Experimental investigation of a new steel friction device with link element for seismic strengthening of structures

Papadopoulos, Panikos K.,Salonikios, Thomas N.,Dimitrakis, Stergios A.,Papadopoulos, Alkis P. Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.4

In the present work a new friction device, with a set of single or double rotational friction flanges and a link element, is described and tested. The mechanism may be applied for the strengthening of existing r/c or steel buildings as well as in new constructed buildings. The device has selectable variable behavior in different levels of displacement and an interlock mechanism that is provided by the link element. The link element may be designed to lock at preselected level of displacement, offering in this way an extra safety reserve against strong earthquakes. A summary of the existing literature about other similar mechanisms is initially presented in this paper. The proposed mechanism is presented and described in details. Laboratory experiments are presented in detail and the resulted response that proves the efficiency of the mechanism at selectable levels of strength capacity is discussed. Drawings of the mechanism attached to a r/c frame with connection details are also included. Finally a dynamic analysis of two r/c frames, with and without the proposed mechanism attached, is performed and the resulted response is given. The main conclusion is that the proposed mechanism is a cheap and efficient devise for the improvement of the performance of new or existing framed buildings to seismic loads.

An algorithm for fast 3D inversion of surface electrical resistivity tomography data: application on imaging buried antiquities

Papadopoulos, N.G.,Tsourlos, P.,Papazachos, C.,Tsokas, G.N.,Sarris, A.,Kim, J.H. Blackwell Publishing Ltd 2011 Geophysical prospecting Vol.59 No.3

<P><B>ABSTRACT</B></P><P>In this work a new algorithm for the fast and efficient 3D inversion of conventional 2D surface electrical resistivity tomography lines is presented. The proposed approach lies on the assumption that for every surface measurement there is a large number of 3D parameters with very small absolute Jacobian matrix values, which can be excluded in advance from the Jacobian matrix calculation, as they do not contribute significant information in the inversion procedure. A sensitivity analysis for both homogeneous and inhomogeneous earth models showed that each measurement has a specific region of influence, which can be limited to parameters in a critical rectangular prism volume. Application of the proposed algorithm accelerated almost three times the Jacobian (sensitivity) matrix calculation for the data sets tested in this work. Moreover, application of the least squares regression iterative inversion technique, resulted in a new 3D resistivity inversion algorithm more than 2.7 times faster and with computer memory requirements less than half compared to the original algorithm. The efficiency and accuracy of the algorithm was verified using synthetic models representing typical archaeological structures, as well as field data collected from two archaeological sites in Greece, employing different electrode configurations. The applicability of the presented approach is demonstrated for archaeological investigations and the basic idea of the proposed algorithm can be easily extended for the inversion of other geophysical data.</P>

Simple nonlinear static analysis of steel portal frame with pitched roof exposed to fire

Papadopoulos, Panagis G.,Papadopoulou, Anastassia K.,Papaioannou, Kyriakos K. Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.29 No.1

Plane steel portal frames, with pitched roof, exposed to fire, are examined. First, a determinate frame is analysed by hand. For flexible columns and shallow roof, snap-through occurs before plastic hinges mechanism is formed. An indeterminate frame with shorter columns and taller roof is also analysed by hand. Then, the same frame is simulated by a truss and a nonlinear static analysis is performed by use of a short computer program. The results of computer analysis by use of truss model are compared with those of analysis by hand and a satisfactory approximation between them is observed.

19세기 초엽 그리스의 해방과 유럽의 외교상황

Papadopoulos, Stephanos 동국사학회 1984 동국사학 Vol.18 No.-

Extraperitoneal Spread of Anorectal Abscess: A Case Report and Literature Review

Papadopoulos S. Konstantinos,Dimopoulos Andreas,Kordeni Kleoniki,Filis Dimitrios 대한대장항문학회 2021 Annals of Coloproctolgy Vol.37 No.S

Supralevator abscess is a rare form of anorectal disease responsible for very rare but morbid manifestations, one of which is superior spread through fascial planes. We present a rare case of a spreading anorectal abscess in a patient who presented with only diffuse abdominal pain, and we review similar cases in the literature according to anatomical considerations, presentation, diagnostic procedures, and treatment options. We identified 7 previously reported cases of spreading anorectal abscesses. Most abscesses had a horseshoe morphology, and all patients presented or developed abdominal pain. All patients had perianal swelling and pain. Five out of 7 patients were previously mistreated. Only 2 abscesses spread through both the pre- and retroperitoneal planes. Abdominal pain is a dominant feature of extraperitoneal inflammation originating from anorectal abscesses. The absence of perianal signs is rare, and proper inspection of the patient along with the medical history can lead to quicker diagnosis and decisive treatment.

