Measurements of local elastic moduli by amplitude and phase acoustic microscope

A new method is suggested for the nondestructive measurement of elastic moduli in a localized area, 100–400 μm in diameter, by the complex V(z) curve using an amplitude and phase acoustic microscope. The inverse Fourier transform of the complex V(z) curve contains the reflectance function of a liquid-specimen interface. Therefore, the longitudinal, transverse and Rayleigh wave velocities for the specimen are simultaneously obtained by the inversion of the complex V(z) curve. The elastic moduli for glass obtained from wave velocities by acoustic microscope agree fairly well with those by other methods. The present method is applied to aluminium alloy, and it is shown that this method is useful in measuring the microscopic characteristics in inhomogeneous materials.     

Accuracy estimation of drilled holes with small diameter and influence of drill parameter on the machining accuracy when drilling in mild steel sheet

The miniaturization of component parts has advanced in the modern industrial product sector. Corresponding with this new wave, there is a strong demand for the establishment of minute-scale techniques to manufacture products with high quality involving the drilling of small holes. Non-traditional machining techniques such as electro discharge machining can be applied to make small holes. However, there is much practical value if small holes can be made by the traditional drilling process. In this paper, a method for estimating the drilled hole accuracy using a Fourier series analysis is proposed and this method is applied to small holes 1 mm in diameter drilled in mild steel for machine structure use. As a result, it is clarified that the bending rigidity of drill and the thinning of the drill point exert a large influence on the drilled hole accuracy.     

Hot-Pressing of TiC-Graphite Composite Materials

Monolithic TiC and TiC-graphite composites were hot-pressed at temperatures ranging from 1800 to 2100 °C and with graphite contents up to 30 wt%. Densification behavior was compared for both monolith and composites based on results of microstructural observation and mechanical tests. Monolithic TiC was well densified at the hot- pressing temperature of 1800 °C; significant grain growth and an accompanying decrease in the flexural strength occurred with an increase in hot- pressing temperature. Conversely, the 10 wt% graphite-containing TiC composite required higher temperatures (1900 to ~2000 °C) to reach a similar degree of densification approaching that of monolithic TiC. As with densification, flexural strength of the composite increased with an increase in hot- pressing temperature. Graphite dispersions in the composites inhibited grain growth of TiC. Contrary to the equiaxed nature of the monolithic TiC grains, in the composite system, the graphite grains were flattened to thin platelets that aligned perpendicular to the hot- pressing axis. Apparent anisotropy in the microstructure was observed in the composites. At a fixed hot-pressing temperature, the relative density of the composites decreased with increasing graphite content.     

Small-angle neutron scattering study of specific interaction and coordination structure formed by mono-acetyl-substituted dibenzo-20-crown-6-ether and cesium ions

This study uses small-angle neutron scattering (SANS) to elucidate the coordination structure of the complex of mono-acetyl-substituted dibenzo-20-crown-6-ether (ace-DB20C6) with cesium ions (Cs⁺). SANS profiles obtained for the complex of ace-DB20C6 and Cs⁺ (ace-DB20C6/Cs) in deuterated dimethyl sulfoxide indicated that Cs⁺ coordination resulted in a more compact structure than the free ace-DB20C6. The data were fitted well with SANS profiles calculated using Debye function for scattering on an absolute scattering intensity scale. For this theoretical calculation of the scattering profiles, the coordination structure proposed based on density functional theory calculation was used. Consequently, we conclude that the SANS analysis experimentally supports the proposed coordination structure of ace-DB20C6/Cs and suggests the following: (1) the complex of ace-DB20C6 and Cs⁺ is formed with an ace-DB20C6/Cs molar ratio of 1/1 and (2) the two benzene rings of ace-DB20C6 fold around Cs⁺ above the center of the crown ether ring of ace-DB20C6.     

Novel write‐erasable input display with memory circuits and photosensors

We have developed a new conceptual liquid crystal display (LCD) with a memory circuit and a photosensor in each pixel to realize excellent handwriting performance. Direct writing and erasing a character in the LCD are available because their direct processing only in the pixel are performed without calculating coordinates by using a light pen and integrated pixel circuits. In addition, this LCD enables to display still image data stored in the pixel memory circuit at a low liquid crystal (LC) driving frequency of 1.0 Hz. In the result, we have achieved faster handwriting response time of 0.5 ms and lower power consumption of 0.7 mW in 7.0‐in. QVGA reflective LCD panel.     

