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Titanium alloys have high specific strength and excellent high-temperature properties. However, Ti alloys have limited weldability with other metals due to the formation of brittle intermetallic compounds. Moreover, when steel is a counterpart of dissimilar metal joining, the soundness of weld is hardly achieved due to weld defects. Numerous studies have been conducted to achieve joint strength by minimizing the effects of Fe-Ti intermetallic compounds. In most studies, pure titanium or Ti-6Al-4V alloy were selected as the Ti base metal, whereas stainless steel, low carbon steel, or alloy steel were selected as the steel base metal. To date, joining processes such as diffusion bonding, brazing, fusion welding, and solid-state joining have been investigated. In this study, the characteristics of each of these joining processes were reviewed. More specifically, the formation of intermetallic compounds was analyzed when Ti alloy and steel were directly joined without using interlayer materials.

Biomolecular condensates participate in diverse cellular processes, ranging from gene regulation to stress survival. Bottom-up engineering of synthetic condensates advances our understanding of the organizing principle of condensates. It also enables the synthesis of artificial systems with novel functions. However, building synthetic condensates with a predictable organization and function remains challenging. Here, we use DNA as a building block to create synthetic condensates that are assembled through phase separation. The programmability of intermolecular interactions between DNA molecules enables the control over various condensate properties including assembly, composition, and function. Similar to the way intracellular condensates are organized, DNA clients are selectively partitioned into cognate condensates. We demonstrate that the synthetic condensates can accelerate DNA strand displacement reactions and logic gate operation by concentrating specific reaction components. We envision that the DNA-based condensates could help the realization of the high-order functions required to build more life-like artificial systems.

With the development of the Internet of things, big data, and AI leading the 4th industrial revolution, it has become possible to acquire, manage, and analyze vast and diverse condition signals from various industrial machinery facilities. In addition, it has been revealed that various and large amounts of signals acquired from the facilities can be utilized for fault diagnosis. Currently, while data-driven fault diagnosis techniques applicable to the facilities are being developed, it has been tried to apply the techniques for the development of fully autonomous ships in the shipbuilding and shipping industry. Since the autonomous ships must be able to detect and diagnose the failures on their own in real time, the overall research is required on how to acquire signals from the ship facilities and use them to diagnose their failures. In this study, a fault diagnosis framework was proposed for condition-based maintenance (CBM) of ship oil purifiers, which are an auxiliary facility in the engine system of a ship. First, an oil purifier test-bed for simulating faults was built to obtain data on the state of the equipment. After extracting features using discrete wavelet decomposition from the data, the features were visualized by using t-distributed stochastic neighbor embedding, and were used to train support vector machine-based diagnostic models. Finally, the trained models were evaluated with Accuracy and F1 score, and some models scored 0.99 or higher, confirming high diagnostic performance. This study can be used as a reference for establishing CBM system and fault diagnosis system. Furthermore, this study is expected to improve the safety and reliability of oil purifiers in Degree 4 MASS.

Phase separation of biomolecules plays key roles in physiological compartmentalization as well as pathological aggregation. A deeper understanding of biomolecular phase separation requires dissection of a relation between intermolecular interactions and resulting phase behaviors. DNA nanostars, multivalent DNA assemblies of which sticky ends define attractive interactions, represent an ideal system to probe this fundamental relation governing phase separation processes. Here, we use DNA nanostars to systematically study how structural flexibility exhibited by interacting species impacts their phase behaviors. We design multiple nanostars with a varying degree of flexibility using single-stranded gaps of different lengths in the arm of each nanostar unit. We find that structural flexibility drastically alters the phase diagram of DNA nanostars in such a way that the phase separation of more flexible structures is strongly inhibited. This result is not due to self-inhibition from the loss of valency but rather ascribed to a generic flexibility-driven change in the thermodynamics of the system. Our work provides not only potential regulatory mechanisms cells may exploit to dynamically control intracellular phase separation but also a route to build synthetic systems of which assembly can be controlled in a signal dependent manner.

