Bibliografie tematiche / Vcact

Letteratura scientifica selezionata sul tema "Vcact"

Autore: Grafiati

Pubblicato: 25 luglio 2024

Ultima modifica: 31 luglio 2024

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Articoli di riviste sul tema "Vcact"

Zhou, Li Ming, Guang Wei Meng, Feng Li e Hui Wang. "Cell-Based Smoothed Finite Element Method-Virtual Crack Closure Technique for a Piezoelectric Material of Crack". Mathematical Problems in Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/371083.

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In order to improve the accuracy and efficiency of solving fracture parameters of piezoelectric materials, a piezoelectric element, tailored for the virtual crack closure technique (VCCT), was used to study piezoelectric materials containing a crack. Recently, the cell-based smoothed finite element method (CSFEM) and VCCT have been used to simulate the fracture mechanics of piezoelectric materials. A center cracked piezoelectric materials with different material properties, crack length, mesh, and smoothing subcells at various strain energy release rates are discussed and compared with finite element method-virtual crack closure technique (FEM-VCCT). Numerical examples show that CSFEM-VCCT gives an improved simulation compared to FEM-VCCT, which generally simulates materials as too stiff with lower accuracy and efficiency. Due to its simplicity, the VCCT piezoelectric element demonstrated in this study could be a potential tool for engineers to practice piezoelectric fracture analysis. CSFEM-VCCT is an efficient numerical method for fracture analysis of piezoelectric materials.

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Noor, Shazia, Hadeed Ashraf, Muhammad Sultan e Zahid Mahmood Khan. "Evaporative Cooling Options for Building Air-Conditioning: A Comprehensive Study for Climatic Conditions of Multan (Pakistan)". Energies 13, n. 12 (12 giugno 2020): 3061. http://dx.doi.org/10.3390/en13123061.

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This study provides comprehensive details of evaporative cooling options for building air-conditioning (AC) in Multan (Pakistan). Standalone evaporative cooling and standalone vapor compression AC (VCAC) systems are commonly used in Pakistan. Therefore, seven AC system configurations comprising of direct evaporative cooling (DEC), indirect evaporative cooling (IEC), VCAC, and their possible combinations, are explored for the climatic conditions of Multan. The study aims to explore the optimum AC system configuration for the building AC from the viewpoints of cooling capacity, system performance, energy consumption, and CO2 emissions. A simulation model was designed in DesignBuilder and simulated using EnergyPlus in order to optimize the applicability of the proposed systems. The standalone VCAC and hybrid IEC-VCAC & IEC-DEC-VCAC system configurations could achieve the desired human thermal comfort. The standalone DEC resulted in a maximum COP of 4.5, whereas, it was 2.1 in case of the hybrid IEC-DEC-VCAC system. The hybrid IEC-DEC-VCAC system achieved maximum temperature gradient (21 °C) and relatively less CO2 emissions as compared to standalone VCAC. In addition, it provided maximum cooling capacity (184 kW for work input of 100 kW), which is 85% higher than the standalone DEC system. Furthermore, it achieved neutral to slightly cool human thermal comfort i.e., 0 to −1 predicted mean vote and 30% of predicted percentage dissatisfied. Thus, the study concludes the hybrid IEC-DEC-VCAC as an optimum configuration for building AC in Multan.

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Low, Audrey, Levinia Lim, Linda Lim, Benjamin Wong, Eveline Silva, Kok Pin Ng e Nagaendran Kandiah. "Construct validity of the Visual Cognitive Assessment Test (VCAT)—a cross-cultural language-neutral cognitive screening tool". International Psychogeriatrics 32, n. 1 (21 maggio 2019): 141–49. http://dx.doi.org/10.1017/s1041610219000504.

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ABSTRACTBackground:The Visual Cognitive Assessment Test (VCAT) is a language-neutral cognitive screening tool designed for use in culturally diverse populations without the need for translations or adaptations. While it has been established to be language-neutral, the VCAT’s construct validity has not been investigated.Methods:471 participants were recruited, comprising 233 healthy comparisons, 117 mild cognitive impairment (MCI), and 121 mild Alzheimer’s disease (AD) patients. VCAT and domain-specific neuropsychological tests were administered in the same sitting. Construct validity was assessed by analyzing domain-specific associations between the VCAT and well-established cognitive assessments. Reliability (internal consistency) was measured by Cronbach’s alpha. Diagnostic ability (area under the curve) and recommended cutoffs were determined by receiver operating characteristic (ROC) analysis.Results:The VCAT and its subdomains demonstrated good construct validity in terms of both convergent and divergent validity and good internal consistency (α = .74). ROC analysis found that the VCAT was on par with the Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) at distinguishing between healthy comparisons, MCI, and mild AD. Consistent with previous studies, VCAT scores were not affected by language of administration or ethnicity in our cohort. Findings suggest the following cutoffs: Dementia 0–19, MCI 20–24, Normal 25–30.Conclusion:This study established the construct validity of the VCAT, which is vital to ensure its subdomains effectively measure the cognitive processes they were designed to. The VCAT is capable of detecting early cognitive impairments and allows for meaningful cross-cultural comparisons, especially useful for international collaborations and clinical trials, and for clinical use in diverse multiethnic populations.

