存储技术安全性分析与对策研究

传输安全和存储安全是数据安全的两个方面。存储安全是指在数据保存上确保其安全性、完整性、可靠性和有效性。该文阐述了安全存储方案,并着重介绍了实现数据安全存储的各种技术,探讨了安全存储技术的发展方向。     

Warming overcomes dispersal-limitation to promote non-native expansion in Lake Baikal

Non-native species and climate change pose serious threats to global biodiversity. However, the roles of climate, dispersal, and competition are difficult to disentangle in heterogeneous landscapes. We combine empirical data and theory to examine how these forces influence the spread of non-native species in Lake Baikal. We analyze the potential for Daphnia longispina to establish in Lake Baikal, potentially threatening an endemic, cryophillic copepod Epischurella baikalensis. We collected field samples to establish current community composition and compared them to model predictions informed by flow rates, present-day temperatures, and temperature projections. Our data and model agree that expansion is currently limited by dispersal. However, projected increases in temperature reverse this effect, allowing D. longispina to establish in Lake Baikal’s main basin. A strong negative impact emerges from the interaction between climate change and dispersal, outweighing their independent effects. Climate, dispersal, and competition have complex, interactive effects on expansion with important implications for global biodiversity.     

ESSA: 一种高效安全的分布式存储系统数据拆分算法

The security of critical data is an important issue for distributed storage system design, especially for long-term storage. ESSA (An Efficient and Secure Splitting Algorithm for Distributed Storage Systems) is presented, which takes advantage of a two level information dispersal scheme to strengthen the security of data. In ESSA, the approach of knight’s tour problem, which is NP-Complete, is introduced to scramble data at the first level, and a split cube is used to split scrambled data at the second level. Thus, it is very difficult for the malicious user to get information because the task of reconstructing the original data needs more computation than they can tolerate. We prove that the security of ESSA is better than encryption algorithm and not inferior to erasure codes and secret sharing. Experimental results show that distributed storage systems exploiting ESSA has greater efficiency than that exploiting keyed encryption, erasure codes and
secret sharing     

Spatial-temporal patterns of recolonizing adult mayflies in Lake Erie after a major disturbance

This 12-year study of Hexagenia male imagos documents the recovery of two species of burrowing mayflies, Hexagenia limbata and Hexagenia rigida in western Lake Erie after a 30-year absence due to hypoxia, resulting from cultural eutrophication. Annual adult mayfly collections were made at night during the peak emergence period at four sites along the north shore of the western basin of Lake Erie, 1997 to 2008. H. rigida, the dominant species in upstream riverine waterbodies, was the early colonizer, representing about 90% of all male imagos sampled in 1997. In 2000, when the two species were co-dominant, both inland aerial dispersal (5.5 km) and lakeward (0.25 to 4 km) oviposition patterns confirmed species co-existence. Twice weekly collections throughout the extended emergence period at one site confirmed that H. rigida was the dominant species in 1997, H. limbata and H. rigida were co-dominant in 2000, and H. limbata was dominant in 2002. Once H. limbata became the dominant species (> 90%) in 2000 to 2002 (depending on the site), it remained so. Both species followed a similar inland dispersal pattern, decreasing in density with increasing distance from shore; most mayflies were present within 1 km from shore. There was no significant difference in mean egg density of the two species among the sites extending lakeward in 2000 when the two species were equally abundant. The transition from the dominance of H. rigida to H. limbata may have resulted from several factors, including differential competition and growth between species or predation effects.     

Patch exploitation by Tribolium castaneum: movement patterns, distribution, and oviposition

Stored-product insects often live in an environment of spatially separated food patches that vary considerably in size, quality, and persistence. The movement of individuals among patches of food influences the probability that stored products will become infested and pest populations will persist within storage facilities, thus affecting many aspects of pest management. We examined how a major stored-product pest, the red flour beetle, Tribolium castaneum (Herbst), exploits patches of food. Individuals are often inactive, periods of inactivity are often outside of food patches, males are more likely to be inactive outside of flour patches than females, and there is considerable variation among individuals in the time spent outside of patches. Beetles outside of food patches tend to be observed near edges due to a tendency to be inactive at edges, to move along edges, and to move more slowly when moving along edges. This tendency to move along edges makes beetles more likely to infest flour patches near the edges than patches further from the edge. A better understanding of the influence of landscape on pest behavior, spatial distribution, and population dynamics is needed to develop effective stored-product pest IPM programs.     