The Reality Deck--an Immersive Gigapixel Display

Papadopoulos, Charilaos,Petkov, Kaloian,Kaufman, Arie E.,Mueller, Klaus IEEE 2015 IEEE computer graphics and applications Vol.35 No.1

<P>The Reality Deck is a visualization facility offering state-of-the-art aggregate resolution and immersion. Its a 1.5-Gpixel immersive tiled display with a full 360-degree horizontal field of view. Comprising 416 high-density LED-backlit LCD displays, it visualizes gigapixel-resolution data while providing 20/20 visual acuity for most of the visualization space.</P>

[說林] 19세기 초엽 그리스의 解放과 유럽의 外交狀況

Stephanos Papadopoulos 동국사학회 1984 동국사학 Vol.18 No.-

19세기 初期에 있어서 그리스의 ?立戰爭과 그리스 ?立國家의 탄생은 발칸 역사의 劃記的인 사실일 뿐 아니라 유럽 전체에 지대한 영향을 끼쳤다. 당시 「그리스 문제」는 오리엔트 전체 문제와 직결되어 있었고 또한 나폴레옹 戰爭 후 유럽 國?社會의 外交문제와도 깊이 연결되어 있었고 따라서 神聖同盟에 심각한 타격을 주었다는데 그 역사적 意義가 있다 하겠다. 1983년 7월 28일부터 31일까지 4일간 「元明?期에 있어서 國家”支配”와 民家像의 재검토 支配 의 中國的 특질」이라는 제목의 심포지엄이 九州大學東洋史 주최로 九州大分縣九重山 筋渴은 천에서 열렸다. 마침 京部大學人交科學硏究所의 招聘敎授로 일년간 체제중이던 필자는 기회만 닿으면 해보리라던 九州地万의 여행도 겸하여 이번 학회에 참가 할 수 있게 된 것은 참으로 다행한 일이었다.

The Medium Access Controller of a Customer Premises Network

C. Papadopoulos,T. Antonakopoulos,V. Makios 한국통신학회 1993 Asia-Pacific Conference on Communications Vol.2 No.1

Electroacupuncture for the Treatment of Calcific Tendonitis. A Pilot Study

Georgios Papadopoulos,Alexandros Mavrodontidis,Antonia Liarmakopoulou,Petros Tzimas,Georgios Angelidakis,Panagiotis Koulouvaris,Anastasios Petrou 사단법인약침학회 2018 Journal of Acupuncture & Meridian Studies Vol.11 No.2

Current treatment for calcific tendonitis consists of arm rest, antiinflammatory medications, and corticosteroid injections. If unsuccessful, a lot of clinicians suggest several physiotherapy modalities, such as shockwave therapy and electrotherapy. The purpose of our study was to assess the efficacy of electroacupuncture, as a substitute for failed medical treatment in calcific tendonitis. In a pilot study, we prospectively followed 10 patients treated with electroacupuncture for calcific tendonitis who failed to respond to medical treatment. Its efficacy was assessed by evaluating the level of pain, the Beck Depression Inventory, the range of active elbow mobility, and by repeated radiological evaluation of the course of calcific deposits. All clinical and radiological observations were recorded before and within 6 months after the onset of treatment. After electroacupuncture treatment (2 Hz, 180 mA for 30–60 seconds at GB21, GB34, LI4, LI 14, LI15, TW5, TW14, Chien Chien SI9, SI12, S37, S38), the visual analog score decreased notably, and the range of motion returned to normal. Radiological evaluation demonstrated almost complete absorption of calcific deposits within 6 months, after treatment. We conclude that electroacupuncture relieved skeletal pain, improved the quality of patient's life, and contributed to total regression of the calcific depositions in followed patients. So, electroacupuncture may be a valuable treatment option for calcific tendonitis, when medical treatment fails to relieve symptoms.

Geochemistry and REE content of beach sands along the Atticocycladic coastal zone, Greece

Argyrios Papadopoulos 한국지질과학협의회 2018 Geosciences Journal Vol.22 No.6

Twenty-eight beach sand samples from the shorelines of Aegean islands adjacent to the plutonic rocks of the Atticocycladic zone were analyzed for major and rare earth element (REE) contents. Results are compared with the adjacent plutonic rocks, in order to determine relative enrichments or depletions and assess the potential for REE exploitation. Among the samples, several are significantly enriched in REE, being deposits of heavy minerals and their concentrations are controlled by the sea waves and local winds. These samples contain Th, U and REE rich minerals such as zircon, xenotime and allanite. The available geochemical characteristics were also used to confirm the parent rocks of the beach sands. The heavy fractions (total, total magnetic and total non-magnetic) of the beach sands are very well correlated with the Heavy REE (HREE) concentrations. Among the minerals of the heavy magnetic fraction, allanite seems to control the REE content in the heavy mineral-enriched samples, while from the heavy non-magnetic fraction, zircon controls mainly the HREE fraction. One site from Mykonos and 3 from Naxos could have potential for REE exploitation as they present the highest ΣREE and ΗREE contents than other beach sand placers measured in Greece (Kavala, Sithonia, Maronia, Samothraki, NE Chalkidiki).