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Prequalification of a set of buckling restrained braces: Part II – numerical simulations
Ciprian Ionut Zub,Aurel Stratan,Dan Dubina 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.4
Buckling restrained braces (BRBs) were developed as an enhanced alternative to conventional braces by restraining their global buckling, thus allowing development of a stable quasi-symmetric hysteretic response. A wider adoption of buckling restrained braced frames is precluded due to proprietary character of most BRBs and the code requirement for experimental qualification. To overcome these problems, BRBs with capacities corresponding to typical steel multi-storey buildings in Romania were developed and experimentally tested in view of prequalification. In the second part of this paper, a complex nonlinear numerical model for the tested BRBs was developed in the finite element environment Abaqus. The calibration of the numerical model was performed at both component (material models: steel, concrete, unbonding material) and member levels (loading, geometrical imperfections). Geometrically and materially nonlinear analyses including imperfections were performed on buckling restrained braces models under cyclic loading. The calibrated models were further used to perform a parametric study aiming at assessing the influence of the strength of the buckling restraining mechanism, concrete class of the infill material, mechanical properties of steel used for the core, self-weight loading, and frame effect on the cyclic response of buckling restrained braces.
Prequalification of a set of buckling restrained braces: Part I - experimental tests
Aurel Stratan,Ciprian Ionut Zub,Dan Dubina 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.4
Buckling restrained braces (BRBs) were developed as an enhanced alternative to conventional braces by restraining their global buckling, thus allowing development of a stable quasi-symmetric hysteretic response. A wider adoption of buckling restrained braced frames is precluded due to proprietary character of most BRBs and the code requirement for experimental qualification. To overcome these problems, BRBs with capacities corresponding to typical steel multi-storey buildings in Romania were developed and experimentally tested in view of prequalification. The first part of this paper presents the results of the experimental program which included sub-assemblage tests on ten full-scale BRBs and uniaxial tests on components materials (steel and concrete). Two different solutions of the core were investigated: milled from a plate and fabricated from a square steel profile. The strength of the buckling restraining mechanism was also investigated. The influence of gravity loading on the unsymmetrical deformations in the two plastic segments of the core was assessed, and the response of the bolted connections was evaluated. The cyclic response of BRBs was evaluated with respect to a set of performance parameters, and recommendations for design were given.
Advances in the treatment of newly diagnosed primary central nervous system lymphomas
Liren Qian,Ciprian Tomuleasa,Ioan-Alexandru Florian,Jianliang Shen,Ioan-Stefan Florian,Mihnea Zdrenghea,Delia Dima 대한혈액학회 2017 Blood Research Vol.52 No.3
Primary central nervous system lymphoma (PCNSL) is a type of highly invasive non-Hodgkin lymphoma. With a growing number of organ transplantation and im-munosuppressant therapy, the incidence of PCNSL has been growing rapidly in recent years, which is attributed to the increased incidence of HIV/AIDS, a prominent risk factor for developing PCNSL. The rising rate of PCNSL incidence is the highest among the intra-cranial tumors. In the past 20 years, dozens of clinical trials related to PCNSL have been registered, but adequate therapeutics are still challenging. Currently, the chemotherapy regimens based on high-dose methotrexate and whole-brain radiotherapy are the two main therapeutic options; however, the toxicity associated with those is the main problem that challenges medical researchers. Novel agents and therapeutic strategies have been developed in recent years. In the current review, we describe advances in the treatment of PCNSL and discuss novel therapeutic approaches currently in development, such as the use of rituximab, disruption of the blood-brain barrier, and state-of-the-art radiotherapy.
Advances in the treatment of newly diagnosed primary central nervous system lymphomas
Liren Qian,Ciprian Tomuleasa,Ioan-Alexandru Florian,Jianliang Shen,Ioan-Stefan Florian,Mihnea Zdrenghea,Delia Dima 대한혈액학회 2017 Blood Research Vol.52 No.3
Primary central nervous system lymphoma (PCNSL) is a type of highly invasive non-Hodgkin lymphoma. With a growing number of organ transplantation and im-munosuppressant therapy, the incidence of PCNSL has been growing rapidly in recent years, which is attributed to the increased incidence of HIV/AIDS, a prominent risk factor for developing PCNSL. The rising rate of PCNSL incidence is the highest among the intra-cranial tumors. In the past 20 years, dozens of clinical trials related to PCNSL have been registered, but adequate therapeutics are still challenging. Currently, the chemotherapy regimens based on high-dose methotrexate and whole-brain radiotherapy are the two main therapeutic options; however, the toxicity associated with those is the main problem that challenges medical researchers. Novel agents and therapeutic strategies have been developed in recent years. In the current review, we describe advances in the treatment of PCNSL and discuss novel therapeutic approaches currently in development, such as the use of rituximab, disruption of the blood-brain barrier, and state-of-the-art radiotherapy.
