This paper presents the deformation behavior of SUS304 specimens during partial diameter-enlarged process in a rotation speed region higher than the rotation speed region of conventional diameter-enlarged processing methods. The deformation behavior of the specimen diameter during the process was measured at various axial-compressive forces, bending angles, and rotation speeds. Next, the effect of rotation speed on the deformation behavior was analyzed based on the concept of deformation-induced martensitic transformation and thermally-activated process associated with plastic deformation. The reduction of axial-compressive force and temperature rise during processing in high rotation speeds were investigated. Finally, the time constant of diameter-enlarged was obtained for the above parameters. By increasing the rotation speed, it is possible to shorten the processing time and perform processing at a low axial-compressive force with little temperature rise, which improves the processing efficiency. The time constant of the diameter-enlarged deformation process can be expressed as a function of the effective rotation parameter.

316FR stainless steel and Mod.9Cr-1Mo steel are candidate structural materials for the present design of sodium-cooled fast reactor (SFR) in Japan. A number of research works have been performed in Japan to develop the SFR for practical use. Aiming at enhancing its economic competitiveness and reducing radioactive waste, Japan Atomic Energy Agency has proposed an attractive plant concept and made great efforts to demonstrate the applicability of some innovative technologies to the plant. One of the most practical means is to extend the design life to 60 years. Accordingly, the material strength standards set by the Japan Society of Mechanical Engineers (JSME) have to be extended from 300,000 to 500,000 hours but this extension requires more precise estimation of creep rupture strength and creep strain of the materials in the long term. This paper describes the development of creep property equations of 316FR stainless steel and Mod.9Cr-1Mo steel considering changes in creep mechanisms at high temperatures in the long term based on evaluations of long-term creep properties of the materials. The creep property equations developed in this study will provide more precise estimation of the creep properties in the long term than the present creep property equations of JSME.

Multilayer thin films polymer have been commonly used in a wide range of electronics applications, such as solar cells, photoconductors, semiconductors, and light-emitting diodes, in which failure due to delamination can occur. For evaluating and improving the quality of a multilayer thin-film product, the interfacial strength between its layers must be measured correctly and accurately. In this work, the interfacial strength of a multilayer thin-film polymer was quantified by measuring the interfacial energy release rate (interfacial fracture toughness), G_i , using the nanoindentation test technique. Three specimens of four-layer thin films were fabricated on a glass substrate. The top layer of each specimen was prepared with different thicknesses. The unloading curve technique introduced by Kozuki and Kishimoto (2010) was implemented to quantify the G_i of each specimen. Then, cross-sectional observation of the specimens was performed to confirm the layer thicknesses and to identify the delamination condition after the test. The measured G_i tended to increase as the range between the two unloading curves used to calculate the delamination energy widened. This phenomenon is believed to be caused by the plastic energy of the deformed films during the indentation process. Finally, an empirical method for eliminating the effect of the plastic energy on the measured G_i was proposed. Using this method, a pure G_i value can be effectively extracted; thus, the interfacial strength of multilayer thin-film polymers can be measured correctly and accurately.

Biocoke (BIC), made from all types of biomass is a solid fuel. Hemicellulose and lignin, essential chemical components of biomass, work as bonding agents of BIC solidification because they have softening and fluidity characteristics. Their characteristics make bonding structure inside of BIC during the formation process. Previous studies suggested that physical and mechanical characteristics of BIC are different if raw materials (kinds of biomass) are different even if forming conditions are the same. It was inferred that the reason was different of content rate of main components. Among various biomass, green tea has excellent formability. In this paper, we focus on the potential of green tea as a raw material of BIC. Firstly, we compared the fluidity of green tea with other biomass. Then, compressive strength tests of BIC made from green tea and other biomass were conducted. We used the trunk of conifers, the bark of conifers, bagasse, and rice straw other than green tea. The result of fluidity test indicated that green tea is easiest-to-flow biomass among the five biomasses. Moreover, the flow starting temperature was able to estimate from a content percentage and moisture content with ±30% accuracy by using our estimated equation. As results of compressive strength test, each BIC which was made from five biomasses have two peak points of compressive strength and apparent density. Green tea BIC made under all the test conditions has high apparent density 1.3-1.4 g/cm³. On the other hand, green tea BIC has the lowest compressive strength among the five biomasses tested. We found out that the raw material which it is easy to fluidize by heating has low compressive strength from these results.

