Influence of longitudinal and transverse members on geogrid pullout behavior during deformation

A series of pullout tests were carried out by using a highly extensible geogrid with the different longitudinal member and transverse member ratios to investigate the influence of the longitudinal and transverse members of a highly extensible geogrid on the pullout behavior. From the results, the following were made clear: the mobilization of bond stress depends on the strain of the geogrid; the influence zones of longitudinal members become isolated with the increase of the longitudinal member spacing; the mobilization of transverse member resistance depends on the displacement of the geogrid at the location of that transverse member; and the contribution of longitudinal members to the pullout force is more significant than that of transverse members during the deformation stage in the case of the highly extensible geogrid, since large elongation occurs in the geogrid, which restricts the mobilization of the full effect of transverse members. Furthermore, the mobilization mechanisms of the longitudinal member and transverse member effects are discussed.     

Review of Topographic and Soil Conditions for Liquefaction-Related Damage Induced by the 2007 Off Mid-Niigata Earthquake

The 2007 Niigata-ken Chuetsu-oki (Off Mid-Niigata) earthquake caused the liquefaction of the sandy soil distributed near the coast of the Japan Sea in the middle of Niigata Prefecture. The liquefaction-induced damage occurring in many residential areas was investigated in detail by means of victim interviews, visual inspections, Swedish Weight Sounding tests, Standard Penetration Tests, old topographical map examinations, etc. Based on in situ soil investigations, the liquefied soil layers were estimated for each area. As a result, it was confirmed that the liquefied areas were mainly sand dune hinterlands, flood plains, reclaimed old river channels and sandy fills with high groundwater table. Among them, damage was especially serious on land having an inclined ground surface due to the flow of foundations, on the cut-fill borders of artificially developed land due to landslides and at the toes of sand dune slopes due to the thrust of the sliding soil and/or the collision of the sliding soil with objects. These investigation results also revealed that soil improvement by cement mixed columns is an effective countermeasure against liquefaction-induced damage unless lateral spreading of the subsoil arises.     

A new model for device degradation in low-temperature N-channel polycrystalline silicon TFTs under AC stress

Enhanced device degradation of low-temperature n-channel polycrystalline thin-film transistors (poly-silicon TFTs) under exposure to ac stress has been quantitatively analyzed. This analysis showed that degradation of the device characteristics of a single-drain (SD) TFT is greater under ac stress than under dc stress over an equivalent period. It was found that hot holes are strongly related to this greater severity of degradation. Moreover, a lightly doped drain (LDD) TFT is less strongly affected, and the effect is dominated by accumulated drain-avalanche hot-carrier (DAHC) stress. It was also found that differences between the electric field in the respective channel regions are responsible for the different degradation properties of SD and LDD TFTs. It was shown that the severe degradation under ac stress in an SD TFT is caused by increased DAHC stress, to which electrons emitted from the trap states when the TFT is turned off make significant contributions.     

设备诊断判定基准的制定方法

在对生产现场的设备进行诊断检测时,由于设备的个性和测试数据的零散性往往很不容易决定正常与异常的边界值,即判定基准.为了解决这问题,笔者应用概率统计方法、可能性理论以及现场的实际情况,对用于设备诊断的有量纲与无量纲的特征参数,提出几种决定设备诊断判定基准的方法.并且采用现场实际数据进行验证.     

Boric Ester-Type Molten Salt via Dehydrocoupling Reaction

Novel boric ester-type molten salt was prepared using 1-(2-hydroxyethyl)-3-methylimidazolium chloride as a key starting material. After an ion exchange reaction of 1-(2-hydroxyethyl)-3-methylimidazolium chloride with lithium (bis-(trifluoromethanesulfonyl) imide) (LiNTf₂), the resulting 1-(2-hydroxyethyl)-3-methylimidazolium NTf₂ was reacted with 9-borabicyclo[3.3.1]nonane (9-BBN) to give the desired boric ester-type molten salt in a moderate yield. The structure of the boric ester-type molten salt was supported by ¹H-, ¹³C-, ¹¹B- and ¹⁹F-NMR spectra. In the presence of two different kinds of lithium salts, the matrices showed an ionic conductivity in the range of 1.1 × 10⁻⁴–1.6 × 10⁻⁵ S cm⁻¹ at 51 °C. This was higher than other organoboron molten salts ever reported.     

Soil element assessment of cyclic-load-induced settlement considering combination of vertical,horizontal, and shear stresses in cohesive soil

Grounds subjected to cyclic loading, either continuous or fragmentary, widely exist in natural deposits and at reclaimed sites, e.g., induced by traffic loads, earthquakes, and wave-induced loading environments. Assessing the ground deformation under cyclic loading conditions is necessary for proper design and maintenance planning for traffic services. Accordingly, a testing program, in which vertical, horizontal, and shear stresses are automatically controlled, were newly developed in this study to reproduce the actual cyclic traffic load conditions using a hollow-cylindrical torsional shear apparatus.Estimations based on the results obtained from cyclic triaxial stress conditions were seen to underestimate the ground settlement compared to actual stresses, with combined vertical, horizontal, and shear stresses. Two kinds of vertical strain arose after a certain number of cycles: incremental collapse, in which unstable deformation (failure) is caused, and plastic creep, in which deformation continues to accumulate with the dampened rate (per cycle). The number of cycles of combined vertical, horizontal, and shear stresses necessary to reach a certain vertical strain increased linearly on a logarithmic scale when the magnitude of loading decreased. Moreover, the relationship between vertical strain and excess pore water pressure presented the same trend independent of the magnitude of loading. Practical uses of the obtained results were proposed and discussed.     

Association of chronic infection of Chlamydia pneumoniae and coronary heart disease in the Japanese

The association of Chlamydia pneumoniae with atherosclerosis of coronary and carotid arteries and the aorta has been demonstrated by seroepidemiology and by detection of the organism in atheromata. We investigated the frequency of C. pneumoniae seropositivity in patients with acute myocardial infarction (AMI). C. pneumoniae-specific antibodies were measured by the microimmunofluorescence test in 160 AMI patients and 160 control subjects matched for age and gender. The odds ratios (ORs) were 2.2 (95% confidence interval (CI), 1.2 to 3.9) for immunoglobulin (Ig)G and 2.7 (95% CI, 1.7 to 4.3) for IgA. After adjustment for other cardiovascular risk factors of age, gender, hypertension, diabetes, cigarette smoking and serum cholesterol, the ORs were essentially unchanged. This study confirmed that the observations of an association between antibody against C. pneumoniae and coronary heart disease in Western nations is also present in Japan. Our results are comparable to the previous seroepidemiological studies reporting ORs of 2.0 or greater.