Improvement Properties of Cohesion-Less Soil Using Recycled Bassanite

Solid waste management is a serious problem over the world. Therefore, reduction, re-use and recycling of waste have become major issues in recent days. Gypsum waste plasterboard is considered one example of these waste materials. This study evaluates the use of recycled bassanite, which is derived from gypsum waste plasterboard, to enhance the performance of two types of cohesion-less soil. Recycled bassanite was utilized as a stabilizing agent to improve both compressive and splitting strengths of the tested soil. The effect of bassanite content, soil type, water content and curing time were investigated to explore the behavior of treated soil with recycled bassanite. Test results showed that increase of bassanite content is associated with increase in optimal moisture content, while no significant increase in the dry unit weight was observed. Both compressive and splitting tensile strengths enhanced with the additives of recycled bassanite. The increase of bassanite content had a more significant effect on the compressive strength compared with the effect on tensile strength. The use of recycled bassanite to enhance the strength of sandy soil had a more significant effect compared with silty soil. The effect of curing time on the strength of treated samples was more significant in early curing ages compared with late curing ages. The strength decreased significantly in case of stabilized samples prepared with water content at the wet-side of the compaction curve. However, insignificant decrease in the strength of the stabilized sample was detected with moisture content at the dry-side of compaction curve. This research meets the challenges of our society to reduce the quantities of gypsum wastes, producing useful material from waste materials that will help to a sustainable society.     

Codeposition of Metallic Components in the Growth of Thin PbTe?Ga? Films on Si Substrates

In depositing thin PbTeGa films onto Si and SiO₂/Si substrates by the hot-wall method, Pb_{1 – x} Ga _x melts were used as Ga vapor sources in combination with separate Pb and Te vapor sources. The vaporization of Pb_{1 – x} Ga _x (0.15 x 0.95) melts was studied between 1000 and 1300 K in the reaction chamber of the deposition unit. Using electron probe x-ray microanalysis, all the deposited films were shown to contain Ga. Pb_{1 – x} Ga _x melts were also used as separate Pb and Ga vapor sources.     

Transport Properties of Ga-Doped PbTe Thin Films on Si Substrates

Thin PbTe films on Si substrates were doped with Ga via annealing in the vapor produced by heating a Ga(l) + GaTe(s) mixture (GaTe(s) + L ₁+ Vequilibrium). Electrical measurements showed that the vapor-phase doping reduced the hole concentration in the films by more than two orders of magnitude. IR irradiation was found to reduce the resistivity of the PbTe films by a factor of 40–100. The films annealed in the vapor over GaTe(s) + L ₁for the longest time exhibited an anomalous temperature variation of resistance, which was interpreted as due to the limited Ga solubility in PbTe.     

Numerical Modeling of an Earthquake-Induced Landslide Considering the Strain-Softening Characteristics at the Bedding Plane

The damage caused by an earthquake-induced landslide can generally be classified as either a limited deformation or a catastrophic failure. From an engineering point of view, the latter can be much more dangerous because the sliding mass may continue moving until it collides with another object. If a catastrophic failure occurs near a river, the debris may block the river, causing serious damage to the adjacent area. Therefore, examination of the mechanism of such catastrophic slope failures is important with respect to the mitigation of earthquake disasters in mountainous districts, although numerical modeling of such phenomena is rather difficult. In the present study, a new numerical model is developed to simulate an earthquake-induced catastrophic landslide that occured at a typical dip slope, namely, the Yokowatashi Landslide in Japan. In this case, the upper part of the bedrock on the planer tectonic dip surface slid more than 70 m. Only shear-strength degradation at the bedding plane could cause such a long-distance traveling failure. To investigate the strain-softening characteristics of the materials that filled the bedding plane, a series of laboratory tests involving undisturbed block samples was performed. The measured stress-displacement relationships under cyclic loading were numerically modeled as a newly proposed elasto-plastic constitutive model to be used in numerical simulations of landslide, based on the dynamic finite element method. The observed phenomena were appropriately simulated by the proposed method. The mechanism of catastrophic failure is discussed in detail in this paper in order to clarify the relationships between the strain-softening characteristics and the global slope stability. Our newly proposed method to evaluate the possibility of a catastrophic failure was applied to the landslide, and the moment when the slope becomes unstable was able to be predicted. The results confirm that the proposed method can predict the catastrophic failure of a slope.     

