Mathematical model and simulation of cooperative manoeuvres among a ship and tugboats

Assisting harbour tugboats are essential for safe navigation in ports and for berthing/unberthing operations. Because the port infrastructure needs to be updated in the coming age of autonomous ships, autonomous tugboats or remotely controlled tugboats are expected to be part of the navigation assistance provided by future ports. Although there have been some studies on the design of cooperative control of tugboats, few studies have focused on the mathematical model of their cooperative manoeuvres. Particularly, in the case of pushing assistance, tugboats have often been treated simply as a kind of side thrusters attached to the assisted ship. Thus, we present a new framework of the mathematical model for cooperative manoeuvres that considers the coupled motions among tugboats and a ship as precisely as possible. Solving the dynamics of all tugboats as well as the assisted ship can render the model more advanced and realistic, and is the most significant contribution of this study. The simulation tool based on the proposed model can be used as a plant model in designing and verifying the tugboat’s manoeuvring control system in the future. In this study, as examples, considering a tentative control method, some unique scenarios were simulated to demonstrate the cooperative manoeuvres

Random dopant model for three-dimensional drift-diffusion simulations in metal–oxide–semiconductor field-effect-transistors

We investigate the dopant model employed in drift-diffusion device simulations for the study of statistical threshold voltage variations associated with discrete random dopants. It is pointed out that the conventional dopant model, when extended to the extreme "atomistic" regime, becomes physically inconsistent with the length-scale presumed in drift-diffusion simulations. Splitting the Coulomb potential of localized dopants between the long-range and short-range parts, we propose a dopant model appropriate for three-dimensional drift-diffusion simulations

Age-dependent vulnerability to ischemia-reperfusion injury of cyanotic myocardium in a chronic hypoxic rat model

This study evaluated the effects of chronic hypoxia from birth on the resistance of rat hearts to global ischemia, with special emphasis on the duration of hypoxia. Male Wistar rats were housed from birth for 4 weeks or 8 weeks either in a hypoxic environment (FiO20.12) or in ambient air (8 animals for each group). Isolated rat hearts were perfused for 40 min with oxygenated Krebs-Henseleit buffer, subjected to 20 min global no-flow ischemia at 37, and then underwent 40 min of reperfusion. A non-elastic balloon was inserted into the left ventricle and inflated until the pre-ischemic LVEDP rose to 8mmHg. Cardiac function was measured before and after ischemia. The post-ischemic percent recovery of LVDP in hypoxic hearts was worse than in normoxic hearts (4 weeks:55+/-7 vs. 96+/-3%, p0.01;8 weeks:40+/-5 vs. 92+/-4%, p0.01), and was worst in the 8-week-hypoxic hearts. Similarly, the percent recovery of dP/dt in the hypoxic hearts was lower than in the normoxic hearts (4 weeks:51+/-5 vs. 96+/-7%, p0.01;8 weeks:31+/-6 vs. 92+/-7%, p0.01), and was lowest in the 8-week-hypoxic hearts. In conclusion, cyanotic myocardium revealed an age-dependent vulnerability to ischemia-reperfusion injury in a chronic hypoxic rat model.</p

Comprehensive Analysis of Bacterial Flora in Postoperative Maxillary Cyst Fluid by 16S rRNA Gene and Culture Methods

Intracystic fluid was aseptically collected from 11 patients with postoperative maxillary cyst (POMC), and DNA was extracted from the POMC fluid. Bacterial species were identified by sequencing after cloning of approximately 580 bp of the 16S rRNA gene. Identification of pathogenic bacteria was also performed by culture methods. The phylogenetic identity was determined by sequencing 517–596 bp in each of the 1139 16S rRNA gene clones. A total of 1114 clones were classified while the remaining 25 clones were unclassified. A total of 103 bacterial species belonging to 42 genera were identified in POMC fluid samples by 16S rRNA gene analysis. Species of Prevotella (91%), Neisseria (73%), Fusobacterium (73%), Porphyromonas (73%), and Propionibacterium (73%) were found to be highly prevalent in all patients. Streptococcus mitis (64%), Fusobacterium nucleatum (55%), Propionibacterium acnes (55%), Staphylococcus capitis (55%), and Streptococcus salivarius (55%) were detected in more than 6 of the 11 patients. The results obtained by the culture method were different from those obtained by 16S rRNA gene analysis, but both approaches may be necessary for the identification of pathogens, especially of bacteria that are difficult to detect by culture methods, and the development of rational treatments for patients with POMC