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Ng, Li Yun, Chen Joo Chin, Monica Danial, Stephenie Ann Albart, Purnima Devi Suppiah, Kurubaran Ganasegeran, Wei Theng Tan et al. "Validation of the Visual Cognitive Assessment Test (VCAT) for the Early Diagnosis of Cognitive Impairment in Multilingual Population in Malaysia". Psych 4, n. 1 (1 gennaio 2022): 38–48. http://dx.doi.org/10.3390/psych4010003.

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As Malaysia undergoes a demographic transformation of population aging, the prevalence of dementia is expected to rise, posing a major public health threat issue. Early screening to detect cognitive impairment is important to implement appropriate clinical interventions. The Visual Cognitive Assessment Test (VCAT) is a language-neutral cognitive assessment screening tool suitable for multilingual populations. This study was aimed to validate the VCAT screening tool for the detection of cognitive impairment amongst the population of Malaysia. A total of 184 participants were recruited, comprising 79 cognitively healthy participants (CHP), 46 mild cognitive impairment (MCI) patients, and 59 mild dementia (Alzheimer’s disease and Vascular Dementia) patients from five hospitals between May 2018 and December 2019 to determine the usefulness of VCAT. Diagnostic performance was assessed using area under the curve (AUC), and receiver operating characteristic (ROC) analysies was performed to determine the recommended cutoff scores. ROC analyses for the VCAT was comparable with that of MoCA (Montreal Cognitive Assessment) in differentiating between CHP, MCI, and mild dementia (AD and VaD) participants. The findings of this study suggest the following optimal cutoff score for VCAT: Dementia 0–19, MCI 20–23, Normal 24–30. The mean ± SD time to complete the VCAT was 10.0 ± 2.75 min in the CHP group and 15.4 ± 4.52 min in the CI group. Results showed that 76.0% of subjects thought that the instructions in VCAT were similar or easier to understand compared with MoCA. This study showed that the VCAT is a valid and useful screening tool for patients with cognitive impairment in Malaysia and is feasible to be used in the clinical settings.

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Yozgat, Can Yilmaz, Yanki Celik Yilmazer e Yilmaz Yozgat. "Pulmonary Atresia with Intact Ventricular Septum associated with Ventriculo-Coronary Arterial Communication in a Fetus at 21 Weeks of Gestation". Case Reports in Obstetrics and Gynecology 2020 (15 luglio 2020): 1–3. http://dx.doi.org/10.1155/2020/7581483.

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Pulmonary atresia with the intact ventricular septum (PA-IVS) is a rare anomaly that has an absent communication between the right ventricle and pulmonary arterial circulation. PA-IVS has a hypoplastic and hypokinetic and thickened right ventricle with the intact ventricular septum. It can be diagnosed with PA-IVS in routine obstetric ultrasound examination because the four-chamber view of PA-IVS is generally abnormal. The size of the right ventricular cavity is proportional to the Z value of the diameter of the tricuspid valve. The essential associated cardiac finding of PA-IVS is ventricular-coronary arterial communications (VCAC). The hypertensive RV forces blood through the intramyocardial sinusoids with continuous fistulous contact with the epicardial branches of RCA. It is called the VCAC. A color Doppler can detect VCAC due to its location in the pericardium along the coronary artery. If patients have VCAC and tricuspid Z score below -4, all of these conditions are infallible signs of high mortality rates in their fetal or postnatal lives. Our aim in presenting this case is to remind perinatologists if they detect an abnormal four-chamber view of the fetus’s heart, they should also carefully examine whether VCAC exists. Herein, we report a case of PA-IVS and VCAC at 21 weeks’ gestation with fetal echocardiographic images.

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Yulisa, Arma, Joonyeob Lee, Sang Hyeok Park e Seokhwan Hwang. "Simultaneous effect of cathode potentials and magnetite concentrations on methanogenesis of acetic acid under different ammonia conditions". Environmental Engineering Research 27, n. 6 (29 novembre 2021): 210317–0. http://dx.doi.org/10.4491/eer.2021.317.

