共查询到20条相似文献，搜索用时 31 毫秒
1.
Ben J. Korgen 《Marine Geophysical Researches》1971,1(3):354-357
A versatile probe for simultaneous studies of heat flow and near-bottom water parameters has evolved through modifications of the Bullard heat probe frame. Suitable sensor arrays have been used with this instrument to study (1) heat flow through the ocean floor, (2) water column temperature structure, (3) near-bottom current speeds, and (4) the differential cooling of water-column temperature sensors placed in a current speed gradient.Some of the advantages of such a modified Bullard probe are: (1) several parameters, including heat flow, can be measured across the sediment-water interface simultaneously, (2) the instrument frame is rigidly pinned to the ocean floor during measurement, permitting true Eulerian measurement in the water column with no effects of ship movement, swaying moorings or cable oscillation, and (3) the device is inexpensive and simple. 相似文献
2.
ABSTRACTMiniature submersible linear variable differential transformer (LVDT) is commonly used for small strain stiffness measurement. However, it has not been widely used on cement-treated clays. This paper proposes a method of installing and setting up submersible LVDT to minimize testing problems and errors for cement-treated clays. In soft clay testing, the LVDT mount can be anchored to the specimen by pressed-in anchor pins or rods. However, this cannot be done on cement-treated clay due to the latter’s hardness. Preliminary trials also indicate that direct attachment of the LVDT mounts to the membrane without anchor pins is not feasible owing to the tendency of the LVDT to tilt and detach from the specimen. The system adopted involves pre-casting holes for the insertion of anchor pins during placement of the admixture into the moulds. The diameter of the anchors pins was found to have significant effect on the results; smaller diameter pins give more consistent results with those of resonant column and bender element tests. This can be attributed to the effect of stress concentration around the anchor pins. The results showed that, used appropriately, submersible LVDTs can give small strain measurements which have a high degree of inner consistency with results from resonant column and bender element tests. 相似文献
3.
4.
Ambient and dynamic pore pressures in fine-grained submarine sediments: Mississippi Delta 总被引：2，自引：0，他引：2
A multisensor piezometer probe has measured pore pressures in fine-grained submarine sediments of the Mississippi Delta over a period of approximately eight months. Data presented here cover the initial 2650 hours of the experiment. Dynamic and ambient pore pressures were recorded. Analogue data collected from the time of probe insertion include decay characteristics, steady-state (ambient) excess pore pressures, and the response of pore pressures to surface wave activity. The probe was installed in 43–44 ft of water near an offshore platform in the East Bay area of the Delta. Sensors were located at 21, 41 and 51 ft below the mudline. Ambient excess pore pressures were determined to be 0.7, 2.8 and 6.6 psi (lb/in2) at the respective depths. The relatively high excess pressures and the measured laboratory wet unit weights of the soil result in a significantly low effective stress. Pressure fluctuations due to tidal and surface wave activity were observed to produce significant pore pressure response in these soils. Preliminary data obtained using high-airentry and corundum stones indicate that considerably more research is necessary in order to fully understand the peculiarities observed in the data and to assess the role of dissolved and free gas on the pore pressures in submarine sediments. 相似文献
5.
自返式微型地热探针水下运动特性以及其贯入深度关系到其能否正常入泥工作,针对自返式微型地热探针的结构,对其进行简化,建立物理模型。并针对海洋流场及海洋底质,抽取关键参数,建立探针投放过程中的流场模型和底质模型。将所建立模型导入数据分析软件,先分析探针在投放过程中竖直方向和水平方向的相关运动特性,然后拟合为探针下行过程中下行深度和横向漂移的轨迹图,可见其水平方向最大位移约为106 m。在理论上论证了探针在下行过程中的姿态稳定性。通过计算论证了自返式微型探针在依靠自身重力的情况下,自动贯入海底沉积物进行热流测量工作方式的可行性。并在最后通过海上试验,对分析结果进行了实践验证。 相似文献
6.
Heat flow estimated from the gas hydrate layers on the landward slope of the Nankai Trough reveals that heat flow increases downslope toward the trench floor. This data plus six new heat flow values obtained by a conventional probe and two values available from DSDP drill holes give a fairly detailed heat flow distribution in the Nankai Trough area, when combined with the already existing data set. There appears to be a zonal pattern parallel to the trough axis, with a high heat flow zone on the floor of the trough that is quite anomalous for a subduction zone. It might be explained as a result of subduction of the hot portion of the Philippine Sea plate, i.e. the Shikoku Basin, and/or of more local effects such as heating due to intrusion of hot water from subducted sediments to shallow depth beneath the trough floor. Surface heat flow patterns landward of the trough were calculated for a simple thermal model of subduction. Perfect reproduction of the observed zonal pattern is difficult to achieve by the simple model, suggesting the necessity for further heat flow and other observations. 相似文献
7.
