Navigation Speed Research Articles

Research on the Heat Dissipation Characteristics of Lithium Battery Spatial Layout in an AUV

To meet the power demand requirements of autonomous underwater vehicles (AUVs), the power supply is generally composed of a large number of high-energy lithium battery groups. The lithium battery heat dissipation properties not only affect the underwater vehicle performance but also bring some security risks. Based on the widespread application of lithium batteries, lithium batteries in an AUV are taken as an example to investigate the heat dissipation characteristics of the lithium battery spatial layout in an AUV. With the aim of increasing the safety of lithium batteries, a model is developed for the heat transfer process based on the energy conservation equation, and the battery heat dissipation characteristics of the spatial layout are analyzed. The results indicate that the most suitable distance between the cells and the cross arrangement is better than the sequence arrangement in terms of cooling characteristics. The temperature gradient and the temperature change inside the cabin with time are primarily affected by the navigation speed, but they have little relationship with the environmental temperature.

Analysis of Profitability for Container Shipping on Arctic Routes by Navigation Speed and Risk of Disruption

Arctic sea routes have long been a worldwide focus because they create shorter distances between the Atlantic and the Pacific Oceans and because of their role in relieving pressure on the two busiest traditional routes for maritime shipping. Models used to address the profitability of Arctic shipping have neglected the variety of navigation speeds along Arctic routes related to various ice situations in the Arctic zone. As well, risks of disruption and recovery costs are seldom taken into account in the models. To improve the accuracy of assessments, this paper analyzes disruptions and delays along Arctic container shipping routes and presents a nonlinear programming model for minimizing operation costs, including penalties for deviations in arrival time and for undelivered containers. Piecewise linear interpolation is used to transform this nonlinear problem into a mixed-integer linear programming problem. Results of a case study are discussed for validity and improvements. This study could help shipping liners design a service network of container shipping through the Arctic routes.

A Novel Eye-Gaze-Controlled Wheelchair System for Navigating Unknown Environments: Case Study With a Person With ALS

Thanks to advances in electric wheelchair design, persons with motor impairments due to diseases, such as amyotrophic lateral sclerosis (ALS), have tools to become more independent and mobile. However, an electric wheelchair generally requires considerable skill to learn how to use and operate. Moreover, some persons with motor disabilities cannot drive an electric wheelchair manually (even with a joystick), because they lack the physical ability to control their hand movement (such is the case with people with ALS). In this paper, we propose a novel system that enables a person with motor disability to control a wheelchair via eye-gaze and to provide a continuous, real-time navigation in unknown environments. The system comprises a Permobile M400 wheelchair, eye tracking glasses, a depth camera to capture the geometry of the ambient space, a set of ultrasound and infrared sensors to detect obstacles with low proximity that are out of the field of view for the depth camera, a laptop placed on a flexible mount for maximized comfort, and a safety off switch to turn off the system whenever needed. First, a novel algorithm is proposed to support continuous, real-time target identification, path planning, and navigation in unknown environments. Second, the system utilizes a novel N-cell grid-based graphical user interface that adapts to input/output interfaces specifications. Third, a calibration method for the eye tracking system is implemented to minimize the calibration overheads. A case study with a person with ALS is presented, and interesting findings are discussed. The participant showed improved performance in terms of calibration time, task completion time, and navigation speed for a navigation trips between office, dining room, and bedroom. Furthermore, debriefing the caregiver has also shown promising results: the participant enjoyed higher level of confidence driving the wheelchair and experienced no collisions through all the experiment.

