Variable frequency heavy-ion linac,RILAC: I. Design,construction and operation of its accelerating structure

A variable frequency linear accelerator at RIKEN (IPCR), which is named RILAC, is designed to accelerate ions of almost every element in the periodic table. In this report, the design, construction and performance of the resonator cavities of this linac are described. A new accelerating structure was developed for the variable frequency scheme. The principal aim of the development was to obtain a configuration within the cavity to keep a uniform voltage distribution along the accelerating axis over the wide range of resonant frequencies required. The final form adopted is a coaxial quarter-wave type resonator with a race-track-like cross section for its coaxial inner and outer conductors. It has a movable shorting device as a frequency tuner and its open end is enlarged and loaded with drift tubes, connected to the inner and outer conductors alternatingly. The structure can maintain the required uniformity of the accelerating voltage within 10% in spite of resonant frequency tuning between 17 and 45 MHz. A relatively modest accelerating gradient was chosen so that cw operation could be realized. The RILAC is composed of six such cavities which are independently excited and it succeeded in the acceleration of a beam through all the cavities in 1981.     

Oxygen evolution reaction on transition metal borides

The oxygen evolution reaction on the transition metal borides (mainly Co_xB and Ni_xB) was investigated with various composition ratio of BMetal and sintering temperature. The activity of oxygen evolution reaction became maximum at the composition range of BCo =$\text{1}\text{3}$ and BNi ? $\text{1}\text{3}$, respectively. The sintering temperature also affected largely the activity of oxygen evolution reaction and the metal borides with the composition ratio BMetal = $\text{1}\text{3}$ gave the highest activity at the sintering temperature lower than 300°C for nickel borides and 400 ～ 500°C for cobalt borides. The oxygen evolution reaction on iron boride and lanthanum hexaboride was also briefly discussed, and the order of the activity of oxygen evolution reaction was as follows:

The Tafel slope of oxygen evolution reaction on metal borides was varied from ca. 40 mV for Ni (ca 70 mV for Co) to ca. 120 mV with the increase in the activity of oxygen evolution reaction. The oxide formation became easier with the increase in the activity of oxygen evolution reaction and the differential capacity of the oxide formation in the range more cathodic than the oxygen evolution increased with the decrease in the apparent activation energy of oxygen evolution reaction at 0.60 V (HgHgO).     

Decolorization of molasses wastewater by Bacillus sp. under thermophilic and anaerobic conditions

Various microorganisms were screened for their ability to decolorize molasses wastewater under thermophilic and anaerobic conditions. Strain MD-32, which was newly isolated from a soil sample, was selected as the best strain. From taxonomical studies, the strain was concluded to belong to the genus Bacillus, most closely resembling B. smithii. The strain decolorized 35.5% of molasses pigment within 20 d at 55 degrees C under anaerobic conditions, but no decolorization activity was observed when it was cultivated aerobically. At all the concentrations tested molasses pigment was effectively decolorized by MD-32, with decolorization yields of around 15% within 2 d. The molecular weight distribution as determined by gel filtration chromatography revealed that the decolorization of molasses pigment by the isolated strain is accompanied by a decrease in not only small molecules but also large ones.     

Effect of ultra-thin polymer membrane electrolytes on dye-sensitized solar cells

In-situ ultra-thin porous poly(vinylidene fluoride-co-hexafluoropropylene) P(VDF–HFP) membranes were prepared by a phase inversion method on TiO₂ electrodes coated with Ru N-719 dye. These membranes were then soaked in the organic liquid electrolyte to form the in-situ ultra-thin porous P(VDF–HFP) membrane electrolytes. Dye-sensitized solar cell (DSC) using the membrane electrolyte exhibited an open-circuit voltage (V_oc) of 0.751 V, a short-circuit current (J_sc) of 16.260 mA cm^?2 and a fill factor (FF) of 0.684 under an incident light intensity of 1000 W m^?2 yielding an energy conversion efficiency (η) of 8.35%. The V_oc, FF and η of the solar cell using the membrane electrolyte increased by about 5.8%, 2.2% and 5.7%, respectively, when compared with the corresponding values of a cell using liquid electrolyte. However, the J_sc decreased by about 2.1%.     

