Probing the Structure of Gamma-Ray Burst Jets with Steep Decay Phase of their Early X-ray Afterglows

We show that the jet structure of gamma-ray bursts (GRBs) can be investigated with the tail emission of the prompt GRB. The tail emission which we consider is identified as a steep-decay component of the early X-ray afterglow observed by the X-ray Telescope onboard Swift. Using a Monte Carlo method, we derive, for the first time, the distribution of the decay index of the GRB tail emission for various jet models. The new definitions of the zero of time and the time interval of a fitting region are proposed. These definitions for fitting the light curve lead us an unique definition of the decay index, which is useful to investigate the structure of the GRB jet. We find that if the GRB jet has a core-envelope structure, the predicted distribution of the decay index of the tail has a wide scatter and has multiple peaks, which cannot be seen for the case of the uniform and the Gaussian jet. Therefore, the decay index distribution tells us the information on the jet structure. Especially, if we observe events whose decay index is less than about 2, both the uniform and the Gaussian jet models will be disfavored according to our simulation study.Comment: 21 pages, 10 figures, the paper with full resolution images is http://theo.phys.sci.hiroshima-u.ac.jp/~takami/research/achievements/papers/003_full.pd

Evaluation function of drinking ease from aluminum beverage bottles relative to optimum bottle opening diameter and beverage type

金沢大学理工研究域機械工学系In recent years, aluminum beverage bottles having screw tops with opening diameters of 28 and 38 mm have been launched in the Japanese market in keeping with the modern-day drinking habits of consumers. Although Japanese consumers are familiar with such bottles, a majority of them feel that the 28 mm opening is too small and the 38 mm opening is too large. Therefore, we felt the need to develop a method for evaluating consumer feelings when they drink a beverage directly from the bottle opening. For this purpose, we propose an evaluation function of drinking ease that calculates the optimum opening diameter of the bottle. From results of our previous study, we know that there exists an ideal volume of beverage flowing into the mouth, at which consumers feel most comfortable while drinking directly from bottles. Therefore, we define the evaluation function of drinking ease in terms of the difference between the actual volume of fluid in the mouth and the expected ideal volume. If this difference is small, consumers probably feel comfortable while drinking the beverage. We consider a design variable, i.e., the opening diameter, and two state variables, i.e., the volume of beverage remaining in the bottle and the height of consumers, and construct the response surface of the evaluation function by using radial basis function networks. In addition, for investigating the influence of beverage type on the evaluation function, we select green tea and a carbonated beverage (Coke) as test beverages. Results of optimization of the proposed function show that when the opening diameters are 35.4 mm and 34.4 mm in the case of green tea and Coke, respectively, the actual volume of fluid in the mouth is closest to the ideal volume and the participants feel most comfortable. These results are in agreement with results of our previous study that an opening diameter of 33 mm is optimum for young Japanese adults. Thus, we confirm that the proposed function is accurate; it can be used to design bottle openings to suit consumers of various age groups and types of beverages. © 2011 Elsevier Ltd and The Ergonomics Society

Development of evaluation function for openability of opening diameter of aluminum beverage bottles and its application to optimum design

The present paper proposes an evaluation function of openability considering the transition of gripping postures, i.e. two-finger gripping and three-finger gripping, so as to evaluate opening ease of aluminum beverage bottles and to specify the rigorous dimension of the cap diameter that is best suited for consumers\u27 satisfaction. First, we have investigated effects of cap diameter on the gripping postures. It is found that subjects tend to shift the gripping posture from two-finger gripping (gripping with thumb and first finger) to threefinger gripping (gripping with thumb, first, and second finger) with increase of the opening diameter. An evaluation function is defined as a ratio between maximum torques that consumers can apply and a required torque for opening. In addition, the cap diameter is the only design variable, and the thumb length, which associates with the transition of the gripping postures and a maximum gripping force, is selected as a state variable in order to take individual differences into consideration. Moreover, an evaluation function is formulated considering the transition of the gripping postures of consumers. The function is composed by using the data obtained from measurement of the maximum gripping force, the maximum torque, and the thumb length, and then the function is optimized. The result of optimization has shown that the optimum opening diameter is obtained at 28.0 mm in case of the subjects. © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

Evaluation of drinking ease relative to the opening diameter and beverage type of aluminum beverage bottles

金沢大学理工研究域機械工学系This paper investigates the effects of different bottle opening sizes (28, 33, and 38 mm in diameter) and beverage types (e.g. green tea, carbonated beverages) on the drinking satisfaction of consumers, in order to enhance their comfort levels when drinking from aluminum beverage bottles. A survey of 120 Japanese subjects was conducted, and the 33 mm opening size emerged as the most preferred, irrespective of beverage type. The factor analysis results of the questionnaire show that drinking satisfaction is primarily affected by two common factors: the volume of flow from the bottle to the mouth and the adjustability of the flow. The results of the three-dimensional fluid-dynamics analysis indicate that differences in beverage type could influence what consumers regard as an appropriate flow. © 2009 Elsevier Ltd. All rights reserved