Speed Optimization Control for Wheeled Robot Navigation with Obstacle Avoidance Based on Viability Theory

The navigation efficiency of wheeled robots needs to be further improved. Although related research has proposed various approaches, most of them describe the relationship between the robot and the obstacle roughly. Viability theory concerns the dynamic adaptation of evolutionary systems to the environment. Based on viability, we explore a method that involves robot dynamic model, environmental constraints and navigation control. The method can raise the efficiency of the navigation. We treat the environment as line segments to reduce the computational difficulty for building the viability condition constraints. Although there exists lots of control values which can be used to drive the robot safely to the goal, it is necessary to build an optimization model to select a more efficient control value for the navigation. Our simulation shows that viability theory can precisely describe the link between robotic dynamics and the obstacle, and thus can help the robot to achieve radical high speed navigation in an unknown environment.

Complexed navigation system based on a strapdown inertial navigation system and correlation meter speed and drift

Integration of data and correlation meter speed strapdown inertial navigation system built by analogy with the Doppler velocity and drift, results in strong disturbances in the control loop movement of the aircraft in the horizontal plane. A method of aggregation, which takes into account the correlation method for measuring the speed, is the need to calculate the long periods of correlation functions of signals received by antennas spaced. This corrected the error strapdown inertial navigation system to speed up, speed and coordinates, eliminating the need for a moving average of the correlation functions and information retrieval speed navigation in every cycle.

Ship-wake induced sediment remobilization: Effects and proposed management strategies for the Venice Lagoon

More than 3000 commercial vessels navigate through the Malamocco-Marghera Industrial Canal in Venice Lagoon, Italy in a given year, leading to an estimated annual resuspension of 1.2 × 106 metric tons of sediment. Hence, ship wakes contribute to the significant erosion of shoals in the central lagoon which has occurred over the last 30 years. Drawdown associated with the surface depression wave from successive ships induces sediment transport towards the shipping canal, where the cost of dredging amounts to tens of millions of Euro per year. Most ship traffic occurs near an industrial zone, resulting in substantial potential for resuspension of contaminated sediment. Thus, sediment resuspension by ship traffic in the Venice Lagoon has the potential for detrimental economic and environmental impacts.This paper illustrates the impacts of ship induced depression waves and discusses management options for mitigating those impacts, based on extensive observational data and analysis conducted in Venice Lagoon, Italy. This article helps to further the understanding of the processes that govern sediment transport along the shipping channel and employ this knowledge to develop specific management recommendations.A reduction in the navigation speed of ships, an increase in the distance between successive ships, and limiting navigation to tidal levels above 0.3 m from the local 1897 reference mean sea level can help to minimize these problems.

The Simulation Study of Marine Propeller Load Characteristics Based on Regression Algorithm

Xu, A. and Sun, J., 2015. The simulation study of marine propeller load characteristics based on regression algorithm.In this paper, in order to avoid the complex calculation with propeller chart, a new model method for marine propeller was put forward. According to the new model method, propeller thrust and torque are calculated based on regression algorithm and it can realize four quadrants simulation. After the propeller model was completed, basic ship operation such as start, stop and emergency astern are simulated with the help of mathematical model of the ship-propeller. Through analyzing the change curves of the revolution speed of the propeller, the navigation speed of the ship and the torque of the ship under all kinds of working conditions, some operable suggestions and theory evidences are provided for the practical operation of the ship.

The Effect of Hull Biofouling on Parameters Characterising Ship Propulsion System Efficiency

Abstract One of most important issues concerning technical objects is the increase of their operating performance. For a ship this performance mainly depends on the efficiency of its main pro-pulsion system and the resistance generated during its motion on water. The overall ship re-sistance, in turn, mainly depends on the hull friction resistance, closely related with the pres-ence of different types of roughness on the hull surface, including underwater part biofouling. The article analyses the effect of hull biofouling on selected parameters characterising the efficiency of the ship propulsion system with adjustable propeller. For this purpose a two-year research experiment was performed on a sailing vessel during its motor navigation phases. Based on the obtained results, three groups of characteristics were worked out for different combinations of engine rotational speed and adjustable propeller pitch settings. The obtained results have revealed that the phenomenon of underwater hull biofouling affects remarkably the parameters characterising propulsion system efficiency. In particular, the development of the biofouling layer leads to significant reduction of the speed of navigation.

