Search

Since the first report of cationic reversible addition-fragmentation chain transfer (RAFT) polymerization in 2015, there have been great developments in many aspects of cationic RAFT and degenerative chain transfer (DT) polymerizations, including effective chain-transfer agents, applicable initiators or catalysts, controllable monomers, and controlled architectures of polymers. Cationic RAFT polymerizations exhibit not only many similarities to radical RAFT polymerizations in terms of thiocarbonylthio-based RAFT agents, RAFT mechanisms, and controlled polymer structures but also differences originating from the cationic polymerizations, such as novel RAFT or DT agents, initiation and propagation mechanisms, controllable monomers, and stereostructures of the resulting polymers. This review covers the progress made with cationic RAFT and DT polymerizations, focusing on the similarities and differences between cationic and radical RAFT polymerizations. In total, the characteristics and expanding potentials of cationic RAFT and DT polymerizations are discussed.

This paper analyzes tax competition and coordination, determining which is better in a multi-region endogenous growth model. With an integrated capital market, increased capital tax in one region generates external benefits to others through an increased tax base originating from capital flight. Because this efficiency cost affects resource allocation between private and public goods and intertemporal consumption and investment choice, a higher cost derives a lower equilibrium capital tax rate, leading to a higher economic growth rate. Consequently, the inefficiency costs exert two opposite welfare effects via inefficiently low public goods supply and high economic growth. Naturally, tax coordination to cope with severe tax competition is welfare improving to resolve the underprovision of public goods instead of accepting low growth. In contrast, tax coordination is not desirable if tax competition is mild because benefits from high growth outweigh the costs of an undersupply of public goods.

In vehicle-to-pedestrian collisions, pedestrian injuries occur due to contact with the car and the ground. Previous studies investigated pedestrian kinematic behavior using a parameter study or through statistical analysis although the force interaction between the pedestrian and the vehicle has not been considered. In this study, multibody analyses were conducted for vehicle–pedestrian collisions for adult and child pedestrian with various vehicle shapes. The impulse and impulse moment acting on the pedestrian from the vehicle were introduced, and the kinematic behavior, rotation and ground impact of the pedestrian model were examined. It was found that if an impulse moment acts on the pedestrian when the pedestrian re-contacts with the hood of the car, the angular velocity of the pedestrian’s torso changes in the opposite direction (away from the car), and the torso angle prior to the ground contact decreases to less than 90°. This re-contact between the pedestrian and the vehicle was more likely to occur for cases where the collision involves an adult pedestrian, lower hood leading edge (HLE), longer hood length, and lower collision velocity. When the pedestrian torso angle in contact with the ground was less than 90°, the head vertical impact velocity with respect to the ground became less than 2.9m/s which corresponds to the injury threshold of the head. This study demonstrated that pedestrian-vehicle re-contact is crucial for reducing ground injury. The vehicle shape, pedestrian size, and collision velocity can determine whether re-contact of the pedestrian with the vehicle occurs. This can then explain the factors affecting pedestrian ground impact injury (e.g., higher HLE, higher risk of ground head injury for children) that were shown in previous studies. A strategy to mitigate ground injury is to apply enough impulse moment onto the pedestrian’s upper body from the hood in order to change the torso angular velocity during re-contact, thus making the torso

A new explicit numerical scheme for integrating the relativistic equations of motion for electrically charged particles is proposed as an alternative to the Boris integrator. It has been known that the original Boris integrator includes a large numerical error in the relativistic motion, although the integrator has been used in particle-in-cell simulations of plasma for a half century. The present integrator approximates the theoretical trajectory of the relativistic E-cross-B motion for a charged particle more accurately than the previous explicit integrators such as the Boris, Vay, and Higuera-Cary ones.

Diamond-like carbon (DLC) has been under the research spotlight as an exceptional solid lubricant. Its friction performance is depending on a well-developed transfer layer upon its counterparts. Nowadays, iron-and brass-based metals have been utilized as the counterpart against DLC, however, it is reported their friction behaviors are somewhat inferior compared to titanium alloys. In this study, we tried to improve their friction behaviors and modified the contact interface from Fe/C to C/C by Ti addition in DLC. It was revealed that Ti, which has good adhesion for Fe and C, promoted the development of carbon transfer on Fe-based counterpart. Furthermore, Ti built-up a thick carbonous transfer layer and make better the friction performance of DLC sliding against Fe.

Thermal conduction was investigated in titanium-chromium oxide natural superlattices with an ordered arrangement of crystallographic shear planes, which were nearly pristine interfaces for thermal phonons. Thermal conductivity exhibited a clear maximum value at around 50 K, which indicates interface roughness as small as 20 pm based on the calculation of thermal conductivity by a modified Debye-Callaway model. With an ordered arrangement of nearly pristine interfaces at nanoscale, the wave contribution to phonon transport was estimated to be predominant at lower temperatures (less than 100 K) and as much as 30 % even at room temperature. We found that the interface roughness greatly influences the thermal conduction in natural superlattice systems, which may lead to variations in the reported value of thermal conductivity. We have demonstrated that the wave contribution of thermal conductivity become apparent in bulk crystal having nano scale periodic structure with pristine interfaces.

