Analysis of creep behavior in thermoplastics based on visco-elastic theory

Plastics and fiber-reinforced plastics (FRP) are used in the aerospace industry because of their mechanical properties. However, despite their excellent high-temperature mechanical properties, plastics and FRP eventually deform visco-elastically at high temperatures. Most of the research has focused on the creep behavior of FRPs, but few studies have investigated the linear visco-elastic behavior. Linear visco-elastic behavior and non-linear visco-elastic behavior occur with physical aging in these plastics. In this study, the non-linear visco-elastic behavior of plastics and FRP was investigated based on the bending creep deformation of polycarbonate (PC) and polyoxymethylene (POM). Moreover, the effects of the fiber volume fraction on the creep characteristics were investigated using glass fiber-reinforced polycarbonate (GFRPC). The creep deformation was calculated using the linear visco-elastic theory based on these effects, and comparison between experimental and estimated data showed that the creep analysis sufficiently predicted the creep behavior.     

The influence of dietary lipids on nephrolithiasis in rats

PURPOSE: The influence of dietary lipids on nephrolithogenesis is unclear. In the present study, I investigated the role of dietary lipids concerning both the etiology and the prevention of nephrolithiasis using 9-week-old male Wistar rats. METHODS: Study 1: The rats were divided into five groups and reared on standard, low protein, high protein and high cholesterol diets for 23 weeks. Study 2: The effects of cholesterol on nephrolithiasis was examined. The animals were given a 30 intraperitoneal injection of 2 ml of 8.5% calcium gluconate. Study 3: A nephrolithiasis model was prepared by intraperitoneal administration of 40 mg/kg of glyoxylic acid and 0.25 microgram of vitamin D3 daily for 2 weeks. The inhibitory effects of eicosapentaenoic acid (EPA) on nephrolithiasis were studied. RESULTS: Study 1: In the groups given the high protein and high cholesterol diets, an increase in renal osteopontin-mRNA, one of the major matrix ingredients of stones containing calcium, was observed. Study 2: Microlith was more frequently observed in the high cholesterol group than in the standard diet group. Study 3: In the EPA group, lithiasis was less extensively than in the groups administered distilled water or olive oil, and this was assumed to be caused by factors other than inorganic substances such as calcium and oxalic acid in the urine. When the renal tissue specimens in Studies 2 and 3 were examined, initial calcium deposition was found to start from the basement membrane of renal tubular cells and gradually spread throughout the cells. CONCLUSION: These results suggested that cholesterol is a risk factor in nephrolithiasis, and EPA is effective in its prevention. The elimination of hyperlipidemia should be included in dietary instructions for nephrolithiasis patients.     

Bauschinger effect and multiaxial yield behavior of stress-reversed mild steel

Thin-walled cylindrical specimens subjected to torsional prestraining are stress-reversed along the Bauschinger curve. The Bauschinger effect (BE), yield behavior, and flow behavior of the stress-reversed mild steel were examined by using combined loadings of axial load, internal pressure, and torsion. The results indicate that the stress-reversed steel has the same yield stress at 0.2 pct offset strain in reloading tests of forward and reverse torsion, when the reverse strain is =0.77 pct. Furthermore, it is possible to cause the yield stresses in forward and reverse torsion to coincide in any offset strain. The yield locus of the stress-reversed steel is symmetric with respect to the tensile stress axis in a tension-torsion stress field. However, it has been found to be an anisotropy in the stress-reversed steel, and the magnitude of anisotropy is related to the offset strain. For example, there is a stronger anisotropy at 0.2 pct offset strain than at 2 pct offset strain, even though the BE is eliminated for the former. It is shown that the reduction in the BE by stress reversal is concerned with the relief of the long-range back-stress generated by prestraining. Besides, the roles of aging in the stress-aging process lie in the contributions to age hardening and development of directional back-stress.     

A determination method of initial camera parameters for coplanar calibration

Most coplanar calibration algorithms determine the initial camera parameters from a single image under the assumption that the principal point is known in advance. However, the camera orientations, the shifted principal point and the noise corrupted on images have an influence on the estimated initial camera parameters under the above assumption. This paper proposes a useful method to determine the initial camera parameters for coplanar calibration. The proposed method can determine the initial camera parameters from the single image, wherein the principal point is considered as a parameter. In our experiments, both synthetic and real images are used. The experimental results show that the proposed method provides both stable initial camera parameters and noise robustness for changes of camera orientations, noise levels and shifts of principal point.     

Machine learning approach for finding business partners and building reciprocal relationships

Business development is vital for any firms. However, globalization and the rapid development of technologies have made it difficult to find appropriate business partners such as suppliers and customers, and build reciprocal relationships among them, while it simultaneously offers many opportunities. In this contribution, we propose AI-based approach to find plausible candidates of business partners using firm profiles and transactional relationships among them. We employ machine learning techniques to build a prediction model of customer–supplier relationships. We applied our approach to the large amount of actual business data. The results showed that our approach successfully found potential business partners with F-values of about 84% and reciprocity among them with F-values of about 77%. Using our method, we also developed the Web-based system that helps people in actual businesses to find their new business partners. These contribute to developing one’s own business in the complicated, specialized and rapidly changing business environments of recent years.     

Using acknowledgement data to characterize funding organizations by the types of research sponsored: the case of robotics research

Funded research has been linked to academic production and performance. While the presence of funding acknowledgements may serve as an indicator of quality to some extent, we still lack tools to evaluate whether funding agencies allocate resources to novel and innovative research rather than mature fields. We address this issue in the present study by using bibliometrics. In particular, we exploit the citation network properties of academic articles to classify specific research fields into four categories: change maker, breakthrough, incremental, and matured. We then use funding acknowledgement information to identify the sponsors involved in each research type to characterize funding agencies. We focus our analysis on the robotics field in order to reveal international trends of financial acknowledgements. We find that the incremental and matured research areas show the highest counts of funding acknowledgements. Moreover, although research funded by some agencies is mostly recognized as incremental-type research, those in other categories may perform better in terms of the number of citations. Additionally, we analyze the interest of selected funding agencies in granular subject categories. The characterization of funding agencies in this study may help policymakers and funding organizations assess or adjust their strategies, benchmark with other key players, and obtain an overview of local and global acknowledgement trends.     

The Attitude Control Performance of the BSE and its Influence on the Received Television Signal Strengths on the Ground

The Japanese Medium-scale Broadcasting Satellite for Experimental Purpose (BSE) is a zero-momentum three-axis stabilized spacecraft and has the ability to broadcast simultaneously two channels of color television in the frequency band of 12 GHz.     

Quantum efficiency of Nd-doped glasses under sunlight excitation

The internal quantum efficiencies under sunlight and laser excitation were measured directly by an integrating sphere method for tellurite, borosilicate and fluoride glasses. The radiative quantum efficiency was also obtained by Judd–Ofelt analysis. The radiative quantum efficiency was almost 100% for tellurite and fluoride glasses and 50% for borosilicate glasses. The quantum efficiency under laser excitation was 86%, 34% and 88% for tellurite, borosilicate and fluoride glasses at a low Nd³⁺ content and decreased by concentration quenching. The quantum efficiency under sunlight excitation was up to 33%, 21% and 70% for tellurite, borosilicate and fluoride glasses. Nd³⁺-doped fluoride glass is a promising candidate for solar pumped laser applications since it has the high quantum efficiency under sunlight excitation.