北極海航路を用いた東アジアと欧州間のコンテナ輸送における二酸化炭素排出量の削減に関する研究

According to the presumption of IMO, the amount of the greenhouse gas emissions from international maritime transportation is represented 850 million tons in 2007. Furthermore, carbon dioxide emissions from international maritime transportation represented 3% of the world's total carbon-dioxide emissions. Therefore, it is necessary to reduce the carbon dioxide emissions from maritime transportation. In this paper, we targeted for distribution of the container transport between East Asia and Europe with a large amount of cargos which examine the reduction effect of the carbon dioxide emissions in the case of Northern Sea Route. We should also consider the depth of water and the speed of navigation when we examine the effect of the carbon dioxide emissions reduction. In this paper, we will examine the reduction of carbon dioxide's emissions when the container vessels are distributed. As a result, the reduction of the carbon dioxide's emissions is approximately 317million tons.

Test Studies of the Resistance and Seakeeping Performance of a Trimaran Planing Hull

Abstract Towing tank tests in calm water were performed on a trimaran planing hull to verify its navigational properties with different displacements and centres of gravity, as well as to assess the effects of air jets and bilge keels on the hull’s planing capabilities, and to increase the longitudinal stability of the hull. Hydrostatic roll tests, zero speed tests, and sea trials in the presence of regular waves were conducted to investigate the hull’s seakeeping ability. The test results indicate that the influence of the location of the centre of gravity on the hull resistance is similar to that of a normal trimaran planing hull; namely, moving the centre of gravity backward will reduce the resistance but lower the stability. Bilge keels improve the longitudinal stability but slightly affect the resistance, and the presence of air jets in the hull’s channels decreases the trim angle and increases heaving but has little effect on the resistance. Frequent small-angle rolling occurs in waves. The heaving and pitching motions peak at the encounter frequency of , and the peaks increase with velocity and move towards greater encounter frequencies. When the encounter frequency exceeds, the hull motion decreases, which leads to changes in the navigation speed and frequency.

선박위치 클러스터링을 활용한 해상교통 근접사고 산출에 관한 연구

해상교통환경에서 선박간 근접사고(Near-miss)는 양 선박이 충돌 위험코스로 서로 근접하여 충돌에 임박한 상황으로 실제 충돌은 발생되지 않은 사고를 말한다. 본 연구에서는 통항 선박들간 근접사고 산출을 위해 선박 범퍼 영역모델을 활용한 근접사고 판별식과 선박 위치 클러스터링을 통해 해역의 근접사고 산출 모듈을 제안하고자 한다. 제안된 근접사고 산출 모듈을 완도해역 통항선박 항적데이터에 적용하여 선종, 항행속력 및 조우방향 등 선박 항해 위험 요인을 평가하고자 한다. In the maritime traffic environment, the near-miss between vessels is the situation approaching on collision course but collision accident is not occurred. In this study, in order to calculate the near-miss between navigating vessels, the discriminating equation using ship bumper theory and vessel position clustering methods are proposed. Applying proposed module to the vessel trajectories of the WANDO waterway, we assessment navigational risk factors of vessel type, navigational speed, meeting situation.

Investigation of Discretionary Lane-Change Characteristics Using Next-Generation Simulation Data Sets

In this article, we investigate discretionary lane change (DLC) characteristics using Next Generation SIMulation (NGSIM) data sets. We first develop a set of heuristic rules to automatically filter out abnormal samples from a massive trajectory data set and identify DLC trajectories from a mixture of mandatory lane change (MLC) and DLC trajectories. Then, we investigate a variety of DLC characteristics. We demonstrate that the kernel part of every normal DLC trajectory can be approximately depicted by a certain fifth-order polynomial. Moreover, we discuss the definition of begin/end points of DLC actions and show that the duration time of DLC actions follows a log-normal distribution with respect to navigation speed. All the findings can help promote temporal and spatial accuracy of lane changing models.

