An inexpensive instrument for measuring benthic current velocity and direction at sea

An instrument which measures the velocity and direction of benthic water currents at depths of up to 80 m is described. Characteristics of this meter include: (i) readings are not affected by water flow during sinking or retrieval; (ii) it is portable; (iii) it operates unattended; (iv) it is inexpensive; and (v) it requires only simple maintenance. A timing circuit which operates two time periods in succession is used to activate and de-activate a revolution counter and a fluidfilled compass which are mounted on a special frame and vane system. In the field, the instrument accurately measured average current velocities of up to 6 m s⁻¹. Data are presented which illustrate the usefulness of this instrument in describing the velocity and direction of benthic currents along the east coast of Australia and demonstrate a positive correlation between benthic current velocity and catch rates of the commercially-exploited spanner crab Ranina ranina.     

An economic device for protecting bridge piers against ship collisions

Ship collisions against bridge piers have caused considerable damage (loss of human lives and partial structural destruction) in some instances. The present technical note discusses, in preliminary form, some of the advantages of a device developed at the Institute of Applied Mechanics. It is hoped that this short report will stimulate discussion, analysis and further development of the current investigations, and contribute to improving the defence of a bridge pier located in a seaway.     

双矩形浮子波能装置辐射问题的解析方法

在有限水深下1个漂浮在水中的矩形浮子和1个淹没在水下的浮子构成双矩形波能装置模型。基于特征函数展开法求解了线性入射波作用下双矩形浮子波能装置的辐射问题,得出了双矩形浮子辐射速度势的1种新解析式,然后根据Haskind关系由入射势和辐射势来计算波浪激励力,并且采用数值方法对相同算例进行了计算,得到了完全一致的结果,从而证明这种方法是正确的。研究了在不同工况下的波浪激励力和系统的水动力学系数变化的规律。     

A simple,inexpensive and large volume pore water sampler for sandy and muddy substrates

The construction and testing of a low cost, simple, intertidal and sub-tidal pore water sampler for use in sandy and muddy substrates are described in this note. The sampler, “porextractor”, is made of polyvinyl chloride (PVC) plumbing materials that can be readily sourced at any local hardware shop and costs AU $ 15.00 to build. The only mechanical component of the porextractor is a plunger that is used only once at the time of deployment. The porextractor has been designed for use on seagrass beds to collect pore water samples with minimal disturbance to the substratum for nutrient flux studies. The relative efficiency of the porextractor was tested against the widely used “Winger and Lasier” sampler, a vacuum operated diffuser stone pore water sampler. The two samplers were compared for the volume of pore water collected in sandy and muddy substrates in the laboratory, and the concentrations of total nitrogen and total phosphorus in samples collected from a sandy substrate in Amphibolis and Posidonia seagrass meadows off the Adelaide coast. While the porextractor and the Winger and Lasier samplers worked equally well in the sandy sediments, the porextractor was more efficient than the latter in muddy sediments, where clogging was a major problem. In addition, there were no significant differences (p ≤ 0.05) in the concentrations of total nitrogen and total phosphorus measured from the pore water samples collected by the two samplers in situ from the seagrass bed. The simplicity, ease of construction, non-substrate specificity, and large sample volume yield are some of the major merits of the porextractor over other conventional techniques used for pore water sampling.     

An ultrasonic device to measure surface displacements of water and floating bodies

Non-intrusive measuring instruments are desirable tools to investigate the response of vessels or marine structures subjected to water waves, whether in a laboratory or in the field. An ultrasonic sensing device is designed and built to measure surface displacements of a floating body. An ultrasonic sensor can sense any surface that lies in front of it, whether it is a solid or a liquid surface. In this study, a specialized electronic circuit board is designed to measure a wide range of surface displacements. The proposed system not only can be used to measure heave, surge, and pitch of a floating body continuously but also it can act as a water waveform recording instrument. The proposed ultrasonic measuring device is far more accurate than the current standard instruments (e.g. potentiometers) based on the simple fact that the measured surface is not disturbed. Furthermore, this device is of low manufacturing cost and has a practical size that renders it suitable for a broad range of applications. Hence, it can be used in a laboratory setup as well as in conducting field tests.     

导管架钢桩测距及切割定位方法研究

过渡段是联接导管架钢桩与组块的结构部件,又作为调节导管架钢桩和组块误差的结构,其有着十分重要的作用.提出一种新方法利用全站仪与CAD结合的方式确定钢桩实际跨距,此方法具有操作简便、误差小等优点.详细叙述了导管架标高的确定,理论切割线的确定,及根据组块尺寸确定钢桩实际切割位置,并描述过渡段正确安装过程.所述方法成功应用于BZ29-4钻井帽和SZ36-1EDP组块海上安装.     

