, a basic issue in geochemistry study, is discussed on that basis.

The article discusses the conditions of foreign relations between China and Pakistan, as of November 2016. It states that 2016 marks 65th anniversary of the establishment of diplomatic relations between China and Pakistan, and mentions that Pakistan was one o f the first nations to recognize the People's Republic of China. Other topics include Pakistan's help to China in the 2008 earthquake, and a visit of Chinese President Xi Jinping to Pakistan in 2015.