Dynamic measurements of the load on castings and the contraction of castings during cooling in sand molds

The load on flange castings in sand molds was gradually increased beginning from the end of the solidification process until the final cooling stage. The maximum tensile load on the flange castings in furan sand molds was larger than that of the flange castings in green sand molds. With the furan sand mold, permanent deformation in the flange castings occurred beginning from the end of the solidification process until reaching a temperature of approximately 250 °C. The mechanical interaction between the casting and the sand mold should be considered for more accurate stress calculations, particularly in furan sand molds.     

Semiconductive behavior of passive films formed on Fe-Cr alloy

Semiconductive properties of passive films formed on Fe-18Cr alloy in a borate buffer solution were investigated using photoelectrochemical response and electrochemical impedance spectroscopy. Band gap energy of the passive films, E_g, was estimated from a photoelectrochemical spectrum that could consist of two components. E_gs were recognized as approximately 2.4 eV and 3.4 eV, which were mainly derived from Cr hydroxide layer and Cr oxide layer, respectively. The values were almost constant independent of passivation time, film formation potential and additive element. Positive photocurrents generated from the outer part hydroxide and the inner oxide in the passive film increased as applied potential increased, which indicates that the passive films behaved as an n-type semiconductor. Mott-Schottky plot of capacitance showed positive slope. This means that the passive films behaved as an n-type semiconductor. Donor densities of the passive films estimated by the Mott-Schottky plots depended on passivation time, film formation potential and additives. Corrosion resistance of Fe-18Cr alloy was discussed in terms of the semiconductive properties.     

A new type of fiber-bonded-ceramic material synthesized from pre-oxidized Si-Ti-C-O fiber

Two types of fiber-bonded-ceramic material (FBC₂₁₂₃ or FBC₁₈₇₃) were synthesized from preoxidized Si-Ti-C-O fibers with oxide layers of 150 to 500 nm in thickness at 2123 K or 1873 K under 50 to 70 MPa. The interstices in both types of the materials were packed by an oxide material, which had existed on the surface of the pre-oxidized Si-Ti-C-O fiber. So, the dense, fiber-bonded-ceramic materials with small amount of the oxide matrix were obtained. During hot-pressing, carbon in excess of the non-stoichiometric ratio was released from the fiber and formed an interfacial layer on the surface of the fiber, beneath the pre-existing oxide material. Both FBC₂₁₂₃ and FBC₁₈₇₃ showed fibrous fracture patterns with high fracture energies at temperatures up to 1573 K and 1773 K, respectively. FBC₂₁₂₃ exhibited some plasticity in air at a temperature of 1673 K or over, due to the existence of amorphous silica in the matrix, and then a reduction in bending strength was observed at 1773 K in air. On the other hand, FBC₁₈₇₃ maintained its initial bending strength up to 1773 K in air, which is attributed to reduced crystallization of Si-Ti-C-O fiber and to the formation of cristobalite in the matrix.     

A design method of spatiotemporal optical pulse using level-set based time domain topology optimization

Recently, two emerging areas of photonics research, ultrafast photonics, and nanophotonics have started to come together. One of the main problems in this field is the precise control of spatial and temporal profiles of the optical pulses. In this paper, we propose a design method for user-specified spatiotemporal optical pulses using a level set-based time-domain topology optimization method. In the proposed method, the optimization problem is formulated based on time domain Maxwell equations so that the spatiotemporal optical pulses can be treated directly. The objective function is defined using the envelope information of the pulses, and an efficient way to calculate this information, based on calculations of the complex electromagnetic field, is introduced. A level set-based topology optimization method is applied to obtain optimized configurations. Using the proposed method, the spatiotemporal user-specified pulse profiles can be designed by modifying the structural details of the nanostructures through which the pulses propagate. As a simple example, we demonstrate that the optimized structures focus optical pulses into a single or multiple focal points with a user-specified pulse-width. The results show that the proposed method is able to design highly controlled spatiotemporal optical pulses by engineering the nanophotonic structure.     

Experimental Evaluation of Program Slicing for Fault Localization

Debugging large and complex software systems requires significant effort since it is very difficult to localize and identify faults. Program slicing has been proposed to efficiently localize faults in the program. Despite the fact that a number of debug systems using program slicing, have been developed, the usefulness of this method to fault localization has not been sufficiently evaluated. This paper aims to experimentally evaluate the usefulness of the program slicing method to fault localization. In order to conduct the experiment, we first developed a debug tool based on program slicing, after which two experimental projects were conducted, in which subjects (debuggers) were divided into two groups. A program that includes several faults is given to each subject of the group. Each subject in Group 1 localizes the faults by using the slicing-based method, whereas in Group 2 each subject localizes the faults by using the conventional debugger-based method. Finally, the effectiveness of program slicing is analyzed by comparing the data collected from both groups. As the results of these experiments, we confirm that the program slicing method is indeed useful to localize program faults.     

