Composite action in connection regions of concrete-filled steel tube columns

Mathias Johansson 국제구조공학회 2003 Steel and Composite Structures, An International J Vol.3 No.1

In a nonlinear finite element study on the mechanical behavior of simple beam connections to continuous concrete-filled steel tube columns, two principally different connection types were analyzed: one with plates attached to the outside of the tube wall, relying on shear transfer, and one with an extended plate inserted through the steel section to ensure bearing on the concrete core. The load was applied partly at the connection within the column length and partly at the top, representing the load from upper stories of a multistory building. The primary focus was on the increased demand for load transfer to ensure composite action when concrete with higher compressive strength is used. The results obtained from the analyses showed that the design bond strength derived from push tests is very conservative, mainly due to the high frictional shear resistance offered by pinching and contraction effects caused by connection rotation. However, with higher concrete strength the demand for load transfer increases, and is hard to fulfill for higher loads when connections are attached only to the steel section. Instead, the connection should penetrate into the concrete core to distribute load to the concrete by direct bearing.

The efficiency of passive confinement in CFT columns

Mathias Johansson 국제구조공학회 2002 Steel and Composite Structures, An International J Vol.2 No.5

The paper describes the mechanical behavior of short concrete-filled steel tube (CFT) columns with circular section. The efficiency of the steel tube in confining the concrete core depending on concrete strength and the steel tube thickness was examined. Fifteen columns were tested to failure under concentric axial loading. Furthermore, a mechanical model based on the interaction between the concrete core and the steel tube was developed. The model employs a volumetric strain history for the concrete, characterized by the level of applied confining stress. The situation of passive confinement is accounted for by an incremental procedure, which continuously updates the confining stress. The post-yield behavior of the columns is greatly influenced by the confinement level and is related to the efficiency of the steel tube in confining the concrete core. It is possible to classify the post-yield behavior into three categories: strain softening, perfectly plastic and strain hardening behavior. The softening behavior, which is due to a shear plane failure in the concrete core, was found for some of the CFT columns with high-strength concrete. Nevertheless, with a CFT column, it is possible to use high-strength concrete to obtain higher load resistance and still achieve a good ductile behavior.

Progressive Multifocal Leukoencephalopathy after Ibrutinib Therapy for Chronic Lymphocytic Leukemia

Mathias Lutz,Arik B. Schulze,Elisabeth Rebber,Stefanie Wiebe,Tarek Zoubi,Oliver M. Grauer,Torsten Keßler,Andrea Kerkhoff,Georg Lenz,Wolfgang E. Berdel 대한암학회 2017 Cancer Research and Treatment Vol.49 No.2

Progressive multifocal leukoencephalopathy (PML) is a devastating neurological disease observed nearly exclusively in immunocompromised patients. Recently, the introduction of monoclonal antibodies significantly inhibiting the immune system such as rituximab has led to an increase in PML cases. Although rituximab-based immunochemotherapy remains the standard of treatment for chronic lymphocytic leukemia (CLL), the importance of Bruton’s tyrosine kinase inhibitors such as ibrutinib is steadily increasing. However, long-term experiences regarding possible side effects of these new substances are rare. Here, we report the development of eventually fatal PML possibly associated with ibrutinib therapy for CLL after multiple prior treatment lines, including rituximab. To the best of our knowledge, this is the first study to report such findings. Since the last course of rituximab was applied over 3 years ago, it is conceivable that the strong B cell inhibition by ibrutinib led to PML. With increased awareness of this potential side effect, further clinical studies are certainly warranted to evaluate this possible association.

Iterative approach for anchor configuration of positioning systems

Mathias Pelka,Grigori Goronzy,Horst Hellbr¨uck 한국통신학회 2016 ICT Express Vol.2 No.1

With anchor positions and measurements of distances between an object and anchors, positioning algorithms calculate the position of an object, e.g. via lateration. Positioning systems require calibration and configuration prior to operation. In the past, approaches employed reference nodes with GPS or other reference location systems to determine anchor positions. In this article, we propose an approach to determine anchor positions without prior knowledge. We evaluate our approach with simulations and real data based on the Decawave DW1000 radio and show that the error is proportional to the mean error of the distance estimation.

논문 : 미국과 독일의 법학 교육: 한국을 위한 교훈?

( Mathias Reimann ) 서울대학교 법학연구소 2001 서울대학교 法學 Vol.41 No.1

System identification of circadian clock in plant Arabidopsis thaliana

Mathias Foo,Hee Young Yoo,Pan-Jun Kim 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

The use of mathematical models in describing the dynamics of circadian clock in the plant Arabidopsis thaliana is gaining popularity. Models used to describe the plant circadian clock are usually derived from laws of physics and they comprise complex nonlinear ordinary differential equations. In this paper, we build mathematical models of the core loop of plant circadian clock using system identification techniques. This core loop involves two main genes (proteins), i.e. LHY/CCA1 and TOC1. Models obtained using system identification techniques are usually simple, sufficient to describe the relevant dynamics of the system and often are able to provide physical interpretation about the system. The obtained models through system identification can be useful for control design and prediction in the event for which we want to do phenotype manipulation and for understanding the behaviour of the system respectively.