Phoretic load of the parasitic mite Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae) affecting mobility and flight take-off of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

Phoresy is the passive transport of an organism on the body of another from a different species, which is a beneficial adaptation for entomophagous arthropods to reach their hosts. Such an interaction occurs between the parasitic mite Acarophenax lacunatus (Prostigmata: Acarophenacidae) and its host, the lesser grain borer Rhyzopertha dominica (Coleoptera: Bostrichidae). Phoresy may have indirect effects in the host species determined by the number of phoretic individuals per carrier (phoretic load) and their distribution on the carrier's body. In the present study, the phoretic load and body distribution of A. lacunatus on adults of R. dominica was assessed. Also the potential interference of the above parameters with host mobility and flight take-off ability were evaluated. Phoretic load and body distribution were assessed by visual inspection under a stereomicroscope, while host mobility was assessed using a computer-automated tracking system. Flight take-off ability was assessed in crowed arenas (containing 50 insects each) at 30 ^°C. The observed mite load ranged from 1 to 11 mites/host, with a peak at around 5 mites/host. Among the host body parts, mites were mainly attached to the thorax (3.70 ± 0.17 mites), where attachment prevailed on the legs and metathorax. Host take-off ability was significantly decreased in the presence of high loads (>7 mites/host) of phoretic mites. Although high phoretic loads (>7 mites/insect) impaired host walking, phoretic loads between 4 and 6 mites/host appeared to favor host walking and consequently the surface dispersal of the parasitic mite.     

Four-dimensional connectivity modelling with application to Australia's north and northwest marine environments

A fully four-dimensional (3D × time) object-oriented biophysical dispersal model was developed to simulate the movement of marine larvae over semi-continuous surfaces. The model is capable of handling massive numbers of simulated larvae, can accommodate diverse life history patterns and distributions of characteristics, and saves point-level information to a relational database management system. The model was used to study Australia's northwest marine region, with attention given to connectivity patterns among Australia's north-western Commonwealth Marine Reserves (CMRs). Animations of larval movement near the Gascoyne canyon CMR, dispersal surfaces over depth and time for CMRs and Key Ecological Features in the northwest, as well as matrices of connectivity values among CMRs are shown. The matrices are further analysed to identify the sensitivity and elasticity of their values. The results generated by this model can aid in designing and managing marine protected area networks that incorporate extensive and complex benthic terrain (including the identification of marine ‘corridors’), and for developing targeted field sampling strategies.     

The Critical Energy of Direct Initiation in Liquid Fuel‐Air and Liquid Fuel‐RDX Powder‐Air Mixtures in a Vertical Detonation Tube

Multiphase cloud detonation is an important but complex process, which has not been fully understood yet. Direct experimental data about the critical initiation energy (CIE) and pressure/velocity revolution of high explosive powder‐based multiphase cloud detonation is not available in the literature. In this paper, propylene oxide (PO), petroleum ether (PE), isopropyl nitrate (IPN), and a mixture of PE/IPN were individually dispersed to form a cloud in a 200 mm×5400 mm vertical detonation tube. Subsequently, this cloud was directly ignited by a high explosive. The critical initiation energy of various mist/air mixtures was measured by the up and down method. Meanwhile, the pressure history was recorded by six sensors along the detonation tube. RDX powder was added to the system and sprayed simultaneously with the liquid fuel to form a three‐phase gas‐liquid‐solid explosive cloud. The detonation pressure and velocity of all three‐phase cases significantly increased while the corresponding critical initiation energy decreased compared to the liquid‐air analogs. The CIE data were found to have a “U”‐shaped curve relationship to the fuel‐air ratio in two‐ and three‐phase systems, the minimum is always on the fuel‐rich side.     

火灾事故照明和疏散指示标志设计中的两个问题

本文就以下两个问题:低层建筑中火灾事故照明及疏散指示标志的设置;高层民用建筑内火灾应急照明灯及疏散指示标志灯的控制;进行了深入的讨论,并且提出了自己的看法。