Feasibility of Acoustic Print Head Monitoring for Binder Jetting Processes with Artificial Neural Networks

The clogging of piezoelectric nozzles is a typical problem in various additive binder jetting processes, such as the manufacturing of casting molds. This work aims at print head monitoring in these binder jetting processes. The structure-born noise of piezoelectric print modules is analyzed with an Artificial Neural Network to classify whether the nozzles are functional or clogged. The acoustic data are studied in the frequency domain and utilized as input for an Artificial Neural Network. We found that it is possible to successfully classify individual nozzles well enough to implement a print head monitoring, which automatically determines whether the print head needs maintenance.

Stator flux in direct torque control using a speed and torque variation-based sector rotation approach

A typical problem of traditional DTCs is that the stator flux fails to regulate at low running speeds. The regulation of stator flux in DTC is disrupted because of the unavoidable voltage drop across the stator resistance. As a result, one of the solutions to the problem is to use a fixed sector rotation technique. The concept is based on decreasing stator flux droop, a simple technique for changing the flux locus sector at a certain angle. This method, however, is only effective at low working speeds at one value of torque. As a result, the stator flux droop effect at various speeds as well as torque must be studied. The study is carried out in this paper using simulation (MATLAB/Simulink) and a practical setup (dSPACE board) where both have performed similar outcomes. The comparison is done between the conventional method (without a strategy) and the proposed method (with strategy). In summary, the effect of stator flux droop has been found to have an inverse linear relationship to the speed and torque variation.

A Meaning for the Second Power of the Number Pi. Determining the Surface of a Regular Conoid by Virtue of Ramanujan’s Approximation

Unlike the volume, the expression for the lateral area of a regular conoid has not yet been obtained by means of direct integration or a differential geometry procedure. As this form is relatively used in engineering, the inability to determine its surface, represents a serious hindrance for several problems which arise in radiative transfer, lighting and construction, to cite just a few. Since this particular shape can be conceived as a set of linearly dwindling ellipses which remain parallel to a circular directrix, a typical problem appears when looking for the length of such ellipses. We conceived a new procedure which, in principle, consists in dividing the surface into infinitesimal elliptic strips to which we have subsequently applied Ramanujan’s second approximation. In this fashion, we can obtain the perimeter of any ellipse pertaining to the said form as a function of the radius of the directrix and the position of the ellipse’s center on the X-axis. Integrating the so-found perimeters of the differential strips for the whole span of the conoid, an unexpected solution emerges through the newly found number psi (ψ). As the strips are slanted in the symmetry axis, their width is not uniform and we need to perform some adjustments in order to complete the problem with sufficient precision. Relevant implications for technology, building science, radiation and structure are derived in the ensuing discussion.

The Path of Promoting the Innovation of Teachers' Teaching Idea in School-based Teaching Research

In the basic teaching reform, school-based teaching research belongs to a very important topic, so how can we integrate the new curriculum reform idea with the teachers' teaching idea reform and set up new teaching requirements and objectives? This is the most typical problem confronted by the majority of teachers in the actual teaching at this stage. In order to solve the problem effectively, it is necessary to carry out diversified teaching activities with "school-based teaching research" as the starting point, so as to set up a new teaching mechanism with rich connotation and various forms and realize the overall improvement of teaching quality. In this paper, the author conduct initial discussion on the characteristics and significance of school-based teaching research, and then think about the ways to promote teachers' teaching idea innovation in school-based teaching research, hoping to comprehensively improve the teaching level of China.

Replacing Out-of-Vocabulary Words with an Appropriate Synonym Based on Word2VnCR

The most typical problem in an analysis of natural language is finding synonyms of out-of-vocabulary (OOV) words. When someone tries to understand a sentence containing an OOV word, the person determines the most appropriate meaning of a replacement word using the meanings of co-occurrence words under the same context based on the conceptual system learned. In this study, a word-to-vector and conceptual relationship (Word2VnCR) algorithm is proposed that replaces an OOV word leading to an erroneous morphemic analysis with an appropriate synonym. TheWord2VnCR algorithm is an improvement over the conventional Word2Vec algorithm, which has a problem in suggesting a replacement word by not determining the similarity of the word. After word-embedding learning is conducted using the learning dataset, the replacement word candidates of the OOV word are extracted. The semantic similarities of the extracted replacement word candidates are measured with the surrounding neighboring words of the OOV word, and a replacement word having the highest similarity value is selected as a replacement. To evaluate the performance of the proposed Word2VnCR algorithm, a comparative experiment was conducted using the Word2VnCR and Word2Vec algorithms. As the experimental results indicate, the proposed algorithm shows a higher accuracy than the Word2Vec algorithm.

Optimization of Temperature Regimes of the Hotend for Devices of Additive Manufacturing

In this work, the authors tried to solve a typical problem of inexpensive 3D printers using FDM technology: material clogging of the hotend. To cope with the problem, it is necessary to solve the problem of optimization the temperature regimes of the hotend. For this, the temperature fields of the heating device were simulated taking into account the physical properties of the printing materials. Modeling was carried out using the ANSYS software package, the verification of theoretical calculations was carried out in a full-scale experiment. The data obtained was used to upgrade the 3D printer hotend.

Partition Quantitative Assessment (PQA): A Quantitative Methodology to Assess the Embedded Noise in Clustered Omics and Systems Biology Data

Identifying groups that share common features among datasets through clustering analysis is a typical problem in many fields of science, particularly in post-omics and systems biology research. In respect of this, quantifying how a measure can cluster or organize intrinsic groups is important since currently there is no statistical evaluation of how ordered is, or how much noise is embedded in the resulting clustered vector. Much of the literature focuses on how well the clustering algorithm orders the data, with several measures regarding external and internal statistical validation; but no score has been developed to quantify statistically the noise in an arranged vector posterior to a clustering algorithm, i.e., how much of the clustering is due to randomness. Here, we present a quantitative methodology, based on autocorrelation, in order to assess this problem.