Photogenerated charges separation and recombination path modification in monocline Lu2WO6 via lattice transition and Bi-O antibonding states

Monoclinic Lu2WO6 undergoes diphase to perovskite BiLuWO6 transition via selective occupancy of Bi in three Lu sites. The transformation mechanism, process, and structures stabilities are revealed by variation cell nudged...

Crowd Motion Editing Based on Mesh Deformation

Computer simulation is a significant technology on making great scenes of crowd in the film industry. However, current animation making process of crowd motion requires large manual operations which are time-consuming and inconvenient. To solve the above problem, this paper presents an editing method on the basis of mesh deformation that can rapidly and intuitively edit crowd movement trajectories from the perspective of time and space. The method is applied to directly generate and adjust the crowd movement as well as avoid the crash between crowd and obstacles. As for collisions within the crowd that come along with path modification problem, a time-based solution is put forward to avoid this situation by retaining relative positions of individuals. Moreover, an experiment based on a real venue was performed and the result indicates that the proposed method can not only simplify the editing operations but also improve the efficiency of crowd motion editing.

Minimizing Flute Engagement to Adjust Tool Orientation for Reducing Surface Errors in Five-Axis Ball End Milling Operations

Surface errors due to force-induced tool and workpiece deflections are one of the major errors in multi-axis machining of parts especially with thin-walled structures. Dominant approaches to reduce these surface errors are re-machining the part, feed scheduling, and tool path modification. These methods are time consuming and computationally costly, and they rely on experimental data which is used in cutting force and deflection predictions. The present paper introduces a pure geometrical approach to reduce surface errors drastically by minimizing the engagement lengths of flutes’ cutting edges when a point on the flute’s cutting edge is in contact with the design surface. The total engagement length of the flutes’ cutting edges when one of them generates a contact point on the workpiece surface is formulated and considered as the minimization objective function of an optimization problem. Tilt and lead angles, which define the tool orientation, are the design variables of the optimization problem subjected to constraints based on the geometrical requirements of the ball end milling process. The optimization problem uses the nominal tool path to generate an optimal tool path with adjusted tool orientations. The presented method is computationally inexpensive and does not need any experimentally calibrated coefficients to predict cutting forces because of the pure geometrical nature of the approach. The method is experimentally validated through five-axis ball end milling experiments in which more than 90% surface error reduction is achieved.

Machining Time Reduction by Tool Path Modification to Eliminate Air Cutting Motion for End Milling Operation

A method to uniquely calculate the tool path and to modify the tool path during air cutting motion to reduce the machining time is proposed. This study presents a contour line model, in which the product model is minutely divided on a plane along an axial direction, and the contour line of the cross-section of the product is superimposed. A method is then proposed to calculate the tool position according to the degree of interference between the product surface and the tool. Furthermore, this study proposes a technique to reduce the machining time by tool path modification during air cutting motion. This is determined by the geometric relationship between the product surface and the tool, and not based on cutting simulations. A cutting experiment was conducted to validate the effectiveness of the proposed method. Based on the results, it was confirmed that the difference in machining time between the tool path with modification and the tool path without modification was large. Moreover, the machining time was significantly reduced by the tool path modification. The results showed that the proposed method has good potential to perform customized manufacturing, and to realize both high productivity and reliability in machining operation.

TECHONOLOGICAL PEDAGOGICAL CONTENT KNOWLEDGE (TPACK) DALAM RANGKA PENINGKATAN KUALITAS PEMBELAJARAN MAHASISWA PPG SD PRAJABATAN

The quality of learning carried out by an educator has not yet received serious attention. This has an impact on the low quality of graduates produced. The core research aims to develop and implement Technology Pedagogical Content Knowledge (TPACK) for participants of the Prajabatan Elementary Teacher Professional Program (PPG). The method used is a combined qualitative and quantitative approach with the R & D method with a 4 D path modification, namely define, design, develop, and disseminate. The subjects in this study were 42 students of Prajabatan Elementary School PPG students who were divided into control and experimental classes. 21 students each. The results of this study are in the form of a literacy and high-level TPACK-based TPACK model and the results of the pretest and posttest scores with a significance value of 0.001 which can be concluded that the TPACK-based literacy model and high-level thinking abilities influence the learning quality of Prajabatan Elementary School students.Kualitas pembelajaran yang dilaksanakan seorang pendidik hingga saat ini belum mendapatkan perhatian yang serius. Hal ini berdampak pada rendahnya kualitas lulusan yang dihasilkan. Penelitian inti bertujuan untuk menyusun dan menerapkan Technology Pedagogical Content Knowledge (TPACK) bagi peserta Program Profesi Guru (PPG) SD Prajabatan. Metode yang digunakan adalah pendekatan gabungan kualitatif dan kuantitatif dengan metode R & D dengan modifikasi alur 4 D, yakni define, design, develop, dan disseminate Subjek pada penelitian ini adalah mahasiswa PPG SD Prajabatan yang berjumlah 42 mahasiswa yang terbagi ke dalam kelas kontrol dan eksperimen yang masing-masing berjumlah 21 mahasiswa. Hasil dari penelitian ini adalah berupa model TPACK berbasis literasi dan kemampuan berpikir tingkat tinggi serta hasil perolehan nilai pretest dan postes dengan nilai signifikansi 0.001 yang dapat disimpulkan bahwa model TPACK berbasis literasi dan kemampuan berpikir tingkat tinggi berpengaruh terhadap kualitas pembelajaran mahasiswa PPG SD Prajabatan.

A Gouge-Free Tool Axis Reorientation Method for Kinematics Compliant Avoidance of Singularity in 5-Axis Machining

When a cutter traverses a region local to the singularity in 5-axis machining, the stability of machine tool motion may be violated and inevitably lead to a reduction in machining quality and accuracy. In this paper, the underlying cause of the singular machine behaviors is first investigated by differentiating tool path motions, on the basis of the tool path motion expressions in part and machine coordinate systems. A further investigation indicates abrupt kinematic changes to be inevitable when the rotary axes approach a singularity. To eliminate such possible singular risks in 5-axis machining, a local tool path modification method is proposed by adjusting the two rotary axes out of a singular configuration. The critical kinematics smoothing and the consequent gouging concerns resulting from reorientation are comprehensively incorporated in the process of singularity avoidance, by means of a novel tool orientation optimization model. Specifically, the algorithm starts with the determination of an appropriate adjustment range in a simple yet effective manner, and then the primary rotary axis is adjusted in a constrained region away from zero, so as to avoid singularity. After that, the second rotary axis is accordingly adjusted, with no gouging requirements being violated. In this way, singularity problems in 5-axis machining are solved, and both the machine axes kinematics and surface gouging errors are under control. Machining simulation and laboratory experiments were conducted to validate the effectiveness of the proposed method.