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Electromethanogenesis (EM) is a system that facilitates direct interspecies electron transfer (DIET) in anaerobic digestion (AD) by providing an external power supply to favor desired reactions. Substrates of AD commonly contain ammonia (NH3) as biodegradation product of nitrogen-rich compounds that can deteriorate the stability of AD process. Optimized cathode potential (VCAT) and magnetite (Mag) concentration ([Mag]) are expected to improve AD efficiency in the presence of NH3. Response surface analysis with central composite face-centered design was used in this study to investigate the effect of VCAT and [Mag] under different total ammonia nitrogen concentration ([TAN]). Highest cumulative methane production was achieved at VCAT = -737.4 mV, [Mag] = 18.2 mM, and [TAN] = 1.5 g/L; highest acetate degradation rate was achieved at VCAT = 757.6 mV, [Mag] = 21.4 mM, and [TAN] = 1.5 g/L. The study demonstrated that VCAT promotes either microbial growth or electrochemical NH3 removal. A Shift from acetoclastic to hydrogenotrophic pathway was also observed by the increase of hydrogenotrophic methanogen populations at the end of experiment. This study is beneficial for process control of AD under different NH3 conditions.

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Manke, Sunanda, Kavita Khare e S. D. Sapre. "VCAT synchroniser-reduction of buffer size in VCAT enabled next generation SDH networks". European Transactions on Telecommunications 22, n. 8 (1 settembre 2011): 500–514. http://dx.doi.org/10.1002/ett.1500.

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Liu, Bing, Jie Meng, Zhen Yang, Ying Wang, Hua Zhi Xie, Wen Chao Zhang, Cheng Ming He e Xiang Yang Deng. "Exploration of the Relationship of the Voltage Critical Clearing Time and the Voltage Transient Transmission Capacity". Applied Mechanics and Materials 488-489 (gennaio 2014): 905–9. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.905.

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Both the voltage critical clearing time (VCCT) and the voltage transient transmission capacity (VTTC) are always used to evaluate the stability of the system transient voltage, and their relationships are studied and clarified in the paper. The stability of the transient voltage is mainly depended on the dynamic reactive characteristics of load and the transmission characteristics of voltage and power. Based on the analysis on the dynamic reactive characteristics of load and the transmission characteristics of a power transmission network, the characteristics of the VCCT and the VTTC are studied in this paper. Finally, a conclusion, i.e. the margin of the VCCT and the VTTC has a nonlinear characteristic, is obtained by simulations on the actual power grid. According to the conclusion, the voltage stability cannot be exactly reflected by the VCCT margin.

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Krscanski, Sanjin, e Josip Brnic. "Prediction of Fatigue Crack Growth in Metallic Specimens under Constant Amplitude Loading Using Virtual Crack Closure and Forman Model". Metals 10, n. 7 (20 luglio 2020): 977. http://dx.doi.org/10.3390/met10070977.

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This paper considers the applicability of virtual crack closure technique (VCCT) for calculation of stress intensity factor range for crack propagation in standard metal specimen geometries with sharp through thickness cracks. To determine crack propagation rate and fatigue lifetime of a dynamically loaded metallic specimen, in addition to VCCT, standard Forman model was used. Values of stress intensity factor (SIF) ranges ΔK for various crack lengths were calculated by VCCT and used in conjunction with material parameters available from several research papers. VCCT was chosen as a method of choice for the calculation of stress intensity factor of a crack as it is simple and relatively straightforward to implement. It is relatively easy for implementation on top of any finite element (FE) code and it does not require the use of any special finite elements. It is usually utilized for fracture analysis of brittle materials when plastic dissipation is negligible, i.e., plastic dissipation belongs to small-scale yielding due to low load on a structural element. Obtained results showed that the application of VCCT yields good results. Results for crack propagation rate and total lifetime for three test cases were compared to available experimental data and showed satisfactory correlation.

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Bernstein, G., D. Caviglia, R. Rabbat e H. Van Helvoort. "VCAT-LCAS in a clamshell". IEEE Communications Magazine 44, n. 5 (maggio 2006): 34–36. http://dx.doi.org/10.1109/mcom.2006.1637944.

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Più fonti

Tesi sul tema "Vcact"

Bellomo, Vito. "Damage tolerance analysis for Blackshape BS 115 programme, EASA CS VLA & CS-23". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8070/.

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The thesis project has been developed in partnership with the Design Department of Blackshape Spa, a carbon – fiber ultra – light airplane company in Monopoli (Bari, Italy). The main goal is the assessment of a starting point for a damage tolerant concept during the design and certification phases of the Blackshape BS 115 airplane, with respect to EASA CS VLA & CS 23 Regulations. This approach has been carried out starting from an initial literary review as far as the way of modeling composites fractures is concerned. Further on, three finite element models have been generated and implemented in order to simulate defects occurring during manufacturing and service phases. At last, the procedures of non - destructive inspections have been taken into account, in order to establish how to investigate primary structures defects and delaminations during maintenance.