Corrosion resistance of ultrasonic soldered aluminium joint using Zn-based solder alloy

In order to obtain high strength aluminium butt joints with high corrosion resistance, ultrasonic soldering of 1070 and 5056 rods was conducted using quasi-melting Zn–18Sn (mass%) alloy and Zn–38A1 alloy. Ultrasonic vibrations were applied at soldering temperature ranging 533–723 K through aluminium rods without using of a solder bath. To evaluate the corrosion resistance of solder joints, tensile tests were conducted after immersion in a 5% NaCl aqueous solution. Though joint strength decreased with an increase in immersion time in the NaCl aqueous solution because of corrosion in the joints, corrosion resistance of 5056 joints with Zn–38A1 alloy was higher than that of joints with Zn–18Sn alloy irrespective of aluminium base material. The strength of joints with Zn–18Sn alloy rapidly decreased by immersion in the NaCl aqueous solution. In these joints, corrosion occurred locally in the soldered interface. Corrosion potential of these joints was unusually lower than that of the solder alloy. In contrast, corrosion occurred slowly in the solder layer in 5056 joints with Zn–38A1 alloy. Corrosion potential of the joints was equivalent to that of the solder alloy.     

Melt synthesis of Eu-doped oxide phosphors using arc-imaging furnace

To synthesize various complex oxide materials and their solid solutions, we applied a novel “melt-synthesis technique” rather than conventional solid-state reaction techniques. Rapid synthesis methods to develop those double oxides have been strongly anticipated. During melt synthesis, the mixture of oxides or their precursors is melted rapidly (1–60 s) in an arc-imaging furnace using strong light radiation. A spherical molten sample with multiple homogeneously mixed cations was solidified directly on a copper hearth with rapid cooling of ca. 10² °C/s.We studied the synthesis of A₂BO₄ type double oxides (AA′)₂BO₄ (A = Sr²⁺, Ca²⁺, A′ = La³⁺, Gd³⁺, Y³⁺, Eu³⁺, B = Al) using this method. Homogeneous samples with Eu³⁺ dopants were synthesized using liquid phase mixing in a few seconds, which is much faster than diffusions of ions in solid phase. Red fluorescence under the irradiation of ultraviolet light (254 and 365 nm) was observed. The excitation band shifted.     

Two-step Design of Critical Control Systems Using Disturbance Cancellation Integral Controllers

An efficient critical control system design is proposed in this paper.The key idea is to decompose the design problem into two simpler design steps by the technique used in the classical loop transfer recovery method (LTR).The disturbance cancellation integral controllcr is uscd as a basic controller.Since the standard loop transfer recovery method cannot bc applied to the disturbance cancellation controller, the nonstandard version recently found is used for the decomposition.Exogenous inputs with constraints both on the amplitude and rate of change are considered. The majorant approach is taken to obtain the analytical sufficient matching conditions.A numerical design example is presented to illustrate the effectiveness of the proposed design.     

Accumulative channel-die compression bonding (ACCB): A new severe plastic deformation process to produce bulk nanostructured metals

This paper introduces a new severe plastic deformation process to produce bulk nanostructured metals: accumulative channel-die compression bonding (ACCB). In the ACCB process, which can be applied to thick billets, the procedure of cutting, stacking and compression bonding in a channel-die is repeated to provide an ultrahigh plastic strain. This process was trialed with high purity aluminum. A fully recrystallized aluminum sample was deformed by ACCB at room temperature for up to 10 cycles, corresponding to an equivalent strain of 8.0. The initially coarse grains were subdivided by deformation-induced high-angle boundaries, and the fraction of such high-angle boundaries increased with increasing strain. Several cycles of ACCB led to a quite uniform ultrafine structure dominated by high-angle grain boundaries. The average boundary spacing of the 10-cycles ACCB sample was as small as 690 nm. The maximum ultimate tensile strength of the ACCB samples was 130 MPa after 5 cycles. Further ACCB cycles, however, led to a slight decrease in strength due to enhanced recovery and boundary migration during the deformation process. It has been demonstrated that the ACCB process can be used to produce bulk nanostructured metals of relatively large dimensions. The results suggest that the ACCB process is equivalent to conventional rolling deformation at high strains.