Performance modeling of beaconless forwarding strategies in multi-hop wireless networks

Recently, routing protocols for mobile ad hoc networks (MANETs), which use position information to improve their efficiency, have been actively studied. In this paper, we develop a mathematical model to evaluate the performance of the beaconless routing algorithm (BLR). We also propose a new forwarding strategy named distance-aware forwarding (DAF) and compare the performance of DAF with that of the traditional strategy referred to as most forwarding within radius (MFR).BLR can efficiently reduce redundancy in its transmissions for flooding. When a node receives a packet, a time variable referred to as deferring time is calculated using the positions of the sender, receiver, and final destination of the packet. Each node forwards the packet after this deferring time unless it notices that another node forwards the same packet during the deferring time. As a result, only the node that is assigned the shortest deferring time forwards the packet. It is important to make this deferring time as short as possible to reduce the total deferring time in a multi-hop transmission.Numerical results demonstrate that the proposed strategy reduces the total deferring time in a multi-hop transmission, although the number of hops slightly increases. We also make a performance analysis considering packet collisions and suggest an implementation guideline of the transmission range.     

Optimizing NFV placement for distributing micro-data centers in cellular networks

With the popularity of mobile devices, the next generation of mobile networks has faced several challenges. Different applications have been emerged, with different requirements. Offering an infrastructure that meets different types of applications with specific requirements is one of these issues. In addition, due to user mobility, the traffic generated by the mobile devices in a specific location is not constant, making it difficult to reach the optimal resource allocation. In this context, network function virtualization (NFV) can be used to deploy the telecommunication stacks as virtual functions running on commodity hardware to meet users’ requirements such as performance and availability. However, the deployment of virtual functions can be a complex task. To select the best placement strategy that reduces the resource usage, at the same time keeps the performance and availability of network functions is a complex task, already proven to be an NP-hard problem. Therefore, in this paper, we formulate the NFV placement as a multi-objective problem, where the risk associated with the placement and energy consumption are taken into consideration. We propose the usage of two optimization algorithms, NSGA-II and GDE3, to solve this problem. These algorithms were taken into consideration because both work with multi-objective problems and present good performance. We consider a triathlon circuit scenario based on real data from the Ironman route as an use case to evaluate and compare the algorithms. The results show that GDE3 is able to attend both objectives (minimize failure and minimize energy consumption), while the NSGA-II prioritizes energy consumption.

     

Unusual Indentation Behavior of Alkali Metaphosphate Glass Above Glass Transition Temperature

The mixed alkali metaphosphate glass 12.5Li₂O–12.5Na₂O–12.5K₂O–12.5Cs₂O–50P₂O₅ (mol%) compressed under uniaxial stress shows unusually large recovery of its shape during heating above its glass transition temperature (T_g). To clarify the mechanism, the viscous, elastic, and plastic behavior of the metaphosphate glass was investigated with the depth‐sensing indentation method. From the load‐displacement (P–h) curves of the glass, a large recovery of the depth displacement was found during unloading above T_g. By analyzing the P–h curves with a viscous–elastic–plastic model, the large recovery was concluded to be due to larger elastic deformation than viscous deformation even above T_g. The phenomenon can be attributed to relaxation to the randomly oriented ‐P–O–P– chain structure from the oriented chain structure formed under stress in the metaphosphate glass .     

Force control and exponential stabilisation of one-link flexible arm

In this paper, we discuss a force control problem for a constrained one-link flexible arm. To solve the force control problem, we propose a simple boundary feedback controller that consists of the bending moment at the root of the flexible arm and its time derivative. The striking point is that information about the force and the rotational angle of the motor is not necessary for the implementation of the controller, and thus we do not need a force sensor or encoder in the construction of the controller. The exponential stability of the closed-loop system is then provided using the energy multiplier method. We describe several experiments carried out to investigate the performance of the proposed controller.     

Diversifying Semantic Image Synthesis and Editing via Class- and Layer-wise VAEs

Semantic image synthesis is a process for generating photorealistic images from a single semantic mask. To enrich the diversity of multimodal image synthesis, previous methods have controlled the global appearance of an output image by learning a single latent space. However, a single latent code is often insufficient for capturing various object styles because object appearance depends on multiple factors. To handle individual factors that determine object styles, we propose a class- and layer-wise extension to the variational autoencoder (VAE) framework that allows flexible control over each object class at the local to global levels by learning multiple latent spaces. Furthermore, we demonstrate that our method generates images that are both plausible and more diverse compared to state-of-the-art methods via extensive experiments with real and synthetic datasets in three different domains. We also show that our method enables a wide range of applications in image synthesis and editing tasks.