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A Q-learning System for Group-Based Container Marshalling with A-Priori Knowledge for Ship Loading
Yoichi Hirashima 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper addresses scheduling problems on the material handling operation at marine container-yard terminals. The layout, removal order and removal destination of containers are simultaneously optimized in order to reduce the waiting time for a vessel. The schedule of container-movements is derived by autonomous learning method based on a new learning model considering container-groups and corresponding Q-Learning algorithm. In the proposed method, the layout and movements of containers are described based on the Markov Decision Process (MDP), and a state is represented by a container-layout with a selection of a container to be removed or a selection of destination on where the removed container are placed. Then, a state transition arises from a container-movement, a selection of container-destination, or a selection of container to be removed. Only the container-movement takes a cost, and a series of container-movements with selections of destination and order of containers is evaluated by a total amount of costs. As a consequent, the total amount of costs reflects the number of container-movements that is required to achieve desired container-layout.
Ken-ichi Hirashima,Keiji Sato,Takashi Tsutsumi,Hiroshi Arai 국제구조공학회 2002 Steel and Composite Structures, An International J Vol.2 No.4
In this paper, the solution of a semi-infinite plane with one circular hole is presented. This solution is induced by repeatedly superposing the solution of an infinite plane with one circular hole and that of a semi-infinite plane without holes to cancel out the stresses arising on both boundaries. This procedure is carried out until the stresses arising on both boundaries converge. This method does not require complicated calculation procedures as does the method using stress functions defined in a bipolar coordinate system. Some numerical results are shown by graphical representations.
FAST SIMULATED ANNEALING PLACEMENT COMBINED WITH INITIAL PLACEMENT METHOD
Mitsuyasu, Masahiro,Hirashima, Victor,Ueda, Kazuhiro 대한전자공학회 1989 ICVC : International Conference on VLSI and CAD Vol.1 No.1
In this paper, a fast simulated annealing method combined with an initial placement is presented. The simulated annealing method starts with initial placement obtained by the AR placement method. The AR (Attractive and Repulsive force) method is a kind of gravitational placement method based on repulsive forces as well as attractive forces. Three methods have been compared : 1)AR-started SA, 2)Random-started SA, 3)AR-started PI(Pairwise Interchange). The AR-started SA method can obtain better solution than the other, and 2-3 times faster than the Random-started SA method.
Impact of COVID-19 Infection on Work Functioning in Japanese Workers: A Prospective Cohort Study
Okawara Makoto,Hirashima Keiki,Igarashi Yu,Mafune Kosuke,Muramatsu Keiji,Nagata Tomohisa,Tsuji Mayumi,Ogami Akira,Fujino Yoshihisa,for the CORoNaWork Project 한국산업안전보건공단 산업안전보건연구원 2023 Safety and health at work Vol.14 No.4
Background: The impact of COVID-19 infection on workers’ work function persists even after the acute phase of the infection. We studied this phenomenon in Japanese workers. Methods: We conducted a one-year prospective cohort study online, starting with a baseline survey in December 2020. We tracked workers without baseline work functioning impairment and incorporated data from 14,421 eligible individuals into the analysis. We estimated the incidence rate ratio for new onset of work functioning impairment due to COVID-19 infection during follow-up, using mixed-effects Poisson regression analysis with robust variance. Results: Participants reporting infection between January and December 2021 showed a significantly higher incidence of new work functioning impairment (adjusted incidence rate ratio: 2.18, 95% confidence interval: 1.75e2.71, p < 0.001). The formality of the recuperation environment correlated with a higher risk of work functioning deterioration in infected individuals (p for trend <0.001). Conclusion: COVID-19-infected workers may continue to experience work difficulties due to persistent, post-acute infection symptoms. Companies and society must urgently provide rehabilitation and social support for people with persistent symptoms, recognizing that COVID-19 is not just a transient acute infection.
