Effect of Process Parameters on the Surface Microgeometry of a Ti6Al4V Alloy Manufactured by Laser Powder Bed Fusion: 3D vs. 2D Characterization

The influence of the main process parameters, laser power, point distance and time exposure, on the surface microgeometry of Ti6Al4V specimens produced by a pulsed powder bed fusion process was investigated. A 3D characterization was carried out and collected data were elaborated to reconstruct the surface and to determine both the 3D and the 2D material ratio curves along different directions. The 3D material ratio curve gives a slightly lower material ratio of peak zone Mr1 and higher material ratio of valley zone Mr2, reduced peak height Rpk and reduced valley height Rvk than the 2D curves. Roughness is greater in the 3D analysis than in the 2D one, skewness is the same and kurtosis increases from <3 in 2D to >3 in 3D. Roughness and skewness increase on increasing point distance and decreasing time exposure and laser power. Within the investigated ranges (27.3–71.2 J/mm3), an increase in energy density reduces the surface roughness while skewness and kurtosis are not significantly affected. The results indicate that a 3D approach allows better characterization of the surface microgeometry than a 2D one.

Angle detection system for crossing compression of retinal artery and vein

The crossing compression of retinal artery and vein is closely related to retinal vein occlusion, so detecting the contraction angle of the crossed vein blood vessel can assist to diagnose the retinal vein occlusion diseases. Through pretreating methods such as filtering, enhancement and edge extraction, the binary edge images can be extracted. The candidate feature points can be obtained by the corner point detection method based on chord-to-point distance accumulation (CPDA). The self-adaptive rectangular filter is used to screen out the crossing point of candidate angle, so as to fit the edge curves and figure out the contraction degree of vein. The experimental results show that this algorithm can better detect the contraction degree of crossed vein blood vessel, with an average error remaining at ± 1∘ under different resolutions.

PENGGUNAAN MEDIA PEMBELAJARAN TIGA DIMENSI DALAM MENINGKATKAN PEMAHAMAN KONSEP MATERI JARAK TITIK, GARIS, DAN BIDANG PESERTA DIDIK DI SMK

Based on the phenomenon that we encounter in Mathematics Learning from Primary School to Upper Secondary School or Vocational High School, it is still not satisfactory. Mathematics learning tends to still be at the achievement of curriculum targets or books used as compulsory books. Learning is still dominated by teachers, where learners are more likely to accept the knowledge provided by teachers without the process of processing the existing potential. Learning does not emphasize on the understanding of the material studied and is not associated with the actual experience of the participants. In other words, the learning of mathematics is not meaningful because the learning has not been associated with the scheme that has been possessed by learners. Based on the above phenomenon, research was conducted on the use of three-dimensional learning media in improving the understanding of the concept of point distance, line, and field of XII OTKP-2 students in SMK Negeri 1 Bandung academic year 2021-2022. This research is a classroom action research that aims to improve students' understanding of mathematics learning concepts by using three-dimensional learning media on the material of point distances, lines, and fields in XII OTKP-2 class SMK Negeri 1 Bandung academic year 2021-2022. Each learner can use this three -dimensional learning media in accordance with their interests, and potential. Because the learning media used is the result of the learners themselves, it means that this learning media will be better understood by learners and more interested. ABSTRAKBerdasarkan fenomena yang kita temui dalam Pembelajaran Matematika mulai dari Sekolah Dasar sampai dengan Sekolah Menengah Atas atau Sekolah Menengah Kejuruan masih belum memuaskan. Pembelajaran Matematika cenderung masih pada pencapaian target kurikulum atau buku yang digunakan sebagai buku wajib. Pembelajaran masih didominasi guru, dimana peserta didik lebih cenderung menerima pengetahuan yang diberikan guru tanpa proses pengolahan potensi yang telah ada. Pembelajaran kurang menekankan pada pemahaman akan materi yang dipelajari dan tidak dikaitkan dengan pengalaman nyata peserta didk. Dengan kata lain, pembelajaran matematika belum bermakna karena pembelajaran belum dikaitkan dengan skema yang telah dimiliki oleh peserta didik. Berdasarkan fenomena di atas, dilakukan penelitian tentang penggunaan media pembelajaran tiga dimensi dalam meningkatkan pemahaman konsep materi jarak titik, garis, dan bidang peserta didik kelas XII OTKP-2 SMK Negeri 1 Bandung tahun pelajaran 2021-2022. Penelitian ini merupakan penelitian tindakan kelas yang bertujuan untuk meningkatkan pemahaman konsep belajar matematika peserta didik dengan menggunakan media pembelajaran tiga dimensi pada materi jarak titik, garis, dan bidang di kelas XII OTKP-2 SMK Negeri 1 Bandung tahun pelajaran 2021-2022. Setiap peserta didik dapat menggunakan media pembelajaran tiga dimensi ini sesuai dengan minat, dan potensi yang dimilikinya. Karena media pembelajaran yang digunakan adalah hasil dari buatan peserta didik sendiri, artinya media pembelajaran ini akan lebih dipahami oleh peserta didik dan lebih tertarik.