Monsoon precipitation affects natural and social systems in East Asia, one of the most densely populated regions in the world. Monsoon precipitation variability is strongly influenced by El Niño-Southern Oscillation (ENSO) and may be related to the phase of the Pacific Decadal Oscillation (PDO). However, a collective understanding of the long-term PDO-ENSO-monsoon relationship remains limited because related studies are almost exclusively based on short instrumental records. Although paleoclimate proxies for PDO and ENSO are currently available, there is a lack of high-quality proxies for East Asian summer monsoon (EASM) precipitation. Moreover, the strengthening of the ENSO-EASM relationship since the 1970s has raised the question of anthropogenic impact. Reconstructing EASM precipitation is thus crucial to understanding its variability under natural and anthropogenic forcings. In this study, we addressed these challenges using tree ring oxygen isotopes of red cypress (Chamaecyparis formosensis Matsum), a long-lived endemic tree species in Taiwan. We developed an annual-resolved and well-validated EASM precipitation proxy from 1533 CE to 2011 which explained 49 % of the variance in instrumental precipitation. In comparison with multiple paleoclimate proxies, we revealed that PDO persistently modulated the ENSO-EASM relationship over the past half-millennium. The ENSO-EASM relationship was enhanced during the positive PDO phases and dynamically weakened during the negative PDO phases, notably in the early-17th, 18th, and early to mid-20th centuries. The strengthened relationship since the 1970s concurred with an unusually high PDO and ENSO and fell within its natural variability. Nevertheless, as the amplitude of the PDO is predicted to weaken under warming, the modulation effects may become less predictable.

In the general turning process, solutions for attaining the tool-workpiece relative position such as in-situ touch probes, external devices mounted with air/electric micrometers, and cameras are either indirect or cost/space-consuming. In this paper, a novel direct contact detection method based on the internal data of the machine tool servo and the self-identification strategy of the rotational center as an application of the detection method are proposed. The former method compares the internal data of the non-contact and contact motions, and then precisely identifies the contact position by processing it backwardly. The latter method makes multiple contacts on the pre-machined surface of the workpiece with a redundant-axis movement, and the rotational center identification is realized using the coordinates of contacts achieved by the former method. The effectiveness of the proposed methods is verified experimentally.

For further gravitational wave (GW) detections, it is significant to invent a technique to reduce all kinds of mirror displacement noise dominant at low frequencies for ground-based detectors. The neutron displacement-noise-free interferometer (DFI) is one of the tools to reduce all the mirror displacement noise at lower frequencies. In this paper, we describe a further simplified configuration of a neutron DFI in terms of neutron incidence direction. In the new configuration, neutrons enter the interferometer with unidirectional incidence at four speeds as opposed to two bidirectional incidences of opposite directions at two speeds as reported previously. This simplification of the neutron DFI is significant for proof-of-principle experiments.

Model-based design and optimization methods facilitate industrial applications of chromatographic separations. The uncertainty of the model parameters must be quantified to ensure robust design and control. In this study, we propose an approach using the sequential Monte Carlo (SMC) method based on the Bayesian principle to estimate the uncertainty of the parameters. The linear driving force model for separation of phenol and p-cresol was considered as an example. By comparing different injection tests, we confirmed the necessity of pulse injection and breakthrough experiments to estimate parameters with sufficient accuracy and precision. We also found that modeling observation errors carefully is critical to obtain reasonable estimation.

Public investment is a central issue in the dynamic analyses of fiscal policy and economic growth. Debt financing for public investment and its effects have recently received great attention because interest rates have been low, almost invariably remaining below economic growth rates. This paper presents examination of the effects of debt-financed public investment subject to a simple fiscal rule in an overlapping generations model with public capital. This topic includes capital budgeting and the debt–deficit criterion of the Maastricht treaty. We show herein that debt financing for public investment enhances economic growth if an economy is dynamically inefficient and if public capital has a sufficiently large productivity effect. Moreover, it reduces economic growth rates in a dynamically efficient economy. Debt and growth can have a monotonic or non-monotonic relation, depending on the steady-state interest rate, growth rate, and productivity effect of public investment. The findings indicate that debt–growth relations match with controversial empirical evidence. Furthermore, existing generations choose perfect debt finance if dynamic inefficiency exists. In contrast, a balanced budget is preferred in a dynamically efficient economy with low productivity effects of public capital. However, an economy with high productivity effects of public capital might cho ose debt financing. This paper contributes to the elucidation of currently emphasized issues of public investment.

The control of the entrainment and diffusion of the heat and mass ejected along the jet flow requires the control of fluid motion. In the present study, optimal initial velocity distributions for suppressing and promoting jet entrainment and diffusion were identified using deep reinforcement learning under constant initial jet flow rate conditions. Two-dimensional jet flow simulations using OpenFOAM were combined with a deep Q-network as the learning algorithm. The spatial distribution of the initial jet (velocity and ejection angle) changed. The results show that to suppress the entrainment of the jet, an optimal initial velocity distribution shape in which the velocity in the centre is almost 0, with an inward velocity just outside of it, and a large outward velocity at the outer edge, is desirable. However, to promote entrainment, a shape with a large velocity in the centre portion and small velocity at the outer edge, with an overall inward angle, is desirable. To suppress the diffusion of the jet, an optimal initial velocity distribution shape with a large velocity in the centre portion, a small velocity at the outer edge, and an overall inward angle is desirable. Conversely, to promote diffusion, a shape with a large outward velocity at both the centre and outer edges is desirable. It is also indicated that, when the initial velocity distribution of the jet has a special shape, and the relationship between flow rate, centre velocity, and centre temperature that is normally observed in a jet flow may not hold. In other words, by changing the initial velocity distribution, the entrainment and diffusion of the jet can be separated and controlled, which is usually difficult to achieve using conventional engineering methods., Version of Record 12 October 2023