Chih Wu 《Ocean Engineering》1990,17(3)
The specific power of a simple irreversible closed-cycle OTEC power plant is analyzed and optimized. The plant uses a working fluid such as ammonia to produce power. Specific power is the net output per unit total heat exchanger surface area. Net output generated by the working fluid is obtained in terms of the rate of heat added to the working fluid from the warm surface ocean water, less the rate of heat removed from the working fluid to the cold deep ocean water. A time factor is added to iimulate the heat exchanges between the OTEC plant and its surroundings. A mathematical expression is derived for the specific power output of the irreversible OTEC heat engine. It is found that there is a bound on the specific power output. This bound provides the basis for a practical engineering effort towards maximizing the per unit time and per unit total heat exchanger area production of work in power plants whose heat transfer area is constrained by economic consideration. 相似文献
8.
9.
Craig B. Kensler 《新西兰海洋与淡水研究杂志》2013,47(4):506-517
The spiny lobster Jasus edwardsii (Hutton) supports a thriving new fishery at the Chatham Islands, about 770 km east of New Zealand. Commercial fishing for J. edwardsii started in November 1965, and within 2 years the area became a major centre of New Zealand's large spiny lobster fishery, which earned >NZ$5,000,000 in 1967. Over 12 months (September 1966 to August 1967) landings at the Chatham Islands made up 39.8% of the total New Zealand spiny lobster catch of 16,600,0001b. In the first year of fishing 2,177,923 lb of spiny lobsters were caught, and in the second 7,129,658lb—a 227% increase. Fishing effort also increased substantially: average number of boats fishing each month rose by 174% in the second year, and the total number of boat‐fishing days by 152%. Most specimens of J. edwardsii caught are large and mature, typical of a virgin stock. 相似文献
10.
A model of sea ice growth as an expanded region of a phase transition (mushy zone) with a linear temperature profile is developed. The linear temperature distribution agrees with the mushy zone by introducing an equivalent porosity determined by its thermodynamical condition. This approach does not require any a priori information about the dependence of the porosity on the temperature and salinity; it rather allows us to obtain this relation from a solution of the mathematical problem. The model makes it possible to calculate the thickness of the growing ice and to estimate its main characteristics as well as the heat capacity of the underice layer under the conditions of undisturbed growth at any moment of the autumn-winter season up to its maximal thickness with account for the snow accumulation, basin depth, varying regime of cooling, and water salinity. 相似文献
11.
Heatflow measurements, on land or at sea have been previously costly to take, and hence there is sparse coverage of the world. The design and field methodology is described of a probe that measures the temperature gradient at depths of up to 5?m into soft sediments. The important features of the probe are that it is modular, digitally recording, and lightweight, allowing deployment by hand. It is self-contained, allowing deployment from almost any available boat. The time per measurement is about 30?min. and therefore makes surveys with multiple readings practicable. 相似文献
12.
13.
14.
Development of efficient global damage detection techniques for offshore structures is of great importance. The present paper applies the iterative modal strain energy (IMSE) method to locate and quantify the damage for three dimensional frame structures, when limited, spatially incomplete modal data are available. One theoretical development is a new procedure to directly incorporate the spatially-incomplete mode shapes in the algorithm, where slave degrees of freedom iterative updating procedure (SDUP) is developed for evaluating the damage indicator and damage severity. The merits of this new method are that both the modal frequencies and spatially incomplete mode shapes can be used. Also, the modal frequencies do not need to pair the mode shapes one by one. To demonstrate the feasibility and effectiveness of the developed algorithm, numerical studies are conducted for a 3D offshore platform based on data generated from finite element models. Numerical results demonstrate that the present method is effective for the damage assessment of a 3D frame structures when limited, spatially incomplete modal data are available. After considering more practical factors, it is expected to be more applicable in structural damage assessment. 相似文献
15.