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Mikulik, Zoltan Mechanical &amp Manufacturing Engineering Faculty of Engineering UNSW. "Application of fracture mechanics to predict the growth of single and multi-level delaminations and disbonds in composite structures". Publisher:University of New South Wales. Mechanical & Manufacturing Engineering, 2008. http://handle.unsw.edu.au/1959.4/41560.

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The high stiffness to weight ratio and fatigue resistance make carbon fibre composites suitable for both military and large civil aircraft. The limited ability of current numerical methods to capture the complex growth of damage in laminated composites leads to a conservative design approach applied in today??s composite aircraft structures. The aim of the presented research was to develop an improved methodology for the failure prediction of laminated composites containing delaminations located between arbitrary layers in the laminate, and to extend the investigations to composite structures subjected to barely visible impact damage (BVID). The advantages of fracture mechanics-based methodologies to predict interlaminar failure in composite structures were identified, from which the crack tip element (CTE) approach and the virtual crack closure technique (VCCT) were selected for assessment. Extensive validation of these fracture mechanics methods is presented on a number of composite structures ranging from coupons to large stiffened panels. It was shown that the VCCT was relatively insensitive to the crack front mesh size, whilst predictions using the CTE methodology were significantly influenced by the element size. Based on the obtained results modelling guidelines for the VCCT and CTE were established. Significant contribution of this research to the field of the analysis of composite structures was the development of a novel test method for the evaluation of embedded single and multi-level delaminations. The test procedure of the single delamination specimen was proposed as an analogous test to conventional compression experiments. The transverse test overcame the inherent problems of in-plane compression testing and produced less scatter of experimental measurements. Quantitative analysis of numerical results employing the validated finite element modelling approaches showed that the failure load and location were in agreement with experiments. Furthermore, new modelling techniques for composite structures containing BVID proposed in this research produced good correlation with test data from the compression after impact (CAI) test. The study of BVID provided a significant contribution toward the knowledge of the applicability of implicit FE solvers to predict failure of CAI specimens as well as the criticality of centrally impacted specimens.

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Ozcan, Riza. "Fatigue And Fracture Analysis Of Helicopter Fuselage Structures". Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615497/index.pdf.

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In this study a methodology is developed for the fatigue and fracture analysis of helicopter fuselage structures, which are considered as the stiffened panels. The damage tolerance behavior of the stiffened panels multiaxially loaded is investigated by implementing virtual crack closure technique (VCCT). Validation of VCCT is done through comparison between numerical analysis and the studies from literature, which consists of stiffened panels uniaxially loaded and the panel with an inclined crack. A program based on Fortran programming language is developed to automate the crack growth analysis under mixed mode conditions. The program integrates the prediction of the change in crack propagation direction by maximum circumferential stress criterion and the computation of energy release rate by VCCT. It allows reducing the computation time for damage tolerance evaluation for mixed mode cases through finite element analysis and runs the procedure file of MSC.Marc/Mentat for numerical analysis and the program generated by Patran Command Language (PCL) of MSC.Patran for remeshing. The developed code is verified by comparing the crack growth trajectories obtained by numerical analysis with the experimental studies from literature. A submodeling technique is utilized to analyze a particular fuselage portion of helicopter tail boom. Effects of different skin/stringer configurations of the helicopter fuselage structure on stress intensity factor are studied by means of the developed program. Fatigue crack growth analysis is performed by using stress intensity factors obtained from numerical analysis and fatigue propagation models proposed in literature.

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Durand, Camille. "Etude thermomécanique expérimentale et numérique d'un module d'électronique de puissance soumis à des cycles actifs de puissance". Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0007/document.