This paper focuses on image sensor communication (ISC) using cameras to receive wireless signals transmitted by visible lights. We summarize the technical principles of ISC from the perspective of transmitting devices. An introduction to the development and applications of ISC was provided, starting with the history of image sensors and visible light communication (VLC). Moreover, the communication mechanism of ISC using complementary metal–oxide–semiconductor (CMOS) sensors is explained in this paper. Specifically, we investigate studies using an optical communication image sensor and the rolling shutter technique for high-speed ISC. Further, we highlight three distinctive transmitting devices in ISC: a LED array, rotating LEDs, and displays, and explain them in terms of structure and signal transmission methods. In particular, we present the parallel transmission of LED arrays and their application in traffic systems and introduce an optical flow-based signal transmission method using rotating LEDs. In addition, two visual transmission techniques in displays-based-ISC using brightness-difference and high-frequency flashing are introduced, respectively. This paper intuitively explains these ISC techniques and reveals ISC’s high versatility.

Since the first report of cationic reversible addition-fragmentation chain transfer (RAFT) polymerization in 2015, there have been great developments in many aspects of cationic RAFT and degenerative chain transfer (DT) polymerizations, including effective chain-transfer agents, applicable initiators or catalysts, controllable monomers, and controlled architectures of polymers. Cationic RAFT polymerizations exhibit not only many similarities to radical RAFT polymerizations in terms of thiocarbonylthio-based RAFT agents, RAFT mechanisms, and controlled polymer structures but also differences originating from the cationic polymerizations, such as novel RAFT or DT agents, initiation and propagation mechanisms, controllable monomers, and stereostructures of the resulting polymers. This review covers the progress made with cationic RAFT and DT polymerizations, focusing on the similarities and differences between cationic and radical RAFT polymerizations. In total, the characteristics and expanding potentials of cationic RAFT and DT polymerizations are discussed.

This paper analyzes tax competition and coordination, determining which is better in a multi-region endogenous growth model. With an integrated capital market, increased capital tax in one region generates external benefits to others through an increased tax base originating from capital flight. Because this efficiency cost affects resource allocation between private and public goods and intertemporal consumption and investment choice, a higher cost derives a lower equilibrium capital tax rate, leading to a higher economic growth rate. Consequently, the inefficiency costs exert two opposite welfare effects via inefficiently low public goods supply and high economic growth. Naturally, tax coordination to cope with severe tax competition is welfare improving to resolve the underprovision of public goods instead of accepting low growth. In contrast, tax coordination is not desirable if tax competition is mild because benefits from high growth outweigh the costs of an undersupply of public goods.

In vehicle-to-pedestrian collisions, pedestrian injuries occur due to contact with the car and the ground. Previous studies investigated pedestrian kinematic behavior using a parameter study or through statistical analysis although the force interaction between the pedestrian and the vehicle has not been considered. In this study, multibody analyses were conducted for vehicle–pedestrian collisions for adult and child pedestrian with various vehicle shapes. The impulse and impulse moment acting on the pedestrian from the vehicle were introduced, and the kinematic behavior, rotation and ground impact of the pedestrian model were examined. It was found that if an impulse moment acts on the pedestrian when the pedestrian re-contacts with the hood of the car, the angular velocity of the pedestrian’s torso changes in the opposite direction (away from the car), and the torso angle prior to the ground contact decreases to less than 90°. This re-contact between the pedestrian and the vehicle was more likely to occur for cases where the collision involves an adult pedestrian, lower hood leading edge (HLE), longer hood length, and lower collision velocity. When the pedestrian torso angle in contact with the ground was less than 90°, the head vertical impact velocity with respect to the ground became less than 2.9m/s which corresponds to the injury threshold of the head. This study demonstrated that pedestrian-vehicle re-contact is crucial for reducing ground injury. The vehicle shape, pedestrian size, and collision velocity can determine whether re-contact of the pedestrian with the vehicle occurs. This can then explain the factors affecting pedestrian ground impact injury (e.g., higher HLE, higher risk of ground head injury for children) that were shown in previous studies. A strategy to mitigate ground injury is to apply enough impulse moment onto the pedestrian’s upper body from the hood in order to change the torso angular velocity during re-contact, thus making the torso

A new explicit numerical scheme for integrating the relativistic equations of motion for electrically charged particles is proposed as an alternative to the Boris integrator. It has been known that the original Boris integrator includes a large numerical error in the relativistic motion, although the integrator has been used in particle-in-cell simulations of plasma for a half century. The present integrator approximates the theoretical trajectory of the relativistic E-cross-B motion for a charged particle more accurately than the previous explicit integrators such as the Boris, Vay, and Higuera-Cary ones.

Monsoon precipitation affects natural and social systems in East Asia, one of the most densely populated regions in the world. Monsoon precipitation variability is strongly influenced by El Niño-Southern Oscillation (ENSO) and may be related to the phase of the Pacific Decadal Oscillation (PDO). However, a collective understanding of the long-term PDO-ENSO-monsoon relationship remains limited because related studies are almost exclusively based on short instrumental records. Although paleoclimate proxies for PDO and ENSO are currently available, there is a lack of high-quality proxies for East Asian summer monsoon (EASM) precipitation. Moreover, the strengthening of the ENSO-EASM relationship since the 1970s has raised the question of anthropogenic impact. Reconstructing EASM precipitation is thus crucial to understanding its variability under natural and anthropogenic forcings. In this study, we addressed these challenges using tree ring oxygen isotopes of red cypress (Chamaecyparis formosensis Matsum), a long-lived endemic tree species in Taiwan. We developed an annual-resolved and well-validated EASM precipitation proxy from 1533 CE to 2011 which explained 49 % of the variance in instrumental precipitation. In comparison with multiple paleoclimate proxies, we revealed that PDO persistently modulated the ENSO-EASM relationship over the past half-millennium. The ENSO-EASM relationship was enhanced during the positive PDO phases and dynamically weakened during the negative PDO phases, notably in the early-17th, 18th, and early to mid-20th centuries. The strengthened relationship since the 1970s concurred with an unusually high PDO and ENSO and fell within its natural variability. Nevertheless, as the amplitude of the PDO is predicted to weaken under warming, the modulation effects may become less predictable.