Lattice parameter of PbTe<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Cl<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> solid solutions

The lattice parameter of PbTe_1?x Cl _x solid solutions is shown to be a nonmonotonic function of chlorine content, with a minimum at x = 0.005. The results are interpreted in terms of a self-compensation model.     

高阶流形方法及其应用

流形方法是一种可进行连续与非连续变形问题分析的灵活而有效的数值计算方法。本文详细地推导了二阶流形方法的具体计算列式,分别开发了一阶流形方法与二阶流形方法的计算程序．通过实例计算表明：提高覆盖函数的阶次可有效地提高流形方法的计算精度。     

Investigation of recycled gypsum in conjunction with waste plastic trays for ground improvement

During the three stages of production, construction and demolition, approximately 15 million tons of gypsum waste plasterboard is generated annually in the world. It is considered a serious problem due to scarcity of land-filling space, increasing the cost of disposal and increasing environmental regulations. Investigations of using recycled gypsum “bassanite” which is derived from gypsum waste plasterboard and waste plastic trays for ground improvement were studied. Recycled gypsum was used as a stabilizing agent to improve the compressive strength while the waste plastic trays were used to improve the tensile strength. Recycled gypsum content, curing time and frost heave property throughout capillary rise test were investigated to determine the behavior of treated soil with recycled gypsum. In addition, size, content and aspect ratio of strips of waste plastic trays were investigated. Test results showed that increasing recycled gypsum content has a more significant effect on compressive strength compared to the tensile strength. The effect of curing time on the strength of treated soil samples with recycled gypsum is much pronounced in the early curing days compared to later ages. Adding strips of waste plastic trays to samples treated with recycled gypsum enhanced both splitting tensile and compressive strengths as well increased the value of secant modulus. Capillary rise rate was reduced with the increase of recycled gypsum content, which helps to reduce the formation of ice lenses; hence the susceptibility of treated soil against frost heave is increased. The size and content of strips of waste plastic trays have significant effect on the potential of capillary rise and the enhancement of strength and stiffness of tested soil.     

Ga Doping of Thin PbTe Films on Si Substrates during Growth

In depositing thin PbTe films onto Si substrates by a modified hot-wall method, Pb_{1 – x} Ga _x melts were used as Ga vapor sources in combination with separate Pb and Te sources. Data on the vaporization behavior of Pb_{1 – x} Ga _x melts were used to devise a new technique for reproducible growth of PbTe/Si and PbTe/SiO₂/Si structures. The lattice parameter of the PbTe films was found to vary nonmonotonically with Ga content, which was interpreted as evidence that the dopant can be incorporated by different mechanisms. Conductivity and Hall effect measurements between 77 and 300 K reveal a nonmonotonic variation of carrier concentration with doping level and suggest that Ga is an amphoteric impurity in narrow-gap IV–VI semiconductors.     

Intelligent differential pressure transmitter with multiple sensorformed on a (110)-oriented circular silicon diaphragm

A multiple piezoresistive gauge sensor was developed for application to intelligent differential pressure transmitters. The sensor can measure differential pressure, static pressure, and temperature. Three piezoresistive gauges are positioned on a (110)-oriented circular monocrystalline silicon diaphragm. Proper dimensional design and optimal gauge positioning maximize the output and minimize crosstalk. Using data maps, three voltage outputs are combined by a microprocessor unit to yield a compensated sensor output. An experimental sensor was fabricated and the compensation scheme was proved useful. The sensor accuracy was within ±0.1% of the full scale in the pressure range of ±80 kPa. The zero and span shifts were less than 0.25% for the temperature range of -20-60°C, and zero shift was less than 0.1% for the static pressure change of 15 MPa     

Electrical properties of thin PbTe films on Si substrates

An attempt was made to reduce the carrier concentration in thin PbTe films on Si substrates by optimizing deposition conditions. A modified hot-wall method was used for reproducible growth ofp-type films with 5 × 10¹⁵ < p(77 K) < 5 × 10¹⁷ cm^-3 andn-type films with 3 × 10¹⁵ < n(77 K) < 5 × 10¹⁶ cm^-3. The IR irradiation was found to have a significant effect on the temperature variation of film resistance. The activation energy of the IR-sensitivity centers was determined to be 0.11 ± 0.005 eV at room temperature and 0.18 ± 0.005 eV between 150 and 180 K.