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141.
Optimal probabilistic design of seismic dampers for the protection of isolated bridges against near-fault seismic excitations 总被引:2,自引:0,他引:2
Alexandros A. Taflanidis 《Engineering Structures》2011,33(12):3496-3508
A probabilistic, simulation-based framework is presented in this paper for risk assessment and optimal design of supplemental dampers for multi-span bridge systems supported on abutments and intermediate piers through isolation bearings. The adopted bridge model explicitly addresses nonlinear characteristics of the isolators and the dampers, the dynamic behavior of the abutments, and the effect of pounding between the neighboring spans against each other as well as against the abutments. Nonlinear dynamic analysis is used to evaluate the bridge performance, and a realistic stochastic ground motion model is presented for describing the time history of future near-fault ground motions and relating their characteristics to the seismic hazard for the structural site. A probabilistic foundation is used to address the various sources of structural and excitation uncertainties and ultimately characterize the seismic risk for the bridge. This risk is given by the expected value of the system response over the adopted probability models. Stochastic simulation is used for evaluating the multi-dimensional integral representing this expected value and for performing the associated optimization when searching for the most favorable damper characteristics. An efficient probabilistic sensitivity analysis is also established for identifying the importance of each of the uncertain model parameters in affecting the overall risk. An illustrative example is presented that considers the design of nonlinear viscous dampers for the protection of a two-span bridge. 相似文献
142.
Despena Trasanidou Alexandros Apostolakis 《Chemical Engineering Communications》2016,203(10):1317-1325
Red grape pomace (RGP), an abundant wine industry solid waste, was used for the recovery of polyphenols and anthocyanin pigments, using ultrasound-assisted extraction and water/glycerol mixtures as the solvent. Glycerol concentration (Cgl) and liquid-to-solid ratio (RL/S) were first optimized by implementing Box?Behnken experimental design and the process was further studied through kinetics. The optimal conditions were found to be Cgl = 90% (w/v) and RL/S = 90 mL g?1, and under these conditions the extraction of total polyphenols (TP) and total pigments (TPm) obeyed first-order kinetics. Maximum diffusivity (De) values were 4.22 × 10?12 and 12.59 × 10?12 m2 s?1, for TP and TPm, respectively, and the corresponding activation energies were (Ea) 13.94 and 8.22 kJ mol?1. 相似文献
143.
Alexandros B. Tsoupras Constantinos A. Demopoulos Katherine M. Pappas 《European Journal of Lipid Science and Technology》2012,114(2):123-133
Platelet‐activating factor (PAF) is a signaling phospholipid with a significant physiological role in multicellular and unicellular organisms, including fermentative organisms such as yeast. Zymomonas mobilis is an ethanologenic α‐proteobacterium currently studied for bioethanol production. In order to examine the presence of PAF and/or PAF inhibitors in Z. mobilis, a new one‐step high performance liquid chromatography (HPLC) separation procedure of total lipids was performed, using a C8 reversed‐phase semi‐preparative column. According to this method and to bioassays based on washed rabbit platelet aggregation, two lipid molecules with PAF‐like activity and same retention times as those of standard PAF were detected; electron‐spray ionization MS and MS/MS analysis revealed that they share similar structure with 16:0 and 18:0 PAF. Furthermore, other lipids extracted from Z. mobilis were found to exhibit a potent anti‐PAF activity. Enzyme activities indicative of key PAF biosynthetic enzymes, such as dithiothreitol‐insensitive cholinephosphotransferase (PAF‐CPT) and lyso‐PAF acetyltransferase were detected in Z. mobilis homogenates. As for PAF degradation, activity similar to that of PAF acetylhydrolase was also discovered. Overall, the presence of PAF, PAF‐specific inhibitors, and enzyme activities relating to PAF metabolism, suggests that PAF may play an intrinsic role in this biotechnological organism. Practical applications: Z. mobilis is a platform microorganism for bioethanol production and a potential source of high‐value chemicals of interest to the food and healthcare industries. Further investigation of PAF's role is bound to affect applications involving this and other biotechnological organisms. The finding that Z. mobilis lipids exhibit potent anti‐PAF activity opens up prospects for their identification, overproduction and pharmaceutical use. The presented HPLC method for lipid fractionation accomplishes a one‐step separation of lipids from dense samples, which may be successfully employed to other lipid‐rich sources such as blood. 相似文献
144.