Model-based design and optimization methods facilitate industrial applications of chromatographic separations. The uncertainty of the model parameters must be quantified to ensure robust design and control. In this study, we propose an approach using the sequential Monte Carlo (SMC) method based on the Bayesian principle to estimate the uncertainty of the parameters. The linear driving force model for separation of phenol and p-cresol was considered as an example. By comparing different injection tests, we confirmed the necessity of pulse injection and breakthrough experiments to estimate parameters with sufficient accuracy and precision. We also found that modeling observation errors carefully is critical to obtain reasonable estimation.

For further gravitational wave (GW) detections, it is significant to invent a technique to reduce all kinds of mirror displacement noise dominant at low frequencies for ground-based detectors. The neutron displacement-noise-free interferometer (DFI) is one of the tools to reduce all the mirror displacement noise at lower frequencies. In this paper, we describe a further simplified configuration of a neutron DFI in terms of neutron incidence direction. In the new configuration, neutrons enter the interferometer with unidirectional incidence at four speeds as opposed to two bidirectional incidences of opposite directions at two speeds as reported previously. This simplification of the neutron DFI is significant for proof-of-principle experiments.

In the general turning process, solutions for attaining the tool-workpiece relative position such as in-situ touch probes, external devices mounted with air/electric micrometers, and cameras are either indirect or cost/space-consuming. In this paper, a novel direct contact detection method based on the internal data of the machine tool servo and the self-identification strategy of the rotational center as an application of the detection method are proposed. The former method compares the internal data of the non-contact and contact motions, and then precisely identifies the contact position by processing it backwardly. The latter method makes multiple contacts on the pre-machined surface of the workpiece with a redundant-axis movement, and the rotational center identification is realized using the coordinates of contacts achieved by the former method. The effectiveness of the proposed methods is verified experimentally.

Thermal conduction was investigated in titanium-chromium oxide natural superlattices with an ordered arrangement of crystallographic shear planes, which were nearly pristine interfaces for thermal phonons. Thermal conductivity exhibited a clear maximum value at around 50 K, which indicates interface roughness as small as 20 pm based on the calculation of thermal conductivity by a modified Debye-Callaway model. With an ordered arrangement of nearly pristine interfaces at nanoscale, the wave contribution to phonon transport was estimated to be predominant at lower temperatures (less than 100 K) and as much as 30 % even at room temperature. We found that the interface roughness greatly influences the thermal conduction in natural superlattice systems, which may lead to variations in the reported value of thermal conductivity. We have demonstrated that the wave contribution of thermal conductivity become apparent in bulk crystal having nano scale periodic structure with pristine interfaces.

Diamond-like carbon (DLC) has been under the research spotlight as an exceptional solid lubricant. Its friction performance is depending on a well-developed transfer layer upon its counterparts. Nowadays, iron-and brass-based metals have been utilized as the counterpart against DLC, however, it is reported their friction behaviors are somewhat inferior compared to titanium alloys. In this study, we tried to improve their friction behaviors and modified the contact interface from Fe/C to C/C by Ti addition in DLC. It was revealed that Ti, which has good adhesion for Fe and C, promoted the development of carbon transfer on Fe-based counterpart. Furthermore, Ti built-up a thick carbonous transfer layer and make better the friction performance of DLC sliding against Fe.

Dry ice has been proposed as a propellant for electric propulsion, as its use may facilitate the realization of a low-cost propulsion system compared to that based on a xenon propellant. In addition, dry ice can be obtained from space (e.g., from the atmosphere of Mars) and human exhalation. This study thus conducted experiments with dry ice storage and carbon dioxide gas supply using triple-point storage. With this method, a constant tank pressure and flow rate was achieved without the application of regulators or control valves. However, the triple-point state was unexpectedly halted, even though solid dry ice remained in the tank. An internal visual observation revealed that the solid phase was surrounded by the liquid phase, which prevented the solid phase from melting. Therefore, heat conduction fins were installed in the tank to enhance the melting process, which successfully extended the triple-point duration. The supply system was applied successfully to the operation of a 1 kW Hall thruster. Furthermore, a mathematical model for estimating the phase characteristics in the tank was developed, with an in-orbit operation analyzed based on the experimental results. The heat input to the tank and the mass flow rate or enthalpy to the thruster determined the phase characteristics in the tank, which means that implementing a thermal design that considers the flow rate to the thruster is crucial. The simulation demonstrated that dry ice can be consumed by controlling the three phases in the tank using an electrical heater. A gas phase separator concept consisting of the heat conduction fins and capillary screen mesh was proposed for orbital microgravity operation.

