Force Model for Complex Profile Tool in Broaching Inconel 718

Complex profile broaches are widely used in the manufacture of complex parts of aero-engines, but their cutting forces in the broaching process are difficult to predict and control. A new numerical model for broaching force with complex profile tools is presented, which considers the area and arc length of curved shear zone projection. The area and arc length were calculated by the curve function of the projection plane, which is firstly predicted by FEM simulation. Compared with the conventional force model, the accuracy of the modified model has been moderately improved. Ultimately, the modified main broaching force (Y-direction) model and the modified normal force (Z-direction) model show a significant improvement in accuracy by 4.8% and 9.7%, respectively. It suggests that the projection area of curved shear zone A1 and the projection arc length of curved shear zone l1 have a big impact on the broaching process. Moreover, the modified model proposed in this paper can provide guidance for the design of complex profile tools and facilitate the efficient and high-precision machining of complex parts.

Validation of a Swimming Direction Model for the Downstream Migration of Atlantic Salmon Smolts

Fish swimming performance is strongly influenced by flow hydrodynamics, but little is known about the relation between fine-scale fish movements and hydrodynamics based on in-situ investigations. In the presented study, we validated the etho-hydraulic fish swimming direction model presented in the River Mandal from Southern Norway, using similar behavioral and hydraulic data on salmon smolts from the River Orkla in Central Norway. The re-parametrized model explained the variation of the swimming direction of fish in the Orkla system in same degree as the original model performed in the Mandal system (R2: 84% in both cases). The transferability of the model when using it from one river to predict swimming direction in the other river was lower (R2: 21% and 26%), but nevertheless relatively high given that the two localities differed in hydraulic conditions. The analyses thus provide support for the fact that the identified hydraulic parameters and their interaction affected smolt behavior in a similar way at the two sites, but that local parametrization of the base model is required. The developed etho-hydraulic models can provide important insights into fish behavior and fish migration trajectories and can be developed into prediction models important for the future development of behavioral downstream migration solutions.

Building a Competency Model Student Training

Decision-making in the field of education is a complex, multi-faceted process, in which a large circle of stakeholders is involved. Of no small importance for making a correct decision is the analysis of information coming from participants in the educational process at its various stages. The article proposes a methodology for constructing and applying a competency-based training direction model. The technique is based on the use of developed algorithms for building competency models. Due to the use of the Bayesian network, an assessment of the formation of the level of competence is possible even with missing data, i.e. with unknown results of competency-based tasks. The technique bridges the gap between strictly subject structuring of assessment tools, which does not fully correspond to the competency-building model of constructing the main educational program, and activity-based structuring. The article describes the conduct of two experiments conducted to verify the algorithms proposed in the theoretical part. Experimental testing showed that the developed algorithms, method and methodology are suitable for constructing a competency-based model of discipline and the direction of training. The models built according to the methodology, make it possible to make informed judgments regarding the level of students' competency levelling, as well as to predict student performance. Thus, using the methods of intellectual analysis of educational data, the tasks of decision support are solved.

A dynamic preferred direction model for the self-organization dynamics of bacterial microfluidic pumping

We set up a continuum model capable of describing the pumping self-organization mechanism of the bacteria and quantifying it to the extent that an agreement with the experimentally observed channel width dependence of the pumping is reached.

Investigation of Oil Adsorption Performance of Polypropylene Nanofiber Nonwoven Fabric

Nanofibers can be used in fields/applications such as medical care, environment protection, apparel, and agriculture. In addition, we believe that this field would continue to show substantial growth in the future. In this study, we focused on its application to oil adsorption. Oil adsorbing performances achieved polymeric nanofiber mass production by a melt-blowing method. We first tested the oil adsorption performance of fiber experimentally under different bulk densities and thicknesses. We also conducted the suction experiment with different bulk densities. Based on experimental result, we considered contact angle, capillarity, and surface tension to be the causes of oil adsorption. We also proposed a three-direction physical model for oil adsorption and used it to calculate the theoretical oil adsorption rate by different free volumes. As a result, we confirmed that the proposed three-direction model could accurately estimate the oil adsorption rate. Moreover, nanofiber has exceptional oil adsorption performance. Further, the fiber with average diameter of 1500 nm exceeds 60 times its self-weight. Therefore, we believe that the proposed nanofiber nonwoven fabric oil adsorption pad could adequately be used as oil adsorption material.

Hybrid Modification of Accelerated Double Direction Method

We present a hybridization of the accelerated gradient method with two vector directions. This hybridization is based on the usage of a chosen three-term hybrid model. Derived hybrid accelerated double direction model keeps preferable properties of both included methods. Convergence analysis demonstrates at least linear convergence of the proposed iterative scheme on the set of uniformly convex and strictly convex quadratic functions. The results of numerical experiments confirm better performance profile in favor of derived hybrid accelerated double direction model when compared to its forerunners.