The spatiotemporal structure of population in the Muskrat (Ondatra zibethicus)

The spatiotemporal structure of the muskrat population has been studied by means of the prenatal radioactive marking of juveniles with 45 Ca and their subsequent recapture in the test area. The muskrat population is characterized by a cyclic type of spatial structure, with seasonal transition from a mosaic type of settling to a diffuse type and, after the breeding season, vice versa.     

SOCIAL CLASS DIFFERENCES IN RESERVOIR VISITS1

ABSTRACT: Previous research provides evidence of a socioeconomic bias in outdoor recreational participation. One explanation of this bias is that socioeconomic groups have differential opportunities to participate, with the “costs” of this participation especially serving to restrict the recreational access of lower class persons living in urban areas. Using driving distance as a measure of cost, this study assessed the effects of travel costs on the attendance of three social class groups from an urban population at rural reservoir facilities. Findings support the contention that, while increased driving distance has a dampening effect on recreational participation, this effect is most pronounced for the lower class person. These findings point to the importance of equity considerations in the planning of outdoor recreational facilities.     

The characteristic of in situ stress in outburst area of China

In order to obtain the characteristics of in situ stress field in outburst mining area, using the hollow inclusion (HI) technique to measure the in situ stress of coal and gas outburst mining area. The measurement sites located in northeast, middle and east of china, which include eight mining areas such as Fuxin, Pingdingshan, Hebi and Huainan. Base on the analysis of measurement data from outburst mining area, conclusions could be obtained as follow: (a) major principal stress and minor principal stress is horizontal stress and interim principal stress is vertical stress, and the type of outburst area’s stress field is dynamic stress field; (b) the major principal stress and minor principal stress are higher than other regions and the tectonic stress is outstanding; and (c) the ratio of major principal and vertical stress is decrease with the increase of depth and the type of stress field is likely transfer dynamic to static. Thus, in situ stress plays a key role during the occurring and development of coal and gas outburst, which is an important reason of severe outburst in China.     

不同类型喷头灭火有效性研究

通过实验研究了不同类型喷头对灭木垛火的影响。实验采用了ZSTX和ZSTP两种类型喷头,在不同的水压力下灭木垛火,通过实验现场观测和测得的烟气温度,烟气组分变化来分析对比灭火的效果和对烟气的影响。通过对比分析实验数据,可知ZSTX喷头在0.2MPa的水压力下可以实现灭火,ZSTP喷头在0.4MPa才可以实现灭火。喷淋实现灭火时产生的CO比只能实现控火产生的CO少。     

美国海军工作服发展现状

本文主要介绍了美国海军现用的工作服装种类、服装构成及穿着场合,并与我国海军07式作训服进行了对比分析。     

产酸脱硫反应器中碳硫比对群落生态特征的影响

通过产酸脱硫反应器处理高浓度含硫酸盐废水的连续流试验,从群落动态的角度研究碳硫比(COD/SO₄^2-)从4.2降低到2.0的过程中,pH值、氧化还原电位(ORP)、碱度(ALK)和末端产物(VFAs)组成、优势种群分布等群落生态特征的变化规律试验证明,在此过程中ORP和ALK提高,而pH值和VFAs中乙酸的分布比例降低,群落类型由高碳硫比稳定型转化为低碳硫比亚稳定型,但仍未改变乙酸型顶极群落的典型特征.     

雨雪冰冻灾害后粤北森林各林型凋落物动态

为了考察中国亚热带不同森林类型对雨雪冰冻灾害的响应模式,以粤北天井山3种代表性的林型—针叶林、阔叶林和混交林为对象,于不同森林类型中比较受损森林与未受损森林在凋落物年产量、成分及月际动态方面的差异,从而在凋落物水平上反映不同森林类型在雨雪冰冻灾害后的早期恢复力。研究结果表明,灾后针叶林、阔叶林和混交林的年凋落量分别为0.52、3.21、1.37 t.hm-2,比未受损的同种森林类型年凋落量显著减少,减少程度分别为87.89%、53.46%、76.78%。由此可以看出阔叶林的植被恢复情况最好,说明在凋落物水平上,其灾后恢复的早期阶段恢复力最强。在凋落物成分方面,灾后各森林类型叶凋落物所占比例显著增加,枝凋落物所占比例则显著减少。受损针叶林和阔叶林的凋落物月动态与未受损森林基本一致,但其波动幅度较小;在混交林中,受损和未受损森林其凋落量的季节动态模式则表现出不一致性且为不规则型。根据研究结果,建议在亚热带地区优先考虑种植阔叶林以促进受损森林在类似雨雪冰冻灾害的极端天气后的恢复。     

危险化学品火灾爆炸事故不安全动作分布规律研究

以我国210起典型危险化学品火灾爆炸事故为样本,对造成事故的不安全动作进行归类统计,应用云模型云发生器算法计算大类不安全动作的云模型参数值并绘制隶属云图,得出了危险化学品火灾爆炸事故中不安全动作类型和发出者分布规律及特点。结果表明:造成火源型火灾爆炸事故的违规型不安全动作平均发生次数最多,分布不均匀且不稳定,其中现场工作缺乏指导或监护发生次数最多,发出对象为监理;蓄热型火灾爆炸事故中技术型不安全动作分布表现出较大的随机性,其中物料添加不当和隐患排查不彻底发生次数最多,发出对象分别为基层人员和监理。     

基于SPA-VFRM的城市要害系统综合应急能力研究

为反映城市要害系统综合应急能力的发展现状及过程,在分析城市要害设施系统构成与面临的主要灾害类型基础上,提出从充分性、精确性、抵御性和及时性4个维度评价应急能力的思路,建立城市要害系统综合应急能力评估指标体系,并应用层次分析法与变异系数法确定指标综合权重,结合集对分析（SPA）与可变模糊识别模型（VFRM）构建城市要害系统综合应急能力的评价模型;运用该模型实证分析某市要害系统综合应急能力发展现状。实证表明:该市要害系统综合应急能力呈现“波浪式升高”的动态发展趋势,灾害抵御能力是构成综合应急能力的主要方面;3种方法的评价结果排序基本一致,表明该模型的评估结果稳健、可靠,能够有效反映城市要害系统综合应急能力发展情况。     

世界替代农业及其发展趋势

本文对世界替代农业的主要类型和特点、中国的生态农业与发达国家的替代衣业的区别以及世界替代农业存在的主要问题进行了较详细的阐述，最后对世界替代农业的发展趋势作了展望。