A 100-W class low power arcjet thruster using a hollow cathode was proposed, with the goal of reducing cathode erosion. The hollow cathode's emitter was lanthanum hexaboride expecting its excellent thermionic emission performance. The experiment used argon as a propellant and compared two different emitter lengths. The estimated emitter temperature was almost the same regardless of the emitter length, however, due to of the efficient heat exchange with the longer arc plasma region, the longer emitter provided better performance with higher discharge voltage. Additionally, the hollow cathode was compared to the conventional rod cathode, and the hollow cathode was found to have some advantages. The specific impulse of the hollow cathodes was higher than that of the rod cathode at low flow rate. The results showed that the hollow cathode is best for high specific power and high specific impulse operation. The unstable transition between low- and high-voltage modes has been observed in the rod cathode, but not in the hollow cathode configurations. Helium was put to the test as a propellant and compared to argon for simulate the future use of hydrogen as a propellant. The thrust efficiency was lower due to the high discharge voltage and significant heat loss, but the specific impulse was higher as expected. No severe recession or erosion of the emitter was observed after the test campaign, but some surface color change was seen which may affect in the long-term operation.

The effects of temperature (750–1300 °C) and gasifying agents (CO2, H2O, and their mixture) on the gasification characteristics of biomass char (biochar) were experimentally studied using a batch-type vertical tube furnace. It was found that gasification behaviors in the atmospheres of CO2, H2O, and their mixture could be classified into two regimes: chemical reaction control and diffusion control. In addition, a mechanism transition phenomenon from additive mechanism to competitive mechanism was observed in the chemical reaction control regime. The syngas results indicated that in the competitive mechanism, both the char-CO2 reaction and char-H2O reaction were inhibited. Based on these results, an assumption of char active sites was proposed to explain the mechanism transition. It appears that the transition is mainly caused by insufficient char active sites, resulting in CO2 and H2O molecules competing for the limited shared active sites. Furthermore, it was observed that in the competitive mechanism, there is no obvious priority for accessing the shared active sites when both CO2 and H2O are present.

Description of the elongational rheology of concentrated polymers appears to require that in fast flows the friction coefficient decreases with respect to its equilibrium value. However, the proposed models typically maintain the validity of the fluctuation-dissipation theorem (FDT) out of equilibrium. On the other hand, FDT is routed in local equilibrium, the latter being clearly violated by the flow-induced monomer coalignment that induces friction change. A recent analysis by Watanabe et al. [Macromolecules, 54, 3700 (2021)] of unentangled polystyrene (PS) melts, based on a nonlinear extension of the Rouse model, indicates that FDT is indeed violated in fast flows. According to their analysis, the Brownian force intensity remains almost independent of the flow rate, even though the friction coefficient drastically decreases. A different violation of FDT is shown by previous nonequilibrium molecular dynamics simulations of PS oligomers [Ianniruberto et al., Macromolecules, 45, 8058 (2012)] where the diffusion coefficient grows more than the inverse friction coefficient. In this paper, Brownian simulations using a multi-chain sliplink model (the so-called primitive chain network model) are reported for two monodisperse entangled PS melts, for which nonlinear shear and elongational data were published. Two different friction reduction models are examined, and the effect of switching FDT on and off is tested. Results demonstrate that, irrespective of FDT, both friction models can reasonably well reproduce the behavior shown by the data. This result lends support to models that retain FDT since its violation appears not to significantly affect predictions of nonlinear rheology.

This study analyzes Japanese university faculty with foreign degrees using data from the School Teacher Survey, covering the academic years 2007–2016. The results demonstrate that the proportion of Japanese faculty with foreign degrees was 2.81% (2016), with a modest increase during the survey period, which is different from previous studies’ predictions. Moreover, the faculty were more likely to be professors, women, specializing in the humanities and social sciences, and working at private universities, especially in metropolitan areas. Multilevel regression analysis also demonstrated that Japanese faculty with foreign degrees have higher ranks than do their counterparts with domestic degrees.

The progressive accumulation of discarded plastic in the environment demands further development of waste management of plastic waste and conversion technologies of such waste to value-added materials. Recently, the conversion of plastic waste to functional materials via chemical recycling has attracted considerable attention. In this report, plastic waste (PET) was utilized for the preparation of a hydrogel-based catalyst via a cross-linking reaction of PET-derived oligo(terephthalamide)s followed by the electroless metallization. The polymeric matrix of PET-derived hydrogel plays multiple roles of (i) an adsorption media for noble metal ions such as Au^3+ and Ag^+, (ii) a reducing agent of Au^3+ and Ag^+ ions to Au^0 and Ag^0, and (iii) a matrix for the controlled growth of Au and Ag nanoparticles (AuNPs and AgNPs). The obtained hybrid hydrogels after metallization contained well-dispersed AuNPs and AgNPs of 6.1 ± 3.7 nm or 6.1 ± 1.4 nm size, respectively. The catalytic activities of the hybrid hydrogels with metal nanoparticles were studied in a model system of p-nitrophenol reduction in an aqueous solution. The hybrid materials of both Au@hydrogel and Ag@hydrogel were catalytically active for the reduction of p-nitrophenol, obeying the first-order kinetics. Importantly, the AuNPs or AgNPs in the hydrogel matrix preserved the original catalytic activity after multiple p-nitrophenol reduction reactions, showing a promising reusability of the catalysts. The proposed here approach aims to broaden the scope of conversion routes of plastic waste to value-added materials as well as to develop new types of polymeric matrices for templating and growth of metal nanoparticles for catalytic applications.

