Mother Ship Research Articles

Abstract TP494: A Continuous Monitoring Led by a Nurse Working Group Plays a Key Role in the Improvement of Acute Ischemic Stroke Workflow-Metrics

Background and Purpose: In the workflow process for the management of acute ischemic stroke (AIS) patients, time is critical to improve functional outcome. Based on the recent 2018 AHA ASA guidelines, median door-to-imaging (DTI) time should be less than 20 minutes and median door-to-needle (DTN) time for tPA administration less than 60 minutes. Our comprehensive stroke center mostly recruits suspected AIS patients following a “mother ship” approach with systematic emergency medical services pre-notification and emergency room by-pass. Based on this specific patient’s care approach, the purpose of our study was to evaluate our capacity to get with the guidelines (GWTG) and to shorten our DTN/DTI times. Methods: In our stroke center, the stroke alert follows a workflow including 15 time-points from call notification to cath lab access. The stroke team work during the stroke alert was evaluated, during two periods of time (oct-to-march and april-to-august) based on its capacity to comply with DTI and DTN recommended median times. Continuous improvement of the workflow was based on prospective data collection analysis and interpretation by a working group led by nurses focusing on knowledge, organization and leadership difficulties identification. Results: From october 2017 to august 2018, 501 stroke alerts were identified in our comprehensive stroke center. Of these, 425 (85%) cases were analyzed. A total of 81 (19%) of the suspected AIS patients received tPA, 44 (10.3%) were treated with combined tPA infusion and thrombectomy and 44 (10.3%) with thrombectomy alone. Median DTI time was 15 min (3-62), median DTN time for tPA administration was 44 min (21-87), median door-to-cath lab time was 64 min (23-140). DTI median time improved significantly between the two time-periods (15,5 (3-62), vs 15(3-50), p= 0,01). Neither DTN time nor door-to-cath lab room time changed significantly during the studied time periods. Conclusion: Our comprehensive stroke center fulfilled the 2018 AHA ASA guidelines for DTI and DTN times. Under the supervision of a nurse working group, shortening of DTI times could be achieved. These findings support the key role of nurses working groups focusing on knowledge and management to improve stroke alert workflow, and finally patient care.

Lever Arm Compensation of Autonomous Underwater Vehicle for Fast Transfer Alignment

Transfer alignment is used to initialize SINS (Strapdown Inertial Navigation System) in motion. Lever-arm effect compensation is studied existing in an AUV (Autonomous Underwater Vehicle) before launched from the mother ship. The AUV is equipped with SINS, Doppler Velocity Log, depth sensor and other navigation sensors. The lever arm will cause large error on the transfer alignment between master inertial navigation system and slave inertial navigation system, especially in big ship situations. This paper presents a novel method that can effectively estimate and compensate the flexural lever arm between the main inertial navigation system mounted on the mother ship and the slave inertial navigation system equipped on the AUV. The nonlinear measurement equation of angular rate is derived based on three successive rotations of the body frame of the master inertial navigation system. Nonlinear filter is utilized as the nonlinear estimator for its capability of non-linear approximation. Observability analysis was conducted on the SINS state vector based on singular value decomposition method. State equation of SINS was adopted as the system state equation. Simulation experiments were conducted and results showed that the proposed method can estimate the flexural lever arm more accurately, the precision of transfer alignment was improved and alignment time was shortened accordingly.

