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21.
Abstract. The utilization of the spatial resources of refuge type, size and depth placement is investigated in the three sympatric species of Acanthemblemaria at the cape region of Baja California, Mexico. A. balanorum occupies barnacle testes (Balanus tintinnabulum), A. macrospilus occupies barnacles and mollusk tubes (vermetid gastropods and pholadids), and A. crockeri occupies only mollusk tubes (pholadids). Refuge diameter overlap is higher than overlap in depth. A. crockeri consistently occupies depths below 5m. Competition experiments for barnacle refuges among the three species indicate that A. balanorum is a superior competitor for such refuges. Prior residency of a less superior species changes the outcome of refuge competition in its favor. The morphological specialization of A. balanorum and A. macrospilus is evident in a high correlation between head size and standard length. A. balanorum selects refuges with entrance diameters highly correlated to standard length. 相似文献
22.
DGPS RTK技术在无验潮水下地形测量中的应用初探 总被引:5,自引:0,他引:5
本文简要介绍了DGPS RTK技术的基本原理和作业流程,阐明了该技术在无验潮水下地形测量中的适用性,并以除六泾水文大断面的测量为例介绍了利用该技术进行工程实测的过程,通过对实测数据成果的分析,得出一些有益的结论。 相似文献
23.
本文介绍了国家标准《潜水员水下用电安全技术规范》的研究、编制过程,以及编者对该标准性质、适用范围、总体结构、电气安全数值取舍等的基本认识,并就该标准制定实施后的经济、社会效益进行了初步预测。 相似文献
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This paper proposes a nonlinear robust adaptive control strategy to force a six degrees of freedom underactuated underwater vehicle with only four actuators to follow a predefined path at a desired speed despite of the presence of environmental disturbances and vehicle’s unknown physical parameters. The proposed controller is designed using Lyapunov’s direct method, the popular backstepping and parameter projection techniques. The closed loop path following errors can be made arbitrarily small. Interestingly, it is shown that our developed control strategy is easily extendible to situations of practical importance such as parking and point-to-point navigation. Numerical simulations are provided to illustrate the effectiveness of the proposed methodology. 相似文献
26.
This paper reports a study of the field measurements and monitoring of wastewater discharge in sea water at Bari East (Italy). A wastewater sea outfall system is an integral and fundamental part of each wastewater treatment with ultimate sink in the sea water. The design of a water treatment plant and wastewater outfall must take into account the use of the environmental water, the values of physicochemical parameters to be respected in order to safeguard the use itself and the quality of the environmental water where wastewater is issued. In the present study measurements of sea current velocity components were carried out with a VM-ADP (Vessel-Mounted Acoustic Doppler Profiler). Salinity, wind directions and velocities were assessed with, for one survey, the total faecal coliforms and other biochemical parameters. It was emphasized that the measurements necessary for monitoring cannot be concentrated in the wastewater outfall pipe zone only, but should be extended to a neighbouring area of the outfall pipe, with an extension depending on the wastewater discharge, the polluting charge and the magnitude of the sea currents and the winds typical of the zone of interest. The analyses presented in this paper confirm that the sea zones close to the wastewater outfall pipe are particularly sensitive and vulnerable. Such results must be considered in the planning of a wastewater outfall pipe. 相似文献
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The upper layer (above 140 m depth) temperature in the western Philippine Sea near Taiwan was sampled using a coastal monitoring
buoy (CMB) with 15 attached thermistors during July 28–August 7, 2005. The data were collected every 10 min at 1, 3, 5, 10,
15, and 20 m using the CMB sensors, and every 15 sec at 15 different depths between 25 m and 140 m. Internal waves and solitons
were identified from the time-depth plot of the temperature field. Without the internal waves and solitons, the power spectra,
structure functions, and singular measures (representing the intermittency) of temperature field satisfy the power law with
multi-scale characteristics at all depths. The internal waves do not change the basic characteristics of the multifractal
structure. However, the internal solitons change the power exponent of the power spectra drastically, especially in the low
wave number domain; they also break down the power law of the structure function and increase the intermittency parameter.
The physical mechanisms causing these different effects need to be explored further. 相似文献
29.
风力对内陆浅水水域磷水平的影响 总被引:1,自引:0,他引:1
本文通过对平度市大泽山水库(面积约0.5平方公里,平均水深约1.5米)的实地观测,研究了风力对内陆浅水水域磷水平的影响。结果表明,影响程度取决于风速、风力作用时间、水深以及风力作用前磷水平的高低等因素。就大泽山水库而言,风速大于2.5米/秒的风力可引起各种形态磷的明显增加。不过对磷酸盐磷来说,如果浓度本来就较高,风力作用下当有大量沉积物颗粒泛起时,会对PO_4~≡产生吸附,因而可能导致水中游离磷酸盐磷含量下降。鉴于此,作者建议对内陆浅水水域进行磷水平调查时应考虑风力的作用。 相似文献
30.