Optimal Magnetic Graphite Heater Design for Impurity Control in Single-Crystal Si Grower Using Crystal Growth Simulation

In this paper, we report a successfully modified single-crystal Si growth furnace for impurity control. Four types of arbitrary magnetic heater (AMGH) systems with 3, 4, 5, and poly parts were designed in a coil shape and analyzed using crystal growth simulation. The concentration of oxygen impurities in single-crystal Si ingots was compared among the designed AMGHs and a normal graphite heater (NGH). The designed AMGHs were confirmed to be able to control turbulence and convection in a molten state, which created a vortex that influenced the oxygen direction near the melt–crystal interface. It was confirmed that replacing NGH with AMGHs resulted in a reduction in the average oxygen concentration at the Si melt–crystal interface by approximately 4.8%.

Abstract 1122‐000063: Postoperative Recanalization Factors of Coil Embolization for Cerebral Aneurysms with Comparable Volume Embolization Ratio

Introduction : Volume embolization ratio (VER) has been reported to be involved in postoperative recanalization of coil embolization. However, despite comparable VER, some cases remained stable, and the others showed recanalization. Hemodynamic and morphological factors, as described in previous studies, may also influence recanalization in addition to VER. In this study, we focused on cerebral aneurysms treated by coil embolization with comparable VER. Blood flow analysis using computational fluid dynamics (CFD) and geometrical measurements were performed to investigate the recanalization factors. Methods : We focused on the aneurysms that underwent coil embolization with 15–20% VER. The criteria for the case selection were that the size of the aneurysms was 5–10 mm and that the aneurysm was treated by only coil (i.e., the stent‐assisted cases were excluded). Aneurysms that recanalized after coil embolization and underwent additional coil deployment were defined as “recanalized”, and aneurysms that remained stable after coil embolization without coil compaction were defined as “stable”. Finally, we selected 7 recanalized cases (ICA: 1, MCA: 3, ACA: 3) and 18 stable cases (ICA: 6, MCA: 3, ACA: 9). CFD analysis and morphometry were performed on the vessel geometry after coil embolization. The coil shape was modeled by the virtual coil technique. We calculated three morphological parameters and 34 hemodynamic parameters, then we compared them between the recanalized and stable cases using the Mann‐Whitney U test to identify recanalization factors. In addition, we reconstructed the coil shape from medical images and compared its structure and flow characters for stable and recanalized cases. Results : The average VER for the cases analyzed in this study were 16.7% for recanalized cases and 17.7% for stable cases. As hemodynamic parameters, the spatially averaged velocity normal to the neck plane into the cerebral aneurysm ( NV neck ), and the ratio of the area where blood flows into the cerebral aneurysm after the coil embolization to the area of the neck surface (inflow area ratio: IAR) showed significant difference. Although the hemodynamic parameters were significantly different, morphological parameters did not show statistically significance. In the recanalized case, NV neck tended to be higher (mean value, recanalized: 0.931, stable: 0.822, P < 0.05), and IAR tended to be lower (mean value, recanalized: 0.319, stable: 0.408, P < 0.01). The high NV neck and low IAR indicate that the aneurysm had concentrated flow with a high velocity at the neck surface. There was the concentrated blood flow with the high velocity that collided with the modeled coil in a CFD result for the recanalized case. The area where the blood flow impinged on the modeled coil coincided with the compacted coil region reconstructed from medical images. Therefore, a large force on the coil indicated by these hemodynamic parameters may cause the postoperative recanalization. Conclusions : Even with the same level of VER, there was a possibility of recanalization in aneurysms with a high velocity and concentrated flow into the aneurysm. It is necessary to consider not only VER but also hemodynamic factors to investigate recanalization factors after the coil embolization.

Study on Thermal Accumulation Risk of e-Cigarettes According to Heating Coil Shape

In this study, factors affecting the degree of heat accumulation and amount of carbonyl compound production of e-cigarettes were studied. Structurally, e-cigarettes consist of an electronic circuit device and a cartomizer. The liquid solution of the e-cigarette is vaporized by a coil in the cartomizer, where heat accumulation and carbonyl compound production occur. The relationship between the two were analyzed according to the shape of the coil. X-ray images of the coil shapes within the cartomizer were obtained and classified according to the relative widths of the coils. The degree of heat accumulation and amount of carbonyl compound generation were examined via inhale and exhale tests. The relationships among the relative width of the coil, degree of heat accumulation, and amount of carbonyl compound generation were derived. For optimal design of the cartomizer, it is suggested that the relative width of the coil be set to to 5 or more.