Datalogging instrument arrays: Powerful yet inexpensive tools for recording the heterogeneous physical environment of coral reefs

The physical structure of coral reefs, like that of rainforests and other spatially-complex ecosystems, modulates light, fluid flow, and other physical variables to create a spatially and temporally complex mosaic of microhabitats. Accurate and affordable methods for quantifying this spatio-temporal variation are required to address many basic and applied research questions related to the ecology and management of reefs. Recent advances in semiconductor electronics technology have made it easier and much less expensive to build small and reliable datalogging instruments, which can be deployed in arrays to record spatio-temporal patterns of ecologically-important variables. Suitable instruments are already commercially available for $100 (US) or less per unit, and more are being produced. Moreover, people with modest electronics training and equipment can now design and build their own instruments successfully using the powerful features and modularity of modern “off-the-shelf” integrated circuits. Commercial instruments, as well as all of the parts necessary to construct custom-made instruments, can be ordered by telephone or internet and shipped worldwide. Thus, these technologies are now available for reef research and monitoring in remote regions, including the many developing island nations whose people depend on healthy reefs for healthy economies.     

A successive elimination method for one-dimensional stock cutting problems in ship production

One-dimensional stock cutting problems can be encountered at the production stage of many areas of engineering as well as in shipbuilding and coastal structures. In this paper, a novel approach is proposed to solve the problem directly by using the cutting patterns obtained by the analytical methods at the mathematical modeling stage. By minimizing both the number of different cutting patterns and material waste, the proposed method is able to capture the ideal solution of the analytical methods. The main advantage of the method comes from the fact that an integer solution is guaranteed. However, in analytical methods it is not always possible to produce integer solutions and the linear programming algorithm must be run repeatedly to select integer solutions from the alternatives to get practical results. The proposed nesting algorithm is a low-cost and efficient tool. Minimizing the number of cutting patterns contributes to time and material savings. Also, by using this method trim loss is minimized and stock usage is maximized. The efficiency of the proposed method is demonstrated by extensive numerical results.     

AUV水下对接装置控制系统设计

自主式水下机器人(Autonomous Underwater Vehicle,简称AUV)在航行使命结束后需要回收至甲板或陆地进行补给和维护。为避免重复布放回收所带来的不便,根据锥形导向式回收原理,针对水下对接装置及其控制系统进行了设计。水下对接装置控制系统由水面控制终端,水下控制系统和水下外部设备等部分组成,使用超短基线引导AUV进入指定区域,在对接过程中依靠行程开关和无线电反馈的信息判断AUV的相对位置及状态,并通过驱动相应的液压机构对AUV姿态进行校正和固定,进而完成对接过程。水下对接装置在千岛湖进行了试验,在吊装水下7 m的情况下实现了AUV的水下对接,并利用湿插拔电连接器完成了对AUV的有线充电和数据上传。试验验证了对接方案的可行性以及控制系统的稳定性,为将来AUV能够进行长时间、不间断航行提供了可能。     

引航员登离船安全防护装置研究

引航员登离软梯过程中,使用手动方式上下移动安全带实现引航员安全防护较为繁琐,且会出现二次伤害风险。为此,提出一种新型登离船安全防护装置,包括姿态监控装置和攀爬防护装置。姿态监控装置通过姿态传感器MPU(Multi-chipUnit)-9250获取人体姿态信息,并实现人体步数的判断;攀爬防护装置以直流电机作为装置驱动源,配合爬绳同步轮组,设计攀爬防护装置机械结构、锁紧结构和电控装置,实现了引航员登离船过程中装置跟随人体的自动跟随功能。实验结果表明:该装置相对于传统手动攀爬方式具有更好的智能性、便携性、安全性。     

SCOPIX: A new X-ray imaging system for core analysis

SCOPIX is a new digital X-ray imaging system for core analysis that uses an X-ray source coupled to a high-energy brightness amplifier and a CCD camera. SCOPIX’s numerical files are images in 256 gray levels equal in value to X-ray densities. Possible data processing approaches include: core logging using grayscale profiles to define the characteristics of sedimentary sequences and image processing to define and quantify lithologic facies and the geometry of physical and biological structures. Applications are: recognition of facies and sedimentary processes, study of sedimentary rhythms and geological cycles, and study of biological and geochemical processes.     

