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Mixing is an inseparable part of many industries. Static mixers are motionless inserts that are widely used for mixing. In this study, planar laser-induced fluorescence (PLIF) was used to study the mixing characteristics of a multilayer static mixer. The effects of the arrangement angle of layer elements of the static mixer were examined. Arrangement angles of 0°, 45°, and 90° were investigated at four different flow-rate ratios of two mixing fluids. The mixing performance of each angle was evaluated with both qualitative and quantitative approaches. The volume fractions of the flows were obtained from the PLIF results, and the mixing index was calculated. The friction factor was measured to assess the pressure loss of each arrangement angle. The results show that the arrangement angles do not affect the mixing index for higher flow ratios. However, at the lowest flow ratio, the angle of 45° resulted in the highest mixing index of 74.9%, while at 0° and 90°, the values reached 66.4% and 69.8%, respectively. In regard to pressure loss, 45° also resulted in the lowest friction factor.

We conjecture that a firm’s organization capital increases its information complexity and has an adverse effect on the accuracy of analysts’ earnings. Using data on analysts’ reports for U.S. firms, we find that analysts’ forecasts are likely to be more biased and less accurate when they cover high organization-capital firms. Our results further indicate that analysts tend to issue more optimistic forecasts for firms with higher organization capital due to the uncertain and positive effect of organization capital on firm value. Overall, our findings suggest that a firm’s organization capital is associated with analysts’ bias and accuracy.

This paper examines how CEO inside debt holdings affect firms’ corporate social responsibility (CSR) activities. Using the US firm-level data over the 2006–2015 period, we find that firms with high CEO pensions and deferred compensation engage more in CSR. This positive relationship however is weakened for firms with greater CEO stock options. We further show that CEO inside debt holdings have a larger impact on CSR for firms in controversial industries where CSR is crucial for risk mitigation. Our results suggest that CEOs with higher inside debt holdings are less likely to take risks, thereby engaging in more CSR.

In recent year, vanadium-doped tribological films have become available as possible candidates for self-lubrication at high temperatures. In this work, quaternary Al–Cr–V–N films were deposited onto silicon wafer and WC-Co substrates by an unbalanced magnetron sputtering using high purity (99.99%) CrAl2 and V targets with argon-nitrogen reactive gases. EPMA results revealed that vanadium atoms can incorporated from 0 to 13 at.% into the films. The maximum hardness value was ~32 GPa at vanadium content of 7.1 at.% in the Al–Cr–V–N films. The high-temperature tribometer was used to analysis the friction characteristics of the films with elevated temperature. As a result of the high temperature friction test after heating up to 700 °C, the average friction coefficient decreased from 0.62 to 0.35 with increasing of vanadium contents in the Al–Cr–V–N films. It is concluded that the reduction of the friction coefficient is attributed to the formation of V2O5, which is a Magnéli phase that acts as a lubrication at high temperature.

High temperature oxidation behavior of nanocomposite films is very important characteristics for application of machining and cutting tools. Quaternary Cr–Al–Si–N nanocomposite films with various compositions were deposited onto WC-Co and Si wafer substrates using a filtered arc ion plating technique. The composition of the films were controlled by different combinations of CrAl2 and Cr4Si composite target power in a reactive gas mixture of high purity Ar and N2 during depositions. The instrumental analyses revealed that the synthesized Cr–Al–Si–N films with Si content of 2.78 at.% were nanocomposites consisting of nano-sized crystallites (3–7 nm in dia.) and a thin layer of amorphous Si3N4 phases. The nanohardness of the Cr–Al–Si–N films exhibited the maximum values of ~42 GPa at a Si content of ~2.78 at.% due to the microstructural change to nanocomposite as well as solid-solution hardening. The Cr–Al–Si–N film shows superior result of oxidation resistance at 1050 °C for 30 min in air. Based on the XRD and GDOES analyses on the oxidized films, it could be revealed that the enrichment of Al (17.94 at.%) and Cr (26.24 at.%) elements in the film leads to form an Al2O3 and Cr2O3 layer on the Cr–Al–Si–N film surface. Therefore, in this study, the microstructural changes on the mechanical properties and oxidation behavior with various compositions in the Cr–Al–Si–N nanocomposite films were discussed and correlated with the deposition parameters.

Kim, H.D.; Aoki, S.; Oh, H.; Kim, K.H.; and Oh, J., 2021. Seabed sub-bottom sediment classification using artificial intelligence. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 305–309. Coconut Creek (Florida), ISSN 0749-0208. Understanding fluid mud density and depth can contribute directly to the development of strategies to reduce dredging costs and other problems in coastal waterways. Although echo sounders are most commonly employed to measure depth, each country has different ways to classify the sub-bottom echo character classification. This study aims to train and test the YOLOv3 artificial intelligence model to classify sub-bottom profiles along with the Darknet-53 framework. Two dataset packages with different amount of image data were used to compare the model performance. The mean average precision (mAP), loss, average intersection of union (IoU), and F1 scores were compared to interpret the results between dataset packages. Throughout the study, it was observed that when the number of images used in training was higher, the model training performances improved. The results of this study show that the YOLOv3 model was successfully trained and tested on the sub-bottom profile datasets, resulting in a high accuracy of classification detection.

