Design analysis of metallic single electron tunneling circuits

We carried out a design study of single electron devices based on submicron metallic islands and tunnel junctions. The results of a first capacitive design analysis using a three-dimensional numerical field computation of separated circuit cells are used as input for an optimization with respect to cross-talk between neighboring circuit cells. We discuss the reduction of parasitic effects by use of additional shielding electrodes on the top of the substrate or in the background. In view of the influenced charge associated with parasitic background charges we discuss the charge distribution on a three-dimensional scan of the substrate below the structures for the study of critical influence regions, where a certain threshold of influenced charge at neighbor electrodes is given. We show that the influence calculation of the parasitic background charge is of significant importance for the design and fabrication of single charge circuits.     

An optimization model for location of subsidized housing in metropolitan areas

This paper presents an optimization model for evaluation of alternative spatial configurations of rent-subsidized housing in a large metropolitan area as well as associated monetary and nonmonetary impacts. Groups affected by these configurations include residents of subsidized housing, owners of nearby single-family housing, employers and society at large. Since impacts of subsidized housing are very localized, the first stage of the model creates potential location patterns for many small geographic areas. The second stage of the model uses local benefits to derive a location scheme for the metropolitan area which balances net social benefit with equity considerations of the geographical impact of subsidized housing. We apply this methodology to a small region in metropolitan Chicago and demonstrate alternative location schemes.     

Splitting tension tests to determine concrete fracture parameters by peak-load method

An experimental program confirms that the peek-load method can be successfully applied to splitting tension tests to determine fracture parameters K_Ic^S and CTOD_c of the two-parameter fracture model from the measured peak loads. The peak-load method requires distinct specimens. It is found that a hole drilled at the axis of splitting tension cylinder can largely expand the specimen distinction. Combination of tests on splitting tension cylinders with and without a hole raises the reliability of the K_Ic^S and CTOD_c values determined by the peak-load method.     

考虑温度相关性的岩石热破裂数值模拟

为解决岩石热力学参数如比热、热传导系数等会伴随温度变化而影响岩石热破裂的问题,基于连续-非连续元方法,采用显式积分建立一种考虑参数温度关联性的岩石瞬态热-力-破裂耦合数值模型,通过该模型研究不同升温速率对岩石热裂过程的影响。结果表明:考虑参数温度关联时,破裂速率、破裂程度比不考虑参数温度关联小;裂缝最大宽度比不考虑参数温度关联时大、开裂持续时间更长。     

A novel alveolate-structured organic-inorganic hybrid with high activity for photocatalytic hydrogen evolution

Organic-inorganic hybrid nano-material has a significant potential for enhancing the charge separation efficiency of photocatalyst. However, it remains an important issue to controllable synthesis new hybrid system with unique structure and earth-abundant materials for boosting photocatalytic hydrogen revolution. We report a facile one-step hydrothermal strategy to fabricate a novel Titania/β-cyclodextrin (TiO₂/β-CD) organic-inorganic hybrid nano-material with an alveolate structure. In this hybrid system, β-CD not only played a critical role in alveolate structure formation, but also served as a bridge connecting target molecular and active sites on the TiO₂ surface to facilitate the separation and transfer of the photoexcited electrons with prolonged lifetime. As a result, this alveolate TiO₂/β-CD composite exhibited outstanding photocatalytic activity and a H₂ evolution rate of 725 μmol/g·h was achieved over TiO₂/β-CD which was 14 times of bare TiO₂ under simulated sunlight. This work paves a way for controllable synthesis of novel organic-inorganic hybrid nano-material with distinct structure for efficient photocatalysis.     

Application of a bi-directional associative memory (BAM) network in computer assisted learning in chemistry

A computer assisted learning software based on a bi-directional associative memory (BAM) network was developed. The software was implemented to assist students in associating the names of the elements in the periodic table with their chemical symbols. The use of the BAM facilitates the analysis and interpretation of students' responses. The software package can be modified easily as an educational tool for other disciplines.