The transient critical heat flux (CHF) due to exponentially increasing heat input was experimentally measured for upward water flowing in vertical small tubes. The heat generation rate was increased exponentially with a function of Q_oexp (t/τ ), where, Q_o is an initial heat generation rate, t represents time and τ is e-folding time. The test tubes were made of platinum with inner diameters of 0.7 mm and 1.0 mm, and heated lengths of 12.0 mm and 40.9 mm. The flow velocities and the inlet liquid temperatures ranged from 2.0 m/s to 8.0 m/s, 90 K to 140 K, and the inlet pressure was 800 kPa. It was obtained that the transient CHF was affected by inner diameter of test tube, liquid subcooling, flow velocity, and e-folding time. The transient CHF values increased with the increases in flow velocity and inlet subcooling. The transient CHFs increased with a decrease in e-folding time at τ <1 s, and they approached steady-state values at τ >1 s. It was understood that the heat transfer is in steady-state at τ >1 s, and it is in transient state at τ <1 s. Moreover, the values of transient CHFs at diameter of 0.7 mm were higher than those at the diameter of 1.0 mm. The correlation by Hata and Noda (2008) can express authors’ transient CHFs at e-folding time larger than about 1 s (steady-state region), however, it shows larger values than authors’ data at e-folding time smaller than 1 s (transient region).

Structural health monitoring (SHM) of building structures is a very important technology in the effort to realize a sustainable society. Various studies on SHM have been carried out, and it is effective because it avoids accidents and predicts behaviour of structures. In this study, we proposed a method of SHM for a layered structure, in which the abnormal layer of the structure was identified by strain measurement. The main point of the study is that rotational degrees of freedom are constrained at both ends of the wall, so that the wall of each layer vibrates individually. First, in the normal condition, a location where the strain is almost zero on the outer wall of each layer is specified, and the strain at that point is constantly measured. Then, when an abnormality occurs in a certain layer, a significant value of strain appears in the abnormal layer where the strain is originally zero. We verify the proposed method by numerical simulation. We consider a three-layered structure, modelled as a cantilever beam. Abnormality is assumed to be the decrement of stiffness at a certain element, and it was shown that the effect of abnormality appeared throughout the structure in the natural vibration mode while it appeared locally in the strain measurement. The random response was then calculated by numerical integration, and the layer where the abnormality occurred could be identified by using the proposed method. Finally, we checked the applicability of the proposed method by experiment. As a result, it was shown that the method was possible to identify the layer where an abnormality occurred as well as numerical simulation.

In this study, an experimental investigation of the electrospinning process has been conducted using two successive Taguchi experimental designs, namely L₁₈ (3⁵) and L₉ (3⁴) for the electrospinning setups with a rotating drum and a stationary plate, respectively. The processing parameters are; concentration of poly(vinyl alcohol) in aqueous solution, applied voltage, distance between the needle and the collector, flow rate of the polymer solution and the rotational speed of the collecting drum. The primary process setup is used to analyse the effects of the parameters to the diameter of nanofibers and its standard deviation (SD), through examinations of the range analysis and graphical interpretations. The secondary process set up is used to gather the data to verify the results and to compare the effects of the collecting methods on the process outputs. A short literature review of the publications on which parameter effects were analysed by statistical methods is also presented.