Operational Interface for Underwater Drone Considering Mother Ship Direction

Operational Interface for Underwater Drone Considering Mother Ship Direction

Design and Optimization for Ship Structure Based on Knowledge-Based Engineering

It is always pursued that the excellent ship structure is rapidly designed and modified on the premise of ensuring security in ship engineering. In this paper, design and optimization method for ship structure based on knowledge-based engineering is put forward. Combining knowledge-based engineering with parametric technology, the knowledge base of ship structure design is established and three-dimensional rapid optimal design is achieved. During the design, positions of ship structure components are driven by positional parameters. Scantlings of ship structural components are obtained by mother ships knowledge base and Non-Uniform Rational B-Splines interpolation, according to rules requirements. Main structures are optimized by quantum-behaved genetic algorithm. Examples show that this method achieves knowledge accumulation and reuse, provides design results inspection, and realizes the obtainment of reliable ship structure. 1. Introduction The ship design quality and efficiency affect ship development cycle. As ship design is a complicated process with many laborintensive activities, how to develop and modify the ship structure rapidly is a major problem for ship designers (Yang et al. 2012). Traditional ship structural design focuses on dealing with data. It is a kind of interactive graphics operation, and the results that designers work out describe only visual shape and size of ship structure, while related knowledge including design idea, expertise, parent ships information, and rules are not reflected. Obviously, it is not convenient for designers to modify and check the design model (Zhao & Kong 2005). To solve this problem, knowledge-based engineering (KBE) method is applied on ship design to integrate design methods, rules, and expertise experience into design process. Based on the related knowledge, system can automatically offer the high-qualified design model rapidly after designers input parameters and requirements. Currently, KBE is well developed in vehicle and machinery (Jin et al. 2006). However, because of the variety and complication of ship design, application of KBE on ship industry is still at the beginning. University of Rostock in Germany planned the knowledge-based system for ship modeling in research programs, which could obtain design criteria and provide tools from the knowledge base (Zimmermann & Bronsart 2007). Park identified that the expert system can significantly improve the efficiency and quality of the ship design, and integrated design knowledge into design system and achieved a highly flexible design environment (Park & Storch 2002). Lee applied KBE to the general arrangement of the engine room, making full use of engineering knowledge data (Lee & Yeun 2006). Wu proposed knowledge-based modeling for ship overall design to achieve information storage and retrieval (Wu & Shaw 2011). Chen applied KBE on ship deck design (Chen et al. 2010). Cui used KBE on midship section structural design (Cui et al. 2012). Cai developed a midship section design system based on AutoCAD, subdivided transverse section into several modules, and obtained the min-area midship section (Cai et al. 1997).

Shortsea liner network design with transhipments at sea: a case study from Western Norway

Short Sea Pioneer (SSP) is a novel concept for shortsea shipping. The concept is based on daughter ships acting as feeder vessels that meet with the mother ship at suitable locations at sea to tranship cargo. Such a system requires that the routes of both mother ship and daughter ships are synchronized. We provide a path flow formulation for the problem of determining the optimal set of routes for both ships. Non-dominated routes are generated a priori using a dynamic programming label-setting algorithm and used as input for the model. We use the model and solution approach to solve a real-world case from the Norwegian west coast. The results can be used to determine the optimal routes for mother and daughter ships as well as the optimal size of the daughter ships.

Optimal in-orbit repositioning of Sun-pointing Smart Dust

A Smart Dust is a femto-spacecraft with an external surface coated with electrochromic material, which exploits the solar radiation pressure to produce a propulsive acceleration. As the optical properties of the electrochromic material change upon application of a suitable electric voltage, its propulsive acceleration may be modulated, within some limits, without the use of any propellant. This paper analyzes the optimal trajectories of a Sun-pointing Smart Dust, which provides a propulsive acceleration aligned with the Sun-spacecraft direction. In particular, the paper describes the relative motion of a Smart Dust with respect to a conventional spacecraft (the Mother Ship) that covers a heliocentric circular orbit of given radius. The Smart Dust is required to vary periodically its angular position with respect to the Mother Ship using an optimal (minimum time) strategy. This problem is addressed using an indirect approach and the optimal control law is obtained in a closed-form solution. The results discussed in this paper ensure interesting improvements over existing models from the recent literature, including the possibility of obtaining a generic phasing angle of the Smart Dust and to take into account an optimal number of on-off switchings of the electrochromic control system.