A Constitutive Model for Sintering of Granulated Ceramic Powders
Shinagawa, K .,Hirashima, Y . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.3
Sintering behavior of granulated powder is investigated to develop a constitutive model for deformation analysis of ceramic powder compacts during sintering. Spray-dried alumina is compacted by CIPing (cold isostatic pressing) and sintered at various temperatures. Shrinkage and the change in grain size of the compacts during sintering are revealed in relation to the inhomogeneous microstructure consisting of fractured and unfractured granules as a consequence of the compaction. A constitutive model for the ceramic powder compacts having the internal structure is presented. The difference in grain growth in dense and sparse regions of the compacts is taken into consideration to the model. The results calculated by the model show good agreement with that obtained by experiment.
Analysis of orthotropic circular disks and rings under diametrical loadings
Tsutsumi, Takashi,Hirashima, Ken-Ichi Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.9 No.1
Very few studies on orthotropic circular disks or rings under diametrical loadings are conducted because of difficulties in treatment. This paper shows analytical solutions and gives the distributions of stresses and displacements by using Lekhnitskii's complex variable method. Several numerical results are shown by graphical representation.
Correlation Effect in bcc Iron at Finite Temperatures
Muneyuki Nishishita,Dai Hirashima,Sudhakar Pan 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
Self-consistent second-order perturbation theory is applied to a multi-band Hubbard model tostudy the static and the dynamical properties of iron at finite temperatures. Reasonable valuesof the Curie temperature and the Curie constant are obtained for a realistic band structure andrealistic values of the local Coulomb interaction. The dynamical transverse susceptibility in theferromagnetic phase is calculated, and a spin wave mode vanishing in the long-wavelength limit iscorrectly obtained. The spin stiffness constant is found to be enhanced compared with that obtainedusing the random phase approximation.
Shiho Kuji,Yasuyuki Hirashima,Satomi Komeda,Aki Tanaka,Masakazu Abe,Nobutaka Takahashi,Munetaka Takekuma 대한부인종양학회 2014 Journal of Gynecologic Oncology Vol.25 No.2
Objective: The purpose of this study was to assess whether peritoneal cytology has prognostic significance in uterine cervical cancer. Methods: Peritoneal cytology was obtained in 228 patients with carcinoma of the uterine cervix (International Federation of Gynecology and Obstetrics [FIGO] stages IB1-IIB) between October 2002 and August 2010. All patients were negative for intraperitoneal disease at the time of their radical hysterectomy. The pathological features and clinical prognosis of cases of positive peritoneal cytology were examined retrospectively. Results: Peritoneal cytology was positive in 9 patients (3.9%). Of these patients, 3/139 (2.2%) had squamous cell carcinoma and 6/89 (6.7%) had adenocarcinoma or adenosquamous carcinoma. One of the 3 patients with squamous cell carcinoma who had positive cytology had a recurrence at the vaginal stump 21 months after radical hysterectomy. All of the 6 patients with adenocarcinoma or adenosquamous carcinoma had disease recurrence during the follow-up period: 3 with peritoneal dissemination and 2 with lymph node metastases. There were significant differences in recurrence-free survival and overall survival between the peritoneal cytology-negative and cytology-positive groups (log-rank p<0.001). Multivariate analysis of prognosis in cervical cancer revealed that peritoneal cytology (p=0.029) and histological type (p=0.004) were independent prognostic factors. Conclusion: Positive peritoneal cytology may be associated with a poor prognosis in adenocarcinoma or adenosquamous carcinoma of the uterine cervix. Therefore, the results of peritoneal cytology must be considered in postoperative treatment planning.
Presenteeism and Traffic Accident Among Taxi Drivers: A Prospective Cohort Study in Japan
Okawara Makoto,Tokutsu Kei,Hirashima Keiki,Ishimaru Tomohiro,Fujino Yoshihisa 한국산업안전보건공단 산업안전보건연구원 2024 Safety and health at work Vol.15 No.2
Department of Environmental Epidemiology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan