Modelling and testing of a dielectic electro-active polymer (DEAP) actuator for active vibration control

Umberto Berardi 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.1

Passive vibration absorbers are really effective only at the tuned frequency. This limit is overcome by adaptive absorbers which offer the possibility to adjust their behaviour according to needs. The paper focuses on a smart actuator for vibration control made up by a dielectric electro-active polymer (DEAP). The DEAP is obtained constraining a silicone corrugated sheet between two silver layers and it is manufactured by Danfoss Polypower A/S. The actuator is fabricated by rolling the DEAP sheet in a cylindrical and core-free shape. The paper describes the static and dynamic characterizations of the actuator. A theoretical model is developed by considering the actuator as a multi-elements model. Moreover, a modal test of the actuator is performed driving it with an electro-dynamic shaker in a frequency range up to 1 kHz. A good agreement between theoretical and experimental data is obtained at lower frequencies. Stiffness and damping laws of the actuator are determined by fitting theoretical expectations and test results. The actuator is proved useful for controlling vibrations at low frequencies because it shows internal resonances at frequencies above 75 Hz. Finally, first results about the use of the DEAP actuator for vibration control of harmonic excitations in a band-limited frequency range below 10 Hz are reported.

Response Spectrum Code-Conforming PEER PBEE using Stochastic Dynamic Analysis and Information Theory

Umberto Alibrandi,Khalid M. Mosalam 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.3

In this paper, the tools of the stochastic dynamic analysis are adopted for Performance-Based Earthquake Engineering (PBEE). The seismic excitation is defined through a evolutionary Power Spectral Density compatible with the response spectrum given by mandatory codes. In this way, the performance-based design is applied considering the excitation coherent with the codes. Inside the framework, the seismic fragility curves are determined through the Kernel Density Maximum Entropy Method (KDMEM), recently proposed by the authors. It is a novel statistical method capable to reconstruct the seismic fragility curves, including the tails, from a small number of code-conforming artificial ground motions. Moreover, KDMEM is based on the Maximum Entropy (ME) principle and it provides the least biased probability distribution given the available information. Comparison between stationary and nonstationary artificial accelerograms is analyzed, and the corresponding model uncertainty discussed. KDMEM provides also credible bounds of the uncertain performances, which is beneficial for risk-informed decisions. The proposed formulation does not require the selection of a suitable set of ground motions. Accordingly, it can be adopted for optimal design in current engineering practice. Therefore, it fills the gap between the classical code-conforming designs and the enhanced performance-based designs.

Percutaneous trans-hepatic rescue and neo-creation of a post-surgical complete hepaticojejunostomy dehiscence

Umberto Geremia Rossi,Andrea DeCensi,Gian Andrea Rollandi,Marco Filauro 한국간담췌외과학회 2021 Annals of hepato-biliary-pancreatic surgery Vol.25 No.3

Biliary leakage complicating hepaticojejunostomy is a therapeutic dilemma for surgeons, gastroenterologist, and interventional radiologist. It is a major cause of postoperative morbidity. Percutaneous biliary intervention techniques have been developed for treating benign post-surgical biliary disease in patients not having severely compromised clinical conditions. Interventional radiology manoeuvres are especially indicated as the first line of treatment if endoscopic procedures are unfeasible for patients due to postsurgical anatomical modifications. We present a case of post-surgical complete hepaticojejunostomy dehiscence that was treated totally by percutaneous techniques with trans-hepatic rescue and hepaticojejunostomy neo-creation.

AERODYNAMIC ANALYSIS FOR A TWO-DIMENSIONAL AIRFOIL WITH A DEFLECTED FLAP

Umberto Visconti,WonJong Eun,JungPyo Kang,JaeHoon Lim,SangJoon Shin 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11

본 논문에서 플랩에 작용하는 힌지 모멘트 값을 예측하기 위해 NACA 0015 익형을 분석하였다. 복잡한 유동장이 포함된 전산유체해석(CFD)이 우선적으로 수행되었다. 이러한 정적 해석은 압전 작동기가 외부의 공력에 견디면서, 플랩 변위 목표 값을 획득하기 위한 플랩 움직임이 가능한지를 평가하기 위해 수행되었다. 몇 가지 받음각에 대한 해석이 수행되었으며, 각각의 경우에 대한 힌지 모멘트 결과가 도출되었다. 그 결과, APA 1000L 작동기가 현재 비행조건에서 플랩 구동에 가장 적합한 모델로 선정되었다. In this paper NACA 0015 airfoil is analyzed in order to estimate the value of the hinge moment acting on the deflected flap. Due to the complexity of the flow field involved, CFD analysis was conducted to have a first estimate. This static analysis is carried on in order to evaluate the capability of the piezo-stack actuator to withstand external forces and thus drive the flap movement according to the deflection desired. Several angles of attack are considered and, per each case, hinge moments were extracted. Thus, a new actuator capable of driving the flap under the present flight condition was chosen.

Spontaneous hepatic haemangioma rupture and hemoperitoneum: a double problem with a single stage interventional radiology solution

Umberto G. Rossi,Nicola Camisassi,Francesco Pinna,Gian Andrea Rollandi 대한응급의학회 2019 Clinical and Experimental Emergency Medicine Vol.6 No.2

Hepatic haemangioma is a congenital vascular malformation, considered the most common benign mesenchymal hepatic tumour. Spontaneous or traumatic rupture is the most severe complication. In case of rupture, surgical resection and enucleation, as a single therapy or after trans-arterial embolization are considered the treatments of choice. We report a case of spontaneous rupture of a hepatic haemangioma with massive hemoperitoneum successfully treated by percutaneous hepatic trans-arterial embolization and pelvic drainage alone.

Efficacy and fertility outcomes of levonorgestrel-releasing intra-uterine system treatment for patients with atypical complex hyperplasia or endometrial cancer: a retrospective study

Umberto Leone Roberti Maggiore,Fabio Martinelli,Giulia Dondi,Giorgio Bogani,Valentina Chiappa,Maria Teresa Evangelista,Viola Liberale,Antonino Ditto,Simone Ferrero,Francesco Raspagliesi 대한부인종양학회 2019 Journal of Gynecologic Oncology Vol.30 No.4

Objective: To investigate the efficacy of levonorgestrel-releasing intra-uterine system (LNG-IUS) treatment in patients affected by atypical complex hyperplasia/endometrial cancer (ACH/EC) wishing to preserve their fertility and to present fertility outcomes of those patients who actively tried to conceive. Methods: Data of consecutive women with ACH/EC who underwent fertility-sparing treatment using LNG-IUS were retrospectively evaluated. Results: Overall, 48 patients and the mean (±standard deviation) length of follow-up was 82.6±47.2 months. Among patients with ACH, 25/28 (89.3%) had a complete response (CR), 2/28 (7.1%) had a partial response (PR) and 1/28 (3.6%) had a progressive disease (PD). Mean (±standard deviation) time to CR was 6.7±4.0 months. Among patients with G1 EC, 13/16 (81.3%) had a CR, 1/16 (6.3%) had a PR and 2/16 (12.5%) had a PD. Mean (±standard deviation) time to CR was 5.0±2.9 months. Among patients with G2 EC, 3/4 (75.0%) had a CR and 1/4 (25.0%) had a PD. Mean (±standard deviation) time to CR was 4.0±0 months. Only 19 (39.6%) patients who had CR actually attempted to conceive. Eleven (57.9%) women tried to conceive naturally while 8 (42.1%) women underwent an in vitro fertilization (IVF). Fourteen (73.7%) patients wishing to conceive achieved a pregnancy (6 spontaneously and 8 through IVF). Conclusions: Fertility-sparing treatment of patient with ACH/EC with LNG-IUS achieves high regression rates and good fertility outcomes. Future larger multi-institutional studies should be designed to confirm these preliminary findings.