The electromigration (EM) technique is a method that is used to ensure the physical growth of metallic micro/nanowires. In the EM technique, the atomic diffusion of metals is intentionally accelerated by controlling the input current and heating the substrate, thus forming a hillock owing to the accumulation of atoms, which is transformed into small-diameter metallic micro/nanowires. The metallic micro/nanowires can be fabricated by discharging the atoms through a hole, which is artificially introduced in the passivation. The fabrication of metallic micro/nanowires has been successfully demonstrated using the EM technique, and the wire growth behavior is dependent on the characteristics of the artificial hole. However, very little information is available about the quantitative assessment of wire fabrication performance even though several experimental attempts have been conducted in prior studies. Additionally, the effect of structural parameters, such as the hole size, on the fabrication performance has not yet been adequately investigated. This study quantitatively evaluates the fabrication performance that is influenced by the hole size in terms of the growth rate of wires and threshold current used for fabrication. Based on the experimental results, the fabrication loss related to the hole size is experimentally revealed; further, an empirical formula for the fabrication loss has been developed. The optimal hole size to achieve the high performance of the micro/nanowire growth using the EM technique can be obtained with this finding.

The present paper proposes a new model of muscle fatigue and recovery considering the roles of slow twitch (ST) and fast twitch (FT) muscle fibers. The proposed model can predict the variation in the degree of muscle fatigue because it considers the properties of muscle fatigue and recovery, which have been neglected in previous models. The aim of the present study was to predict not only the progression of muscle fatigue under maximum voluntary contraction (MVC) but also the endurance time for a force maintenance task and the variation in the output force achieved during MVC with regular intervals of rest. To validate the proposed model, a case study were conducted. The parameters of the proposed model, which depend on the anatomical properties of the individual, were determined from the measured variation in the output force under MVC. The endurance time for a force maintenance task with an arbitrary output force and the variation of the output force during MVC with intervals of rest were measured in the case study and compared with those predicted using the proposed model and a previously developed model that does not consider the roles of ST and FT fibers. In the case study, the proposed model showed good agreement with the measurement results and achieved better accuracy than the previous model. Therefore, the proposed model can be applied in cases with a low output force or intervals of rest, which are beyond the scope of the previous model.

Previous studies have reported gender differences in loudness perception. To clarify factors that affect loudness perception of men and women, so that differences in their processing of auditory stimuli might be revealed, we conducted four experiments using innovative experimental approaches. A rating experiment employed a wider range of sound stimuli and a greater number of categories on the verbal interval scale to elicit participants’ ratings of sounds at different sound pressure levels. As in previous studies, male participants tended to rate the same sounds as less loud than did females. An experiment with the method of adjustment measured the limits of sound pressure level perceived as soft or as loud, and replicated the gender effect: female participants selected lower levels than did males to represent both soft and loud sound categories. The final two experiments sought to measure perceived loudness on a (numeric) ratio scale rather than a (verbal) interval scale. Using the methods of magnitude estimation and magnitude production, these experiments did not produce the clear gender differences seen in the first two experiments. Differences in loudness judgments between males and females may actually reflect differences in the use of verbal expression rather than differences in perception of intensity.

Fretting wear is surface damage caused by repeated slight relative slips between two contact surfaces. In railway applications, fretting wear can occur between the inner ring and the backing ring of an axle journal tapered roller bearing. The authors supposed that the fretting wear of the backing ring can be prevented by means of hard-film coatings if hard films can follow the deformation of the backing ring. A segment-structured diamond-like carbon (S-DLC) film has been proposed to solve this problem. In this work, the authors investigated the effect of S-DLC film on the fretting wear through rotation tests of full-scale railway axle bearings with the backing ring side face coated with S-DLC film or conventional continuous diamond-like carbon (C-DLC) film. As the result, the S-DLC film coated backing ring demonstrated less wear compared to the C-DLC film coated backing ring. In addition, the iron content of the grease in the bearing with the S-DLC film coated backing ring was lower than that of the grease in the bearing with the C-DLC film coated backing ring. It is conceivable that the relative sliding motion in the radial direction between them may be restrained by the latticed pattern of the S-DLC film being pressed into the inner ring large side face. It is concluded that the S-DLC film is effective in suppressing the fretting wear generated on the contact surfaces between them of the axle bearings.