Acoustic measurements of cohesive sediment transport: Suspension to consolidation

This dissertation aims at utilizing the acoustic approach to measure cohesive sediment behaviors including (1) suspension, (2) settling, (3) deposition and (4) consolidation. The first two processes were attempted to interpret by means of backscattered signal analysis, while the last two processes were done by echo signal analysis. The acoustic instruments used in this study include Acoustic Doppler Velocimeter (ADV), Pulse Coherent Acoustic Doppler Profiler (PC-ADP) and Micro-Chirp system. Used sediments are pure kaolinite and in-situ sediments collected from Mai Po and Clay Bank. 5-MHz ADV was used to estimate the suspended sediment concentration (SSC) and settling velocity (ws). For a limited range of SSC, the time-averaged backscatter wave strength can be well correlated with the SSC. Backscattered signals would be sometimes too noisy due to high amplification ratio, high sampling rate and small sampling volume, and thus, a moving average was used to yield the instantaneous changes of SSC. The measurement of ws with Clay Bank sediment showed that turbulence can increase ws, up to one order larger than that for calm water. When turbulence is stronger than a limit, however, it contributes to the decrease in ws. For the measurement of SSC profile, the performance of 1.5 MHz PC-ADP was evaluated. Clay Bank sediment showed a higher correlation coefficient between range-corrected volume scattering (SSC) and backscattered signal within a limited SSC range (ca. \u3c 10 g/L). On the other hand, kaolinite showed a much smaller range of SSC for linear correlation. This different response might be attributed to the fact that the acoustic response is primarily controlled by the SSC and particle size in suspension at a given frequency. This study suggests that PC-ADP is a potential instrument to reveal the high-resolution (about 1.6 cm) SSC profiles near the bed, if the sediment is sufficiently large. Annular flume experiments with Mai Po sediment were conducted to address a debatable issue regarding the critical shear stress for deposition (tau cd). The direct observation from the flume bottom suggests that tau cd does exist, and that the deposition only occurs when the local bed shear stress (taub) is less than taucd. The changes of deposit length and SSC under the simulated tidal cycles demonstrate that deposition can happen only at tidal decelerating phases with a recognizable tau cd. This study further proves that both taub (a hydrodynamic parameter) and taucd (a sediment parameter) are the main controlling parameters for determining cohesive sediment deposition. A non-intrusive acoustic technique and a signal-processing protocol were developed to estimate the bulk density at consolidating sediment interface. Using high-frequency (300-700 KHz) Chirp acoustic waves, laboratory measurements were carried out in a consolidation tank filled with clay-water mixtures. Because the acoustic echo strength is proportional to the difference in acoustic impedance, and the sound speed in water is close to that in clay, the approximation of bulk density could be successfully presented. The acoustic wave reflectivity increased with increasing the bulk density at the water-sediment interface, which are well correlated with the consolidation status

No-rebound trend of sea ice reduction in the Arctic Ocean: Role of "inertia effect" of the ocean

第4回極域科学シンポジウム横断セッション：[IA] 「急変する北極気候システム及びその全球的な影響の総合的解明」―GRENE北極気候変動研究事業研究成果報告2013―11月12日（火） 国立極地研究所 ２階大会議

What is Store Window Creativity? The Effect of Store Window Creativity on Window Attitude and Intention to Visit a Store

The current research attempts to investigate the multi-dimensional structure of creativity in store window displays based on originality and relevance and its effect on customer responses

Sex- and Age-Related Changes in Connexin 43 Expression in Normal Rat Bladder

Purpose Gap junctions are intercellular channels to facilitate electrical and metabolic communication between adjacent cells. Connexin 43 is the most predominant type of connexin expressed on rat detrusor muscle cells. We investigated the connexin 43 expressions in various age groups of either sex in normal rats. Methods Eighty Sprague-Dawley rats were used for analysis. Each group was quantified by 8 rats at 1 week, 2 weeks, 1 month, 3 months, and 6 months of age in either sex. In each animal, bladder was removed without any kind of intervention and fresh-frozen in liquid nitrogen. Total RNA extraction was done with easy-BLUE total RNA extraction kit. Reverse transcription polymerase chain reaction was done for connexin 43 and glyceraldehyde-3-phosphate dehydrogenase as an internal control using ImProm-II Reverse Transcription System. Results In female rats, no age-related change was detected in connexin 43 expressions. In male rats, connexin expression at 3 months of age showed significant decrease compared with 1 week, 2 weeks, and 6 months of age (P<0.05). When connexin expression at the same age in male and female were compared, only 3 months group in male showed significant decrease than the same age group in female. Conclusions Our data suggest that the expressions of connexin 43 mRNA in normal detrusor muscle cell showed age-related changes especially in male rats. Although it is difficult to interpret these findings at this stage, age should be considered as a possible compounding factor affecting connexin 43 expressions in male rats