The linear relationship between wave amplitude and wave torque based on the boundary element method (BEM) is widely employed for small-amplitude waves. However, linear relationships are unsuitable for bottom-hinged oscillating wave surge converters (OWSCs) under high waves owing to nonlinearities, such as wave overtopping. This paper presents an improved BEM introducing an incident wave amplitude correcting factor to simplify the complex nonlinearities under high regular waves. The correcting factors were calibrated with computational fluid dynamics (CFD) using OpenFOAM. An Oyster 800-like OWSC was adopted as the study model. A quadratic fitting curve of correcting factor vs. wave height is applicable because the calibrated correcting factors significantly correlate with wave heights but are almost irrelevant to wave periods. Though the time–history responses differ in BEM and CFD under high waves, BEM-based time-averaged results show good accuracy and high computational efficiency, such as equivalent pitch amplitude and capture width ratio (CWR). At mid-low periods, simultaneously varying power take-off (PTO) stiffness and damping than solely varying PTO damping, significantly increases CWR, especially under low waves. The capturing power under high waves substantially increases because of pitch motion amplification. At long periods, adjusting PTO inertia produces negligible efficiency improvement even with amplified oscillation.

Twinned structure of metal nanoparticles can strongly affect catalysis because of its unique atomic alignment and bond strain in metal nanoparticles. Here, the twin and single crystal structures of supported Ag nanoparticles are controlled reversibly by gas treatment. The single crystal Ag nanoparticles were formed in Ag/Al2O3 by H2 treatment, and subsequent CO gas treatment changed the Ag particle structure to twin. The change in the Ag particle structure from single to twin caused enhancement of CO oxidation activity. In addition, the catalytic activity was reversibly changed from low to high by applying H2 and CO gas treatment to Ag/Al2O3. The kinetic analysis for CO oxidation revealed that the twin Ag nanoparticles have stronger CO adsorption energy than the single crystal ones, which is responsible for the enhanced CO oxidation activity of twin Ag nanoparticles.

Purpose: The research aims to understand the co-existence of nimbleness and resilience in a continuous digital transformation, along with the dynamic capabilities needed to balance the challenges of their co-existence. Methodology: The current study draws on Dialogical Action Design Research (D-ADR) to investigate interactions among practitioners and executives. Data is collected from a major Australian Financial Services Organisation (FSO) and many international experts. Findings: The study presents a framework, the Continuous Transformation Model (CTM), to describe digital transformation within an FSO context, emphasizing nimbleness and resilience as its foundational pillars. This framework facilitates the identification of the critical role of organisational capabilities in managing continuous digital transformation, supported by dynamic IT capabilities. More importantly, the findings underscore how these capabilities enable managers to effectively balance the coexistence of nimbleness and resilience. Research implications: The CTM contributes to the enterprise information systems literature by offering a coherent understanding of balancing resilience and nimbleness to succeed in digital transformation. In particular, the research model elucidates the relationship between dynamic capabilities and continuous digital transformations. Practical implications: Digital transformations are not a one-off exercise. Managers in the FSO context must cultivate their organisational capabilities to achieve nimbleness and resilience during their digital transformation journey. Originality: The relationship between dynamic capabilities and continuous digital transformation sheds light on establishing successful management processes within FSOs.

Conventional shipping is increasingly unable to address the social and economic needs of remote and underprivileged coastal and island communities. Barriers include rising fuel costs affecting the viability of on-water activities, which are compounded by the challenges presented by a lack of deepwater ports and related infrastructure that prevent docking by larger more fuel-efficient vessels. The environmental externalities of shipping-related fossil-fuel consumption, which harbour both local pollution and anthropogenic climate change impacts, adversely affect these communities. Amid limited research on strategies to address the challenges presented by conventional shipping methods to small island developing States (SIDS), this paper proposes the adoption of policy initiatives for the adoption of small, modern non-fuel vessels that could assist these important yet underserved niches. One of several initiatives developing renewable-energy based shipping solutions is the Greenheart Project, an international non-profit organization in the process of developing an open-source hybrid solar-sail cargo vessel conforming to the conditions faced in coastal and island communities. This paper discusses the socio-economic and environmental challenges presented by conventional shipping with reference to SIDS and the potential of non-fuel shipping. Policy proposals to facilitate the beneficial adoption of such vessels in developing communities will also be offered.

An optical fiber-based neutron detector can be used as a real-time neutron monitor for an intense neutron field. In this study, optical fiber-based neutron detectors were fabricated using Li-glass scintillator. The thermal neutron sensitivity, upper limit of the output linearity, and response to gamma rays from 60Co and Cd were evaluated. The thermal neutron sensitivity was proportional to the mass of the Li-glass scintillator, and the calibration factor was 2.06 × 10^-6 and 3.18 × 10^-6 cps/(n/cm 2/s)/g for the lower-level discrimination of the peak and valley channel, respectively. The detector output linearity was confirmed to be up to nearly 2 Mcps. While evaluating the response to gamma rays, for both 60Co and Cd, the gamma-ray counting rate was found to be smaller than the uncertainty associated with counting statistics in most expected applications where the neutron counting rate was >1 kcps.

This study investigates the effects of downstream flow in the voice prosthesis (Provox® Vega) on the esophageal wall during shunt vocalization to identify the dominant factors influencing the sound generated in the esophagus (the original sound in shunt vocalization). The trachea and esophagus were simulated to measure flow in the esophageal section through the voice prosthesis by using particle image velocimetry, and pressure distribution in the esophageal section was calculated by solving Poisson's equation. Downstream flow in the voice prosthesis fluctuated over time due to oscillations of the valve. This flow impinged on the esophageal wall and created a strong shear region that fluctuated over time to give rise to fluctuations in pressure at the same frequency as that of oscillations of the valve on the esophageal wall near the point of impingement. The sound pressure, estimated by using the measured velocity field based on the Ffowcs Williams–Hawkings equation, was compared with the sound pressure measured by a microphone. The results showed that temporal variations in pressure downstream of the voice prosthesis and its impinging on the esophageal wall were the main sources of the sound generated from the voice prosthesis within the esophageal section. The frequency of the generated sound depended on the frequency of oscillations of the valve.

