This study introduces a novel authentication methodology; it is based on pattern recognition of fingers size and pressure when users touch smartphone screen. By analyzing diagrams of these touches ...and applying data mining for the first time as an authentication technique, this paper presents three new approaches. First, an exact-range evaluation approach has been verified that size is more recognition consistency than pressure. Second, a pattern-range is a new technique reliance on size frequency position. At last, using a size-range has been facilitated the login. The association rules have been modified to work on finger touchscreen data files. To login, 94.1111% of 18 authorized users are succeeded and 98.9% of 20 unauthorized users are failed. Android device and Android studio are used. Size and pressure are normalized to 1; a training set is applied; the password is not considered.
Understanding postgraduate students' university choice criteria is essential for developing marketing strategies in higher education settings. The purpose of this study was to investigate ...postgraduate students’ perceptions in terms of their university choice decisions and evaluates the correlation between their personal and social support factors and university choice decisions. A questionnaire survey was disseminated to 401 postgraduate students from five member universities of Vietnam National University Ho Chi Minh City, Vietnam. The findings revealed that rated a fairly high degree of agreement on university choice decisions and demographic characteristics differences exist regarding their choice (such as living place, registration level, university studies, and Admission methods). In addition, the findings also found that personal and social support factors had a statistically significant impact on their university choice decisions. The findings of this study carry both theoretical and practical implications for Vietnamese higher education. The suggestions inferred from university managers and other stakeholders are also discussed.
This article proposes a method for the justified choice of the fixing method, the type of supports and their stiffness for flat beam structures of an axisymmetric cross section in order to ensure the ...specified values of the first frequency of natural bending vibrations and the first critical load, by taking into account the action of longitudinal forces and temperature changes. The technique is based on the well-known provisions of the theory of beam oscillations, the Euler’s theory of stability, and uses the coefficients of supports as a criterion for choosing a fixing method, which are pre-normalized to achieve comparable values. The selected fixing provides the specified value of the first natural oscillation frequency, the value of the first critical temperature, or simultaneously both conditions of working efficiency. According to the developed method, comparative calculations of a flat bar structure using the finite element method have been performed. They has shown good convergence of the results for all controlled parameters. The proposed approach can be used in the design of support fixing of flat beam structures for various purposes to ensure their dynamic behavior.
This study aimed to investigate factors influencing building consumers' initial trust in e-commerce in Ethiopia. Mizan-Tepi University academic staffs were chosen as the population for this study. A ...quantitative research approach with an explanatory research design was employed. All the independent variables used in the research were formulated based on the extant literature review, and initial trust in e-commerce adoption used as an outcome variable. A total of 130 usable questionnaires collected from respondents using a convenience sampling method and the data were analyzed using SPSS version 23 software. The results show that website design quality, security and reputation, purchase characteristics and advertising factor positively contributes to consumers trust in e-commerce. Diversely, the purchase characteristics and support factors have no significant effect on consumers’ initial trust in e-commerce. Thus, it is essential that managers and owners of shopping websites need to consider these effective initial trust-building factors in e-commerce adoption.
This work presents new insights about how solutions of support factor‐based rectangular packings behave in relation to their static stability. In particular, we address the constrained ...two‐dimensional packing problem, for the solution of which is used a known integer linear programming model that positions items over a grid of points. The model has embedded constraints based on a support factor parameter that ensure a minimum support for the base of items. The solutions obtained from the model are then evaluated by a procedure that verifies the conditions for the static stability. Computational tests were performed on a large variety of randomly generated instances, and the outputs were assessed by means of regression analysis (linear and logistic). The results show which characteristics of the instances contribute directly and inversely to the probability of obtaining statically stable packing patterns. This outcome may be useful to guide the choice of support factor values in some practical contexts.
The fatigue properties and cyclic deformation behaviour of materials are usually determined using cylindrical specimens (e.g., Ø7.5 mm). Since the transferability to very small dimensions has not ...been comprehensively considered so far, this study investigates the transferability of specimen data from high-strength steel X5CrNiCuNb16-4 to real structures characterised by a wall thickness of 100 µm. Regarding fatigue, extensive calculations demonstrate that for notched specimens and thin structures, both the material-mechanical support factor concept according to the FKM guideline and the point method of the Theory of Critical Distance (TCD) make correct predictions of the local fatigue strength, with a maximum deviation from experimental values of less than 5%. However, the study points out that the TCD is only conditionally applicable for thin-walled structures, as the material parameter a0 must be significantly smaller than the wall thickness. Regarding the deformation behaviour, the material reveals special flow characteristics in the first hysteresis. Nevertheless, a combined hardening approach is suitable for modelling. The validation of the model by a plastic deformation of the structure seems plausible, although geometric influences prove to be dominant. In conclusion, even 100 µm thin structures can be evaluated using conventional specimen tests and established assessment or modelling methods.
