The discharge properties of Na/Ni3S2 cell at ambient temperature

The discharge properties of a Na/Ni₃S₂ cell using 1 M NaCF₃SO₃ in tetra(ethylene glycol)dimethyl ether liquid electrolyte were investigated at room temperature. The products were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Electrochemical properties of Na/Ni₃S₂ cells were also presented by cyclic voltammetry and the galvanostatic current method. Na/Ni₃S₂ cells have an initial discharge capacity of 420 mAh g⁻¹ with a plateau potential at 0.94 V versus Na/Na⁺. After the first discharge, Ni₃S₂ and Na react at room temperature and then form sodium sulfide (Na₂S) and nickel. Sodium ion can be partially deintercalated from Na₂S charge reaction. The discharge process can be explained as follows: Ni₃S₂ + 4Na ↔ 3Ni + 2Na₂S.     

Microstructural Evolution of Transparent PLZT Ceramics Sintered in Air and Oxygen Atmospheres

Transparent lanthanum-doped lead zirconate titanate (PLZT) ceramics were fabricated by air-pressure sintering. When the PLZT (9/65/35) specimens were sintered in air, the microstructure was not uniform throughout the body; the outer region near the surface was completely dense, while the inner region of the body was porous. The thickness of the outer dense layer increased parabolically with sintering time. When the specimen was sintered in air at 1200°C for 8 h, the thickness of the dense layer was ∼0.25 mm. Therefore, when the specimen had a thickness of <0.5 mm, it was dense and transparent. This difference in microstructure was attributed to the formation of lattice vacancies as a result of PbO evaporation from the surface. The sintering atmosphere also was important in determining the thickness of the dense layer. The thickness was strongly dependent on the oxygen partial pressure of the atmosphere. The oxygen-gas trapped in pores was deemed to migrate easily through the lattice vacancies. By sintering in an oxygen-gas atmosphere at 1200°C for 8 h, a transparent PLZT with thickness up to 2 mm was fabricated.     

A numerical approach to determine creep constants for Time-Temperature Parametric methods

This study dealt with how to mathematically obtain creep constants of C, Q/2.3R, T _a and t _a used in Time-Temperature Parametric (TTP) methods. A number of creep rupture data from 550 °C to 800 °C for Type 316LN stainless steel were collected through a worldwide literature survey and experimental data produced at KAERI. It was found that the creep rupture data revealed a linear relationship when the data were plotted by the semilogarithmic coordinates of log (t _r ) versus stress. On the basis of this linear relationship, the creep constants of C, Q/2.3R, T _a and t _a used in the Larson-Miller (LM), the Orr-Sherby-Dorn (OSD), and the Manson-Haferd (MH) methods were obtained by a new numerical method. This approach can be utilized as a useful method to predict the long-term creep life of Type 316 stainless steel.     

Method for Calculating Schedule Delay Considering Lost Productivity

A delay claim often occurs when a difference between the actual completion date and the contract completion date exists. The duration of a delay is an essential piece of information required for determining the cause of a delay. However, it is difficult to analyze a delay claim due to the fact that numerous factors that cause this delay, thereby making it a very complex issue. One of such factors is the lost productivity or loss of productivity. Despite the fact that it is one of the major causes of delay, there have been only a few studies that focus on converting lost productivity into delay duration carried out to date. Claims for productivity losses are generally the result of tension between the contractor and the owner. This tension arises due to the great difficulty involved in quantifying disruption effects. Thus, to calculate accurately the delay duration, a logical method for analyzing schedule delay caused by lost productivity is necessary. Therefore, in this study, we propose a method for analyzing construction schedule delay where this lost productivity is taken into consideration. This methodology was implemented on a case project to ascertain its practicability, and to decide whether it can be utilized in the case of a delay claim related to lost productivity. The significance of this paper is twofold. One is the method to convert the lost productivity into the delay duration, which can be applied to reasonable delay claim settlement. The other is the process to analyze the construction schedule delay considering lost productivity.     

Preparation and absorption properties of ZnO nanostructures for cleanup of H2S contained gas

A nano-size zinc oxide sorbents was formulated for the effective removal of sulfur compounds (H₂S) at a very low concentration (under 50 ppmv) in a gasified fuel gas. They were prepared by a matrix-assisted method in this study. An active carbon was used as a matrix and zinc acetate (Zn(C₂H₃O₂)₂ 2H₂O) was selected as a precursor. About 10–40 wt% of zinc was doped over the activated carbon in the preparation of the sorbents. Content of the zinc doped over the activated carbon had an influence on the morphology of zinc oxide nanostructure. The reactivity tests of the ZnO nanostructures having various morphologies were performed in a fixed bed reactor. Their reactivity increased as their sizes became smaller and their surface areas made larger. Most prepared nanosize zinc oxides showed an excellent performance for the removal of H₂S at a very low concentration.     

Large Electrostrain in K(Nb1−xMnx)O3 Lead‐Free Piezoelectric Ceramics

K(Nb_1?xMn_x)O₃ (KN_1?xM_x) ceramics with 0.005 ≤ x ≤ 0.015 were sintered at 1020°C through a normal sintering process without the formation of a liquid phase. They exhibited double polarization versus electric field (P–E) hysteresis and sprout‐shaped strain versus electric field (S–E) curves owing to the presence of a defect dipole (P_D), which was formed between the acceptor Mn³⁺ ion and the oxygen vacancy. Moreover, the aging process was not required to develop the P_D. The KN_1?xM_x ceramics exhibited a large strain of ~0.2% at 6.0 kV/mm. For the KN_0.985M_0.015 ceramic, this large strain was maintained after 10⁴ cycles of an electric field of 6.0 kV/mm. This ceramic also maintained a double hysteresis curve at 200°C. Therefore, the KN_0.985M_0.015 ceramic has a large electric field‐induced strain, along with good thermal and fatigue properties for multilayer piezoelectric actuators.     

Historical index structure for reducing insertion and search cost in LBS

A major issue in LBS (Location Based Service) is the handling of numerous historical moving object data, affecting query performance and service quality in application systems. In order to store and search lots of data rapidly, an effective index structure is required for improving not only the insertion method, but also the search performance.In order to improve the performance of both applications, we propose the GIP⁺ (Group Insertion tree with Projection Plus) for historical data management such as the trajectory of a vehicle. This index structure, based on the GIP, employs the separated buffer node method for reducing overlaps. The GIP⁺ also uses projection storage for improving search performance by grouping the intersected child node in a node. Additionally, the link between the buffer nodes is designed to directly connect to the next buffer node. To effectively combine these methods and improve the performance, different node levels in the GIP⁺ are also arranged for applying the separated buffer node, the projection storage, and the link. The designed historical index structure is useful for inserting and searching data which is arranged on a time axis.