A Study on Dredged Sea Sand as an Optimum Replacement for Fine Aggregate in Concrete

This paper deals with the study and feasibility on utilization of dredged sea sand by conducting various experiments on physical properties like sieve analysis, gap grading. Chemical properties like percentage of organic content, chloride content, sulfur content, presence of deleterious material and volatile solids in dredged sea sand have been determined. The experiments like rapid chloride penetration test, water absorption test, alkalinity test, accelerated corrosion test, sulphur resistance test, acid resistance test, and sorptivity. Durability and strength of concrete have been studied by considering various properties of fine aggregate. The mix design have been done for M30 grade of concrete and the percentage of replacements 25%, 50%, 75%, and 100% of M-Sand (Manufacture Sand) of concrete specimen for all the experiments is considered. As we all know our current scenario of increase in demand of fine aggregate leads to scarcity of river sand. This has increased in research on dredged sea sand as a fine aggregate in concrete to reduce the demand on fine aggregate in construction industries. Comparative study of M-sand, river sand and dredged sea sand has been done. The dredged sand which is used for the study and testing is dredged to increase the sea bed depth of Ennor port for the accessibility of mother ship, it was collected from the coastal areas of Ennore Port (Kamarajar Port) and subjected to rain, and atmospheric conditions for a year.

Модель взаимодействия носителя с погруженным автономным необитаемым подводным аппаратом по гидроакустическому каналу

Модель взаимодействия носителя с погруженным автономным необитаемым подводным аппаратом по гидроакустическому каналу

Abstract WP42: Factors Affecting Care Withdrawal After Acute Ischemic Stroke Treatment: A Comparison Between Standardized Treatment Modalities

Background: A higher percentage of acute ischemic stroke patients resort to care withdrawal after standardized treatments have been instituted. Objective: We aimed at identifying the factors responsible for care withdrawal among patients with acute ischemic stroke receiving various standardized treatment modalities in a clinical trial setting. Design and Methods: We analyzed data from Interventional Management of Stroke (IMS) III; a multicenter, double-blinded, randomized clinical trial. The patients who had resorted to care withdrawal during the course of trial were identified and divided into three groups based on the type of acute stroke treatment: IV-thrombolysis only, IA-thrombectomy only, and combined IA-thrombectomy with IA-thrombolysis. The three groups were compared for their baseline characteristics and major outcomes such as neurologic deterioration within 24-hours of randomization, hemorrhagic complications, and length of hospital stay. Bonferroni adjusted p-value of 0.016 was considered significant. Results: Out of 123 patients who had withdrawal of care in the IMS-III trial, 47 (38.2%) received IV-thrombolysis only, 25 (20.3) received IA-thrombectomy only, and 51 (41.5) received combined IA-thrombectomy and IA-thrombolysis. The three groups were similar for age, gender, baseline NIHSS score, stroke etiology, time from stroke onset to randomization, and status prior to stroke. Patients who received IV-thrombolysis only had significantly more mother ship transfers followed by IA-thrombectomy only and combined treatment groups (89.4 vs 68.0 vs 76.5; p=0.006). The combined treatment group had significantly greater rate of asymptomatic intracranial hemorrhage (ICH) followed by IA-thrombectomy only and IV-thrombolysis only treatment arms (41.2% vs 28% vs. 14.9%; p=0.015). Higher rates of patients undergoing IV-thrombolysis only treatment resorted to full palliative care as compared to the other two groups (p=0.07). The three groups did not differ in their rates of neurologic deterioration and length of hospital stay (p=0.84 and p=0.42 respectively). Conclusions: Asymptomatic ICH is a major determinant of care withdrawal after treatment of acute ischemic stroke with combined IA-thrombolysis and IA-thrombectomy.