VERTICAL STIFFNESS DURING MAXIMAL SPRINTING IN A TRANSFEMORAL AMPUTEE: A CASE STUDY

Running-specific prostheses emulate the spring-like behaviour of biological limbs during human running, but little is known about the spring-like leg functions in transfemoral amputees. Understanding of running mechanics is expected to benefit the design of prostheses and to prevent injuries. The purpose of this study was to clarify the spring-like behaviour of sprinters with transfemoral amputations using running specific prosthesis. The vertical stiffness was calculated using a spring-mass model. The vertical stiffness in prosthetic limbs tends to be greater than in intact limbs for transfemoral amputees

Copyright (c)JCPDS-International Centre for Diffraction Data

ABSTRACT This paper describes the effect of renitriding for hot work die steel. We noticed a decrease of compressive residual stress on the nitrided die surface during thermal fatigue process. X-ray stress measurement was used to detect the decomposition of nitride layer on hot work die steel (H13). As a result, compressive residual stress decreased gradually during the thermal fatigue test, almost restoring to the pre-test level by renitriding. The number of cracks decreased with the frequency of test by surface removal effect of shot peening while renitriding. Comparing the renitrided specimen with non renitrided specimen (single nitride), the number of cracks had decreased. 1.INTRODUCTION On the surface of hot work die, such as die-casting die, heat cycles are applied during the operation. Then, the cracks occurred due to thermal stresses caused by thermal cycles. To extend die-casting die life, nitriding is often applied to the die surface 1) . Even with nitriding, the nitride layer is damaged by heat during the die-casting operation. Thus, if renitriding will be available with the detecting damaged layer quantitatively, extension of die life can be expected. On the other hand, high compressive residual stress about -900MPa is caused on the surface of hot work die steel (AISI-H13) by nitriding. And the reheating decreases the residual stress 2) . We noticed the compressive residual stress, and tried to detect decomposition of nitride layer in thermal fatigue process by X-ray stress measurement. And repair effect of nitride layer by renitriding with shot peening was investigated. During the thermal fatigue test, renitriding was applied several times and changes of residual stress and half-value breadth were measured. After the test, distribution of residual stress, maximum crack length and number of cracks were measured

Usefulness of helical computed tomography in diagnosing pulmonary vein stenosis in infants.

We investigated the usefulness of helical computed tomography(CT)in the morphological diagnosis of pulmonary vein stenosis, particularly that in infants and small children. In total, 20 helical CT examinations were performed in 10 post-operative cases of Total Anomalous Pulmonary Venous Drainage(TAPVD), 3 cases of single right ventricle, and 1 case of single left ventricle. In all cases, distinct morphological imaging was possible. Pulmonary vein stenosis could be categorized into three types: (1)stenosis from the anastomosis of the common pulmonary vein (CPV)-the left atrium (LA) to the peripheral pulmonary vein; (2) stenosis only at the anastomosis of CPV-LA; and (3) stenosis due to compression by nearby organs. Coronal views by multiplanar reconstruction (MPR) provided morphological information along the up-down direction of the body axis. Morphological diagnosis of pulmonary vein stenosis is important in deciding prognosis and therapeutic regimens, and helical CT was considered useful for such diagnosis in our 14 young patients.</p

Genetic analysis of TP53 in childhood myelodysplastic syndrome and juvenile myelomonocytic leukemia

信州大学博士（医学）・学位論文・平成23年3月31日授与（甲第886号)・齋藤章治ArticleLEUKEMIA RESEARCH. 35(12):1578-1584 (2011)journal articl

Optimization of salt concentration in PEG-based crystallization solutions

Optimal salt concentration in a PEG-based crystallization solution is important for successful crystal growth and can be predicted prior to performing crystallization experiments