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61.
A new benthic index, named Daphne, is proposed for the Northern Adriatic coastal area, near the Po river delta. It is based on six characteristics of the community that do not require in-depth taxonomic expertise: number of mollusc species, % of bivalves, % of polychaetes, abundance of the opportunistic species Corbula gibba, % of amphipods and number of ‘typical mollusc species’ that are individuated by multivariate analysis. The application of the index in selected stations along a gradient of decreasing disturbance shows that it is simple to use in regular monitoring campaigns and that the results are consistent with environmental quality data in the special conditions of this area subjected to considerable river runoff. The index can be used in addition and as a complement to more widespread indices (such as M-AMBI); a comparison of the two indices performance is discussed. 相似文献
62.
63.
上海市生活垃圾的处理现状及对策探讨 总被引:6,自引:0,他引:6
阐述了上海市目前生活垃圾收运及处理情况,对2000年上海生活垃圾的产量作了预测,对生活垃圾处理对策的分析中,提出技术,资金和管理等方面的支持条件。 相似文献
64.
65.
Dominance relationships in solitary species may be an important factor in the maintenance of long-term, stable relationships
among territorial neighbors. We examined the mediation of intraspecific interactions in a solitary, territorial kangaroo rat,
Dipodomys heermanni, and tested whether unfamiliar kangaroo rats establish a dominance hierarchy and then decrease aggression and increase communication
(via footdrumming and sandbathing) after initial interactions and the establishment of a social structure. Results revealed
that both dominance hierarchies and familiarization with particular individuals are likely to mediate social interactions.
After only one pairing per dyad, an almost linear dominance hierarchy emerged, which became perfectly linear after a 90-min
familiarization period. During the course of subsequent interactions between dyad partners, fighting decreased and non-agonistic
communication increased. Dominant kangaroo rats sandbathed at higher rates than subordinates, possibly to deposit scent to
advertise competitive ability, whereas subordinate kangaroo rats footdrummed from inside the burrow, which seemed to indicate
an unwillingness to interact. We suggest the kangaroo rats use a conditional strategy when deciding to fight (be dominant)
or withdraw (be subordinate) by employing different modes to communicate status and minimize the potential risk of injury
during unnecessarily prolonged fights. 相似文献
66.
从宿迁市木材工业粉尘污染控制现状存在的问题入手,分析了木材工业企业粉尘污染的原因,提出了控制粉尘污染的若干建议。保护环境是实现木材工业可持续发展的必然要求,必须从工艺、技术和装备方面控制生产过程中的粉尘,使作业环境和大气污染排放达到国家环境保护标准和法规的要求。 相似文献
67.
Earlier studies on fault diagnosis of the pipeline and pump unit systems (PPU) relied mainly on independent equipment analyses, which usually lead to false alarms because of the loss of information fusion. The aim of this study is to utilize the status coupling relationship to improve fault detection sensitivity and reduce false alarm rate. A real-time status identification of related equipment step is added between capturing abnormal signals and listing out diagnosis results. For example, when the pipeline pressure fluctuation is found abnormal, a status analysis of pump units is performed immediately, if the pump units are proven to be operational normally, then the pipeline leak alarm is acknowledged valid. The logical reasoning algorithm is used to capture abnormal conditions of pipeline pressures. The pump unit faults are captured by combining information from multiple sources. Field applications show that the proposed method significantly improves the PPU fault detection capability on fault detection sensitive and accuracy. 相似文献
68.
A methodology of characterizing status and trend of land changes in oases: a case study of Sangong River watershed, Xinjiang, China 总被引:11,自引:0,他引:11
Land change is often studied with Markov models to develop a probability transition matrix. The existing methods dependent on such matrixes cannot effectively characterize some important aspects associated with land change such as status, direction, trend and regional variations. This study presents mathematical models to quantify these elements, defining unbalanced, quasi-balanced and balanced status, one- and two-way transitions and the rising or falling trends. Using these models and remote-sensing imageries, the landscape was studied for a case area, the oasis of Sangong River in Xinjiang, Northwest China where typical arid conditions prevail. Land expansion and contraction among various land types and for the entire oasis were analyzed for the periods of 1978-1987, 1978-1998 and 1987-1998. The changes were closely related to a strong economic growth after the land-reform campaign and adoption of the market economy in China in the 1980s to early 1990s, a process not strictly Markovian that requires stationarity and randomness. Information on land-change status and trend is important for a better understanding of the underlying driving processes but also for land-use planning and decision-making. 相似文献
69.
In monogamous species, females often choose between males according to the quality of the territories they defend, but the
extent to which females themselves contribute to territory defence is frequently underestimated. Here we test for differences
in male and female roles during paired scent-marking bouts, a key component of territorial defence, in a monogamous antelope.
In two populations (Kenya, Zimbabwe) of klipspringer, Oreotragus oreotragus, both males and females usually scent-marked at the same site, but there were significant differences between sexes in terms
of investment within bouts. Females initiated most bouts, thus dictating the marking strategy of the pair. Males initiated
relatively few bouts, but deposited more scent marks per bout than females and were usually the last to scent-mark before
leaving the site; they marked on the same branches as the female and thus overmarked her scent. Both sexes deposited more
marks during paired than solo visits. Immediately preceding and following scent-marking bouts, males approached females and
females left males more often than expected. Female scent-marking rates were higher when they were receptive than at other
times, and this increase was matched by elevated marking rates of males. Females may increase marking rates when they are
receptive in order to test the quality of their mate or to incite male competition. However, these ideas are unlikely to explain
female scent-marking behaviour outside the mating season, which appears to be related primarily to territorial defence. We
suggest that these differences in investment in scent-marking bouts are consistent with predictions that females may be autonomously
territorial and that overmarking of female scent by males is a form of mate-guarding.
Received: 17 November 1999 / Received in revised form: 24 February 2000 / Accepted: 13 March 2000 相似文献
70.
A new benthic index, named Daphne, is proposed for the Northern Adriatic coastal area, near the Po river delta. It is based on six characteristics of the community that do not require in-depth taxonomic expertise: number of mollusc species, % of bivalves, % of polychaetes, abundance of the opportunistic species Corbula gibba, % of amphipods and number of 'typical mollusc species' that are individuated by multivariate analysis. The application of the index in selected stations along a gradient of decreasing disturbance shows that it is simple to use in regular monitoring campaigns and that the results are consistent with environmental quality data in the special conditions of this area subjected to considerable river runoff. The index can be used in addition and as a complement to more widespread indices (such as M-AMBI); a comparison of the two indices performance is discussed. 相似文献