Modeling of DC-DC Converters

Non

Improving the Earthquake Resilience of Existing Multi-Storey Concentrically Braced Frames Office Buildings in Moderate to High Seismic Zones

In the past decades, concentrically braced frames (CBF) have been frequently employed as earthquake resistant systems for low- and middle-rise buildings. Their configuration and straightforward design made them appealing for engineers. It is noted that building structures designed and built in Canada prior to 1970 were not proportioned to carry seismic loads, while those constructed between 1970 and 1985 were designed to withstand lower seismic forces than those required by the current code. As a consequence, these buildings are characterized by lack of seismic resilience and therefore are vulnerable to earthquakes. Herein, the building’s resilience is defined as the capability of a system to maintain a level of functionality in the aftermath of an earthquake event and is characterized by the performance metrics such as fragility, loss, and recovery functions. To quantify the seismic resilience of existing office buildings, a methodology was proposed and exemplified in a case study comprising of 3- and 6-storey fictitious CBF office buildings located in Quebec City and Vancouver. These buildings were designed in accordance with the requirements of the 1980 edition of the National Building Code and CSA/S16.1-M78 standard. It is noted that before 1985, Quebec City and Vancouver were located in the same seismic zone (the seismic demand was identical) and the Vancouver buildings were selected for comparison purpose. The proposed seismic resilience methodology consists in selecting the Rehabilitation Objective Class and the associated performance levels corresponding to earthquake hazard levels (e.g. 2%/50 yrs., 10%/50 yrs. and 50%/50 yrs.). To achieve this step, nonlinear dynamic time-history analyses are required and fragility curves computed for different hazard levels for both existing and retrofitted 3- and 6-storey fictitious buildings were generated from the Incremental Dynamic Analysis curves (IDA). Both aleatoric and epistemic uncertainties were considered. The loss estimation model is a function of system’s components deficiency determined by the use of performance limit thresholds for different damage states. In addition, functionality curves computed for different hazard levels using an exponential recovery model are also shown. The seismic assessment process was done according to performance based design principles and nonlinear time-history analysis by means of IDA using the OpenSees framework (Open System for Earthquake Engineering Simulation). Herein, all studied buildings were assessed against the current code demand. Based on the results, the buildings located in Quebec City and Vancouver show deficiencies at the level of structural members, especially the buildings located in Vancouver. Moreover, all brace-to-frame connections had insufficient strength and showed failure due to shearing of the welds. As reported from IDA curves, all existing buildings experienced collapse when subjected to ground motion intensities in agreement with the current code demand and a retrofit action was required. To respond to the Rehabilitation Objective Class defined as Basic Safety by the ASCE/SEI 41-13 provisions, the selected rehabilitation strategy consisted in local strengthening of system’s components (e.g. cover plating steel columns or beams and gusset plate replacement). According to the results, when the 3- and 6-storey retrofitted buildings located in Quebec City were subjected to ground motions scaled to the current code demand, their functionality was higher than 86.67% and 75.7%, respectively. Conversely, for the Vancouver buildings, besides the retrofit action, it is suggested to double the number of CBFs in order to pass the current code requirements. In conclusion, the proposed retrofit scheme for Quebec City buildings was able to improve the building performance and implicitly its earthquake resilience

Collective awareness platforms and digital social innovation mediating consensus seeking in problem situations

In this paper we show the results of our studies carried out in the framework of the European Project SciCafe2.0 in the area of Participatory Engagement models. We present a methodological approach built on participative engagements models and holistic framework for problem situation clarification and solution impacts assessment. Several online platforms for social engagement have been analysed to extract the main patterns of participative engagement. We present our own experiments through the SciCafe2.0 Platform and our insights from requirements elicitation

Improving workplace-based assessment and feedback by an E-portfolio enhanced with learning analytics

Electronic portfolios (E-portfolios) are crucial means for workplace-based assessment and feedback. Although E-portfolios provide a useful approach to view each learner’s progress, so far options for personalized feedback and potential data about a learner’s performances at the workplace often remain unexploited. This paper advocates that E-portfolios enhanced with learning analytics, might increase the quality and efficiency of workplace-based feedback and assessment in professional education. Based on a 5-phased iterative design approach, an existing E-portfolio environment was enhanced with learning analytics in professional education. First, information about crucial professional activities for professional domains and suited assessment instruments were collected (phase 1). Thereafter probabilistic student models were defined (phase 2). Next, personalized feedback and visualization of the personal development over time were developed (phase 3). Then the prototype of the E-portfolio—including the student models and feedback and visualization modules—were implemented in professional training-programs (phase 4). Last, evaluation cycles took place and 121 students and 30 supervisors from five institutes for professional education evaluated the perceived usefulness of the design (phase 5). It was concluded that E-portfolios with learning analytics were perceived to assist the development of students’ professional competencies and that the design is only successful when developed and implemented through the eyes of the users. Feedback and assessment methods based upon learning analytics can stimulate learning at the workplace in the long run. Practical, technological and ethical challenges are discussed

