Refined geometric transition and qqqq-characters

We show the refinement of the prescription for the geometric transition in the refined topological string theory and, as its application, discuss a possibility to describe $qq$-characters from the string theory point of view. Though the suggested way to operate the refined geometric transition has passed through several checks, it is additionally found in this paper that the presence of the preferred direction brings a nontrivial effect. We provide the modified formula involving this point. We then apply our prescription of the refined geometric transition to proposing the stringy description of doubly quantized Seiberg--Witten curves called $qq$-characters in certain cases.Comment: 44 pages, 11 figures; v2: references corrected, text corrected, published in JHE

Optical Evidence of Itinerant-Localized Crossover of 4f4f Electrons in Cerium Compounds

Cerium (Ce)-based heavy-fermion materials have a characteristic double-peak structure (mid-IR peak) in the optical conductivity [$\sigma(\omega)$] spectra originating from the strong conduction ($c$)--$f$ electron hybridization. To clarify the behavior of the mid-IR peak at a low $c$-$f$ hybridization strength, we compared the $\sigma(\omega)$ spectra of the isostructural antiferromagnetic and heavy-fermion Ce compounds with the calculated unoccupied density of states and the spectra obtained from the impurity Anderson model. With decreasing $c$-$f$ hybridization intensity, the mid-IR peak shifts to the low-energy side owing to the renormalization of the unoccupied $4f$ state, but suddenly shifts to the high-energy side owing to the $f$-$f$ on-site Coulomb interaction at a slight localized side from the quantum critical point (QCP). This finding gives us information on the change in the electronic structure across QCP.Comment: 6 pages, 4 figures. To appear in JPSJ (Letters

Optimization of the moment of inertia and the release conditions of a discus

AbstractThis paper describes the concurrent optimization of the design of a discus and the skill with which it is thrown. The objective function for optimization is the flight distance, where longer is better. Thirteen control variables are considered, twelve of which are concerned with the skill of the thrower. These determine the launch conditions, which are controlled by the thrower when he or she throws the discus. The final variable is concerned with the discus itself. This is the moment of inertia on its transverse axis. The optimization was carried out with the aid of a genetic algorithm, and the entire trend for each generation between the objective function and the control variables could be visualized with the aid of self organizing maps. It was found that the flight distance achieved with concurrent optimization was longer than that optimized for skill alone. In the case of the optimal flight, the angle of attack should always be less than the stalling angle

Electronic-Structure-Driven Magnetic Ordering in a Kondo Semiconductor CeOs2Al10

We report the anisotropic changes in the electronic structure of a Kondo semiconductor CeOs$_2$Al$_{10}$ across an anomalous antiferromagnetic ordering temperature ($T_0$) of 29 K, using optical conductivity spectra. The spectra along the $a$- and $c$-axes indicate that a $c$-$f$ hybridization gap emerges from a higher temperature continuously across $T_0$. Along the b-axis, on the other hand, a different energy gap with a peak at 20 meV appears below 39 K, which is higher temperature than $T_0$, because of structural distortion. The onset of the energy gap becomes visible below $T_0$. Our observation reveals that the electronic structure as well as the energy gap opening along the b-axis due to the structural distortion induces antiferromagnetic ordering below $T_0$.Comment: 4 pages, 4 figure

Effect of Subcooling Control on Residential Heat Pump Systems’ Performance

An electronic expansion valve can be used to improve efficiency and capacity in residential heat pump system by changing the focus of its control method on condenser subcooling and allowing slightly wet compressor suction to reduce discharge temperatures. This paper will present results of an experimental and theoretical analysis of the use of subcooling control. An investigation based on ideal cycle analysis shows potential improvements in HPF can be obtained if the subcooling is controlled by the system’s expansion valve, but higher specific heating capacity and pressure ratios may reduce the overall improvement as outdoor temperatures are further decreased. A 2-Ton (7 kW) off-the-shelf residential system was used to evaluate the effect of subcooling control the system’s performance characteristics under a range of external conditions for HSPF calculation and compared with the original system’s expansion control. HPF (Heating performance factor) was increased by up to 19.1% in low load conditions and up to 4.2% in high load conditions. Heating capacity was also improved by up to 18.1%, which penalizes low load conditions by requiring more often on/off cycling but could lead to even higher HPF increase if the compressor speed is lowered to match the load of the residence in higher load conditions and can also improve efficiency at conditions that require auxiliary heating. HSPF was calculated for both subcooling controlled and baseline system showing an improvement of 19.2% in HSPF with a negative effect only observed between 0C and 5.5C which suffer from higher cycling degradation. The control scheme was defined as a linear function of the refrigerant condensation and indoor air inlet temperature difference. The control curve showed good agreement with both experimental and model data for the system, with the charge compensator causing some deviation from the rest of the data. The use of an accumulator as a charge receiver may eliminate the requirement of a charge compensator simplifying the cycle architecture while still providing an increase in efficiency with subcooling control

Experimental and Theoretical Analysis of Subcooling Control in Residential Air Conditioning Systems

Widespread use of electronic expansion valves in residential air conditioning systems has provided an opportunity to further improve performance by use of alternative refrigerant flow control strategies. This paper focuses on an experimental and theoretical investigation on the effect of subcooling control in air conditioning system. A 2 Ton (7 kW) R410-A system was used in the experimental study and a model for the same system was developed and validated. The paper provides a theoretical analysis and determination of a control scheme to maximize COP and an experimental validation on the performance of a RAC system with subcooling control against a TXV-based baseline system. The theoretical analysis showed that subcooling can be defined as a linear function of temperature difference of refrigerant condensation and condenser air (����������������) and that the effect of the evaporator conditions on its COP-maximizing values are negligible. The system was evaluated at AHRI 240/270 dry conditions with a properly charged TXV (6600g) and EXV subcooling control (8500g) comparison. Results show an average 9.8% increase in COP and 10.4% in capacity using subcooling control for the SEER conditions and a resulting increase of 9.4% in SEER. Validation with both experimental and model data show that subcooling control based on ���������������� prov ides a co nt rol sche me with good agreement to the data for air conditioning system capable of increasing both COP and capacity