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Software safety requirements are crucial for safety assurance of safety-critical software systems. A novel accident causality model, Systems-theoretic accident modeling and processes (STAMP), has been proposed to overcome the limitations of traditional safety techniques in software safety requirements elicitation. However, the STAMP-based method is ad-hoc with no rigorous procedure to elicit software safety requirements effectively. Furthermore, the time-related safety requirements, which are important to software safety, have been paid little attention in STAMP-based method. With the purpose of overcoming these limitations, this paper strives to find a systematic approach to elicit software safety requirements with STAMP, especially the time-related safety requirements. Firstly, a new process model of STAMP is proposed to model all the system varilables and the ralationship of them in control processes. Then based on the process model, an approach HCAT-SSRA is proposed to elicit the software safety requirements by building Hazardous control action tree (HCAT) for each control action in system control processes. Additionally, several rules are proposed to guide time-related software safety requirements analysis. Finally, a case study is given to illustrate the availability and feasibility of the proposed method.

Whole-rock geochemical, zircon U-Pb geochronological and Sr-Nd-Hf isotopic data are presented for the Early Cretaceous volcanic rocks from the northern Da Hinggan Mountains. The volcanic rocks generally display high SiO2 (73.19–77.68 wt%) and Na2O+K2O (6.53–8.98 wt%) contents, with enrichment in Rb, Th, U, Pb and LREE, and depletion in Nb, Ta, P and Ti. Three rhyolite samples, one rhyolite porphyry sample, and one volcanic breccia sample yield weighted mean 206pb/238U ages of 135.1±1.2 Ma, 116.5±1.1 Ma, 121.9±1.0 Ma, 118.1±0.9 Ma and 116.9±1.4 Ma, respectively. All these rocks have moderate (87Sr/86Sr)i values of 0.704912 to 0.705896, slightly negative eNd(t) values of –1.4 to –0.1, and positive eHf(t) values of 3.7 to 8. Their zircon Hf and whole-rock Nd isotopic model ages range from 594 to 1024 Ma. These results suggest that the Early Cretaceous volcanic rocks were originated from melting of subducted oceanic crust and associated sediments during the closure of the Mongol-Okhotsk Ocean.

Geochemical data of altered wall rocks are important for the metallogenic prognosis of hydrothermal gold deposits. Indicator elements of altered wall rocks such as K, Al, As, Sb, and Hg have been successfully used to assess gold anomalies in lithogeochemical survey. However, such researches have rarely been done in stream sediment survey for the exploration of gold from various landscapes. On the basis of the geochemical analysis of altered wall rocks of gold deposits in the cold desert areas of Gansu Province in Northwest China, it is found that the combination of Al, K, and Sn could serve as an important indicator of hydrothermal gold deposits and can be used to evaluate the metallogenic prospective of gold anomalies in stream sediments. More studies performed in the cold grassland areas and the moderate-low relief mountainous areas showed that, both weak and strong geochemical anomalies can be extracted, if strictly abiding by the ways of calculation and addition of the binary values of the indicator elements with equal weight, and this provides the sound delineation of metallogenic perspective areas.

To cope with the transfer of user interest and improve the accurate of prediction in recommender system, this paper proposes a Dynamic User-Interest-Model (DUIM). The model adopts the memory curve equation to address the influence of time factor. Users' long term interest and short term interest can be embodied clearly in this model. Based on the model, the paper presents a novel collaborative filtering recommender algorithm (Model-based Collaborative Filtering Recommender Algorithm, MCF). Experiments prove that MCF gets better prediction and higher time efficiency compared with other similar algorithms.

Studies on the soil-geological transects at gold mining areas in northwest Sichuan show that the distribution of soil Bacillus cereus spore counts can indicate the underlying gold mineralization. The anomalies of spore counts flanked the subsurface orebodies while low spore counts occurred right in soils above the outcrops of the orebodies. This microbial exploration technique has the potential to be employed at promising exploration areas or mining areas. Non-mineralization factors such as soil types strongly influence the spore number, which leads to varied background values at different mining areas. Application of this bio-method in regional exploration awaits the establishment of background database of B . cereus spore numbers at different soil environments.