This study presents the contribution of the large-scale motions to the turbulent energy using custom-made arrays of hot-wire probes arranged in the span-wise direction. Decomposing the stream-wise velocity fluctuations into large- and small-scale components through the Fourier transform in the span-wise direction and evaluating their scales using the two-point correlation, it is found that the large-scale components have a large contribution in the generation of the outer peak of the turbulent pre-multiplied spectrum (PMS). The outer peak remains even in the low Reynolds number, and it is related to the span-wise organization of large-scale structure of fluctuations. The spatial correlation in the stream-wise direction shows the large scale of 10, where is the boundary layer thickness, which is consistent with the outer peak wavenumber of PMS.

A new correction method for laser Doppler velocimetry (LDV) measurement volume effects on the time-averaged velocity statistics is proposed by considering the probability density function of streamwise fluctuating velocity and the streamwise cross-sectional area of the measurement volume. The proposed correction method is fundamentally different from previous correction methods using a laser intensity profile of LDV. We propose a simple equation to correct the measurement volume effects. By using the equation and calculating both measurement locations and volumes precisely, the correction for the measurement volume effects on time-averaged velocity statistics can be performed on the basis of LDV measurement data. By comparing with the correction method proposed by Durst et al. (1995), the two correction methods provide almost the same results. In addition, the validity and applicability to high Reynolds numbers or low spatial resolution conditions of the two correction methods are confirmed.

Although numerous studies have investigated droplets in shear flows, the features of these droplets are incompletely understood. This paper reports our experimental visualization results of sessile droplets in fully developed turbulent shear flows and the onset of their movement. The visualization was performed from the side and bottom views. Furthermore, the droplet height is much smaller than the boundary-layer thickness, and the droplet motions are strongly affected by turbulent velocity fluctuation. The droplets were deformed toward the front and spread in a spanwise direction. The front and rear-side contact angles recover the balance position, that changes symmetrically over time and are not clearly related to sessile droplet oscillation. The droplet oscillation frequencies were well predicted by the model based on the resonant vibrations of the standing waves except for the lowest mode. Based on the critical air velocity and droplet height, the motion onset was adequately approximated by a simple empirical relation between the Weber and Reynolds numbers.

We have investigated thermal conduction in bulk titanium oxide natural superlattices with crystallographic shear (CS) structures, in which dense planar faults are introduced with different periodicities, prepared by reductive annealing of rutile TiO2 and crystal growth by the floating zone method. High-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) revealed that (132)rutile and (121)rutile CS planes with interspacings of 2.7 and 1.0 nm were introduced in the mother rutile structure. Time-domain thermoreflectance (TDTR) revealed that the thermal conductivity decreased by the introduction of CS planes, but that the decrease is not monotonic with increasing density of CS planes. Calculation of the thermal conductivity and the mean free path for phonons revealed that a crossover from incoherent to coherent thermal conduction took place, and coherent interfaces with nanoscale periodicity were formed as thermodynamically stable phases in bulk titanium oxide natural superlattices., Available online 11 October 2021.

In the present paper, we develop a new in situ low-friction technology for diamond-like carbon coatings using surface discharge in ambient air. As a result, the friction coefficient dropped from 0.18 to 0.06 shortly after surface discharge. Surface profiles and Raman analysis revealed the effectiveness of surface discharge to provide a thick and soft transfer layer, providing the optimal low friction condition described by Halling. Finally, we clarified the optimum surface discharge design that low-energy surface discharge produced a thick transfer layer due to concentration of the produced debris, resulting in low friction.

This paper presents a shape optimisation system to design the shape of an acoustically-hard object in the three-dimensional open space. The boundary element method (BEM) is suitable to analyse such an exterior field. However, the conventional BEM, which is based on piecewise polynomial shape and approximate (interpolation) functions, can require many design variables because they are usually chosen as a part of the nodes of the underlying boundary element mesh. In addition, it is not easy for the conventional method to compute the gradient of the sound pressure on the surface, which is necessary to compute the shape derivative of our interest, of a given object. To overcome these issues, we employ the isogeometric boundary element method (IGBEM), which was developed in our previous work. With using the IGBEM, we can design the shape of surfaces through control points of the NURBS surfaces of the target object. We integrate the IGBEM with the nonlinear programming software through the adjoint variable method (AVM), where the resulting adjoint boundary value problem can be also solved by the IGBEM with a slight modification. The numerical verification and demonstration validate our shape optimisation framework.

For solution growth of silicon carbide, it is significant to understanding the evolutionary mechanism of step bunching. This study infers that solute’s incorporation into steps and transport together determines step bunching progress. The occurrence of step bunching is due to the depletion of solute in the region with high step density, caused by a high step kinetic coefficient. On the other hand, by promoting the transport of the solute in the solution, the step speed becomes uniform, thereby the step bunching can be prevented. Furthermore, we proposed a non-dimensional Damköhler number for crystal growth in step-flow mode. It correlates incorporation rates with bulk diffusion rates and can build a phase map of growth rates and step bunching stability. Several solvents are located in the phase map, demonstrating the possible usage of the phase map as a pointer for solvent designing.