We propose a time synchronization method which is applicable to both offset quadrature amplitude modulation based filter-bank multicarrier (FBMC-OQAM) system and quadrature amplitude modulation based filter-bank multicarrier (FBMC-QAM) system. Based on the relation between the transmitted data symbols and FBMC signal, we design the scattered symbols to make a specific time domain region empty. Then, we insert the preamble in that region so as to transmit it perfectly. The performance of the proposed synchronization method is compared with the conventional time synchronization methods for the FBMC systems in terms of root mean square error (RMSE) of symbol timing offset (STO), bit error ratio (BER) and correctly detected data bit ratio per frame. Since the proposed method can reduce the resource usage for the synchronization, the resources for data transmission can be increased, thereby improving the spectral efficiency of the FBMC systems.

A well-designed proton exchange membrane (PEM) fuel cell requires a robust design of cell components. Therefore, the understanding of the deformation mechanism of each component is essential for a successful design. This study deals with the induced deformation of gas diffusion layer (GDL) due to the deformation of the membrane during fuel cell operation. A parametric study with six cases is constructed and the corresponding responses of a stress variation, distribution of contact pressure and a channel intrusion are selected to assess the effect of design parameters on the deformation of the GDL. The variation in the thickness of the GDL is considered as a parameter of the study in addition to the material model of the membrane. The variation in stress levels in the GDL induced due to the cyclically deformed membrane is calculated with different material models of the membrane. Through-plane stiffness of the GDL represented by the thickness of the GDL affects the three responses of the model considered. However, the material model of the membrane influences the planned responses selectively. An observation of contact loss at the interface is a strong indication of the importance of through-plane stiffness of the GDL on the deformation between the GDL and the membrane. In order to come up with a way that improves the cell’s performance, we numerically show that the manipulation of through-plane stiffness of the GDL is needed by employing an appropriate thickness of the GDL. The results from this study assist in understanding the interrelation between the GDL and the membrane for the deformation of the GDL.

A series of material tests were performed on cryogenic metallic materials meant for liquid hydrogen storage tanks using a 20 K tensile cryostat and an electrochemical hydrogen-charging apparatus. Mechanical evaluation of the electrochemically hydrogen-charged specimens was performed in a tensile cryostat using helium gas at ambient temperature and cryogenic temperature (20 K). The tensile cryostat was equipped with a vacuum jacket and a G-M cryocooler with gaseous helium. Furthermore, the cathodic electrolysis cell used for charging the specimens was adopted for internal hydrogen conditions with a reflux condenser and heating mantle to increase hydrogen diffusivity. The target materials were austenite stainless steel and aluminum alloy, which are suitable for liquefied natural gas and gaseous hydrogen environments. No significant change in the yield strength and flow stress of the hydrogen-charged specimen up to 20% strain was observed. However, changes in tensile strength and elongation were observed thereafter. Electrochemical hydrogen charging of stainless steel leads to a high concentration of hydrogen on the surface of the specimen. The resulting surface cracks reduced the flow stress. The 20 K tensile test showed discontinuous yielding in the austenitic stainless steel with an abrupt increase in temperature. The mechanical performance of the aluminum alloys improved in terms of strength and elongation. Changes in the mechanical performance and relative area reduction were observed for all the metallic materials at 300 K and 20 K.

Microfoundations of institutions are central to constructing place – the interplay of location, meaning, and material form. Since only a few institutional studies bring materiality to the fore to examine the processes of place-making, how material forms interact with people to institutionalize or de-institutionalize the meaning of place remains a black box. Through an inductive and historical study of Boston’s North End neighborhood, the authors show how material practices shaped place-making and institutionalized, or de-institutionalized, the meaning of the North End. When material practices symbolically encoded meanings of diverse audiences into the church, it created resonance and enabled the building’s meanings to withstand environmental change and become institutionalized as part of the North End’s meaning as a place. In contrast, when the material practices restricted meaning to a specific audience, it limited resonance when the environment changed, was more likely to be demolished and, thus, erased rather than institutionalized into the meaning of the North End as a place.

