A practical and accurate dosimetry method is essential to support basic research aimed at advancing ultra-high dose rate radiation therapy (UHDR, >40 Gy/s). However, applying conventional dosimetry methods which have been developed and characterized under low dose rates (approximately 0.03 Gy/s) directly to these conditions remains highly challenging. The dose and dose rate dependences of passive dosimeters, optical stimulated luminescence dosimeter (OSLD), Fricke chemical dosimeter and cellulose triacetate (CTA) film dosimeter, were investigated for dosimetry under UHDR irradiation of proton and electron beams. Under 230 MeV proton irradiation with an average dose rate of 50 Gy/s, no dose rate dependence was observed in either OSLD or Fricke dosimeter. The applicable dose range was below 10 Gy for OSLD and above 10 Gy for the Fricke dosimeter. In contrast, under 14 MeV electron irradiation with an instantaneous dose rate exceeding 100 kGy/s, dose rate dependence was observed in OSLD and CTA film dosimeter, while the Fricke dosimeter remained dose rate independent. Since the observed dose-rate dependence in OSLD appears to contradict existing theoretical models, further experimental validation is required. These results demonstrate that the dose assessment at the accelerator facilities can be effectively characterized using a combination of OSLD and Fricke dosimeters, covering a wide range of proton dose and dose rate, whereas the Fricke dosimeter is applicable for dosimetry of high-intensity short-pulsed electron beam.
In manufacturing and construction industries, heavy objects lifted with cranes are manually positioned by floor workers pushing and pulling the object to bring it to a desired location. Skills are required, especially for mating a crane-suspended object with a fixture, a process called fixture loading. This letter aims to automate this dangerous and difficult task using a multi-cable crane capable of contact-rich dexterous manipulation, the DexCrane. A prototype DexCrane suspends an object and guides it to a target pose through a series of contacts with jigs. This is accomplished by taking advantage of manipulation with cables. When jigs are touched, the cables become slack and thus exhibit a compliant behavior without active force and compliance control. A trajectory planning method is presented to generate trajectories so that a cable-suspended object can be guided to a target pose through a series of jig contacts. Accessibility conditions are analyzed to determine whether the cable-suspended object can reach the target pose while interacting with the jigs. Dynamic Programming (DP) is applied to trajectory optimization subject to contact constraints and cable slack conditions. The proposed approach is implemented on a DexCrane prototype and validated through hardware experiments and simulations, demonstrating its effectiveness and practical feasibility.
First, amorphous W-doped In2O3 films with thicknesses ranging from 3 to 10 nm were deposited on glass substrates at room temperature by ion plating with direct current arc discharge. Second, they were then annealed in vacuum at 5 & times; 10-4 Pa or in air at atmospheric pressure for 30 min at 250 degrees C. Out-of-plane grazing incidence and in-plane X-ray diffraction measurements revealed that the postdeposition annealing in vacuum at 5 & times; 10-4 Pa process produced polycrystalline IWO films with thicknesses of 5, 7, and 10 nm, whereas the postdeposition annealing in air at atmospheric pressure produced 7-and 10-nm-thick polycrystalline IWO films. Atomic force microscopy measurements showed that the annealing in vacuum at 5 & times; 10-4 Pa tended to produce spiky surfaces, whereas bumpy surfaces were formed through the annealing in air at atmospheric pressure. For polycrystalline IWO films, the Urbach energy, calculated using the optical absorption coefficient data, decreased with increasing thickness regardless of the postdeposition annealing conditions. Hall effect measurements at room temperature showed that, at any given thickness, the carrier concentration and Hall mobility of the polycrystalline IWO films postdeposition-annealed in vacuum at 5 & times; 10-4 Pa were higher than those of the polycrystalline IWO films postdeposition-annealed in air at atmospheric pressure.
