Diquarks and the production of charmed baryons

Utilizing a quark model characterized by parameters that effectively replicate the masses of ground state hadrons, we illustrate that $(us)$ or $(ds)$ diquarks exhibit greater compactness in comparison to $(ud)$ diquarks. Concretely, the binding energy of the $(us)$ diquark - defined as the diquark's mass minus the combined masses of its individual quarks - is found to be more attractive than that of the $(ud)$ diquark. This heightened attraction present in $(us)$ diquarks could lead to enhanced production of $\Xi_c/D$ particles in high-energy pp or ultrarelativistic heavy-ion collisions.Comment: 9 pages, 5 figure

Performance Characteristics of a Refrigerator-Freezer with Parallel Evaporators using a Linear Compressor

A linear compressor for a domestic refrigerator-freezer has energy saving potential compared with a reciprocating compressor because of a low friction loss and free piston system. A linear compressor can control the piston stroke since it does not have mechanical restriction of piston movement. Therefore, the energy consumption of a domestic refrigerator-freezer using a linear compressor can be reduced by changing the cooling capacity of the compressor. In order to investigate the performance of a refrigerator-freezer with parallel evaporators using a linear compressor and the relation between cooling capacity of the linear compressor and cooling load, experimental simulation is conducted with variation of the capacity of a linear compressor, an ambient temperature, and cooling load. In addition, the power consumption of a linear compressor is compared to that of an inverter reciprocating compressor in a refrigerator-freezer. The performance of a linear compressor is measured with variation of the capacity of a linear compressor from 60% to 100% of the maximum capacity in a refrigerator-freezer. Based on the experimental data, the power consumption of a linear compressor is reduced by 22.4% with 70% capacity compared to 100% but on-time ratio is increased by 12.8%

Effect of Cooling Rate on Microstructure and Mechanical Properties According to Heat Treatment Temperature of Inconel 625

Inconel 625 is typically used in extreme environments due to excellent mechanical properties such as high strength, corrosion resistance, abrasion resistance and low-temperature toughness. When manufacturing a hot forged flange with a thick and complex shape, the cooling rate varies depending on the location due to the difference in thermal gradient during the cooling process after hot forging. In this study, to evaluate the microstructure and mechanical properties of Inconel 625 according to the cooling rate, we performed heat treatment at 950°C, 1050°C, and 1150°C for 4 hours followed by water cooling. Additionally, temperature data for each location on the flange were obtained using finite element method (FEM) simulation for each heat treatment temperature, revealing a discrepancy in the cooling rate between the surface and the center. Therefore, the correlation between microstructure and mechanical properties according to cooling rate was investigated

酸化物分散強化フェライト鋼の接合技術開発

京都大学0048新制・課程博士博士(エネルギー科学)甲第15685号エネ博第226号新制||エネ||49(附属図書館)28222京都大学大学院エネルギー科学研究科エネルギー変換科学専攻(主査)教授 木村 晃彦, 教授 小西 哲之, 教授 長﨑 百伸学位規則第4条第1項該当Doctor of Energy ScienceKyoto UniversityDA

Effect of Rhenium Addition on Microstructures and Mechanical Properties of Oxide Dispersion Strengthened Ferrtic Steels

In this study, to investigate effects of rhenium addition on the microstructures and mechanical properties, 15Cr-1Mo ODS ferritic steels with rhenium additions were fabricated by the mechanical alloying, hot isostatic pressing, and hot rolling processes. Unremarkable differences on grain morphologies and nano-oxide distributions were estimated in the microstructure observations. However, the ODS ferritic steels with 0.5 wt.% rhenium showed higher tensile and creep strengths at elevated temperature than that without rhenium. It was found that rhenium is very effective to improve the mechanical properties

Difference of Microstructures and Mechanical Properties between 9Cr-1W Ferritic/martensitic Steel and ODS Steel

Ferrtic/martensitic and ODS steels were fabricated by the mechanical alloying process, and their microstructures and mechanical properties were investigated. The 9Cr-1W and 9Cr-1W-0.3Ti-0.35Y2 O3 (in wt.%) steels were prepared by the same fabrication process such as mechanical alloying, hot isostatic pressing, and hot rolling processes. A microstructural observation of these steels indicated that the Ti and Y2 O3 additions to 9Cr-1W steel were significantly effective to refine the grain size and form nano-sized Y-Ti-O oxide particles. As a result, the tensile strengths at room and elevated temperatures were considerably enhanced. Considerable improvement of the creep resistances at 700°C was also evaluated. It is thus concluded that 9Cr-1W ODS steel with Ti and Y2 O3 additions would be very effective in improving the mechanical properties especially at elevated temperatures