To evaluate equipment survivability of the polymer Viton, used in sealing materials, the effects of its thermal degradation were investigated in severe accident (SA) environment in a nuclear power plant. Viton specimens were prepared and thermally degraded at different SA temperature profiles. Changes in mechanical properties at different temperature profiles in different SA states were investigated. The thermal lag analysis was performed at calculated convective heat transfer conditions to predict the exposure temperature of the polymer inside the safety-related equipment. The polymer that was thermally degraded at postaccident states exhibited the highest change in its mechanical properties, such as tensile strength and elongation. Keywords: Equipment Survivability, Severe Accident, Thermal Degradation, Thermal Lag Analysis, Viton

To maintain sustainability of nuclear energy as an important energy source, both safety problem and Spent Nuclear Fuels(SNFs) problem should be solved. In case of Gen-IV reactors such as fast reactor, SNFs can be used as fuels by using fast neutrons. It can be a suitable treatment method of high-level waste in near future. Liquid metals such as Sodium or Lead-Bismuth Eutectic (LBE) can be possibly used as a coolant to use fast neutrons. In this paper, it was described that natural circulation parameter studies, design analyses, material selections and a completion of facilities. To develop a natural circulation facility, thermal hydraulic analyses were performed. Installation technique of liquid metal natural circulation were secured.

This paper proposes a supplementary control for tighter control of the air&ndash, fuel ratio (AFR), which directly affects the environmental emissions of thermal power plants. Dynamic matrix control (DMC) is applied to the supplementary control of the existing combustion control loops and the conventional double cross limiting algorithm for combustion safety is formulated as constraints in the proposed DMC. The proposed supplementary control is simulated for a 600-MW drum-type power plant and 1000 MW ultra-supercritical once-through boiler power plant. The results show the tight control of the AFR in both types of thermal power plants to reduce environmental emissions.

The Internet of Things (IoT) has become a powerful element of next generation networking technologies. In an IoT-enabled environment, things or physical objects no longer stay unresponsive. Instead they are connected to the Internet and embedded with processing and communication capabilities. A great rise of mobile network users is causing identity management problems on mobile service provider through mobile networks. This paper proposes improved I2DM to solve user ID management and security problems on mobile Internet application services over 5G/IoT networks. IIDM protocol breakup loads which made by existing I2DM protocols mutual authentication via mobile operator, via sending some parts to Internet application service provider, enhancing mobile and ID management of service provider and network load and process load from information handling and numbers of transmitting packets, to propose more optimized protocol against further demanding of 5G/IoT mobile networks.

We propose a novel per-tone minimum mean square error (MMSE) receiver for filter-bank multicarrier (FBMC) systems to transmit quadrature amplitude modulation (QAM). To mitigate the residual interference problem, we consider interference channels from the other subcarriers and symbol durations. Simulation results show that the proposed receiver can improve the bit error rate (BER) performance of FBMC systems in multipath fading channels compared to the conventional per-tone receiver with same size of receiver matrix.

In this paper, we present WearLove, a wrist-worn device and mobile application for enhancing affective communication between users. It enables two users to send a heart symbol to each other's wristband monitors by touching the sensor on the band. Given that the gamification causes the user motivation, we add the gamification elements to the app. The more they express their love to each other via the wristband, the bigger a tree will be grown in the app. By using WearLove, we would like to figure out it can actually enhance the affective communication between users. Add to this, we also investigate the gamification elements in the app can evoke the user motivation for affective communication. To address these questions, three group interviews were conducted during one hour for each couple. (N = 6, 3 couples) Results indicated that WearLove may evoke user motivation for affective communication. Key findings and limitations are going to be discussed in the paper.