Evaluation method of drinking ease for aluminum beverage bottles

金沢大学理工研究域機械工学系This paper has investigated effects of the bottle opening size on drinking feelings in order to improve the comfort level of consumers when drinking directly from the opening of aluminum bottle. A survey over 120 subjects has been performed based on a drinking test using three kinds of bottles with opening diameters of 28, 33 and 38 mm, respectively. Two questionnaires have been conducted. Statistical analysis results of Questionnaire 1 have shown that 33-mm opening is best for adult consumers with no matter the type of contents, gender and the mouth size. The factor analysis results of Questionnaire 2 based on Kansei Engineering have shown that drinking feeling is affected by two common factors, which considered as the flow from the bottle to the mouth and the flow adjustability. Moreover, the fluid-dynamics analysis model has been developed to simulate the bottled liquid in a drinking action consisting of survey results and experimental observations of consumers\u27 drinking actions. Numerical simulations have been performed to understand how consumers control the flow during the drinking actions. It is found that the consumers usually try to realize the ideal and preferable condition by adjusting the inclination angle of the bottle. Copyright © 2007 by ASME

Vertical oxide semiconductor field-effect transistor with extremely low off-state current

Oxide semiconductor field-effect transistors (OSFETs) are actively developed for display applications. An OSFET exhibits a lower off-state current than a silicon FET and enables low-frequency driving. We developed the measurement method and revealed the OSFET exhibits an extremely low off-state current [1]. In addition, we discovered a c-axis aligned crystalline indium-gallium-zinc oxide (CAAC-IGZO) which was unique crystal morphology [2]. A display with a backplane formed using CAAC-IGZO FETs achieves low power consumption owing to idling-stop driving that allows an extremely low refresh rate [3]. Please click Download on the upper right corner to see the full abstract

Embedded DRAM using c-axis-aligned crystalline In-Ga-Zn oxide FET with 1.8V-power-supply voltage

An embedded memory using c-axis aligned crystalline In-Ga-Zn oxide (CAAC-IGZO) FETs with an extremely low off-state current on the order of yoctoamperes (yA) (yocto- is a metric prefix denoting a factor of 10-24) is known as a potential next-generation memory [1][2]. A dynamic oxide semiconductor RAM (DOSRAM), where each memory cell is composed of one CAAC-IGZO FET and one capacitor, enables long data retention and long interval of refresh operations with an advantage of extremely low off-state current of the CAAC-IGZO FET. However, negative backgate voltage (Vbg) and word-line driving voltages of 0/3.3 V (VSSL/VDDH) had been required for an access transistor of the memory cell to satisfy high on-state current and low off-state current. This work shows that DOSRAM operates with 1.8 V-power supply voltage by using a novel driving method. Figure 1 shows Vg-Id performance of a CAAC-IGZO FET used as a cell transistor. The threshold voltage (Vth) of the CAAC-IGZO FET is controlled by changing a level of Vbg, whereas Vth of the Si FET is controlled by channel doping. Figure 2 shows a block diagram of a prototyped DOSRAM. The refresh rate in DOSRAM mainly depends on the leakage current of cell transistors. To reduce the refresh rate to once an hour, the off-state current of the cell transistors on a non-selected word line needs to be reduced to 200 zeptoamperes (zA) per FET (zepto- is a metric prefix denoting a factor of 10-21) or lower at 85C. The required Vbg is -7.0 V to achieve such an off-state current at Vg 0 V, for example. To obtain approx. 100 MHz-driving frequency, the required on-state current is at least several microamperes. The voltage level difference in the word line, VDDH VSSL, is a factor that determines the on-state current, and in this work is fixed to 3.3 V so that the combination of Vbg and the word line voltage is optimized. The application of negative voltage to the word line enables the leakage current of the cell transistor to be maintained low even when Vbg is increased. For example, whereas the existing driving method meets the above off-state current value with Vbg -7.0 V and the VSSL 0 V, the novel driving method meets the value with Vbg 0 V and VSSL -1.5 V. In the novel driving method, VDDH 1.8 V. There has been a report of a reduction in leakage current of a memory cell by application of negative voltage to a top gate in DRAM using Si CMOS [3]. In contrast to it, DOSRAM including CAAC-IGZO FETs with L 60 nm has a leakage current of 200 zA or lower, which is 7-digit lower than that of the DRAM using Si CMOS, and enables longer data retention. The evaluation results of the prototyped DOSRAM verify that a reduction in power-supply voltage from 3.3 V to 1.8 V is possible in terms of operation and data retention. This suggests a highly compatible and efficient configuration of an embedded DRAM and a logic circuit where signals can be transmitted with low VDD. References [1] S. H. Wu, et al., IEEE Symp. VLSI Tech., pp. 166-167, 2017. [2] T. Ishizu, et al., IEEE Symp. VLSI Cir., pp. 162-163, 2017. [3] F. Hamzaoglu et al., IEEE Journal of Solid-State Circuits, vol. 50, no. 1, pp. 150-157, Jan. 2015