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Polyimide membranes have been widely investigated in gas separation applications due to their high separation abilities, excellent processability, relatively low cost, and stabilities. Unfortunately, it is extremely challenging to simultaneously achieve both improved gas permeability and selectivity due to the trade-off relationship in common polymer membranes. Diamine modification is a simple strategy to tune the separation performance of polyimide membranes, but an excessive loss in permeability is also generally observed. In the present work, we reported the effects of diamine type (i.e., non-fluorinated and fluorinated) on the physicochemical properties and the corresponding separation performance of a modified membrane using a commercial Matrimid

The effect of the Fe/Co ratio on the catalytic performance of Fe–Co/alumina catalysts has been investigated in the production of high-calorific synthetic natural gas (SNG) from syngas. Fe–Co/alumina catalysts with different Fe/Co molar ratios were synthesized by the co-precipitation method and characterized using XRD, BET, H2-TPR, Raman, XAS, and XPS. At higher Fe/Co ratios (≥2), the calcined Fe–Co/alumina catalysts were mainly composed of α-Fe2O3 and CoFe2O4. The presence of Co improved the dispersion of iron oxides and the catalyst reducibility under H2 atmosphere. The Fe–Co/alumina catalysts partially formed FeCo alloys when they were reduced at 350 °C under H2. The formation of FeCo alloy destabilized the iron carbide phase and suppressed the carbon chain growth. These Fe–Co/alumina catalysts were efficient in producing high calorific SNG with a heating value of over 60 MJ/Nm3.

Polyimide membranes have been widely investigated in gas separation applications due to their high separation abilities, excellent processability, relatively low cost, and stabilities. Unfortunately, it is extremely challenging to simultaneously achieve both improved gas permeability and selectivity due to the trade-off relationship in common polymer membranes. Diamine modification is a simple strategy to tune the separation performance of polyimide membranes, but an excessive loss in permeability is also generally observed. In the present work, we reported the effects of diamine type (i.e., non-fluorinated and fluorinated) on the physicochemical properties and the corresponding separation performance of a modified membrane using a commercial Matrimid® 5218 polyimide. Detailed spectroscopic, thermal, and surface analyses reveal that the bulky fluorine groups are responsible for the balanced chain packing modes in the resulting Matrimid membranes compared to the non-fluorinated diamines. Consequently, the modified Matrimid membranes using fluorinated diamines exhibit both higher gas permeability and selectivity than those of pristine Matrimid, making them especially effective for improving the separation performance towards H2/CH4 and CO2/CH4 pairs. The results indicate that the use of fluorinated modifiers may offer new opportunities to tune the gas transport properties of polyimide membranes.

A voyage optimization model is proposed to minimize the operating costs of LNGC (Liquefied Natural Gas Carrier). The model is utilized to suggest the RPM and route plan of the vessel based on the amount of boil-off gas generated. Voyage optimization of LNGC is different from that of general cargo ships because of the natural characteristics of its product, LNG. LNG is vaporized by heat ingress in the cargo containment system. Releasing it into the atmosphere becomes an economic loss since this boil-off gas is a commodity to be transported despite a phase transition. Therefore, LNGC uses it as fuel or reliquefies and reloads it in cargo tanks. A voyage planning problem to minimize the total consumption of fuel and cargo is formulated as an optimization model. For this study, LNGC with a dual-fuel engine is considered. The daily amount of BOG (Boil-Off Gas) is predicted based on forecasts of seawater temperature and atmospheric temperature on the route. Ship's speed and the total amount of fuel consumption in-service condition is estimated considering marine weather forecast. The proposed model is applied to various voyage planning problems of the actual route of LNGC. The results obtained from the case studies show that the total cost of operation can be reduced compared to sailing the shortest route.

In industry 4.0, the paradigm of technologies has been actively changing in fields of artificial intelligence and autonomous system. Shipbuilding industry is also investing autonomous navigation system, including collision avoidance supporting system and navigation assistance system using leading-edge technologies such as deep learning, sensor fusion, and augmented reality (AR). Hyundai heavy industry has developed advanced navigation assistance system called Hi-NAS, which uses radar ARPA, AIS as well as a forward-looking camera. The output of Hi-NAS is an AR-based display overlayed information on own ship’s and other ships status and indices of collision risk. It is expected that the display can assist crews to navigate safer.

Although steam methane reforming (CH4 + 2H2O → 4H2 + CO2) is the most commercialized process for producing hydrogen from methane, more than 10 kg of carbon dioxide is emitted to produce 1 kg of hydrogen. Methane pyrolysis (CH4 → 2H2 + C) has attracted much attention as an alternative to steam methane reforming because the co-product of hydrogen is solid carbon. In this study, the simultaneous production of hydrogen and separable solid carbon from methane was experimentally achieved in a bubble column filled with molten potassium chloride. The melt acted as a carbon-separating agent and as a pyrolytic catalyst, and enabled 40 h of continuous running without catalytic deactivation with an apparent activation energy of 277 kJ/mole. The resultant solid was purified by water washing or acid washing, or heating at high temperature to remove salt residues from the carbon. Heating the solid product at 1200 °C produced the highest purity carbon (97.2 at%). The economic feasibility of methane pyrolysis was evaluated by varying key parameters, that is, melt loss, melt price, and carbon revenue. Given a potassium chloride loss of 0.45 per kg of produced carbon. In this case, methane pyrolysis using molten potassium chloride may be comparable to steam methane reforming with carbon capture storage.

The fluorescence quenching of CdSe/CdS core/shell quantum dots (QDs) with various shell thicknesses is investigated. Inducing aggregation of the core/shell QDs with the addition of NaCl shows that the fluorescence quenching efficiency decreases monotonically as the CdS shell thickness increases because of the reduced spectral overlap between the emission and absorption spectra. In addition, hybridization between the oligonucleotide-functionalized QDs and its complementary DNA with the fluorescent dye is used to study the fluorescence quenching caused by the Forster resonance energy transfer (FRET) and any uncontrolled aggregation. These experiments allow quantitative estimation of the effects of FRET and uncontrolled aggregation on the fluorescence quenching efficiency, which can be used to determine conditions to minimize undesirable fluorescence quenching due to uncontrolled aggregation in energy transfer-based biosensor applications.

In this study, we propose a new approach for solving the weather routing problem with an efficient speed schedule that minimizes fuel consumption. The procedure used to solve the problem comprises two phases. The first phase aims to obtain the optimal route at each time step using the A* algorithm. During this phase, the speed of the ship is fixed and only the heading angle is optimized. The safety regulations published by IMO are applied as constraints during the first phase. The second phase is the speed scheduling phase. The original problem is highly nonlinear and nonconvex optimization problem and it can be converted into a geometric programming problem. By solving the geometric programming problem, we can determine the optimal speed schedule for the ship. The optimal speed obtained using this procedure guarantees the global optimum because the problem is convex. This method can produce an almost optimal solution to the weather routing problem more efficiently than existing methods.