邛海湖盆形态研究

邛海是四川省第二大淡水湖泊,本研究是为更好地利用和保护该人类资源所做的基础研究工作之一。通过基于GPS-RTK技术以及测深仪的水下地形测量,结合原有历史资料,应用湖沼学理论,对邛海的湖盆形态进行定量化研究。经研究,邛海为南北长、东西宽湖体较为接近半球体形式的断陷湖泊,正常高水位(1510.3m)下最大水深18.80m,平均水深10.63m,湖长10.85km,湖面最大宽度5.24km,平均宽度2.53km,岸线长37.4km,湖面面积27.408km2,湖底真面积27.411km2,容积291.43×107m3。研究结果对邛海流域的深入研究及保护与开发提供了基础信息支持。     

水下电缆探测技术浅谈

水域电缆位置探测直接影响到各项水域工程的设计施工安全和保障电力、通信的畅通。本文根据工作经历，对水下电缆探测技术进行了简要分析，提出目前采用的几种方法。     

711数字化天气雷达定标方法

对711数字化天气雷达的标定原理和方法进行了讨论，给出了雷达各项标定参数的详细标定方法。     

DEVELOPMENT OF A LOW-COST MOBILE MAPPING SYSTEM: A SOUTH AMERICAN EXPERIENCE

This paper presents the prototype of a low-cost terrestrial mobile mapping system (MMS) composed of a van, two digital video cameras, two GPS receivers, a notebook computer, and a sound frame synchronisation system. The imaging sensors are mounted as a stereo video camera on top of the vehicle together with the GPS antennae. The GPS receivers and the notebook computer are configured to record data referred to the vehicle position at a planned time interval. This position is subsequently transferred to the road images. This set of equipment and methods provide the opportunity to merge distinct techniques to make topographic maps and also to build georeferenced road image databases. Both vector maps and raster image databases, when integrated appropriately, can give spatial researchers and engineers a new technique whose application may realise better planning and analysis related to the road environment. The experimental results proved that the MMS developed at the São Paulo State University is an effective approach to inspecting road pavements, to map road marks and traffic signs, electric power poles, telephone booths, drain pipes, and many other applications important to people's safety and welfare. A small number of road images have already been captured by the prototype as a consequence of its application in distinct projects. An efficient organisation of those images and the prompt access to them justify the need for building a georeferenced image database. By expanding it, both at the hardware and software levels, it is possible for engineers to analyse the entire road environment on their office computers.     

Participatory video in geographic research: a feminist practice of looking?

This paper explores how participatory video – a methodology increasingly used in community development and anthropological research – may enable a feminist practice of looking which does not perpetuate hierarchical power relations and create voyeuristic, distanced and disembodied claims to knowledge. I reflect on experiences from a participatory video project with members of a Maaori tribe in Aotearoa New Zealand in light of geographers' uses of video to date. I argue that participatory video, if used within carefully negotiated relationships, has potential to destabilize hierarchical power relations and create spaces for transformation by providing a practice of looking 'alongside' rather than 'at' research subjects.     

A waypoint-tracking controller for a biomimetic autonomous underwater vehicle

This work develops a control system for the waypoint-tracking of a biomimetic autonomous underwater vehicle (BAUV). The BAUV swims forward by oscillating its body and caudal fin. It turns by bending its body and caudal fin toward the turning direction. The control algorithm uses the oscillating frequency to control the forward velocity, and applies a body-spline offset parameter to control the heading velocity. The motion of the BAUV is undulatory, so moving averages of swimming velocity and heading errors are used as feedback signals. The stability of the control system is discussed using a Lyapunov function. Finally, the effectiveness of the control algorithm is experimentally confirmed.     

Robust trajectory control of underwater vehicles using time delay control law

A new control scheme for robust trajectory control based on direct estimation of system dynamics is proposed for underwater vehicles. The proposed controller can work satisfactorily under heavy uncertainty that is commonly encountered in the case of underwater vehicle control. The dynamics of the plant are approximately canceled through the feedback of delayed accelerations and control inputs. Knowledge of the bounds on uncertain terms is not required. It is shown that only the rigid body inertia matrix is sufficient to design the controller. The control law is conceptually simple and computationally easy to implement. The effectiveness of the controller is demonstrated through simulations and implementation issues are discussed.     

Transverse vibrations of circular annular plates with edges elastically restrained against rotation, used in acoustic underwater transducers

Simply supported or clamped boundary conditions are rather ideal situations difficult to satisfy from a physical viewpoint. This paper considers a more “moderate” restriction: the case of edges elastically restrained against rotation for which no exact solution appears in the open literature. Eigenvalues corresponding to a wide range of the intervening geometric and mechanical parameters are determined. Good agreement is obtained with frequency coefficients determined two decades ago by means of a variational method. Obviously the problem is of basic interest in many ocean engineering applications: from the design of certain underwater acoustic transducers to pump and compressor elements passing through the design of naval vehicles and ocean structures.     

Control Experiments for Underwater Cultural Relics Survey by Marine Geophysical of Acoustics

Marine geophysical acoustic methods are a powerful tool for high-precision, large-scale underwater archaeological relics investigations and research in the shallow water. There is a complex coupling relationship between the marine environment and the preservation of underwater cultural relics, which leads to great uncertainty based on the detection data to deduce the existence and distribution of underwater cultural relics. In the past 30 years, the controllable experiments of acoustic methods for underwater cultural relics show that different side-scan sonar systems have varied acoustic response. Multi-beam sonar can be used to study the temporal variation of underwater cultural relics, while shipwreck partially or totally embedded in seabed sediments can be detected by sub-bottom profile. The control experiment will increase the understanding of the acoustic response for different underwater cultural types. Control experiment on the underwater cultural relics can provide a reference for the correlation between detection results and interpretation accuracy, and hopefully provide a systematic solution for underwater cultural survey in an efficient way and on a wide-scale, thus better protecting and managing underwater cultural relics.