Implications of oral dysbiosis and HPV infection in head and neck cancer: from molecular and cellular mechanisms to early diagnosis and therapy

Head and neck cancer (HNC) is the sixth most common type of cancer, with more than half a million new cases annually. This review focuses on the role of oral dysbiosis and HPV infection in HNCs, presenting the involved taxons, molecular effectors and pathways, as well as the HPV-associated particularities of genetic and epigenetic changes and of the tumor microenvironment occurred in different stages of tumor development. Oral dysbiosis is associated with the evolution of HNCs, through multiple mechanisms such as inflammation, genotoxins release, modulation of the innate and acquired immune response, carcinogens and anticarcinogens production, generation of oxidative stress, induction of mutations. Thus, novel microbiome-derived biomarkers and interventions could significantly contribute to achieving the desideratum of personalized management of oncologic patients, regarding both early diagnosis and treatment. The results reported by different studies are not always congruent regarding the variations in the abundance of different taxons in HNCs. However, there is a consistent reporting of a higher abundance of Gram-negative species such as Fusobacterium, Leptotrichia, Treponema, Porphyromonas gingivalis, Prevotella, Bacteroidetes, Haemophilus, Veillonella, Pseudomonas, Enterobacterales, which are probably responsible of chronic inflammation and modulation of tumor microenvironment. Candida albicans is the dominant fungi found in oral carcinoma being also associated with shorter survival rate. Specific microbial signatures (e.g., F. nucleatum, Bacteroidetes and Peptostreptococcus) have been associated with later stages and larger tumor, suggesting their potential to be used as biomarkers for tumor stratification and prognosis. On the other hand, increased abundance of Corynebacterium, Kingella, Abiotrophia is associated with a reduced risk of HNC. Microbiome could also provide biomarkers for differentiating between oropharyngeal and hypopharyngeal cancers as well as between HPV-positive and HPV-negative tumors. Ongoing clinical trials aim to validate non-invasive tests for microbiome-derived biomarkers detection in oral and throat cancers, especially within high-risk populations. Oro-pharyngeal dysbiosis could also impact the HNCs therapy and associated side-effects of radiotherapy, chemotherapy, and immunotherapy. HPV-positive tumors harbor fewer mutations, as well as different DNA methylation pattern and tumor microenvironment. Therefore, elucidation of the molecular mechanisms by which oral microbiota and HPV infection influence the HNC initiation and progression, screening for HPV infection and vaccination against HPV, adopting a good oral hygiene, and preventing oral dysbiosis are important tools for advancing in the battle with this public health global challenge

Genetic implications in vitiligo and vitiligo-associated diseases

Vitiligo is a chronic, asymptomatic, disease that affects the patient from a cosmetic point of view. It is characterized by the appearance of depigmented areas on the skin or mucous membranes. Depending on the morphology of the lesions, vitiligo can be classified into: segmental, non-segmented or mixed. Vitiligo is associated with a range of autoimmune disorders, most commonly autoimmune thyroid diseases, alopecia areata, halo nevi, psoriasis, diabetes, etc. Etiology is not entirely elucidated, autoimmune theory related to specific genetic mutations being the most studied

Studies on the hydrothermal synthesis of CdxZn1-x S compounds

In this study series of CdxZn1-xS solid solutions with different amounts of Cd and Zn were synthesized by the hydrothermal treatment of aqueous solutions containing CdCl2, Na2S · 9 H2O and ZnSO4 · 7 H2O. The aim was to examine the influence of Zn concentration and processing conditions (hydrothermal temperature and duration) on the structure of the obtained powders and their photocatalytic activity (in water splitting process). The obtained photocatalysts (with and without Pd co-catalyst) were analysed by X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) method and gas chromatography (GC). The XRD results confirmed the crystallinity of the compounds and transition from hexagonal to cubic phase with increasing Zn content. Complete transformation from hexagonal to cubic phase did not take place, and both phases were present in almost all samples. BET analysis showed the importance of the pore distribution and pore size, especially in the case of photocatalysts with different duration treatment. GC measurements of the photocatalysts without and with Pd co-catalyst confirmed the production of hydrogen for all tested compounds. The best photocatalytic performance was achieved by the sample Zn50230/72-Pd prepared at 230 °C, for 72 hours, with 50% Zn and in the presence of Pd co-catalyst. The synthesis implied neither stabilizer nor organic compound