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De nos jours, la durée de vie des modules d’électronique de puissance est désormais limitée par les technologies standards de conditionnement, telles que le câblage par fils et le brasage. Ainsi une optimisation des technologies actuellement employées n’est pas suffisante pour satisfaire les futures exigences de fiabilité. Pour dépasser ces limites, un nouveau module de puissance remplaçant les fils de connexion par des clips en cuivre a été développé. Ce design innovant vise à améliorer la fiabilité du module puisqu’il empêche la dégradation des fils de connexion, constituant bien souvent la principale source de défaillance. La contrepartie de ce gain de fiabilité réside dans la complexification de la structure interne du module. En effet, l’emploi d’un clip en cuivre nécessite une brasure supplémentaire fixant le clip à la puce. Ainsi, le comportement thermomécanique et les différents modes de rupture auxquels le composant est soumis lors de son utilisation doivent être caractérisés. Cette étude utilise la simulation numérique pour analyser avec précision le comportement de chaque couche de matériaux lors des cycles actifs de puissance. De plus, une étude de sensibilité à la fois expérimentale et numérique concernant les paramètres de tests est réalisée. Les zones critiques du module ainsi que les combinaisons critiques des paramètres de tests pour les différents modes de rupture sont mis en évidence. Par ailleurs, une analyse en mécanique de la rupture est conduite et la propagation des fissures à différentes zones clés est analysée en fonction des différents paramètres de tests. Les résultats obtenus permettent la définition de modèles de prédiction de durée de vie
Today a point has been reached where safe operation areas and lifetimes of power modules are limited by the standard packaging technologies, such as wire bonding and soft soldering. As a result, further optimization of used technologies will no longer be sufficient to meet future reliability requirements. To surpass these limits, a new power module was designed using Cu clips as interconnects instead of Al wire bonds. This new design should improve the reliability of the module as it avoids wire bond fatigue failures, often the root cause of device failures. The counterpart for an improved reliability is a quite complicated internal structure. Indeed, the use of a Cu clip implies an additional solder layer in order to fix the clip to the die. The thermo-mechanical behavior and failure mechanisms of such a package under application have to be characterized. The present study takes advantage of numerical simulations to precisely analyze the behavior of each material layer under power cycling. Furthermore an experimental and numerical sensitivity study on tests parameters is conducted. Critical regions of the module are pointed out and critical combinations of tests parameters for different failure mechanisms are highlighted. Then a fracture mechanics analysis is performed and the crack growth at different locations is analyzed in function of different tests parameters. Results obtained enable the definition of lifetime prediction models

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HASANI, NAJAFABADI SEYED HUSEIN. "Numerical-Experimental Assessment of Stress Intensity Factors in Ultrasonic Very-High-Cycle Fatigue". Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2712549.

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The continuous enhancement of reliability and durability requirements for many machinery components is significantly pushing the experimental research on the Very-High-Cycle Fatigue (VHCF) response of metallic materials. In order to significantly reduce testing time, ultrasonic testing machines are widely adopted when carrying out VHCF tests. In the VHCF literature, the critical Stress Intensity Factor (SIF) is estimated by applying analytical SIF formulations to the typical semi-circular surface crack geometry revealed by fracture surfaces at final failure. However, when subjected to ultrasonic VHCF tests, analytical SIF formulations valid for static loading conditions could eventually lead to significant estimation errors. The correct computation of the SIF in ultrasonic VHCF loading conditions is a key issue when investigating the crack growth rate curve with pre-cracked specimens or when evaluating critical SIF values from fracture surfaces of failed specimens. Dynamic conditions related to the resonance of the vibrating specimen, contact nonlinearity between crack faces and stress singularity at the crack tip make the SIF computation difficult and cumbersome. Numerical computation through Finite Element Models under non-linear dynamic conditions makes use of direct integration methods (implicit or explicit). However, in the high-frequency regime of ultrasonic VHCF tests, the procedure may lead to unacceptable computational time. The present thesis aims at finding a robust, accurate, and simple method to calculate the critical SIF at final failure fracture of VHCF samples. In order to cope with the inefficiency of the time domain direct integration method, frequency domain analysis, and Multi Harmonic Balance Method were employed in this thesis. Even though the frequency domain analysis significantly reduced the computational time the overall reduction was still considered insufficient. Hence, reduction techniques via Reduce Order Modeling were also applied to decrease the total number of degrees of freedom for the system. The solution obtained with the ABAQUS implicit solver was employed to verify the proposed hybrid technique. Results showed that the present method can accurately predict the displacement field and the SIF together with a drastic decrease of the computational time. The proposed method was then applied to two models based on real sample geometries (Hourglass and Gaussian samples failed under ultrasonic VHCF) in order to evaluate the effect of the geometry on the critical SIF value. Results calculated by classical solutions valid for static conditions were also compared with the results obtained with the proposed hybrid method. The comparison showed that conventional static solutions for SIFs could not be used to compute SIF values in ultrasonic conditions since computational errors are significant. Another important finding was that, for the Gaussian sample, the SIF in both loading conditions (static and dynamic) is smaller than that for the Hourglass sample. The difference in static conditions is considerable and larger than that in dynamic conditions. Besides the efficient and accurate computation of the critical SIF values from samples failed under ultrasonic VHCF tests, the proposed method can also be used: i) to design fatigue crack growth samples for investigating the near-threshold region with ultrasonic testing machines; ii) to accurately evaluate the SIF at the border of the relevant crack growth zones in ultrasonic VHCF (e.g., at the border of the fisheye and of the Fine Granular Area).

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Islam, Mohammad Majharul. "Global-local Finite Element Fracture Analysis of Curvilinearly Stiffened Panels and Adhesive Joints". Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/38687.