Aksi Penyerangan Non-Player Character (NPC) Menggunakan Metode Naive Bayes pada Shooter Game

<p>Aksi penyerangan pada <em>non-player character </em>(NPC) merupakan salah satu substansi penting dalam pembuatan <em>game</em>. Dalam melakukan penyerangan diperlukan strategi khusus agar NPC tidak mudah dikalahkan. Salah satunya adalah adanya variasi serangan terhadap pemain. Salah satu metode yang digunakan untuk mengatur penyerangan NPC adalah <em>rulebase</em>. Metode <em>rulebase </em>dapat memberikan variasi serangan sesuai kondisi NPC, namun metode <em>rulebase </em>bisanya menghasilkan <em>behaviour </em>yang statis dan tidak adaptif jika terdapat kondisi baru. AI seperti ini akan mudah diprediksi dan repetitif sehingga menurunkan tingkat tantangan bermain <em>game</em>. Untuk mengatasi masalah tersebut banyak peneliti yang menggunakan teknik <em>learning</em>. Salah satunya menggunakan metode <em>naïve bayes.</em> Pada penelitian ini dilakukan penerapan metode <em>naïve bayes </em>sebagai strategi penyerangan NPC pada <em>shooter game</em>. Metode <em>naïve bayes </em>digunakan untuk keputusan serangan yang diambil oleh NPC. Adapun parameter yang digunakan untuk keputusan penyerangan adalah nyawa, jarak, jumlah granat, dan jumlah amunisi yang dimiliki NPC. Sedangkan keputusan penyerangan dibagi menjadi serangan tembak, serangan granat, dan serangan pisau. Hasil penelitian menunjukkan penerapan metode <em>naïve bayes </em>membuat NPC mampu melakukan penyerangan secara otonom jika terdapat kondisi baru dengan akurasi 80%. Penerapan metode <em>naïve bayes </em>juga lebih unggul dalam persentase kemenangan NPC dibanding metode <em>rulebase</em>. Tingkat kemenangan NPC menggunakan metode <em>naïve bayes </em>sebesar 60% sedangkan <em>rulebase </em>sebesar 16%.</p><p> </p><p><em><strong>Abstract</strong></em></p><p><em>Non-Player Character’s (NPC) attacks behaviour is one important substance in making games. While NPC attacks needs specific strategy to not get defeated easily. One of the NPC attacks strategy is a variation of offense to player. One of the methods to manage the NPC attack strategy is rulebase. Rulebase method can give variations of the NPC attacks according in conditions, but rulebase method usually producing static behaviour and not adaptive where there is new condition. AI like this would easy too predictive and repetitive so that decrease the challenge of playing games. To overcome these problems, we use naïve bayes method. In this study, naïve bayes method are applied as an NPC’s attack strategy to the shooter game. Naïve bayes method used for attack decisions taken by the NPC. The parameters used for the attack’s decision are health point, distance, number of grenades, and number of ammunitions owned by the NPC. While attacks decision is divided into firing attacks, grenade attacks, and melee attacks. The results showed that the use naïve bayes method can attack autonomously if there are new condition with an accuracy of 80%. The implementation of naïve bayes method at NPC more superior than rulebase method in percentage of NPC winning. The NPC win rate uses the naïve bayes method is 60% while the rulebase is 16%.</em><em></em></p><p><em><strong><br /></strong></em></p>

Effect of Process Parameters and Layer Thickness on the Quality and Performance of Ti-6Al-4V Fabricated by Selective Laser Melting