Research on Collision Avoidance in Terminal Area Based on RNP and 3D Paths

We describes an operational concept in this paper, it enables increased airspace and airport capacity by using the Flight Management System (FMS), Required Navigation Performance capabilities (RNP) and air traffic management automation tools. This concept can be applied to en route and terminal operation. It realizes ground to air communication by using of voice and data chain. This paper analyzes several key performance parameters which affect arrival management process. This concept models the arrivals by using the performance modeling approach. The results of the modeling proves several factors that influence the delivery accuracy and delay in the arrival process ,these factors include the path and speed discretization, wind, trajectory prediction and navigation performance.

명량수도 해역에서 항해속력 규제와 선박운용에 관한 연구

This study provided safe sailing speed and appropriate passing time to areas of known strong current water to prevent marine accident of the ships. To the interpretation of these data which target Myeongnyang waterway, AIS data of the ship was collected from July to July 2010 and site environment was investigated on September 2010. On the basis of the collected data, the `Minimum Navigation Speed` and `Optimum Navigation Speed` were calculated. It has also considered the `Spare control force` or allowance and the `Respond Rudder Angle` for each tidal current speed. Additionally, it suggested the safe passing time to strong current area by analyzing tidal level and tidal current speed. The conclusion of the research are as follows : (1) If the flow rate is greater than 4.4 kn, it is difficult for the model ship to control herself by her own steering power and to cope with tidal current pressure force and yaw moment caused by the tidal current.. (2) The minimum navigation speed should be over 2.3 times the tidal current and the optimum navigation speed should be over 4.0 times the tidal current. (3) When spring tide, the optimum passing time at Myeongnyang waterway is between 30 minutes to 1 hour before the time of high/low water, and at 5 hours after high/low water, passing of ships should be avoided because it is time when the flow rate is over 4 kn.

자율이동로봇의 안전주행을 위한 주행성 맵 작성

This paper presents a method for developing a TM (Traversability Map) from a DTM (Digital Terrain Model) collected by remote sensors of autonomous mobile robots. Such a map can be used to plan traversable paths and estimate navigation speed quantitatively in real time for robots capable of performing autonomous tasks over rough terrain environments. The proposed method consists of three parts: a DTM partition module which divides the DTM into equally spaced patches, a terrain information module which extracts the slope and roughness of the partitioned patches using the curve fitting and the fractal-based triangular prism method, and a traversability analysis module which assesses traversability incorporating with extracted terrain information and fuzzy inference to construct a TM. The potential of the proposed method is validated via simulation works over a set of fractal DTMs.

Online Control of DC Motors Using Fuzzy Logic Controller for Remote Operated Robots

In this paper, a fuzzy logic controller is designed for a DC motor which can be used for navigation control of mobile robots. These mobile robots can be used for agricultural, defense and assorted social applications. The robots used in these fields can reduce manpower, save human life and can be operated using remote control from a distant place. The developed fuzzy logic controller is used to control navigation speed and steering angle according to the desired reference position. Differential drive is used to control the steering angle and the speed of the robot. Two DC motors are connected with the rear wheels of the robot. They are controlled by a fuzzy logic controller to offer accurate steering angle and the driving speed of the robot. Its location is monitored using GPS (Global Positioning System) on a real time basis. IR sensors in the robot detect obstacles around the robot. The designed fuzzy logic controller has been implemented in a robot, which depicts that the robot could avoid obstacle as well as perform its operation efficiently with remote online control.