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Global-local finite element analyses were used to study the damage tolerance of curvilinearly stiffened panels; fabricated using the modern additive manufacturing process, the so-called unitized structures, and that of adhesive joints. A damage tolerance study of the unitized structures requires cracks to be defined in the vicinity of the critical stress zone. With the damage tolerance study of unitized structures as the focus, responses of curvilinearly stiffened panels to the combined shear and compression loadings were studied for different stiffenersâ height. It was observed that the magnitude of the minimum principal stress in the panel was larger than the magnitudes of the maximum principal and von Mises stresses. It was also observed that the critical buckling load factor increased significantly with the increase of stiffenersâ height. To study the damage tolerance of curvilinearly stiffened panels, in the first step, buckling analysis of panels was performed to determine whether panels satisfied the buckling constraint. In the second step, stress distributions of the panel were analyzed to determine the location of the critical stress under the combined shear and compression loadings. Then, the fracture analysis of the curvilinearly stiffened panel with a crack of size 1.45 mm defined at the location of the critical stress, which was the common location with the maximum magnitude of the principal stresses and von Mises stress, was performed under combined shear and tensile loadings. This crack size was used because of the requirement of a sufficiently small crack, if the crack is in the vicinity of any stress raiser. A mesh sensitivity analysis was performed to validate the choice of the mesh density near the crack tip. All analyses were performed using global-local finite element method using MSC. Marc, and global finite element methods using MSC. Marc and ABAQUS. Negligible difference in results and 94% saving in the CPU time was achieved using the global-local finite element method over the global finite element method by using a mesh density of 8.4 element/mm ahead of the crack tip. To study the influence of different loads on basic modes of fracture, the shear and normal (tensile) loads were varied differently. It was observed that the case with the fixed shear load but variable normal loads and the case with the fixed normal load but variable shear loads were Mode-I. Under the maximum combined loading condition, the largest effective stress intensity factor was very smaller than the critical stress intensity factor. Therefore, considering the critical stress intensity factor of the panel with the crack of size 1.45 mm, the design of the stiffened panel was an optimum design satisfying damage tolerance constraints. To acquire the trends in stress intensity factors for different crack lengths under different loadings, fracture analyses of curvilinearly stiffened panels with different crack lengths were performed by using a global-local finite element method under three different load cases: a) a shear load, b) a normal load, and c) a combined shear and normal loads. It was observed that 85% data storage space and the same amount in CPU time requirement could be saved using global-local finite element method compared to the standard global finite element analysis. It was also observed that the fracture mode in panels with different crack lengths was essentially Mode-I under the normal load case; Mode-II under the shear load case; and again Mode-I under the combined load case. Under the combined loading condition, the largest effective stress intensity factor of the panel with a crack of recommended size, if the crack is not in the vicinity of any stress raiser, was very smaller than the critical stress intensity factor. This work also includes the performance evaluation of adhesive joints of two different materials. This research was motivated by our experience of an adhesive joint failure on a test-fixture that we used to experimentally validate the design of stiffened panels under a compression-shear load. In the test-fixture, steel tabs were adhesively bonded to an aluminum panel and this adhesive joint debonded before design loads on the test panel were fully applied. Therefore, the requirement of studying behavior of adhesive joints for assembling dissimilar materials was found to be necessary. To determine the failure load responsible for debonding of adhesive joints of two dissimilar materials, stress distributions in adhesive joints of the nonlinear finite element model of the test-fixture were studied under a gradually increasing compression-shear load. Since the design of the combined load test fixture was for transferring the in-plane shear and compression loads to the panel, in-plane loads might have been responsible for the debonding of the steel tabs, which was similar to the results obtained from the nonlinear finite element analysis of the combined load test fixture. Then, fundamental studies were performed on the three-dimensional finite element models of adhesive lap joints and the Asymmetric Double Cantilever Beam (ADCB) joints for shear and peel deformations subjected to a loading similar to the in-plane loading conditions in the test-fixtures. The analysis was performed using ABAQUS, and the cohesive zone modeling was used to study the debonding growth. It was observed that the stronger adhesive joints could be obtained using the tougher adhesive and thicker adherends. The effect of end constraints on the fracture resistance of the ADCB specimen under compression was also investigated. The numerical observations showed that the delamination for the fixed end ADCB joints was more gradual than for the free end ADCB joints. Finally, both the crack propagation and the characteristics of adhesive joints were studied using a global-local finite element method. Three cases were studied using the proposed global-local finite element method: a) adhesively bonded Double Cantilever Beam (DCB), b) an adhesive lap joint, and c) a three-point bending test specimen. Using global-local methods, in a crack propagation problem of an adhesively bonded DCB, more than 80% data storage space and more than 65% CPU time requirement could be saved. In the adhesive lap joints, around 70% data storage space and 70% CPU time requirement could be saved using the global-local method. For the three-point bending test specimen case, more than 90% for both data storage space and CPU time requirement could be saved using the global-local method.
Ph. D.

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Jun-YouPan e 潘均祐. "The Development, Design and Demonstration of Vacuum Cathode Arc Thruster (VCAT)". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/a87z53.