SCOPIX: A new X-ray imaging system for core analysis

 SCOPIX is a new digital X-ray imaging system for core analysis that uses an X-ray source coupled to a high-energy brightness amplifier and a CCD camera. SCOPIX’s numerical files are images in 256 gray levels equal in value to X-ray densities. Possible data processing approaches include: core logging using grayscale profiles to define the characteristics of sedimentary sequences and image processing to define and quantify lithologic facies and the geometry of physical and biological structures. Applications are: recognition of facies and sedimentary processes, study of sedimentary rhythms and geological cycles, and study of biological and geochemical processes. Received: 31 March 1998 / Revision received: 25 June 1998     

A painting type of flexible piezoelectric device for ocean energy harvesting

Energy harvesting using piezoelectric materials can be realised by periodic external force. Piezoelectric material directly converts strain energy into electric power to capture a wasted ambient kinetic energy. This recovered energy can be used for operating wireless sensors, such as those found in environmental monitoring, mechanical sensing and structural diagnostic. In our previous work, a flexible piezoelectric device, FPED, was proposed and developed as an energy harvester for generating electric power from flow-induced vibration in ocean and wind environments. In this study a FPED with a painted piezoelectric layer, highly durable in order to withstand extreme bending and weathering caused by waves and currents, is proposed and developed by spray coating for use as an ocean energy harvester. A numerical method is developed to predict electro-fluid–structure interactions and to evaluate electrical performance and mechanical behaviours of the painted FPED. Additionally, validation of the numerical model is provided through several experimental tests. This study also investigates the relationship between the stiffness of the painted FPED and the vibrated frequency, as well as determining their influence on the electrical performance. Finally, the outcomes from a field test, conducted in real ocean space, is presented to provide information on electrical performance, mechanical behaviours and durability of painted FPEDs. The paper shows that a painted FPED is a useful and robust energy harvester for generating electric power from harsh environments.     

新型水下钻井装置水动力特性研究

以锚泊半潜式钻井平台在规则波作用下的运动数值预报为基础,分析钻井平台诱导运动下,与平台相连的新型水下钻井装置水动力特性,以及该钻井装置各关键节点处的受力情况,评估该诱导水动力作用的重要性,及该系统在各种海况下的安全性能。     

Novel use of an ultrasonic cleaning device for fish reproductive studies

A major challenge commonly faced in reproductive studies of teleosts is to cost effectively and safely separate oocytes from one another and from surrounding ovarian tissue. This challenge is exacerbated when ovarian tissue has been chemically preserved. Using Platycephalus caeruleopunctatus, a platycephalid species found within oceanic waters along the east coast of Australia, as an example species, within this study we describe and assess the utility of an ultrasonic cleaning device to separate oocytes from preserved ovarian tissue. The ultrasonic cleaning device was observed to separate oocytes from the surrounding ovarian tissue within less than 80 min of treatment and had no deleterious effects on the number of oocytes present. Treatment within the ultrasonic cleaning device reduced oocyte diameters at a constant rate of 3.9 μm per hour among the samples tested. As the ultrasonic cleaning device was able to separate oocytes from connective tissue within 80 min, this observed rate of reduction in oocyte diameters is unlikely to be detected at the resolution at which oocytes are traditionally measured and is less than that reported to occur using alternate chemically derived methods to separate oocytes from preserved connective tissue. Following the assessment of using an ultrasonic cleaning device to separate oocytes from ovarian tissue for P. caeruleopunctatus, this technique has been successfully employed to separate oocytes from preserved ovarian tissue for a variety of other teleost species including Macquaria colonorum, Platycephalus longispinis and Ratabulus diversidens. The use of an ultrasonic cleaning device to separate oocytes from preserved ovarian tissue will increase the efficiency of future investigations into teleost reproductive biology and potentially in other fields of research where particle separation and analysis are required.     

基于磁力耦合器的载人潜水器电力推进装置研究

基于磁力耦合传动技术,对载人潜水器电力推进装置进行了系统设计与传动特性研究。采用电磁场有限元方法研究了永磁式磁力耦合器的运行机理和矩角特性,分析了其稳定传动区域和失步条件;分析了螺旋桨的负载特性,采用切比雪夫多项式研究了螺旋桨的四象限全工况动态模型;建立了水下无刷直流推进电机的数学模型和传递函数,设计了推进电机的转速闭环控制系统以抑制转速波动,提高输出推力的平稳度。完成了样机的设计与制造,通过水池试验验证了该推进装置在载人潜水器上的可行性与适用性。     

运用分子标记辅助构建海带核心种质资源

海带(Saccharina japonica)是一种具有重要经济和生态价值的大型海藻,配子体是其种质资源保存的形式,也是海带杂交育种、育苗的材料。为有效管理和评价海带种质资源,初步构建了海带核心种质资源,利用RAPD标记技术对海带"早厚成一号"的28份配子体进行了遗传学评价。采用UPGMA聚类法,根据遗传相似性系数进行分组,采用简单比例法进行取样(25%、35%、50%、65%)分析,计算不同取样比例时的遗传多样性参数,结合样本的生长状态和雌、雄比例,综合评价遗传多样性的各种参数,取样比例为50%时构建的核心种质库相对合理。本研究为海带品种(系)的核心种质的筛选和遗传学评价打下基础。