•Design S–N curves for machined low alloy steel forgings are presented.•The S–N curve is selected based on the tensile strength and the surface roughness.•A method for adjusting the peak stress in ...the notch root is presented.•Fatigue life estimates are compared with fatigue test results for notched specimens.
Design S–N curves are presented for low alloy machined steel forgings. Separate S–N curves are given for air and for seawater with cathodic protection. The selection of the S–N curve is made based on the tensile strength and the surface roughness. S–N curves for four tensile strength classes and two surface roughness classes are given. The tensile strength classes cover steels with a tensile strength in the range of 517–793MPa. The two surface roughness classes cover surface roughnesses up to Ra=6.3μm. Separate S–N curves are given for a stress ratio of R=0 and for a high mean tensile stress. Secondly, a method for adjusting the peak stress in the notch root with respect to the stress gradient is presented. The stress gradient corrected peak stress is used with the presented S–N curves for estimating the fatigue life of fatigue tested notched specimens with typical subsea design features. All estimated fatigue lives are demonstrably conservative compared to the test results for the wide variety of notched specimens types considered.
The notch stress concept has been established for fatigue life calculations of welded components. One of its advantages is that the
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curve is not based on an
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curve catalog in which the ...user has to identify a suitable FAT class; instead, a single
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curve (based on modeling, failure location, and material) is used for different weld geometries. In return, however, the weld needs to be modeled in a detailed manner for finite element analysis. The evaluation of experimental fatigue results collected in a database shows a relatively high degree of scattering (low accuracy) of the strengths calculated according to the notch stress concept. With fatigue tests on different specimen geometries manufactured from the same welded base plates, a correlation between the highly stressed weld seam length and the experimentally determined notch stress strength can be observed. The fatigue strength decreases with the increasing length of the highly stressed weld seam area. The latter quantity can be calculated using the finite element simulations that are needed to determine the notch stress. The presented results are used to describe the statistical size effect as a qualitative influence and quantitative support factor that can be used within the notch stress concept to increase its accuracy.
•Seven models for the notched fatigue limit are applied to members with spherical cavities.•Both ‘traditional’ and fracture-mechanics based models are considered.•Cavity size ranges from μm to ...mm.•Overall, there is considerable variability between model predictions.•Fracture-mechanics based models yield promising predictions of fatigue limit at corrosion pits.
In a recent paper by Härkegård (2015), the effect of corrosion pits on the fatigue limit of 12% Cr steel was predicted based on an equivalent ΔK model for an annular crack at the equator of a spherical cavity. Predictions were compared with estimates due to Smith and Miller and Murakami and with data from fatigue testing. In the present study, four traditional methods for notch assessment have been added: Neuber’s and Peterson’s equations for the notch sensitivity, the ‘support’ factor due to the German FKM Guideline, and the ‘point method’ from the theory of critical distances (TCD). The seven methods have been applied to spherical cavities of various size in a 12% Cr steel. As expected, all methods predict the nominal stress range at the fatigue limit, ΔSA, to be a decreasing function of the radius of the cavity, r′. Models involving the threshold for fatigue-crack growth predict a fairly steep decrease of ΔSA from the intrinsic fatigue limit, ΔσA, in reasonable agreement with the trend of fatigue test data for members with corrosion pits, whereas the notch sensitivity and the FKM support factor predict a more gradual decrease.
► Support factor concepts for P/M parts are compared and evaluated. ► A broad database of 153 experimental support factors is considered. ► The Theory of critical distances shows the best results.
...Structural parts made of P/M (powder metallurgy) materials are increasingly used in lightweight construction for high performance applications. Due to their low density, they substitute for wrought steel in automotive applications e.g. gears or synchronizer hubs. This raises the need for reliable fatigue design concepts. Different concepts to estimate the endurance limit of notched components have been examined and statistically evaluated based on a broad database of various steel-based P/M materials. The sensitivity to notches of P/M materials is highly dependent on the chemical composition and the density, which makes it difficult to fit empirical models for different P/M materials. El Haddad’s fictitious crack length proves to be a good parameter to account for this dependency. Using the theory of critical distances, the fatigue properties of a material can be transferred to parts effectively and with low scatter.
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