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Libri sul tema "Vcact"

Pizer, Jason. Pizer's annotated VCAT Act. Pyrmont, N.S.W: Lawbook Co., 2001.

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Tarlow, David M. VCAT: Veterinary college admission test. St. Louis, Mo: Educational Testing Consultants, 2002.

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Vcat-Veterinary College Admissions Test. Datar Pub Co, 1999.

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VCAT: Veterinary College Admission Test. St. Louis: Educational Testing Consultants, 1997.

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Veterinary College Admission Test (VCAT). National Learning Corporation, 2018.

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VMware VCloud Architecture Toolkit vCAT. Pearson Education (US), 2013.

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Alpacas, by Lemarli. Dead Baby Alpaca Goes to VCAT. Blurb, 2012.

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Tarlow, David M. Veterinary College Admission Test (Vcat) - Core Content. Educational Testing Consultants, Inc., 1996.

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Tarlow, David M. Vcat Exam 1 (Veterinary College Admission Test). 7^a ed. Datar Pub Co, 1996.

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Tarlow, David M. Practice Examination #2: Veterinary College Admissions Test Vcat. Datar Pub Co, 1994.

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Capitoli di libri sul tema "Vcact"

Kim, T. W., H. Y. Jeong, J. H. Choe e Y. H. Kim. "Prediction of the Fatigue Life of Tires Using CED and VCCT". In Key Engineering Materials, 102–7. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-978-4.102.

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Keene, Alex Ruck, e Mary Sealy. "Australia—Victoria". In The International Protection of Adults. Oxford University Press, 2015. http://dx.doi.org/10.1093/9780198727255.003.0032.

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Australia is a common law country. Australia is a federation of five states and two territories. Laws affecting adults in need of protection are generally made at state level. In Victoria, adult protection matters are decided by the Victorian Civil and Administrative Tribunal (‘VCAT’) in its Guardianship List. VCAT is the lowest court body—with Magistrates, County, and Supreme Court the hierarchy within the state. The High Court of Australia is the highest appellate court.

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Tschida, Christina M., Jennifer L. Gallagher, Kimberly L. Anderson, Caitlin L. Ryan, Joy N. Stapleton e Karen D. Jones. "Using Video Capture and Annotation Technology to Strengthen Reflective Practices and Feedback in Educator Preparation". In Advances in Early Childhood and K-12 Education, 314–32. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-8009-6.ch015.

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In this chapter, the authors share the history of a video capture and annotation technology (VCAT) implementation and provide summaries of research findings to support its continued use and refinement. They also detail the multiple uses and particular objectives they aimed to meet with the technology across different content areas and even across multiple educator preparation programs, including a collaboration between a teacher education program and principal preparation program that was enabled by the technology.

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de Jesus, A., e J. Correia. "Stress intensity factors evaluation for riveted beams applying FEA with VCCT". In Bridge Maintenance, Safety, Management and Life-Cycle Optimization, 613. CRC Press, 2010. http://dx.doi.org/10.1201/b10430-480.

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Atti di convegni sul tema "Vcact"

Carmagnola, Francesca, Andrea Loffredo e Giorgio Berardi. "Vcast on facebook". In the 20th ACM conference. New York, New York, USA: ACM Press, 2009. http://dx.doi.org/10.1145/1557914.1557972.

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"VCACS 2016 organizers". In 2016 IEEE Virtual Conference on Applications of Commercial Sensors (VCACS). IEEE, 2016. http://dx.doi.org/10.1109/vcacs.2016.7888782.

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Xu, Meng, Linh Thi, Xuan Phan, Hyon-Young Choi e Insup Lee. "vCAT: Dynamic Cache Management Using CAT Virtualization". In 2017 IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS). IEEE, 2017. http://dx.doi.org/10.1109/rtas.2017.15.

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KRUEGER, RONALD, e NELSON V. DE CARVALHO. "DEVELOPMENT OF A C-ELS SPECIMEN-BASED NUMERICAL BENCHMARK FOR MODE II DELAMINATION AND ASSESSMENT OF TWO VCCT-BASED PROPAGATION STRATEGIES". In Proceedings for the American Society for Composites-Thirty Seventh Technical Conference. Destech Publications, Inc., 2022. http://dx.doi.org/10.12783/asc37/36366.