Kay I. Ohshima Genta Mizuta Motoyo Itoh Yasushi Fukamachi Tatsuro Watanabe Yasushi Nabae Koukichi Suehiro Masaaki Wakatsuchi 《Journal of Oceanography》2001,57(4):451-460
In the southwestern part of the Okhotsk Sea, oceanographic and sea-ice observations on board the icebreaker Soya were carried out in February 1997. A mixed layer of uniform temperature nearly at the freezing point extending down to a
depth of about 300 m was observed. This is much deeper than has previously been reported. It is suggested that this deep mixed
layer originated from the north (off East Sakhalin), being advected along the shelf slope via the East Sakhalin Current, accompanied
with the thick first-year ice (average thickness 0.6 m). This vertically uniform winter water, through mixing with the surrounding
water, makes the surface water more saline (losing a characteristic of East Sakhalin Current Water) and the water in the 100–300
m depth zone less saline, colder, and richer in oxygen (a characteristic of the intermediate Okhotsk Sea water). The oceanographic
structure and a heat budget analysis suggest that new ice zone, which often appears at ice edges, can be formed through preconditioning
of thick ice advection and subsequent cooling by the latent heat release due to its melting.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
17.
一种基于边缘信息的车辆检测和跟踪方法 总被引：1，自引：0，他引：1
针对智能交通系统中运动车辆的检测和跟踪问题,提出1种基于边缘信息车辆检测和跟踪方法。利用背景边缘提取模板提取当前帧的精确背景边缘,进而获得前景车辆边缘,用形态学方法对其进行修复,寻找车辆的外轮廓,确定跟踪区域;由于车辆运动的特殊性,以当前帧的车速作为下一帧车速的预测值,并结合跟踪区域的外形信息进行匹配。从实验效果来看,该算法简单有效,适合于实时的车辆检测和跟踪系统。 相似文献
18.
自落式贯入仪(Free-Falling Penetrometer, FFP)是一种新型海底沉积物原位测量设备,用于海底沉积物工程性质原位调查。本文基于自主研发的FFP设备在黄海海域开展现场贯入试验,分析探头尺寸对判断沉积物性质的影响。研究表明,在不同沉积物中探头尺寸对贯入深度、贯入阻力和沉积物类型判断有不同影响。在细粒沉积物中探头尺寸对贯入深度、贯入阻力影响较小;在根据贯入阻力变化划定分层时,小直径探头能反应贯入阻力更为细小的变化。在粗粒沉积物中探头尺寸影响更明显,大尺寸探头使贯入阻力变大,贯入深度减小。根据标准化深度和硬度因子可区分粗粒沉积物和细粒沉积物,在粗粒沉积物中探头尺寸增大,硬度因子减小,有利于细化沉积物类型。 相似文献
19.
In this paper the probability of green water occurrence is investigated by taking into account the threshold of the vertical relative motion exceeding the freeboard. The number of wetting of the unit/vessel is predicted using probabilistic method. This paper compares the significant load, due to shipping of green water with the works of other researchers, and the loads are found to be close with the results presented in this paper. There is no direct relation between the velocities in the waves and the water velocity over the deck. The water velocities around the bow are heavily distributed by the presence of the bow. This scenario makes the flow very complex for schematic modelling. 相似文献
20.
Understanding heat transport in sedimentary basins requires an assessment of the regional 3D heat distribution and of the main physical mechanisms responsible for the transport of heat. We review results from different 3D numerical simulations of heat transport based on 3D basin models of the Central European Basin System (CEBS). Therefore we compare differently detailed 3D structural models of the area, previously published individually, to assess the influence of (1) different configurations of the deeper lithosphere, (2) the mechanism of heat transport considered and (3) large faults dissecting the sedimentary succession on the resulting thermal field and groundwater flow. Based on this comparison we propose a modelling strategy linking the regional and lithosphere-scale to the sub-basin and basin-fill scale and appropriately considering the effective heat transport processes. We find that conduction as the dominant mechanism of heat transport in sedimentary basins is controlled by the distribution of thermal conductivities, compositional and thickness variations of both the conductive and radiogenic crystalline crust as well as the insulating sediments and by variations in the depth to the thermal lithosphere–asthenosphere boundary. Variations of these factors cause thermal anomalies of specific wavelength and must be accounted for in regional thermal studies. In addition advective heat transport also exerts control on the thermal field on the regional scale. In contrast, convective heat transport and heat transport along faults is only locally important and needs to be considered for exploration on the reservoir scale.The general applicability of the proposed workflow makes it of interest for a broad range of application in geosciences including oil and gas exploration, geothermal utilization or carbon capture and sequestration issues. 相似文献