Dual-eyes Vision-based Docking System for Autonomous Underwater Vehicle: an Approach and Experiments

A critical challenge for autonomous underwater vehicles (AUVs) is the docking operation for applications such as sleeping under the mother ship, recharging batteries, transferring data, and new mission downloading. The final stage of docking at a unidirectional docking station requires the AUV to approach while keeping the pose (position and orientation) of the vehicle within an allowable range. The appropriate pose therefore demands a sensor unit and a control system that have high accuracy and robustness against disturbances existing in a real-world underwater environment. This paper presents a vision-based AUV docking system consisting of a 3D model-based matching method and Real-time Multi-step Genetic Algorithm (GA) for real-time estimation of the robot’s relative pose. Experiments using a remotely operated vehicle (ROV) with dual-eye cameras and a separate 3D marker were conducted in a small indoor pool. The experimental results confirmed that the proposed system is able to provide high homing accuracy and robustness against disturbances that influence not only the captured camera images but also the movement of the vehicle. A successful docking operation using stereo vision that is new and novel to the underwater vehicle environment was achieved and thus proved the effectiveness of the proposed system for AUV.

Fuzzy sliding mode control of an offshore container crane

A fuzzy sliding mode control strategy for offshore container cranes is investigated in this study. The offshore operations of loading and unloading containers are performed between a mega container ship, called the mother ship, and a smaller ship, called the mobile harbor (MH), which is equipped with a container crane. The MH is used to transfer the containers, in the open sea, and deliver them to a conventional stevedoring port, thereby minimizing the port congestion and also eliminating the need of expanding outwards. The control objective during the loading and unloading process is to keep the payload in a desired tolerance in harsh conditions of the MH motion. The proposed control strategy combines a fuzzy sliding mode control law and a prediction algorithm based on Kalman filtering for the MH roll angle. Here, the sliding surface is designed to incorporate the desired trolley trajectory while suppressing the sway motion of the payload. To improve the control performance, the discontinuous gain of the sliding control is adjusted with fuzzy logic tuning schemes with respect to the sliding function and its rate of change. Chattering is further reduced by a saturation function. Simulation and experimental results are provided to verify the effectiveness of the proposed control system for offshore container cranes.

海底ステーション間を移動するAUVのナビゲーション手法

AUVs(Autonomous Underwater Vehicle) have a problem that they need mother ship to be deployed, be recovered and recharge batteries. In these days, seafloor sensor network which consist of seafloor stations connected by cables to research seafloor environment is suggested around the world. If AUVs use this seafloor sensor network for localization and recharging batteries, activity area will be extended. This paper proposes a navigation method for AUVs to move between seafloor stations. The proposed method consists of local navigation and internode navigation. Local navigation is used near the seafloor station and internode navigation is used to move between seafloor stations. This paper describes details of the method. Additionally, we present simulation results to evaluate the performance of the method.

A basic study of acoustic communications between an autonomous surface vehicle and an autonomous underwater vehicle

Recently, there has been an increasing interest in submarine resources and demand to survey them. For that purpose, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) has developed autonomous underwater vehicles (AUVs). Currently, only one AUV is operated by a research vessel because a mother ship must always follow an AUV. However, to make survey more efficient, the project of multiple AUVs operation, paired with autonomous surface vehicles (ASVs), is being progressed. In this plan, one ASV always monitor status and position of its paired AUV with acoustic communication and localization, and follow it autonomously. The size of an ASV is desired to be as small as possible in terms of operation. Thus, it causes two difficulties. First, such a small ASV rolls and pitches up to a large angle easily. Second, receivers are close to the noise sources, such as thrusters or sea surface. As a basic study, at-sea experiments were demonstrated with various types of modulation using a prototype of an ASV. The results show that OFDM signals are more sensitive to rolling and pitching movement than single carrier modulation (SCM) and that it is possible to achieve demodulation with SCM in spite of noise as mentioned above.