This article reports a study of the chemical cure kinetics and the development of glass transition temperature of a low temperature (40°C) curing epoxy system (MY 750/HY 5922). Differential scanning calorimetry, temperature modulated differential scanning calorimetry, and dielectric spectroscopy were utilized to characterize the curing reaction and the development of the cross‐linking network. A phenomenological model based on a double autocatalytic chemical kinetics expression was developed to simulate the cure kinetics behavior of the system, while the dependence of the glass transition temperature on the degree of cure was found to be described adequately by the Di Benedetto equation. The resulting cure kinetics showed good agreement with the experimental data under both dynamic and isothermal heating conditions with an average error in reaction rate of less than 2 × 10?3 min?1. A comparison of the dielectric response of the resin with cure kinetics showed a close correspondence between the imaginary impedance maximum and the calorimetric progress of reaction. Thus, it is demonstrated that cure kinetics modeling and monitoring procedures developed for aerospace grade epoxies are fully applicable to the study of low temperature curing epoxy resins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
145.
Impact of irradiation on fish and seafood shelf life: a comprehensive review of applications and irradiation detection 总被引:1,自引:0,他引:1
Arvanitoyannis IS Stratakos A Mente E 《Critical reviews in food science and nutrition》2009,49(1):68-112
Irradiation is one of the most important and effective methods towards food preservation despite the consumer lack of trust and aversion towards this method. Irradiation effectiveness greatly depends on the dose provided to food. This review aims at summarizing all available information regarding the impact of irradiation dose on the shelf life and microflora and sensory and physical properties of fish, shellfish, molluscs, and crustaceans. The synergistic effect of irradiation in conjunction with other techniques such as salting, smoking, freezing, and vacuum packaging was also reported. Another issue covered within the frame of this review is the detection (comparison of methods in terms of their effectiveness and validity) of irradiated fish and seafood. The information related to fish and seafood irradiation and its detection is presented by means of 11 comprehensive tables and 9 figures. 相似文献
146.
Alexandros Gasparatos Mohamed El-Haram Malcolm Horner 《Renewable & Sustainable Energy Reviews》2009,13(5):956-970
By building on the first part of our analysis, this second part attempts to provide a further understanding of the UK society's metabolism, its impact and offer policy suggestions that could promote a shift towards sustainability. The methodologies employed in this second part include Exergy Analysis (EA) and Extended Exergy Analysis (EEA). Exergy inputs and outputs amounted to 17423.9 and 11888.7 PJ, respectively, with energy carries, mainly fossil fuels, being both the predominant inputs (15597.1 PJ) and outputs (5147.1 PJ). Exergy consumption and efficiency for various economic sectors and subsectors have been calculated with the residential and service sector showing the lowest exergy conversion efficiencies (11.2% and 12.3%, respectively) while certain industrial subsectors, such as the aluminium and iron/steel industries showed the highest exergy conversion factors (67.0 and 62.1%). Extended exergy efficiencies were somewhat different owing to the different calculation procedure. Extended exergy efficiencies were 91.4% for the extraction sector, 38.9% for the conversion sector, 49.1% for the agriculture sector, 31.5% for the transportation sector, 38.6% for the industrial sector and 80.0% for the tertiary sector. 相似文献
147.
Alexandros G. Charalambides Christos N. Maxoulis Orestis Kyriacou Erik Blakeley Laura Soto Frances 《国际可持续能源杂志》2019,38(1):1-12
The purpose of this paper is to investigate the effect of Energy Performance Certificates (EPCs) on the renovation of buildings. Thus, through the European project ENERFUND, 2 online web-based surveys were conducted in 12 countries of the European Union. It was shown that the results varied significantly both between countries and age groups and, that, on average, EPCs did play a role both in renovation decisions and whether to rent/buy a certain flat. In addition, this paper presents major key drivers and parameters related to energy renovation investment mobilisation and suggests actions that can contribute to the promotion of investments for deep energy renovation of buildings. Furthermore, it highlights potential benefits and effectiveness of using retrofitting online tools, such as the ENERFUND tool, pinpoints market failures in the building sector and provides suggestions on increasing the deep energy renovation market in Europe. 相似文献
148.