Hepatic artery aneurysms: Endovascular therapeutic techniques

Umberto Geremia Rossi,Francesco Petrocelli 한국간담췌외과학회 2021 Annals of hepato-biliary-pancreatic surgery Vol.25 No.2

Hepatic Artery Aneurysm (HAA) is a rare disease, but it can be a life-threatening pathology if it is ruptured. Multi-Detector Computed Tomography has to be considered the “gold standard” diagnostic imaging in detecting HAA and it is essential for treatment planning. Treatment for HAA can be surgical or endovascular. Endovascular approaches in HAA, compare to conventional abdominal surgery, benefit in less invasive treatments. The aim of our paper is to emphasize the three possible endovascular therapeutic techniques in HAA: packing embolization, isolation embolization and stenting deployment.

Diaphragmatic rupture with inferior phrenic artery bleeding caused by cardiopulmonary resuscitation

Umberto G. Rossi,Anna Maria Ierardi,Maurizio Cariati 대한응급의학회 2020 Clinical and Experimental Emergency Medicine Vol.7 No.3

Diaphragmatic lesions (varying from tearing of a muscle bundle to full-strength breakage) with inferior phrenic artery bleeding due to blunt trauma is a rare emergency event. Diaphragmatic rupture caused by CPR is even rarer. To our knowledge, this is the first case involving a diaphragmatic lesion and inferior phrenic artery rupture caused by CPR, leading to hemoperitoneum. This is a potentially life-threatening condition requiring prompt diagnosis and treatment. In selected cases involving active traumatic bleeding in thoraco-abdominal organs, transcatheter embolization techniques have been successfully used as the first-line treatment. In conclusion, the possibility of injury to abdominal organs, such as the diaphragm, must be considered while performing vigorous CPR.

Anismus, Physiology, Radiology: Is It Time for Some Pragmatism? A Comparative Study of Radiological and Anorectal Physiology Findings in Patients With Anismus

Umberto Pisano,Lesley Irvine,Justina Szczachor,Ahsin Jawad,Andrew MacLeod,Michael Lim 대한대장항문학회 2016 Annals of Coloproctolgy Vol.32 No.5

Purpose: Anismus is a functional disorder featuring obstructive symptoms and paradoxical contractions of the pelvic floor. This study aims to establish diagnosis agreement between physiology and radiology, associate anismus with morphological outlet obstruction, and explore the role of sphincteric pressure and rectal volumes in the radiological diagnosis of anismus. Methods: Consecutive patients were evaluated by using magnetic resonance imaging proctography/fluoroscopic defecography and anorectal physiology. Morphological radiological features were associated with physiology tests. A categorical analysis was performed using the chi-square test, and agreement was assessed via the kappa coefficient. A Mann-Whitney test was used to assess rectal volumes and sphincterial pressure distributions between groups of patients. A P-value of <0.05 was significant. Results: Forty-three patients (42 female patients) underwent anorectal physiology and radiology imaging. The median age was 54 years (interquartile range, 41.5–60 years). Anismus was seen radiologically and physiologically in 18 (41.8%) and 12 patients (27.9%), respectively. The agreement between modalities was 0.298 (P = 0.04). Using physiology as a reference, radiology had positive and negative predictive values of 44% and 84%, respectively. Rectoceles, cystoceles, enteroceles and pathological pelvic floor descent were not physiologically predictive of animus (P > 0.05). The sphincterial straining pressure was 71 mmHg in the anismus group versus 12 mmHg. Radiology was likely to identify anismus when the straining pressure exceeded 50% of the resting pressure (P = 0.08). Conclusion: Radiological techniques detect pelvic morphological abnormalities, but lead to overdiagnoses of anismus. No proctographic pathological feature predicts anismus reliably. A stronger pelvic floor paradoxical contraction is associated with a greater likelihood of detection by proctography.

온라인을 통한 이탈리아어 강좌에서의 언어 모델

(Umberto Cassano) 한국이탈리아어문학회(구-한국이어이문학회) 2001 이탈리아어문학 Vol.9 No.-