VOB를 이용한 선형 설계 실용화에 대한 연구

In general, ship hull form design is carried out in two stages. In the first stage, the longitudinal variation of the sectional area curves is adapted from a similar mother ship to determine the volume distribution in ships. At this design stage, the initial design conditions of displacement, longitudinal center of buoyancy, etc. are satisfied and the global hydrodynamic properties of the structure are optimized. The second stage includes the local designing of the sectional forms. Sectional forms are related to the local pressure resistance in the fore- and aft-body shapes, cargo boundaries, interaction between the hull and propeller, etc. These relationships indicate that the hull sections need to be optimized in order to minimize the local resistance. The volumetric balanced (VOB) variation of ship hull forms has been suggested by Kim (2013) as a generalized, systematic variation method for determining the sectional area curves in hull form design. This method is characterized by form parameters and is based on an optimization technique. This paper emphasizes on an extensional function of the VOB considering a geometrical wave profile. We select a container ship and an LNG carrier to demonstrate the applicability of the proposed technique. Through analysis, we confirm that the VOB method, considering the geometrical wave profile, can be used as an efficient tool in the hull form design for ships.

통합공통구조규칙 기반 중형 살물선의 중량 절감에 관한 연구

H-CSR(Harmonized Common Structural Rules) integrating CSR-BC(Common Structural Rules for Bulk Carriers) and CSR-OT(Common Structural Rules for Double Hull Oil Tankers) came into effect in July of 2015, so that bulk carrier and double hull oil tanker should comply with this rules. So far, several studies for trend analysis of requirements of structure scantling based on H-CSR have been carried out briskly. However, those studies are rare to apply H-CSR in actual structural design of ships, especially bulk carriers. In this study, an automated system for compartment arrangement is used to search the design case that minimizes still water bending moment(S.W.B.M) in 38k bulk carrier designed by Far East Ship Design & Engineering Co. Ltd. Also, various structural design cases are considered by changing arrangement of structural members to reduce ship weight. The SeaTrust-Hullscan software developed by Korean Register is used to perform structural design of ships based on mother ship and proper design cases are selected by user. The DSA(Direct Strength Analysis) is performed to evaluate structural safety for the yielding and buckling analysis by using MSC Nastran software. The effect of weight reduction is verified by comparison of ship weight between mother ship and the selected design cases.

Dynamic load applied to shear pin and motion prediction of flexible hose

A flexible hose that is unwound along with fiber-optic cables from a mother ship helps prevent interference with the mother ship during the unwinding of the fiber-optic cable. Because the density of fiber-optic cables is close to the fluid density, if there is no flexible hose, the fiber-optic cable is more likely to interfere with the mother ship because of the motion of underwater vehicles or mother ships. Hence, it is necessary to prevent the interference of fiber-optic cables by using flexible hoses made of stainless steel. Flexible hoses unwound as an underwater vehicle moves are coupled to the vehicle by shear pins, and once all flexible hoses are unwound, the underwater vehicle continues to move forward as the pins fracture. Here, a dynamic load applied on the shear pin for connection in the early stages of the unwinding of the flexible hose is an important factor that controls the position, which should be accurately predicted, prior to the motion of the underwater vehicle. Further, it is essential that the shear pin of the connection part be designed to fracture under the selected load so that underwater vehicle can continue to move forward as the pin breaks. In this study, analysis results based on loading information measured in real experiments were compared and verified, and based on the findings, an analytical model that can predict loads applied on the shear pin was developed.

수중모함에서 사출되는 고속 수중운동체의 초기 거동 모델링 및 시뮬레이션

ABSTRACT Heavy-weight high speed underwater vehicle(HSUV) is launched from the submerged mother ship. For the safety point of view, it is important to confirm whether the HSUV would touch the launching mother ship. In this paper, the hydrodynamic force and moment were modeled by the polynomials of motion variables and the simple lift and drag acting on a plate and cylinder which consist of the HSUV’s several parts. The mother ship was assumed as the Rankine half body to consider the flow field near the moving ship. Such hydrodynamic force and moment were included in the 6 DOF equations of motion of the HSUV and the dynamic simulations for the various conditions of the HSUV until the propeller activation were performed. Developed simulation program is expected to reduce the number of expensive sea trial test to develop safety logic of the HSUV at the initial firing stage.Key Words : High Speed Underwater Vehicle(고속 수중운동체), Modeling and Simulation(모델링 및 시뮬레이션), Initial Firing Stage(초기 발사단계), Dynamics(동력학)