This study aims to investigate the effects of fiber cross-sectional shape on the trans- verse crack extension of carbon fiber reinforced plastics (CFRP) both experimentally and numerically. Kidney-shape carbon fiber was compared with the laminates using conventional round-shape carbon fiber by monitoring the transverse crack accumu- lation behavior during static tensile tests. The experimental results showed that kidney-shape carbon fibers retard the initiation of transverse cracks and suppress their accumulation. Moreover, a micromechanical simulation based on finite ele- ment method was performed to consider the effects of fiber cross-sectional shape on crack propagation. In the case of the major damage process of the two kinds of CFRPs to be different in the simulations, the numerical results agreed well with the experimental ones. It was experimentally and numerically demonstrated that the kidney-shape carbon fiber suppresses the transverse crack accumulation and retards the crack initiation in CFRP laminates compared with round-shape carbon fiber.

Desiccant coated heat exchanger (DCHE) systems have significant potential in improving dehumidification performance. The moisture transfer occurring in one single air channel of DCHE can dominate the overall system performance. In this study, the adsorber with an approximate air channel of DCHE was designed to experimentally investigate the kinetics of silica gel and two aluminophosphate zeolites (FAM Z01 and FAM Z05). Their dehumidification performances also were simulated at regeneration temperature range of 50–80 °C to reveal the applicability in air-cooled cross-flow DCHE. Results showed that linear driving force (LDF) model could well describe the dynamic water uptake behaviors. Adsorption rate coefficient k_ads increased with increasing inlet air humidity ratio and velocity, but decreased with increasing coating thickness. It is worth noting that increasing regeneration temperature had a little effect on k_ads, while desorption rate coefficient k_des increased significantly. Simulation results showed that moisture removal capacity (MRC) and dehumidification coefficient of performance (DCOP) of FAM Z05 coated DCHE could reach 0.495 g/kg and 0.57 at regeneration temperature of 50 °C, which were 2.3 and 15.4 times higher than these of silica gel and FAM Z01 coated DCHEs. It demonstrated that FAM Z05 was more promising to utilize lower-grade heat energy.

In the high Knudsen number flows, like micro gaseous flows and flows in vacuum, the gas-surface interaction plays an important role. Among many gas species, water is a common and useful fluid in wide area of engineering applications, and it is one of the main residual gas components in the high vacuum environment. However, experimental measurements on the gas-surface interaction of water molecules are still limited. In this study, we focus on the accommodation coefficient, which represents the mean behavior of gas molecules on the scattering process from a surface. We measure the thermal accommodation coefficient (TAC) and the tangential momentum accommodation coefficient (TMAC) of water molecules. TAC is measured from the heat flux between two surfaces with different temperatures in vacuum. TMAC is derived through the viscous slip coefficient from the measurement of the mass flow rate through a microtube. To investigate the characteristics of water molecules clearly, the measured accommodation coefficients are compared with those of noble gases, helium, neon, and argon, measured with the same apparatus and procedures. For the accommodation coefficients of noble gases, TAC increases with increasing the molecular weight, while TMAC decreases, which are in good agreement with the previous studies. The TAC and TMAC of water are slightly larger than those estimated from the corresponding molecular weight of noble gases.

Improving the hardness of amorphous carbon nitride with tantalum was realized by using ion beam assisted filtered arc deposition to obtain a low friction coefficient and low specific wear rate in ambient air. The coatings were prepared with different nitrogen flow during coating at different discharge cycles of tantalum. The wear scar and as-deposited surfaces were observed and analyzed by means of FESEM, AES, XPS, and Raman analysis. The lowest friction coefficient (~0.07) was obtained for ta-C:Ta200, which exhibited a low specific wear rate of < 1.0 × 10−7 mm3/Nm. The XPS analysis revealed the existence of amorphous Ta2O5, and the friction coefficient seemed to be positively correlated with oxygen desorption from the coatings.

This paper proposes an isogeometric boundary element method (IGBEM) to solve the electromagnetic scattering problems for three-dimensional doubly-periodic multi-layered structures. The main concerns are the constructions of (i) an open surface (between two layers) and (ii) a vector basis function with using the B-spline functions. Regarding (i), we considered an algorithm to generate a doubly-periodic open surface with the tensor product of the B-spline functions of any degree. Regarding (ii), we employed the vector basis function based on the B-spline functions, which was proposed by Buffa et al. (2010), and adapted it to the underlying periodic problems so that it can satisfy the quasi-periodic condition on the boundary of an open surface. The proposed IGBEM worked for solving some numerical examples satisfactorily and proved the applicability to plasmonic simulations.

Open air channels coated with porous desiccant are widely applied in solid desiccant cooling systems. In this study, the isothermal adsorption and desorption characteristics of silica gel coated single-channel adsorber were investigated. A modified LDF model considering air- and solid-side resistances was derived to evaluate the kinetics and estimate the total mass transfer rate for numerical modelling. Results show that the modified LDF model can well describe the dynamic behavior of isothermal dehumidification. A new numerical model predicting the mass transfer characteristics of dehumidification process was proposed and strictly validated. Parametric studies reveal that the moisture transfer strongly depends on kinetic constants, isotherm shapes and thermal boundaries. The higher kinetic constants, the larger adsorption/desorption rate and the faster equilibrium. It was found that neither too high nor too low shape factor R are conducive to improve dehumidification capacity. The isotherm with R=0.1 is considered as the optimum isotherm shape. With the transition of thermal boundary from ideal isothermal to adiabatic condition, the mass transfer performance decreases. The peak value of transient mass transfer rate of adsorption process under ideal isothermal boundary is almost twice and 2.6 times higher than these of the third type thermal boundary and adiabatic boundary, respectively.