Influence of Electroacupuncture on Thermal Changes in a Soft Tissue Defect
Valentin Parmen,Cosmin Pestean,Ciprian Ober,Mircea Mircean,Laurentiu Ognean,Liviu Oana 사단법인약침학회 2014 Journal of Acupuncture & Meridian Studies Vol.7 No.5
This study investigated thermal changes in the skin at locations where soft tissue defects existed and acupuncture needles stimulated by using bipolar electroacupuncture (EA) had been inserted. Under general anesthesia (GA), experimental defects were made at the dorsum site of five New Zealand rabbits. Bipolar EA was used for 20 minutes to stim- ulate the experimental defects, and the skin temperature was monitored at the sites where the acupuncture needles had been inserted and the soft tissue defects existed. The initial thermography of those defects had the same trend as that of the negative pole of EA stimulation at the first acupoint. Skin thermography during the first 3 minutes of bipolar EA indicated a centrifugal vasoconstriction and a vasodilatation at the negative and positive poles, respectively. After that, the thermal change in soft tissue undergoing EA stimulation was not modified by a different EA polarity. The local temperature at the defect and its surroundings under both positive and negative electric loads was increased by 0.2e0.3 ℃ for vasodilatation. This study indicates that EA influences sympathetic modulation of soft tissue defects and that selective sympathetic modulation caused by bipolar EA is responsible for the clinical perception.
Paraclinical Investigations of Electroacupuncture Analgesia in a Rabbit Ovariohysterectomy
Valentin Parmen,Cosmin Pestean,Ciprian Ober,Mircea Mircean,Liviu Oana 사단법인약침학회 2015 Journal of Acupuncture & Meridian Studies Vol.8 No.1
The aim of this study is to investigate paraclinical changes in glycemia, serum cortisol, and adrenocorticotropic hormone (ACTH) due to electroacupuncture analgesia (EAA) in a rabbit undergoing an ovariohysterectomy. Seven clinically healthy New Zealand white rabbits were used in this study. Local and systemic analgesia was represented by EAA. Blood samples were collected at preoperative, operative, and postoperative times. At the operative time, increased cortisolemia does not promote a proportional increase in glycemia even though it is correlated with an increased level of ACTH. EAA follows the stress mechanism, which is coordinated by neuroendocrine activity. EAA in a rabbit ovariohysterectomy underscores the crucial involvement of the hypothalamus–pituitary–adrenal axis with a direct influence on paraclinical changes, including changes in glycemia, cortisol, and ACTH, which are specific for stress changes.
Influence of Electroacupuncture on the Soft Tissue Healing Process
Valentin Parmen,Marian Taulescu,Ciprian Ober,Cosmin Pestean,Liviu Oana 사단법인약침학회 2014 Journal of Acupuncture & Meridian Studies Vol.7 No.5
The aim of this study was to determine the effect of bipolar electroacupuncture (EA) on a soft tissue defect in rabbits. Ten clinically healthy New Zealand white rabbits were divided into two groups: the control group (Group C, n = 5) and the experimental (EA) group (Group T, n = 5). During neuroleptanalgesia, defects of soft tissue (skin and mus- cle) were made at the dorsum site on the rabbits in both groups, and those defects were stimulated using EA. The biopsy samples were collected on Day 2, Day 4, and Day 6, pre- pared for histology, and examined microscopically. On the 2 nd day, in Group C, the inflam- matory degree was higher than it was in Group T; on subsequent days, low or identical degrees of inflammation were observed in both groups. Proliferative fibrous activity was increased on Day 4 for Group T and identical for both groups on Day 6. The dynamics of the epidermal thickness were characterized by a high rate on Day 2, Day 4, and Day 6 for Group T. EA facilitates a low tissue mechanical stress and has a positive effect on the healing of muscular defects. EA enhances the healing process, with no side effects.
Least squares estimator for the parameter of the fractional Ornstein–Uhlenbeck sheet
Jorge Clarke De la Cerda,Ciprian A. Tudor 한국통계학회 2012 Journal of the Korean Statistical Society Vol.41 No.3
We will study the least square estimator θT ,S for the drift parameter θ of the fractional Ornstein–Uhlenbeck sheet which is defined as the solution of the Langevin equation Xt,s = −θ t 0 s 0Xv,udvdu + Bα,βt,s , (t, s) ∈ [0, T ] × [0, S]. driven by the fractional Brownian sheet Bα,β with Hurst parameters α, β in ( 12 , 58). Using the properties of multiple Wiener–Itô integrals we prove that the estimator is strongly consistent for the parameter θ. In contrast to the one-dimensional case, the estimatorθT ,S is not asymptotically normal.