Abstract 5: Analysis of Workflow Aad Determinants of Delays in the Escape Randomized Controlled Trial

Introduction: The ESCAPE trial used innovative imaging and aggressive target time metrics to demonstrate the benefit of additional endovascular treatment over standard care in patients with disabling acute ischemic stroke. We performed a detailed analysis of workflow and determine modifiable factors resulting in delays. Methods: The trial enrolled 316 patients fulfilling eligibility criteria and presenting within 12 hours of stroke symptom onset from 22 sites across 3 continents between February 2013 and October 2014. We considered four specific interval times: onset-to-ED arrival, ED-arrival-to-qualifying CT scan, qualifying CT scan-to-groin puncture, groin puncture-to-reperfusion. Missing times were not imputed. When reperfusion was not achieved, the reperfusion time was considered missing and was not imputed. Interval times from stroke symptom onset to first reperfusion are reported using medians and inter-quartile range. To assess the relationship between patient, hospital and health system characteristics as predictors of longer interval times, a negative binomial regression provided the best fit to the data. Results: Stroke symptom onset to arrival in emergency room of endovascular capable hospital time was 42% (34 mins) longer among patients who received intravenous alteplase at the referring hospital (drip and ship) vs. patients directly transferred to the endovascular capable hospital (direct to mother ship) (Figure). Qualifying CT to groin puncture time was 15% (8 mins) shorter among patients presenting during work hours vs. off hours. Time from qualifying CT to groin puncture was 41% (24 min) shorter in drip and ship patients than vs. when intravenous alteplase was administered after qualifying CT (mothership). General anesthesia prolonged this time by 43% (22 min). Balloon guide catheter during endovascular procedure shortened time from groin puncture to reperfusion by 21% (8 mins). Conclusions: Inefficiencies in triaging systems, presentation during off hours, intravenous alteplase administration, GA utilization and endovascular techniques offer major opportunities for improvement.

深海曳航体システムに関する研究

The importance of deep ocean surveying and monitoring is increasing because of the change of situation of energy, oceanicresources and CCS (Carbon Capture and Storage) under the seabed. In recent years, AUVs (Autonomous Underwater Vehicles) have been operated for deep ocean scientific research. However, their long cruising is limited because of their battery performance. Although deep tow systems will solve this problem, the towing speed of current systems is not fast, and sizable motions are induced by the mother ship. We therefore propose a deep tow system which consists of a launcher and a towed vehicle to achieve high speed towing and good depth and motion control of the vehicle. Model experiments were carried out in a towing tank and simulated results were compared with the experimental ones. Interesting results of depth and motion control are shown in this paper.

An Acoustic OFDM System with Symbol-by-Symbol Doppler Compensation for Underwater Communication.

We propose an acoustic OFDM system for underwater communication, specifically for vertical link communications such as between a robot in the sea bottom and a mother ship in the surface. The main contributions are (1) estimation of time varying Doppler shift using continual pilots in conjunction with monitoring the drift of Power Delay Profile and (2) symbol-by-symbol Doppler compensation in frequency domain by an ICI matrix representing nonuniform Doppler. In addition, we compare our proposal against a resampling method. Simulation and experimental results confirm that our system outperforms the resampling method when the velocity changes roughly over OFDM symbols. Overall, experimental results taken in Shizuoka, Japan, show our system using 16QAM, and 64QAM achieved a data throughput of 7.5 Kbit/sec with a transmitter moving at maximum 2 m/s, in a complicated trajectory, over 30 m vertically.