To improve the quality of thick powder bed and realize the matching of thick powder bed and thin powder bed in the later stage, the influence of process parameters for the single-track, multi-layer fabrication, relative density, surface quality, defect, remelting, and boundary optimization performance of different layer thicknesses of Ti-6Al-4V fabricated by selective laser melting were investigated. It is more conducive to the stable forming of single-track when the point distance is half the diameter of the laser beam, and the exposure time is appropriately extended. The thin powder bed needs the corresponding point distance and exposure time under the laser power of 280–380 W to obtain high-density specimens. The thick powder bed needs to be able to ensure the formation of high-quality specimens under the smaller point distance and longer exposure time under higher laser power of 380 W. Both thick powder bed and thin powder bed will cause un-melted defects between molten pools, spheroidization defects caused by splashing, and microporous defects. The remelting process can significantly improve the surface quality of the formed specimen, but the surface quality of the thick powder bed is worse than that of the thin powder bed. The boundary quality of thick powder bed is worse than that of thin powder bed, and the boundary shape has a greater influence on the quality of the SLM forming boundary. Different strategies should be adopted to form the boundary of different shapes. Increasing the boundary count and increasing the laser power are more conducive to the improvement of boundary quality.

An Analysis of the Femoral Drilling Angle to Avoid Tunnel Collision during Double-Bundle Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction on the Knee

Concomitant anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction has been reported as an effective technique for providing rotational control of the knee. However, the intraoperative risk of collision with an ACL tunnel during the drilling for the femoral ALL tunnel has been described. The purpose of this study was to investigate the various femoral drilling procedures to avoid tunnel collisions during combined double-bundle ACL and ALL reconstruction. Nine cadaveric knees were used in this study. ACL drilling was performed through the anteromedial portal to footprints of the posterolateral bundle at 120° (PL120) and 135° (PL135) knee flexion and the anteromedial bundle at 120° (AM120) and 135° (AM135) knee flexion. ALL drilling was performed at 0° (Cor0-ALL) and 30° (Cor30-ALL) coronal angles using a Kirschner wire (K-wire). The distance between the ALL footprint and ACL K-wire outlets, axial angles of ALL K-wires colliding with ACL K-wires, and distances from the ALL footprint to the collision point were measured. From these values, the safe zone, defined as the range of axial angles in which no collisions or penetrations occurred, was identified by simulation of tunnels utilized for reconstruction grafts in each drilling procedure. The point-to-point distance from the ALL footprint to the K-wire outlet was significantly greater in the AM120 than the AM135 (13.5 ± 3.1, 10.8 ± 3.2 mm; p = 0.048) and in the PL135 than the PL120 (18.3 ± 5.5, 16.1 ± 6.5 mm; p = 0.005) conditions, respectively. During an ACL drilling combination of PL135/AM120, a safe zone of > 45° in Cor30-ALL was identified. With a narrow safe zone during the PL135/AM120 combination only, the risk of femoral tunnel collisions in combined double-bundle ACL and ALL reconstruction is high. AM drilling at 120° and PL drilling at > 135° knee flexion, combined with ALL drilling at 30° coronal angle and > 45° axial angle, may reduce this risk.

The precision of gingival recession measurements is increased by an automated curvature analysis method

Background The extent of gingival recession represents one of the most important measures determining outcome of periodontal plastic surgery. The accurate measurements are, thus, critical for optimal treatment planning and outcome evaluation. Present study aimed to introduce automated curvature-based digital gingival recession measurements, evaluate the agreement and reliability of manual measurements, and identify sources of manual variability. Methods Measurement of gingival recessions was performed manually by three examiners and automatically using curvature analysis on representative cross-sections (n = 60). Cemento-enamel junction (CEJ) and gingival margin (GM) measurement points selection was the only variable. Agreement and reliability of measurements were analysed using intra- and inter-examiner correlations and Bland–Altman plots. Measurement point selection variability was evaluated with manual point distance deviation from an automatic point. The effect of curvature on manual point selection was evaluated with scatter plots. Results Bland–Altman plots revealed a high variability of examiner’s recession measurements indicated by high 95% limits of agreement range of approximately 1 mm and several outliers beyond the limits of agreement. CEJ point selection was the main source of examiner’s variability due to smaller curvature values than GM, i.e., median values of − 0.98 mm− 1 and − 4.39 mm− 1, respectively, indicating straighter profile for CEJ point. Scatter plots revealed inverse relationship between curvature and examiner deviation for CEJ point, indicating a threshold curvature value around 1 mm− 1. Conclusions Automated curvature-based approach increases the precision of recession measurements by reproducible measurement point selection. Proposed approach allows evaluation of teeth with indistinguishable CEJ that could be not be included in the previous studies.