Microstructures and Mechanical Properties of ODS Ferritic Stainless Steels for High Temperature Service Applications

In this study, ODS ferritic stainless steels were fabricated using a commercial alloy powder, and their microstructures and mechanical properties were studied to develop the advanced structural materials for high temperature service applications. Mechanical alloying and uniaxial hot pressing processes were employed to produce the ODS ferritic stainless steels. It was revealed that oxide particles in the ODS stainless steels were composed of Y-Si-O, Y-Ti-Si-O, and Y-Hf-Si-O complex oxides were observed depending on minor alloying elements, Ti and Hf. The ODS ferritic stainless steel with a Hf addition presented ultra-fine grains with uniform distributions of fine complex oxide particles which located in grains and on the grain boundaries. These favorable microstructures led to superior tensile properties than commercial stainless steel and ODS ferritic steel with Ti addition at elevated temperature

Structural Evolution of Nano-sized Oxide Particles Formed in Mechanically Alloyed Fe-10Cr-5Y2O3 Powders

Fe-10Cr-5Y2O3 powders were mechanically alloyed using a high energy horizontal ball-mill apparatus, and the effect of heat treatment on the behavior of nano-sized oxide particles formed in the mechanically alloyed Fe-10Cr-5Y2O3 powders was investigated. Elongated Cr-rich and Y-rich oxides were observed in the mechanically alloyed powders. During the heating of these powders above 700 °C, the elongated Cr-rich oxides were dramatically changed to a near- spherical morphology. Cubic-Y2O3, monoclinic-Y2O3 and YFeO3 phases were also found after heat treatment at 1150 °C for 1h, indicating that the Y-rich oxide phase was transformed to the cubic-Y2O3, monoclinic-Y2O3 and YFeO3 ones. It is thus concluded that both a morphological change of Cr-rich oxide and a phase transformation of Y-rich oxide during the heating of mechanically alloyed powders could be mainly attributed to extremely high energy, accumulated by the mechanical alloying process

Effect of Radial Stress on the Nanoparticle-Based Electrolyte Layer in a Center-Wound Roll with Roll-to-Roll Systems

Recently, slot-die coating based on the roll-to-roll process has been actively used to fabricate nanoparticle-based electrolyte layers because it is advantageous for high-speed processes and mass production of uniformly thick electrolyte layers. In this process, the fabricated electrolyte layer is stored as a wound roll throughout the rewinding process. We analyzed the defects and geometric changes in an electrolyte layer, i.e., gadolinium-doped cerium oxide (GDC), due to the radial stress in the wound roll. We found that the thickness of the coated layer could be decreased by increasing the radial stress, i.e., cracks can be generated in the coated layer if excessively high radial stress is applied to the wound-coated layer. More thickness changes and crack defects were generated with time due to the residual stress in the wound roll. Finally, we analyzed the effects of taper tension profiles on the defects of the coated layer in the wound roll and determined the taper tension profile to minimize defects

INFLUENCE OF MECHANICAL ALLOYING ATMOSPHERES ON THE MICROSTRUCTURES AND MECHANICAL PROPERTIES OF 15Cr ODS STEELS

Mechanical alloying under various gas atmospheres such as Ar, an Ar-H2 mixture, and He gases were carried out, and its effects on the powder properties, microstructure and mechanical properties of ODS ferritic steels were investigated. Hot isostatic pressing and hot rolling processes were employed to consolidate the ODS steel plates. While the mechanical alloyed powder in He had a high oxygen concentration, a milling in Ar showed fine particle diameters with comparably low oxygen concentration. The microstructural observation revealed that low oxygen concentration contributed to the formation of fine grains and homogeneous oxide particle distribution by the Y-Ti-O complex oxides. A milling in Ar was sufficient to lower the oxygen concentration, and this led a high tensile strength and fracture elongation at a high temperature. It is concluded that the mechanical alloying atmosphere affects oxygen concentration as well as powder particle properties. This leads to a homogeneous grain and oxide particle distribution with excellent creep strength at high temperature