舰船辐射噪声模拟发射系统的设计研究

本文依据典型舰船噪声的频谱特性规律,设计研制了一套舰船辐射噪声发射系统实验样机,包括信号结构设计、换能器选择配置、系统构成设计等,本噪声模拟发射系统具有100Hz～16kHz频带噪声的模拟发射功能,包括线谱、连续谱成分,频谱分配和谱线形式可调可控,信号总声源级动态范围达60dB。     

GC-MS技术在舰船复合板毒性评价中的应用

海军舰船舱室多为密闭环境,其舱室狭小,设备庞杂,人员密集。舱室内部的防护装饰多系非金属材料,随着现代各种复合、聚合材料的迅速发展和广泛使用,周围环境特别是密闭舱室空气污染的问题也更为突出。本文根据有关军用标准和规程[1],应用GC-MS技术对2种舰船复合板常温释放物和高     

Parametric study of ship maneuverability in laterally restricted waters: Stochastic control approach

A stochastic control approach is used in a parametric study of ship maneuverability in a restricted channel of prescribed geometry. A realistic method, based on some empirical data, is used for the mathematical modelling of the ship motion in deep water.The authors are grateful to Mr. Lodewyk Wessels, Department of Electrical and Electronic Engineering, University of Pretoria, for generating the plots in this article.     

Inventory constrained maritime routing and scheduling for multi-commodity liquid bulk,Part I: Applications and model

This paper formulates a model for finding a minimum cost routing in a network for a heterogeneous fleet of ships engaged in pickup and delivery of several liquid bulk products. The problem is frequently encountered by maritime chemical transport companies, including oil companies serving an archipelago of islands. The products are assumed to require dedicated compartments in the ship. The problem is to decide how much of each product should be carried by each ship from supply ports to demand ports, subject to the inventory level of each product in each port being maintained between certain levels that are set by the production rates, the consumption rates, and the storage capacities of the various products in each port. This important and challenging inventory constrained multi-ship pickup–delivery problem is formulated as a mixed-integer nonlinear program. We show that the model can be reformulated as an equivalent mixed-integer linear program with special structure. Over 100 test problems are randomly generated and solved using CPLEX 7.5. The results of our numerical experiments illuminate where problem structure can be exploited in order to solve larger instances of the model. Part II of the sequel will deal with new algorithms that take advantage of model properties.     

A 3D-BPP approach for optimising stowage plans and terminal productivity

This paper addresses the problem of determining stowage plans for containers in a ship, that is the so-called master bay plan problem (MBPP).     

GC-MS技术在舰船胶粘材料毒性评价中的应用

胶粘材料简称胶粘剂、粘合剂、粘结剂、接着剂。因其能把各种材料紧密地粘合在一起,并具有各种良好的性能,因而广泛地应用于海军舰船的制造及维修中。应用GC-MS技术对在使用环境及条件下其释放物及高温热解物的定性分析是对其进行使用过程中毒性评价的重要步骤。1实验部分1.1仪器与材料仪器:JMS-D300(日本JEOL);PIATFORMⅡGC-MS。     

船舶操纵运动方程系数的系统辨识

作者设计并制作了伪随机二进制(PRBS)信号发生器。井以PRBS信号操舵,辨识了船舶操纵运动方程的系数。用离散时间测量决定线性连续时间模型参数。给出了Mariner标准模型和一艘渔轮的辨识结果,井与标准的Nomoto及,T计算结果进行了比较,结果令人满意。     

Influences of the separation distance,ship speed and channel dimension on ship maneuverability in a confined waterway

Ship maneuvering in the confined inland waterway is investigated using the system-based method, where a nonlinear transient hydrodynamic model is adopted and confinement models are implemented to account for the influence of the channel bank and bottom. The maneuvering model is validated using the turning circle test, and the confinement model is validated using the experimental data. The separation distance, ship speed, and channel width are then varied to investigate their influences on ship maneuverability. With smaller separation distances and higher speeds near the bank, the ship's trajectory deviates more from the original course and the bow is repelled with a larger yaw angle, which increase the difficulty of maneuvering. Smaller channel widths induce higher advancing resistances on the ship. The minimum distance to the bank are extracted and studied. It is suggested to navigate the ship in the middle of the channel and with a reasonable speed in the restricted waterway.     

遗传算法优化变分模态分解提取舰船辐射噪声特征线谱方法

特征线谱提取是舰船目标识别的一个重要研究环节,常采用传统的DEMON谱分析方法,处理过程中,一般对舰船噪声时域信号未予抑噪,低信噪比情况下,传统DEMON谱分析性能差。对此,提出一种采用遗传算法优化变分模态分解方法,用于分解舰船噪声原时域信号,获得抑制噪声后的舰船噪声重构信号,进而有效提取了舰船目标噪声幅度调制特征线谱。该方法首先采用遗传算法优化变分模态分解的两个关键输入参数(分解所取模态个数和惩罚因子),对变分模态分解得到的各阶固有模态分量加以判别,去除噪声主导分量,保留信号主导分量,使重构舰船噪声信号显著抑制了干扰噪声,然后对降噪后的重构信号进行频谱分析,获得目标噪声调制特征线谱。理论分析、仿真和实验数据处理结果表明,相比传统DEMON谱分析法,基于遗传算法优化变分模态分解的舰船噪声特征线谱提取方法具有更好的噪声抑制能力,所获取的舰船噪声幅度调制特征线谱信噪比明显高于传统DEMON方法,具有一定优势,前景良好。     

Optimal ship navigation with safety distance and realistic turn constraints

We consider the optimal ship navigation problem wherein the goal is to find the shortest path between two given coordinates in the presence of obstacles subject to safety distance and turn-radius constraints. These obstacles can be debris, rock formations, small islands, ice blocks, other ships, or even an entire coastline. We present a graph-theoretic solution on an appropriately-weighted directed graph representation of the navigation area obtained via 8-adjacency integer lattice discretization and utilization of the A^∗ algorithm. We explicitly account for the following three conditions as part of the turn-radius constraints: (1) the ship’s left and right turn radii are different, (2) ship’s speed reduces while turning, and (3) the ship needs to navigate a certain minimum number of lattice edges along a straight line before making any turns. The last constraint ensures that the navigation area can be discretized at any desired resolution. Once the optimal (discrete) path is determined, we smoothen it to emulate the actual navigation of the ship. We illustrate our methodology on an ice navigation example involving a 100,000 DWT merchant ship and present a proof-of-concept by simulating the ship’s path in a full-mission ship handling simulator.