q-Rung orthopair fuzzy frank power point aggregation operators with new multi-parametric distance measures

The recently proposed q-rung orthopair fuzzy set (q-ROFS) whose main feature is that the qth power of membership degree (MD) and the qth power of non-membership degree (NMD) is equal to or less than 1, is a powerful tool to describe uncertainty. The major contribution of this paper lies to investigate power point average (PPA) aggregation operators with q-rung orthopair fuzzy information based on Frank t-conorm and t-norm. Since the existing power average (PA) operators all rely on the traditional distance measures to measure support degree between the input values, it cannot reflect decision makers’ attitude. In response, this paper introduces firstly a series of distance measures for q-rung orthopair fuzzy numbers (q-ROFNs) based on point operators, from which the corresponding support measures can be obtained. Secondly, based on the proposed point distance measures, new Frank power point average aggregation operators are proposed to aggregate q-rung orthopair fuzzy information. Finally, a novel multiple attribute decision making (MADM) technique is presented based on the proposed Frank power point average aggregation operators. The developed MADM method not only can get more objective information, but also avoid the influence of unduly high or low attribute values on the decision result, providing a new way for decision makers (DMs) under q-rung orthopair fuzzy environment.

The precision of gingival recession measurements is increased by an automated curvature analysis method

Background The extent of gingival recession represents one of the most important measures determining outcome of periodontal plastic surgery. The accurate measurements are, thus, critical for optimal treatment planning and outcome evaluation. Present study aimed to introduce automated curvature-based digital gingival recession measurements, evaluate the agreement and reliability of manual measurements, and identify sources of manual variability. Methods Measurement of gingival recessions was performed manually by three examiners and automatically using curvature analysis on representative cross-sections (n = 60). Cemento-enamel junction (CEJ) and gingival margin (GM) measurement points selection was the only variable. Agreement and reliability of measurements were analysed using intra- and inter-examiner correlations and Bland-Altman plots. Measurement point selection variability was evaluated with manual point distance deviation from an automatic point. The effect of curvature on manual point selection was evaluated with scatter plots. Results Bland-Altman plots revealed a high variability of examiner's recession measurements indicated by high 95% limits of agreement range of approximately 1mm and several outliers beyond the limits of agreement. CEJ point selection was the main source of examiner's variability due to smaller curvature values than GM, i.e., median values of -0.98mm− 1 and − 4.39mm− 1, respectively, indicating straighter profile for CEJ point. Scatter plots revealed inverse relationship between curvature and examiner deviation for CEJ point, indicating a threshold curvature value around 1mm− 1. Conclusions Automated curvature-based approach increases the precision of recession measurements by reproducible measurement point selection. Proposed approach allows evaluation of teeth with indistinguishable CEJ that could be not be included in the previous studies.

Improving 3D-3D facial registration methods: potential role of three-dimensional models in personal identification of the living

Personal identification of the living from video surveillance systems usually involves 2D images. However, the potentiality of three-dimensional facial models in gaining personal identification through 3D-3D comparison still needs to be verified. This study aims at testing the reliability of a protocol for 3D-3D registration of facial models, potentially useful for personal identification. Fifty male subjects aged between 18 and 45 years were randomly chosen from a database of 3D facial models acquired through stereophotogrammetry. For each subject, two acquisitions were available; the 3D models of faces were then registered onto other models belonging to the same and different individuals according to the least point-to-point distance on the entire facial surface, for a total of 50 matches and 50 mismatches. RMS value (root mean square) of point-to-point distance between the two models was then calculated through the VAM® software. Intra- and inter-observer errors were assessed through calculation of relative technical error of measurement (rTEM). Possible statistically significant differences between matches and mismatches were assessed through Mann–Whitney test (p < 0.05). Both for intra- and inter-observer repeatability rTEM was between 2.2 and 5.2%. Average RMS point-to-point distance was 0.50 ± 0.28 mm in matches, 2.62 ± 0.56 mm in mismatches (p < 0.01). An RMS threshold of 1.50 mm could distinguish matches and mismatches in 100% of cases. This study provides an improvement to existing 3D-3D superimposition methods and confirms the great advantages which may derive to personal identification of the living from 3D facial analysis.