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A finite element (FE) benchmark example inspired by the calibrated end-loaded split (C-ELS) specimen is developed and used to assess the performance of delamination propagation capabilities based on linear elastic fracture mechanics (LEFM). The C-ELS specimen has the advantage of a longer region of stable delamination propagation compared to the existing mode II benchmark case. The new benchmark example may therefore provide a better assessment tool by enabling more stable crack growth in regions further away from the boundary conditions or load application. First, a benchmark result is created manually using two-dimensional finite element models of the C-ELS specimen with different delamination lengths. Second, the performance of the virtual crack closure technique (VCCT) delamination propagation capabilities in the Abaqus/Standard®1 FE code and the recently developed Progressive Release eXplicit-VCCT (PRX-VCCT) method are assessed by comparing the results to the benchmark case. Two examples with different starter delamination lengths are studied. A shorter starter length is chosen to create a scenario with unstable delamination propagation. A longer delamination encourages stable delamination propagation. Detailed results from three-dimensional analyses with aligned and misaligned meshes and two levels of mesh refinement are provided. In general, good agreement can be achieved between the results obtained from the quasi-static propagation analysis and the benchmark analysis. Numerical artifacts including anomalous unreleased nodes in the crack wake and zig-zag crack fronts occur for propagation analyses using Abaqus/Standard VCCT. In comparison, continuous, smooth, delamination fronts are observed for PRX-VCCT. The use of the benchmark case to assess different VCCT-based propagation strategies illustrates the value of establishing benchmark cases.

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DRAKE, DANIEL A., NELSON VIEIRA DE CARVALHO e ANDREW E. LOVEJOY. "REDUCTION IN COMPUTATIONAL COST OF PROGRESSIVE FAILURE ANALYSIS". In Proceedings for the American Society for Composites-Thirty Eighth Technical Conference. Destech Publications, Inc., 2023. http://dx.doi.org/10.12783/asc38/36515.

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Designing aircraft structures requires efficient modeling approaches to iterate on multiple structural configurations to achieve an optimal design. Typically, damage tolerance is not considered at the design stage because of the high computational cost in its implementation within a finite element modeling approach. Therefore, analytical or empirical approaches are often used to size critical damage-tolerant structures once an optimal design is determined. In this study, the Progressive Release eXplicit Virtual Crack-Closure Technique (PRX-VCCT) is assessed for its capability to costeffectively evaluate skin-stringer separation of a blade-stiffened panel that is subjected to seven-point bend loads. An initial verification study was performed to evaluate PRX-VCCT to accurately simulate skin-stringer separation with respect to existing cohesive element approaches. Furthermore, the influence of element size, ranging from 0.10 in. to 0.40 in., on the total computational time using the PRX-VCCT is investigated. The results indicate that the PRX-VCCT can be used to accurately simulate skin-stringer separation using large element lengths (0.40 in.). Additionally, a significant reduction in the computational time to simulate skin-stringer separation is observed using the PRX-VCCT. Large-scale progressive damage analysis using PRXVCCT can be implemented early in the design cycle of composite structures without requiring a global-to-local modeling approach. DANIEL A. DRAKE

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Gao, Jianhua, e Dan Li. "BoD Service with VCAT/LCAS and GMPLS Signalling". In NOMS 2008 - 2008 IEEE Network Operations and Management Symposium Workshop. IEEE, 2008. http://dx.doi.org/10.1109/nomsw.2007.35.

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Alicherry, M., C. Phadke e V. Poosala. "Delay distributed VCAT for efficient data-optical transport". In 2005 Optical Fiber Communications Conference Technical Digest. IEEE, 2005. http://dx.doi.org/10.1109/ofc.2005.193009.

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Mate, Tamas, e Peter T. Zwierczyk. "A VCCT Approach Of Crack Propagation In Railway Wheels". In 34th International ECMS Conference on Modelling and Simulation. ECMS, 2020. http://dx.doi.org/10.7148/2020-0266.

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"The Delamination Study of Laminated Composites with XFEM/VCCT". In 2018 3rd International Conference on Materials Science, Machinery and Energy Engineering. Clausius Scientific Press, 2018. http://dx.doi.org/10.23977/msmee.2018.72127.

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Wang, Peng, Jishi Li, Depeng Jin e Lieguang Zeng. "Towards more practical LCAS for VCAT in MSTP ASIC". In Asia-Pacific Optical Communications, a cura di Kwok-wai Cheung, Gee-Kung Chang, Guangcheng Li e Ken-Ichi Sato. SPIE, 2005. http://dx.doi.org/10.1117/12.631519.

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Rapporti di organizzazioni sul tema "Vcact"

Cleland, Timothy J., David W. Forslund e Catherine A. Cleland. VCAT: Visual Crosswalk Analysis Tool. Office of Scientific and Technical Information (OSTI), agosto 2012. http://dx.doi.org/10.2172/1050471.

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Caviglia, D., R. Rabbat e H. van. Operating Virtual Concatenation (VCAT) and the Link Capacity Adjustment Scheme (LCAS) with Generalized Multi-Protocol Label Switching (GMPLS). A cura di G. Bernstein. RFC Editor, agosto 2011. http://dx.doi.org/10.17487/rfc6344.

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