A Case of Retinal Detachment in Colobomatous Macrophthalmos With Microcornea Syndrome

We report a rare case of retinal detachment in colobomatous macrophthalmos with microcornea syndrome. A 25-year-old female who had suffered from poor vision in her left eye since early childhood and high myopia in her right eye (-11 D) visited our clinic because of a sudden deterioration of vision. Examination of the anterior segment showed microcornea with coloboma of the inferior pupil margin in the left iris. Fundus examination of the left eye revealed an inferior choroidal coloboma extending from the optic disc and macula. The patient also had total bullous retinal detachment. Pars plana vitrectomy with silicone oil tamponade was performed, and the retina was reattached. In the very rare condition of colobomatous macropthalmos with microcornea, retinal detachment may develop. Pars plana vitrectomy with additional silicone oil tamponade may be performed to treat this condition

Effects of Berberine and Hwangryunhaedok-Tang on Oral Bioavailability and Pharmacokinetics of Ciprofloxacin in Rats

Hwangryunhaedok-Tang (HR) and berberine-containing single herbs are used to treat bacterial infection and inflammatory diseases in eastern Asia. The combination of berberine-containing herbal medicines and ciprofloxacin can be an excellent antibacterial chemotherapy against multidrug resistance bacteria. To evaluate the pretreatment effect of berberine and HR, vehicle, berberine (25 and 50 mg/kg/day), and HR (1.4 g/kg/day) were daily administered to rats for five consecutive days. On day 6, ciprofloxacin was administered (10 mg/kg, i.v. and 20 mg/kg, p.o.) to rats. To assess cotreatment effect of berberine and ciprofloxacin, berberine (50 mg/kg) and ciprofloxacin (20 mg/kg) were coadministered by single oral gavage. Pharmacokinetic data were estimated by noncompartmental model. Compared with ciprofloxacin alone (control group), coadministration of berberine (50 mg/kg) and ciprofloxacin significantly decreased Cmax of ciprofloxacin (P<0.05). In addition, the pretreatment of berberine (50 mg/kg/day) and HR (1.4 g/kg/day) significantly decreased Cmax and AUC0→∞, compared with control group (P<0.05). The oral bioavailability of ciprofloxacin was reduced by cotreatment of berberine and pretreatment of berberine and HR. Our results suggest that the expression of P-glycoprotein and organic anion and/or organic cation transporters (OAT/OCT) could take a role in reduced oral bioavailability of ciprofloxacin by berberine and HR

A Hybrid Approach of Data-driven and Physics-based Methods for Estimation and Prediction of Fatigue Crack Growth

Lamb-wave-based nondestructive testing and evaluation (NDT/E) methods have drawn much attention due to their potential to inspect plate-like structures in a variety of industrial applications. To estimate and/or predict fatigue crack growth, many research efforts have been made to develop data-driven or physics-based methods. Data-driven methods show high predictive capability without the need for physical domain knowledge; however, fewer data can lead to overfitting in the results. On the other hand, physics-based methods can provide reliable results without the need for measured data; however, small amounts of physical information can worsen their predictive capability. In real applications, both the measurable data and the physical information of systems may be considerably limited; it is thus challenging to estimate and/or predict the crack length using either the data-driven or physics-based method alone. To make use of the advantages and minimize the disadvantages of each method, the work outlined in this paper aims to develop a hybrid approach that combines the data-driven and the physics-based methods for estimation and prediction of fatigue crack growth with and without Lamb wave signals. First, with Lamb wave signals, a data-driven method based on signal processing and the random forest model can be used estimate crack lengths. Second, in the absence of Lamb wave signals, a physics-based method based on an ensemble prognostics approach and Walker’s equation can be used to predict crack lengths with the help of the previously estimated crack lengths. To demonstrate the validity of the proposed approach, a case study is presented using datasets provided in the 2019 PHM Conference Data Challenge by the PHM Society. The case study confirms that the proposed method shows high accuracy; the RMSEs for specimens T7 and T8 are calculated as 0.2021 and 0.551, respectively. A penalty score is calculated as 7.63; this result led to a 2nd place finish in the Data Challenge. To the best of the authors’ knowledge, this is the first attempt to propose a hybrid approach for estimation and prediction of fatigue crack growth