Diel and seasonal movement pattern of the dusky grouper Epinephelus marginatus inside a marine reserve

Temporal movement patterns and spawning behaviour of the dusky grouper Epinephelus marginatus were investigated using depth and temperature sensors combined to acoustic telemetry. Results showed that these fish are year-round resident, remaining inside the fully protected area of the marine reserve of Cerbère-Banyuls (65 ha) and display a diurnal activity pattern. Records from depth sensors revealed that groupers range inside small, distinct, and individual territories. Individual variations in habitat depth are only visible on a seasonal scale, i.e., between the spawning season and the rest of the year. In fact, during summer months when the seawater temperature exceeded 20 °C, tagged groupers made vertical spawning migrations of 4–8 m in amplitude. These vertical migrations are characteristic of the reproductive behaviour of dusky groupers, during which they release their gametes. The results are notable for the implementation of management rules in marine protected areas, such as reduced navigation speed, boating or attendance during spawning season.

A Fault Tolerant Integrated Navigation Scheme Realized through Online Tuning of Weighting Factors for Federated Kalman Filter

Strapdown Inertial navigation (SINS) is a highly reliable navigation system for short term applications. SINS functions continuously, less hardware failures, renders high speed navigation solutions ranging from 50 Hz to 1000 Hz and exhibits low short-term errors. It provides efficient attitude, angular rate, acceleration, velocity and position solutions. But, the accuracy of SINS solution vitiates with time as the sensor (gyros & accelerometers) errors are integrated through the navigation equations. Average navigation grade SINS are capable of providing effective stand-alone navigation for shorter duration (few minutes) applications Stand-alone SINS capable of providing solutions for applications exceeding 10 minutes duration, are generally highly expensive ($0.1M to $2.0M). To cope with this limitation, a cost effective solution is the integrated navigation system wherein the unboundedly growing errors of SINS are contained with the help of external non-inertial navigation aids like GPS, Celestial Navigation System (CNS), Odometer, Doppler radars etc. The efficient methodology for integrated or multi-sensory navigation is the Federated Kalman Filter (FKF) scheme. In FKF architecture, a reference SINS solution is integrated independently with each of the aiding navigation systems in a bank of local Kalman filters. There are a number of different ways in which the local filter outputs may be combined to produce an integrated navigation solution. The no-reset, fusion-reset, zero-reset, and cascaded versions of federated integration have been used by different researcher and navigators over the years. All different schemes of FKF have certain pros and cons. Fusion-reset method although nearly optimal is less fault tolerant while no-resent scheme renders highly fault tolerant solutions but with sub-optimal solutions and compromised precision. To enhance the fault tolerance ability of fusion-reset scheme of FKF, additional parameters called weighting factors are introduced to tune the contribution of each local filter in the final data fusion. The presented scheme has been found nearly optimal and expressively fault tolerant.

Early intervention in the 3xTg-AD mice with an amyloid β-antibody fragment ameliorates first hallmarks of Alzheimer disease

The single-chain variable fragment, scFv-h3D6, has been shown to prevent in vitro toxicity induced by the amyloid β (Aβ) peptide in neuroblastoma cell cultures by withdrawing Aβ oligomers from the amyloid pathway. Present study examined the in vivo effects of scFv-h3D6 in the triple-transgenic 3xTg-AD mouse model of Alzheimer disease. Prior to the treatment, five-month-old female animals, corresponding to early stages of the disease, showed the first behavioral and psychological symptoms of dementia -like behaviors. Cognitive deficits included long- and short-term learning and memory deficits and high swimming navigation speed. After a single intraperitoneal dose of scFv-h3D6, the swimming speed was reversed to normal levels and the learning and memory deficits were ameliorated. Brain tissues of these animals revealed a global decrease of Aβ oligomers in the cortex and olfactory bulb after treatment, but this was not seen in the hippocampus and cerebellum. In the untreated 3xTg-AD animals, we observed an increase of both apoJ and apoE concentrations in the cortex, as well as an increase of apoE in the hippocampus. Treatment significantly recovered the non-pathological levels of these apolipoproteins. Our results suggest that the benefit of scFv-h3D6 occurs at both behavioral and molecular levels.

부산항내 제트포일 여객선의 항해 속력에 대한 연구

부산항내 제트포일 여객선의 항해 속력에 대한 연구