The purpose of this study is to analyze the applicability of a sunken vessel as an artificial reef in a high wave energy area in a shallow water zone. Artificial reefs in general shapes are unlikely to be installed and maintained stably in high-energy wave zones. To solve this problem, a method for using a large 2000-ton class sunken vessel as an artificial reef was proposed in this study. Accordingly, we analyzed the applicability, including stability, of the sunken vessel as an artificial reef on the east coast of South Korea, where high-energy waves and swells are observed frequently. In the analysis process, various methods, such as numerical simulation and a hydraulic model experiment, were utilized. 2D and 3D numerical simulations were conducted to simulate the wave energy in the area where the sunken vessel was installed as an artificial reef to identify wave force applied to the vessel. Moreover, a hydraulic model experiment using a sunken vessel model as an artificial reef was performed to compare the stability and motion properties of the vessel model. The experimental results indicated that the stability and motion properties of the sunken vessel differed depending on the water depth. Additionally, the water depth that ensured the stability of the sunken vessel was identified.

The COVID-19 outbreak has restricted international travel, halting tourism globally. Thus, travel demand has shifted from international to domestic destinations. The prolonged travel restriction has changed travel trends and travelers’ behaviors, adversely affecting the tourism industry worldwide. This study attempted to understand and examine the changes in travel preferences, such as choice of destinations, activities, and transportation modes, following the COVID-19 outbreak. This study used primary survey data of 200 respondents collected in June 2020 and secondary survey data collected by the Korea Tourism Organization in 2015 and 2017. The study also examined the role of the government in supporting strategies to prepare for the post-COVID tourism landscape. The analysis showed that the pandemic has caused travelers to favor short-haul destinations where non-contact (socially distanced) travel is possible. The study also found that the distributed land strategy that can make “untact” tourism a possibility could boost the struggling tourism industry.

When erosion occurs, sand beaches cannot maintain sufficient sand width, foreshore slopes become steeper due to frequent erosion effects, and beaches are trapped in a vicious cycle of vulnerability due to incident waves. Accordingly, beach nourishment can be used as a countermeasure to simultaneously minimize environmental impacts. However, beach nourishment is not a permanent solution and requires periodic renourishment after several years. To address this problem, minimizing the period of renourishment is an economical alternative. In the present study, using the Tuvaluan coast with its cross-sectional gravel nourishment site, four different test cases were selected for the hydraulic model experiment aimed at discovering an effective nourishment strategy to determine effective alternative methods. Numerical simulations were performed to reproduce gravel nourishment, however, none of these models simultaneously simulated the sediment transport of gravel and sand. Thus, an artificial neural network, a deep learning model, was developed using hydraulic model experiments as training datasets to analyze the possibility of simultaneously accomplishing the sediment transport of sand and gravel and supplement the shortcomings of the numerical models.

Oxidation behavior of nanocomposite films is very important characteristics for application of machining and cutting tools. In this study, Ti-Al-Si-N-O nanocomposite films were fabricated onto WC-Co and Si wafer substrates. The composition of the Ti-Al-Si-N-O films was analyzed by X-ray photo-electron spectroscope (XPS). Also X-ray diffactometer (XRD) analysis was conducted to investigate the crystallinity and phase transformation of the films. As a result of XRD, Ti-Al(18 at.%)-Si-N-O films showed the great oxidation resistance of 950 °C for 30 min in air. Based on glow discharge optical emission spectroscopy (GDOES) depth profiles, Ti-Al(18 at.%)- Si-N-O film annealed at 950 °C for 30 min shows formation of aluminum oxide layer on the film surface. On the other hand, Ti-Al(7.56 at.%)-Si-N-O film had a titanium oxide layer on the surface after annealing at 950 °C for 30 min.

This study experimentally explores the two-dimensional heat transfer characteristics of an impinging sweeping jet generated from a feedback–channel-type fluidic oscillator. The results were compared to those of a steady square jet. A phosphor thermometry technique was used to measure the surface temperature field on an aluminum plate for different Reynolds numbers and jet-to-wall spacing. A two-dimensional planar Particle Image Velocimetry (PIV) measurement of the sweeping impinging jet was also conducted to couple the flow characteristics and heat transfer performance. The local Nusselt number distributions on the flat plate were evaluated by converting the temperature fields. The heat transfer performance of the sweeping jet is much higher than that of the steady jet because the sweeping motion of the jet induces significant turbulent flow and clearly improves the thermal transport near the impingement plate. However, when the jet-wall spacing becomes greater than 5, the heat transfer performance of the sweeping jet drastically decreases due to the reduced impinging velocity, and the heat transfer of the steady square jet surpasses that of the sweeping jet. In the ensemble averaged velocity fields, two main jet streams are ejected to the plate like oblique impinging jets near the sidewalls of the exit because the jet flow is attached to sidewall one or the other for more than 70% of an oscillation period. There was high similarity between the ensemble averaged velocity profiles and the Nusselt number profiles.

This study proposes a secondary flow mixer for neutralizing reagent in a de-ballast pipe. Because the proposed mixer has a U-bent pipe configuration, it can be fabricated using commercially available pipe parts at low cost. Numerical simulations were conducted with four computational domains: one straight pipe (SP) and three U-bent pipes. The normalized coefficient of variation (CoV/CoV0) values of the U-bent pipe outlet for UP1, UP2 and UP3 were 0.096, 0.036 and 0.015 (90.4%, 96.4% and 98.5% degree of mixing, respectively). Instability was observed in the secondary flow motion because of the continuous curvature change of the U-bent pipe series and the density difference between mixing fluids. This instability enhances the mixing performance. Despite the high mixing quality, the U-bent pipe mixer caused a pressure drop of 0.5–2.1 % compared to the backpressure of a ballast water treatment system.

This paper examines how the investment horizons of a firm's institutional investors affect its corporate social responsibility (CSR) activities. Using data on U.S. firms’ CSR ratings over the 1995–2012 period, we find that longer investment horizons are positively related to CSR. Further, active long-term institutions increase CSR whereas passive long-term institutions have no significant effect. Our results suggest that investors with long-term horizons have more incentives to monitor their firms which leads managers to engage in more vigorous CSR activities.