There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

The path of chemical reactions - the IRC approach

Since the 3rd century for more than a thousand years chemistry has been thought of as a complicated, hard-to-predict science. Efforts to improve even a part of its unpredictable character are said to have born fruit first of all in the success of the \" electronic theory \". This was founded mainly by organic chemists , such as Fry, Stieglitz, Lucas, Lapworth and Sidgwick, brought to a completed form by Robinson and Ingold, and developed later by many other chemists. 1 In the electronic theory, the mode of migration of electrons in molecules is noted and is considered under various judgements. For that purpose, a criterion is necessary with respect to the number of electrons which should originally exist in an atom or a bond in a molecule. Therefore, it can be said to be the concept by Lewis of the sharing of electrons that has given a firm basis to the electronic theory. 2 In the organic electronic theory, the chemical concepts such as acid and base, oxidation and reduction and so on, have been conveniently utilized from a long time ago. Furthermore, there are terms centring closer around the electron concept, such as electrophilicity and nucleophilicity, and electron donor and acceptor both being pairs of relative concepts. One may be aware that these concepts can be connected qualitatively to the scale of electron density or electric charge. In the electronic theory, the static and dynamic behaviours of molecules are explained by the electronic effects which are based on nothing but the distribution of electrons in a molecule. The mode of charge distribution in a molecule can be sketched to some extent by the use of the electronegativity concept of atoms through organic chemical experience. At the same time, it is given foundation, made quantitative , and supported by physical measurements of electron distribution and theoretical calculations based on quantum theory. The distribution of electrons or electric charge-with either use the result is unchanged-in a molecule is usually represented by the total numbers (generally not integer) of electrons in each atom and each bond, and it was a concept easily acceptable even to empirical chemists as having a tolerably realistic meaning. Therefore, chemists employed the electron density as a fundamental concept to explain or to comprehend various phenomena. In particular, for the purpose of promoting chemical investigations, researchers usually rely upon the analogy through experience, and the electron density …

https://science.sciencemag.org/content/sci/218/4574/747.full.pdf

Role of Frontier Orbitals in Chemical Reactions

The ability of platinum and gold catalysts to effect powerful atom-economic transformations has led to a marked increase in their utilization. The quite remarkable correlation of their catalytic behavior with the available structural data, coordination chemistry, and organometallic reactivity patterns, including relativistic effects, allows the underlying principles of catalytic carbophilic activation by π acids to be formulated. The spectrum of reactivity extends beyond their utility as catalytic and benign alternatives to conventional stoichiometric π acids. The resulting reactivity profile allows this entire field of catalysis to be rationalized, and brings together the apparently disparate electrophilic metal carbene and nonclassical carbocation explanations. The advances in coupling, cycloisomerization, and structural reorganization—from the design of new transformations to the improvement to known reactions—are highlighted in this Review. The application of platinum- and gold-catalyzed transformations in natural product synthesis is also discussed.

Catalytic Carbophilic Activation: Catalysis by Platinum and Gold π Acids

https://onlinelibrary.wiley.com/doi/pdf/10.1002/eej.23245

Reduction of sixth-order radial force by harmonic current control and its application to EPS motors

The paper proposes a method to improve the tran- sient characteristics of current overshoot and oscillation at the start of power transmission for a dynamic wireless power transfer system. The system is important to reduce the settling time as short as possible without current overshoots for a stable power supply. However, conventional methods to suppress current overshoot have a slow response on the secondary side. This paper proposes the superposition of primary and secondary responses. The proposed method controls the secondary voltage by comparing the steady-state current with the current value on the secondary side. The method can effectively suppress the oscillations in the transient response by applying the secondary voltage at the appropriate timing. This paper also studied the ro- bustness of constraints based on model analysis and experimental verification. In the experiments, the proposed method reduces the current overshoot and the settling time of the secondary current, and maximizes the receiving energy. 

Fast Start-Up Control of Both-Side Current without Overshoot Focusing on Rectification Timing for Dynamic Wireless Power Transfer Systems

Research and development are active in electric vertical takeoff and landing (eVTOL) aircraft. In particular, tilt-wing eVTOL aircraft receives much attention as one of the most efficient configurations; however, they are likely to be unstable during the transition from hover to cruise because the lift and thrust have limitations depending on the airflow and tilt angle. This study proposes a new aerodynamic force control method using airflow vector estimation. The airflow vector is estimated by combining motor current, rotational speed, and Pitot-tube measurements. Aerodynamic force control is achieved through the proper design of a feedback controller using disturbance observers (DOBs) to cope with propeller-wing interference caused by the propeller slipstream. This method takes advantage of the motor control performance and is unique in which it monitors the airflow vector and actively changes the tilt angle to quickly obtain the desired acceleration. The effectiveness of the method is verified via simulations and experiments in a wind tunnel.

Aerodynamic Force Control for Tilt-Wing eVTOL Using Airflow Vector Estimation

原子間力オブザーバに基づく高速フォースカーブ測定;原子間力オブザーバに基づく高速フォースカーブ測定;High-Speed Force Curve Measurement based on Atomic Force Observer

In order to improve the mileage per charge of battery electric vehicles, dynamic wireless power transfer systems are being developed. There are some problems, such as are the wide gap between coils when mounted under the floor of a vehicle and the effect of foreign metal objects between coils during power transmission. In-wheel coil, which is a receiver coil and placed inside a wheel, have been proposed to solve the above problems. However, the wheel should be made of non-metal because large eddy current loss occurs. In addition, the gap is still large. In this paper, we propose a coil configuration in which the coils are placed inside the tire and the wheel. This method has the advantage that the conventional aluminum wheel can be used while reducing the gap between coils. The effectiveness of this method is demonstrated by simulations and experiments.

Hiroshi Fujimoto

Papers

Reduction of sixth-order radial force by harmonic current control and its application to EPS motors

Fast Start-Up Control of Both-Side Current without Overshoot Focusing on Rectification Timing for Dynamic Wireless Power Transfer Systems

Aerodynamic Force Control for Tilt-Wing eVTOL Using Airflow Vector Estimation

原子間力オブザーバに基づく高速フォースカーブ測定;原子間力オブザーバに基づく高速フォースカーブ測定;High-Speed Force Curve Measurement based on Atomic Force Observer

Novel Dynamic Wireless Power Transfer System for Battery Electric Vehicles Using In-Tire and In-Wheel Repeater Coil