Improved performance of stellarator coil design optimization

Following up on earlier work which demonstrated an improved numerical stellarator coil design optimization performance by the use of stochastic optimization (Lobsien et al., Nucl. Fusion, vol. 58 (10), 2018, 106013), it is demonstrated here that significant further improvements can be made – lower field errors and improved robustness – for a Wendelstein 7-X test case. This is done by increasing the sample size and applying fully three-dimensional perturbations, but most importantly, by changing the design sequence in which the optimization targets are applied: optimization for field error is conducted first, with coil shape penalties only added to the objective function at a later step in the design process. A robust, feasible coil configuration with a local maximum field error of 3.66 % and an average field error of 0.95 % is achieved here, as compared to a maximum local field error of 6.08 % and average field error of 1.56 % found in our earlier work. These new results are compared to those found without stochastic optimization using the FOCUS and ONSET suites. The relationship between local minima in the optimization space and coil shape penalties is also discussed.

PENGARUH JUMLAH LILITAN KUMPARAN STATOR TERHADAP KINERJA GENERATOR MAGNTE PERMANEN FLUKS AKSIAL SATU FASA

The purpose of this research is to know to know the influence of stator coil shape to performance (induced voltage and output power) of single phase axial flux permanent magnet generator. The method used is an experimental method. The population in this study is a unit of single phase axial flux permanent magnet generator. The sample in this study is the stator coil. Experiments were carried out by testing the performance of a single-phase axial flux permanent magnet generator in each variation the number of coil windings which had the 90 turns, 120 turns, and 350 turns. Experiments were carried out with no -load testing and with a resitive load that used 30 Watt incandescent lamps. The conclusion of this study shows that there is an influence from the number of coil windings on the performance (induced voltage and output power) of the generator. From three variations of the stator coil that used as sample, the highest performance is shown by the single phase axial flux permanent magnet generator which used the highest number of coil stator turns. The more number of turns, the better the performance of a single-phase axial flux permanent magnet generator. Abstrak Tujuan dari penelitian ini adalah untuk mengetahui pengaruh jumlah lilitan kumparan stator terhadap kinerja generator fluks aksial satu fasa yang berupa tegangan induksi dan daya listrik yang dihasilkan. Metode yang digunakan adalah metode eksperimen. Populasi pada penelitian ini ialah satu unit generator magnet permanen fluks aksial satu fasa. Sampel pada penelitian ini ialah kumparan stator. Eksperimen dilakukan dengan menguji kinerja generator magnet permanen fluks aksial satu fasa pada setiap variasi jumlah lilitan kumparan stator 90 lilitan, 120 lilitan, dan 350 lilitan. Ekperimen dilakukan dengan pengujian tanpa beban dan dengan beban resitif berupa lampu pijar 30 Watt. Kesimpulan pada penelitian ini menunjukkan bahwa adanya pengaruh jumlah lilitan kumparan stator terhadap kinerja generator yang berupa tegangan induksi dan daya listrik keluaran. Dari ketiga variasi sampel kumparan stator, kinerja tertinggi ditunjukkan oleh generator magnet permanen fluks aksial satu fasa yang menggunakan jumlah lilitan kumparan stator terbanyak. Semakin banyak jumlah lilitan, semakin baik kinerja generator magnet permanen fluks aksial satu fasa.

Parameter study of an inductively powered railgun

This article deals with the numerical simulation of an inductively powered railgun in order to determine the electrical parameters of the inductive storage of the pulsed power supply. A numerical model was set up and validated by experimental results. A parameter sweep was performed by varying the time constant of the coil, the initial current and the initially stored energy. The results show that the generated pulse shape, and thus the transfer efficiency and electromagnetic forces, strongly depend on the inductance of the storage coil. On the contrary, the dependency on the coil time constant, and thus on the coil volume for a given coil shape and conductor material, is small and can be neglected for high time constants.

Performance of Inductive Coupled Power Transfer Versus the Coil Shape - Investigation using Finite Element Analysis

The objective of this paper is to investigate the impact of the spiral coil shape of inductive coupled power transfer on its performance. The coil shapes evaluated are: circular, square and pentagon spiral shapes. The coils are modelled in Ansoft Maxwell software. Simulations are carried out to determine the mutual inductance, coupling coefficient and magnetic flux density. The performance in term of magnetic flux density, mutual inductance and coupling coefficient of the three coils shapes are compared. Of the three shapes, the pentagon is shown to have the best performance in term of its mutual inductance, coupling coefficient and magnetic flux density.