Analysis of Heat Transfer between Two Particles for DEM simulations

The purpose of the present study was to develop a model of heat transfer between particles that can be incorporated into the discrete element method (DEM). The flow around a particle was measured by particle imaging velocimetry (PIV) and the temperature of the particle was measured using a thermocouple and an infrared camera. The experimental data of heat transfer were classified according to the heat transfer mechanism, namely convection, conduction and contact. These values for heat transfer were compared with those calculated using previously derived estimation equations. From these results, we adopted the thermal contact resistance model, which is related to the surface roughness and contact force. Experiments were also carried out to examine the validity of the model. The heat transfer increased with as the surface roughness increased. This is a not general trend because a large surface roughness causes a large thermal resistance, resulting in a small heat transfer. This trend is considered to be due to the increase in the contact area that accompanies an increase in surface roughness. The contact heat transfer calculated by considering the effect of the surface roughness on the contact area was found to show better agreement with the experimentally obtained values

90° マガッタ ノズル カラノ フンリュウ ニオケル ミダレ ノ カイセキ

A free jet has been investigated experimentally and analytically, which is issued from a 90°curved nozzle. Turbulence data have been analzed by estimating a balance of turbulence energy and Reynolds stress in a symmetric plane of the jet. Analytical results are compared with predicted ones by a Reynolds-Stress-Model which was proposed by LRR, to confirm the performance of the turbulence model in the complex three-dimensional turbulent flow

Gene Suppression of Mouse Testis In Vivo Using Small Interfering RNA Derived from Plasmid Vectors

We evaluated whether inhibiting gene expression by small interfering RNA (siRNA) can be used for an in vivo model using a germ cell-specific gene (Tex101) as a model target in mouse testis. We generated plasmid-based expression vectors of siRNA targeting the Tex101 gene and transfected them into postnatal day 10 mouse testes by in vivo electroporation. After optimizing the electroporation conditions using a vector transfected into the mouse testis, a combination of high- and low-voltage pulses showed excellent transfection efficiency for the vectors with minimal tissue damage, but gene suppression was transient. Gene suppression by in vivo electroporation may be helpful as an alternative approach when designing experiments to unravel the basic role of testicular molecules

Numerical study of air-entraining and submerged vortices in a pump sump

Numerical detection of harmful vortices in pump sumps, such as an air-entraining vortex (AEV) and a submerged vortex (SMV), is crucially important to develop the drain pump machinery. We performed numerical simulations of the benchmark experiments of the pump sump conducted by Matsui et al. (2006 and 2016) using the OpenFOAM and compared the simulation results with the experimental data considering the effects of turbulence model, grid density and detection method of the vortices. We studied the threshold of the gas-liquid volume fraction of the VOF method and the second invariant of velocity gradient tensor to identify AEV and SMV. The methods proposed in the present paper were found to be very effective for the detection of the vortices, and the simulation results by RANS with the SST k-omega model successfully reproduced the experimental data. LES with the Smagorinsky model, however, was sensitive to the grid system and difficult to reproduce the experimental data even for the finest grid system having 3.7 million cells in the present study

スポーツ活動時のエネルギー消費量推定のためのHR-VO_2関係式作成のプロトコールの検討

本研究の目的は, HR-VO_2関係式によってスポーツ活動時のエネルギー消費量を推定する際, 漸増負荷法によって作成した式だけでなく, 漸減負荷法によって作成した式も組み合わせて利用することの有効性を検討することであった。方法は, 負荷の設定以外をできるだけ等しい条件にし, 3種類のプロトコールによって毎分50回転に規定した自転車こぎ運動を行った。このうちの2つはHR-VO_2関係式を作成するためのものであり, 4分間ごとの漸増負荷法 (UP式) と, 4分間ごとの漸減負荷法 (DOWN式) であった。そして残りの1つは, スポーツ活動を想定した負荷の増減が繰り返される運動であり, この時の酸素摂取量をUP式とDOWN式のそれぞれの関係式によって求めるとともに, 算出すべきある時点の心拍数が, 直前の1分間値と比較して, 上昇あるいは同じ場合にはUP式を, 下降した場合にはDOWN式を用いる2つの式を組み合わせた方法 (U-D式) の合計3種類の方法によって推定し, 実測による値との比較を行った。結果は, U-D式が最も実測値に近い値を得ることができた。したがって, 心拍数からスポーツ活動時のエネルギー消費量を推定する場合には, 漸増負荷法と漸減負荷法による2つのHR-VO_2関係式を組み合わせることが, より実測値に近い値を得るのに有効であると考えられる。It is very difficult to estimate the intensity of sports activity by heart rate with a HR-VO_2 relationship because intensity of the sports activity during a game is undulatory. This study aimed at establishing the validity of estimated energy consumption with combined applications of HR-VO_2 relationships under stepwise increased workloads (UP-formula) and stepwise decreased workloads (DOWN-formula). Nine male physical education majors pedaled a bicycle ergometer under undulatory workloads for 16 min. Oxygen uptake was estimated from UP-formula, DOWN-formula and combination usage of UP and DOWN formulas. Results showed that the estimated value with combination usage was nearest to the actually measured value. It was concluded that combination usage is more valid than single use of the UP or DOWN formulas in estimating energy consumption of sports activity

Description of the Diversity in Surgical Indication and Surgical Strategies for Primary Spinal Cord Tumors: A Nationwide Survey by the Neurospinal Society of Japan

Objective To assess the current management of primary spinal cord tumors (PSCTs) and determine whether and to what extent there are differences in surgical strategies for PSCTs. Methods The Neurospinal Society of Japan conducted a survey between April 1 and 30, 2021. Certified spine surgeons were requested for information on the frequency of surgeries in 2020 and the surgical strategies adopted for each PSCTs. The following tumor histologies were focused: schwannoma, meningioma, and cauda equina tumor as extramedullary tumors; and ependymoma, hemangioblastoma, astrocytoma, and cavernoma as intramedullary tumors. The participants were divided according to their response as follows: experts, who had experienced ≥ 100 surgeries for PSCTs, and nonexperts. Results Among 308 participants (63%), 35 (11%) were experts. The total number of PSCTs in 2020 was 802 of which 564 tumors were extramedullary and 223 were intramedullary. Schwannoma accounted for 53% of the extramedullary tumors, and ependymoma accounted for 39% of the intramedullary tumors. Surgical strategies significantly differed among both the experts and nonexperts groups. Some discrepancies in the adopted surgical strategies were observed between groups. Some of the nonexperts, and none of the experts, ruled out surgery for schwannomas (Eden type 4), astrocytomas, or cavernomas. Five nonexperts (2.2%), and none of the experts, resected the entire dura for meningiomas. Conclusion A nationwide survey revealed that a sufficient consensus did not exist regarding surgical strategies for PSCTs. A disease-specific registry for PSCTs is necessary in academic societies