Denso (United States)

Understanding the behavior of water droplets has become increasingly important for automotive products as the industry moves toward electrification in recent years. Particularly, predicting the pinning effect, where water droplets remain stationary against external forces by changing their contact angle or surface tension, is crucial for assessing drainage behavior. Hoffman and Kistler proposed dynamic contact angle models based on the capillary number (Ca) to predict droplet motion. However, since the Ca number includes the contact line speed, it is difficult to predict the pinning effect by way of dynamic contact angle equations formulated by the Ca number. This study aims to predict the pinning effect by analyzing the balance of forces acting on the water droplets. Through experimental observations of the contact angles of water droplets under shear flow and numerical simulations to evaluate the drag force acting on the droplets under the same conditions, we derived a relationship between the drag force and the dynamic contact angle. Furthermore, this relationship was implemented in commercial computational fluid dynamics (CFD) software, and its effectiveness was validated by comparing predicted critical airflow velocities with experimental results. These results demonstrate that the numerical simulation method, which accounts for the balance of forces on the droplets, effectively predicts the pinning effect.

Introduction All-solid-state batteries (ASSBs) utilize non-flammable solid electrolytes, offering enhanced safety. In addition, the application of lithium metal anodes is expected to further improve energy density. Among solid electrolytes, oxide-based solid electrolytes have attracted increasing attention due to their higher stability under atmospheric conditions compared to sulfide-based solid electrolytes. However, oxide-based solid electrolytes exhibit lower ionic conductivity compared to sulfide-based and liquid electrolytes, leading to inferior performance on high-rate cycling.We focused on a novel oxide-based solid electrolyte, lithium lanthanum niobium oxyfluoride (Li1.25La0.58Nb2O6F, LLNOF) [1], which has a bulk ionic conductivity of 7 mS cm-1, which is the highest among oxide-based solid electrolytes reported so far. However, the electrolyte with a high relative density is difficult to be prepared, and the residual voids in the electrolyte easily allow lithium dendrite formation, leading to short circuits. Consequently, improving the sintered density remains an important issue for the LLNOF electrolyte to be used in practical cells. We have reported that the co-addition of alumina (Al2O3) [2] and lithium tungstate (Li2WO4) [3] as sintering aids increased the relative density of lithium lanthanum zirconium tantalate (Li6.4La3Zr1.4Ta0.6O12, LLZT) [4]. In this study, we investigated the effects of various sintering aids on the densification and ionic conductivity of the LLNOF electrolyte. Experimental LLNOF powder used in this experiment was provided by DENSO Corporation [1]. Sintering aids such as Li2WO4, Al2O3, Li2ZrO3, Li2MoO4, and Li2.2C0.8B0.2O3 (LBCO)[5] were used, with each added at 2 wt.%. The LLNOF powder and sintering aids were mixed using a planetary ball mill. A powder of 0.5 g was then pressed into a green pellet at 98 MPa. The green pellet was wrapped in copper foil and sintered at 1000 ℃ for 6 h under Ar atmosphere. The sintered pellet was dry polished to adjust the thickness at 1.0 mm, and Au blocking electrodes were sputtered on both sides of the pellet for conductivity measurements. AC impedance measurements were performed at an applied voltage of 10 mV over the frequency range from 7 MHz to 1 Hz in the temperature range 60 to -20°C. Results and Discussion Table 1 summarizes the relative density, ionic conductivity, and lattice parameters of LLNOF electrolytes with and without sintering aids. The highest relative density (92.7%) was obtained when Li2WO4 was added. However, the bulk ionic conductivity decreased to 2.73 mS cm-1, which was lower than that of LLNOF without sintering aids. The increase in relative density can be attributed to the fact that Li2WO4 has a melting point (742°C) lower than the sintering temperature, leading to the formation of a liquid phase that enhances sintering density.Figure 1 shows the relationship between lattice parameters and ionic conductivity. The ionic conductivity decreased with a decrease in the lattice parameter except for Li2ZrO3. The highest ionic conductivity was observed for the sample prepared without sintering aids. This can be attributed to elemental substitution within LLNOF caused by the addition of sintering aids. Figure 2 shows the cross-sectional SEM images of LLNOF pellets. The pellets prepared with Li2WO4 and LBCO, which generate a liquid phase, exhibit relatively larger grain sizes and fewer voids, resulting in higher relative densities. On the other hand, the sample with Al2O3 has a relatively higher number of residual pores within the grains, which is considered to have led to a decrease in relative density. These results suggest that liquid-phase sintering facilitates the densification of LLNOF.

If scattered X-rays carry information that is independent of that is carried by primary X-rays, the accuracy of attenuation coefficients estimated using both primary and scattered X-rays is expected to be better than that estimated using only primary X-rays. However, because scattered X-rays cannot be easily introduced into conventional X-ray computed tomography (CT), the issue has gained scant attention. This study demonstrates theoretically that the measurement of scattered X-rays improves the accuracy of reconstruction in CT, even in a photoelectric absorption scenario. Here, the CT geometry was simplified for a system that targeted a homogeneous thin cylinder, retaining the necessary configuration. Furthermore, we constructed a mathematical model termed the π-junction model. This model is an extension of the T-junction model used in one of our previous studies. It addresses the photoelectric effect, which was not considered in the T-junction model. The variance in the estimation of the attenuation coefficients of this model from the measurements of both primary and scattered photons was evaluated as the Cramer-Rao lower bound. Both the theory and numerical experiments using Monte Carlo simulation showed that the accuracy of estimating the attenuation coefficient could be improved by measuring the scattered X-rays together with the primary X-rays, even in the presence of photoelectric absorption. This result provides a basis for the superiority of using scattered X-rays.

This article presents a comprehensive solution to address the lack of a native client communication module in Merative Cram Social Program Management (SPM) software, widely used for managing social services in government health and humanSudhakar Mattem https://iaeme.com/Home/

Bioethanol is gaining popularity as a renewable energy source, and understanding the wear characteristics of materials used in its engine components is crucial for improving engine durability. Wear tests of stainless steel (SUS304) were conducted using an autoclave friction testing machine in a high-temperature, high-pressure ethanol-water environment to investigate the wear mechanism of SUS304 in a bioethanol engine environment. The tests were performed under two types of bubbling gases, oxygen and nitrogen, and sodium sulfate concentrations ranging from 0 to 4.00 ppm. The results showed that under nitrogen bubbling conditions, the wear of SUS304 increased with rising sodium sulfate concentration, from 3.49 × 10-5 mm3/Nm at 0 ppm to 12.78 × 10-5 mm3/Nm at 4.00 ppm. In contrast, under oxygen bubbling conditions, the wear decreased from 9.93 × 10-5 mm3/Nm at 0 ppm to 4.58 × 10-5 mm3/Nm at 4.00 ppm as the sodium sulfate concentration increased. Additionally, Atomic Force Microscopy (AFM) scratch tests and X-ray Photoelectron Spectroscopy (XPS) analysis on the wear scar revealed that under oxygen bubbling conditions with 4.00 ppm sodium sulfate concentration, the scratch depth was the smallest, and a significant amount of Cr2O3 was detected on the topmost surface. These results suggest that under oxygen bubbling conditions, the formation of a hard chromium oxide film on the surface helps suppress wear.