An LP-based heuristic algorithm for the node capacitated in-tree packing problem

In this paper, we deal with the node capacitated in-tree packing problem. The input consists of a directed graph, a root node, a node capacity function and edge consumption functions for heads and tails. The problem is to find a subset of rooted spanning in-trees and their packing numbers, where the packing number of an in-tree is the number of times it is packed, so as to maximize the sum of packing numbers under the constraint that the total consumption of the packed in-trees at each node does not exceed the capacity of the node. This problem is known to be NP-hard.We propose a two-phase heuristic algorithm for this problem. In the first phase, it generates candidate spanning in-trees to be packed. The node capacitated in-tree packing problem can be formulated as an IP (integer programming) problem, and the proposed algorithm employs the column generation method for the LP (linear programming) relaxation problem of the IP to generate promising candidate in-trees. In the second phase, the algorithm computes the packing number of each in-tree. Our algorithm solves this second-phase problem by first modifying feasible solutions of the LP relaxation problem and then improving them with a greedy algorithm. We analyze upper and lower bounds on the solution quality of such LP-based algorithms for this problem.We conducted computational experiments on graphs used in related papers and on randomly generated graphs. The results indicate that our algorithm has a better performance than other existing methods.     

Improved particle concentration by cascade AC electroosmotic flow

The importance of electrokinetics in microfluidic technology has been growing owing to its versatility and simplicity in fabrication, implementation, and handling. Alternating-current electroosmosis (ACEO), which is the motion of fluid due to the ion movement by an interaction between AC electric field and an electrical double layer on the electrode surface, has a potential for a particle concentration method to detecti rare samples flowing in a microchannel. This study investigates an improved ACEO-based particle concentration by cascade electrokinetic approach. Flow field induced by ACEO and accumulation behavior of particles were parametrically measured to discuss the concentrating mechanism. The accumulation of particles by ACEO can be explained by a balance between the attenuating electroosmotic flow to transport particles and the inherent diffusive motion of the particles, which is hindered due to the near-wall location. Although a parallel double-gap electrode geometry enables particles to be collected at the center of electrode very sharply, it has scattering zones with accumulated particles at sidewalls of the channel. This drawback can be overcome by applying sheath flow or introducing cascade electrode pattern upstream of the focusing zone. As a result, total concentration efficiency was 98.4 % for all the particles flowing in the cascade device. The resultant concentrated particles exist on the electrode surface within 5 μm, and three-dimensional concentration of particle with the concentration factor as large as 700 is possible using a monolithic channel, co-planar electrode, and sheathless solution feeding. This cascade electrokinetic method provides a new and effective preconcentrator for ultra-sensitive detection of rare samples.     

Training data selection with user’s physical characteristics data for acceleration-based activity modeling

This paper proposes an activity recognition method that models an end user’s activities without using any labeled/unlabeled acceleration sensor data obtained from the user. Our method employs information about the end user’s physical characteristics such as height and gender to find and select appropriate training data obtained from other users in advance. Then, we model the end user’s activities by using the selected labeled sensor data. Therefore, our method does not require the end user to collect and label her training sensor data. In this paper, we propose and test two methods for finding appropriate training data by using information about the end user’s physical characteristics. Moreover, our recognition method improves the recognition performance without the need for any effort by the end user because the method automatically adapts the activity models to the end user when it recognizes her unlabeled sensor data. We confirmed the effectiveness of our method by using 100 h of sensor data obtained from 40 participants.     

High‐mobility self‐aligned top‐gate oxide TFT for high‐resolution AM‐OLED

High‐mobility and highly reliable self‐aligned top‐gate oxide thin‐film transistor (TFTs) were developed using the aluminum reaction method. Al diffusion to the oxide semiconductor and homogenization of the oxygen concentration in the depth direction after annealing were confirmed by laser‐assisted atom probe tomography. The high mobility of the top‐gate TFT with amorphous indium tin zinc oxide channel was demonstrated to be 32 cm²/V s. A 9.9‐in. diagonal qHD active‐matrix organic light‐emitting diode (AM‐OLED) display was fabricated using a five‐mask backplane process to demonstrate an applicable solution for large‐sized and high‐resolution AM‐OLEDs.     

Mapping coffee crops in southeastern Brazil using spectral mixture analysis and data mining classification

The task of mapping coffee crops using multispectral data sets is not yet a trivial routine. This is because coffee fields are extremely heterogeneous in terms of spectral reflectance. This study therefore aims to contribute to the mapping of coffee crops using multispectral imagery with 23.5 m spatial resolution taken by the Linear Imaging Self Scanner (LISS III) instrument on board the Indian Remote Sensing (IRS) satellite system. The section of land covered by this study is a traditional coffee-producing province located in the south of the State of Minas Gerais, southeastern Brazil. Whereas the pixel mixture effect was managed using spectral mixture analysis (SMA), the classification was carried out using data mining (DM) techniques. The decision tree (DT) outcomes were evaluated using a simple and qualitative method based on the elements of photointerpretation. In total, eight land-use and land-cover (LULC) types were mapped, including three classes of coffee-growing land expressing different phenological conditions and management. These were named ‘Production Coffee’, ‘Mixed Coffee’, and ‘Old/Pruned Coffee’. The results showed that the methodology was effective for mapping LULC types, as the workflow adopted simplified image interpretation and offered improvements in the classification performance. Despite the coffee-cultivation classes having a large spectral variability, which increases the chances of classification errors, not many confusions were observed involving the three coffee classes mapped with other categories of use. This therefore shows that the method was efficient in isolating the coffee classes (with an accuracy greater than 70%) from other categories of use. Comparing the results obtained in this work with a conventional maximum-likelihood (ML) classification, the results revealed that when using the methodology described, the confusions between classes were less dispersed and an improvement of approximately 10% was observed in the mapping of the Production Coffee class.