Disease progression and recurrence in women treated for vulvovaginal intraepithelial neoplasia

Mathias K. Fehr,Marc Baumann,Michael Mueller,Daniel Fink,Siegfried Heinzl,Patrick Imesch,Konstantin Dedes 대한부인종양학회 2013 Journal of Gynecologic Oncology Vol.24 No.3

Objective: The malignant potential of intraepithelial neoplasia of the vulva and vagina after treatment is not well defined. Our objective was to examine risk factors for recurrence and invasive disease. Methods: Four hundred sixty-four women with biopsy proven high-grade intraepithelial neoplasia of the vulva and vagina were identified in the electronic databases of four colposcopy clinics. Inclusion criteria were a follow-up of more than one year, no history of invasive cancer and no invasive cancer within the first year after initial treatment. We investigated the potential factors associated with recurrence and progression using a logistic regression analysis to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Results: Of the 411 eligible patients, 123 patients (29.9%) recurred later than one year after initial treatment and 24 patients (5.8%) progressed to invasive disease. According to multivariate analyses, the risk factors associated with recurrence were multifocality (OR, 3.33; 95% CI, 2.02 to 5.51), immunosuppression (OR, 2.51; 95% CI, 1.09 to 5.81), excision as initial treatment (vs. laser evaporation; OR, 1.79; 95% CI, 1.11 to 2.91) and smoking (OR, 1.61; 95% CI, 1.02 to 2.55). Risk factors for progression to invasive disease were immunosuppression (OR, 4.00; 95% CI, 1.30 to 12.25), multifocality (OR, 3.05; 95% CI, 1.25 to 7.43) and smoking (OR, 2.97; 95% CI, 1.16 to 7.60), but not treatment modality. Conclusion: Laser evaporation combined with extensive biopsy is at least as efficacious as initial treatment of intraepithelial neoplasia with excision. Smoking is a risk factor for both recurrence and progression to invasive disease. Hence, smoking cessation should be advised and maintaining a long follow-up period due to late relapses is necessary.

System Identification of the Arabidopsis Plant Circadian System

Mathias Foo,David E. Somers,김판준 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.4

The circadian system generates an endogenous oscillatory rhythm that governs the daily activitiesof organisms in nature. It offers adaptive advantages to organisms through a coordination of theirbiological functions with the optimal time of day. In this paper, a model of the circadian systemin the plant Arabidopsis (species thaliana) is built by using system identification techniques. Priorknowledge about the physical interactions of the genes and the proteins in the plant circadian systemis incorporated in the model building exercise. The model is built by using primarily experimentallyverifieddirect interactions between the genes and the proteins with the available data on mRNAand protein abundances from the circadian system. Our analysis reveals a great performance of themodel in predicting the dynamics of the plant circadian system through the effect of diverse internaland external perturbations (gene knockouts and day-length changes). Furthermore, we found thatthe circadian oscillatory rhythm is robust and does not vary much with the biochemical parametersexcept those of a light-sensitive protein P and a transcription factor TOC1. In other words, thecircadian rhythmic profile is largely a consequence of the network’s architecture rather than itsparticular parameters. Our work suggests that the current experimental knowledge of the geneto-protein interactions in the plant Arabidopsis, without considering any additional hypotheticalinteractions, seems to suffice for system-level modeling of the circadian system of this plant and topresent an exemplary platform for the control of network dynamics in complex living organisms.

Improving the Precision of Specifications by Evaluating the Influence of Test Parameters on Tribological Results

Mathias Woydt,Hartwig Weber 한국트라이볼로지학회 2003 한국트라이볼로지학회 학술대회 Vol.37 No.-

A series of cooperative interlaboratory tests (round robins) was conducted in 1997, 1998, 1999, 2000, 2001, 2002 and 2003 by the DIN 51834 Working Group on Tribological Tests in Translatory Oscillation Apparatus. The statistical analysis of these test results shows the influence of cleaning solvent, machine model and evaluation criteria on the tribological properties of the lubricants tested. Coefficients of friction and wear results are ranked according to the effects of ten different cleaning solvents, where isopropanol gave the lowest values and isoparaffin solvents the highest. The effect of machine model on coefficients of friction varied from about 0.2 % to 0.9 % of the mean. Wear results were not affected. The tests also showed that the seizure criteria and methods of measuring wear required for in the test procedure do not provide a suitable measure of the tribological properties of some lubricants. The precision was improved by introducing a grease apply caliper as well as an increased stroke to 1,5 mm and running-in. The temperature does not affect the precision of the oil test procedure.

SRV®-Testing of the Tribosystem Piston Ring and Cylinder Liner Outside the Engine

Mathias Woydt,Johannes Ebrecht 한국트라이볼로지학회 2005 한국트라이볼로지학회 학술대회 Vol.2005 No.11

An OEM driven working group started in January 2004 to elaborate the philosophies, concepts and test procedures for testing piston ring and cylinder liner materials as well as engine oils outside the engine using the SRV® test equipment. The different SRV® test philosophies in use by OEMs are compiled. The working group focuses on a.) ASTM sequence VIB (Fuel economy by aging oils), b.) friction and wear in the top dead region under mixed/boundary lubrication, c.) extreme pressure load under under mixed/boundary lubrication and d.) hydrodynamic friction. Tribological test results and precision data are presented.