Within the multi-functionality of educational buildings, the energy conservation potential can be very different. In addition, among different retrofitting solutions investigated involving interventions on the building envelope, ventilation strategies, artificial lighting systems as well as equipment upgrading, different saving potential would come from different aspects. The opportunities for energy saving potential from the overall point of view and from the detailed aspect view of different retrofitting solutions would be very useful and important for building renovation decision making. This study presents a detailed retrofitting study of two different educational buildings. One represents a building with average occupancy variation and containing mainly offices and labs. The other one represents a building with high occupancy variation and containing mainly lecture rooms and studios. This comparison of the results gives an idea of the different energy saving potential for different types of educational buildings. Principal component analysis is also adopted to investigate the detailed performance of one of the buildings which is influenced stronger by these retrofitting solutions. 相似文献
149.
Stavros P. Papadakos Leonidas Petrogiannopoulos Alexandros Pergaris Stamatios Theocharis 《International journal of molecular sciences》2022,23(5)
The EPH/ephrin system constitutes a bidirectional signaling pathway comprised of a family of tyrosine kinase receptors in tandem with their plasma membrane-bound ligand (ephrins). Its significance in a wide variety of physiologic and pathologic processes has been recognized during the past decades. In carcinogenesis, EPH/ephrins coordinate a wide spectrum of pathologic processes, such as angiogenesis, vessel infiltration, and metastasis. Despite the recent advances in colorectal cancer (CRC) diagnosis and treatment, it remains a leading cause of death globally, accounting for 9.2% of all cancer deaths. A growing body of literature has been published lately revitalizing our scientific interest towards the role of EPH/ephrins in pathogenesis and the treatment of CRC. The aim of the present review is to present the recent CRC data which might lead to clinical practice changes in the future. 相似文献
150.
Iason Psilopatis Alexandros Pergaris Kleio Vrettou Gerasimos Tsourouflis Stamatios Theocharis 《International journal of molecular sciences》2022,23(6)
Gynecological cancers represent some of the most common types of malignancy worldwide. Erythropoietin-producing hepatocellular receptors (EPHs) comprise the largest subfamily of receptor tyrosine kinases, binding membrane-bound proteins called ephrins. EPHs/ephrins exhibit widespread expression in different cell types, playing an important role in carcinogenesis. The aim of the current review was to examine the dysregulation of the EPH/ephrin system in gynecological cancer, clarifying its role in ovarian, endometrial, and cervical carcinogenesis. In order to identify relevant studies, a literature review was conducted using the MEDLINE and LIVIVO databases. The search terms ephrin, ephrin receptor, ovarian cancer, endometrial cancer, and cervical cancer were employed and we were able to identify 57 studies focused on gynecological cancer and published between 2001 and 2021. All researched ephrins seemed to be upregulated in gynecological cancer, whereas EPHs showed either significant overexpression or extensive loss of expression in gynecological tumors, depending on the particular receptor. EPHA2, the most extensively studied EPH in ovarian cancer, exhibited overexpression both in ovarian carcinoma cell lines and patient tissue samples, while EPHB4 was found to be upregulated in endometrial cancer in a series of studies. EPHs/ephrins were shown to exert their role in different stages of gynecological cancer and to influence various clinicopathological parameters. The analysis of patients’ gynecological cancer tissue samples, most importantly, revealed the significant role of the EPH/ephrin system in the development and progression of gynecological cancer, as well as overall patient survival. In conclusion, the EPH/ephrin system represents a large family of biomolecules with promising applications in the fields of diagnosis, prognosis, disease monitoring, and treatment of gynecological cancer, with an established important clinical impact. 相似文献