MOLECULAR TETRAPODS FOR OPTOELECTRONIC APPLICATIONS

In this dissertation, several molecular tetrapods were synthesized for optoelectronic applications. In the first two sections, two tetrapodal breakwater-like small molecules: SO and SFBTD were synthesized and characterized. Absorption, X-ray scattering and differential scanning calorimetry experiments indicate crystalline nature of these compounds but slow crystallization kinetics. Solar cells employing SO or SFBTD and phenyl-C61-butyric acid methyl ester (PCBM) were fabricated and evaluated. Relatively low performance was obtained mainly due to the lack of appropriate phase separation, which was caused by molecularly mixed blends with PCBM. The molecularly mixed blends is the result of slow crystallization feature of SO and SFBTD, which may be intrinsically resulted from its tetrahedral geometry. Addition of low bandgap highly crystalline conjugated polymer poly(thienylene vinylene) (PTV) into the SO/PCBM blend was found to induce appreciable phase separation. Our findings can give useful insight on the structure-property relationships of such 3-D small molecules and their applications in organic solar cells. In the last section, a series of fullerene-borate ionic complexes were synthesized successfully. Various chromophores can be introduced into our fullerene-borate ionic complex system through facile Sonogashira coupling reaction, and thus the optical and electrical properties of complex can be easily tuned. The fluorescence quenching study on FP-Ant indicated the efficient photo-induced charge transfer in our complex system, while the existence of long-lived charge separated states is under exploration. The success of obtaining single crystal of FP-Ph might give us some insight to develop the infinite crystalline structures of fullerene-borate ionic complex through ionic interaction

Laser Deposition Cladding On-Line Inspection Using 3-D Scanner

Laser deposition directly deposits metal cladding to fabricate and repair components. In order to finish the fabrication or repair, 3-D shape of the deposition needs to be inspected, and thus it can be determined if it has sufficient cladding to fabricate a part after deposition process. In the present hybrid system in the Laser Aided Manufacturing Lab (LAMP) at the University of Missouri - Rolla, a CMM system is used to do the inspection. A CMM requires point-by-point contact, which is time consuming and difficult to plan for an irregular deposition geometry. Also, the CMM is a separate device, which requires removal of the part from the hybrid system, which can induce fixture errors. The 3-D scanner is a non-contact tool to measure the 3-D shape of laser deposition cladding which is fast and accurate. In this paper, A prototype non-contact 3-D scanner approach has been implemented to inspect the free-form and complex parts built by laser deposition. Registration of the measured model and 3-D CAD model allows the comparison between the two models. It enables us to determine if the deposition is sufficient before machining.Mechanical Engineerin

Exploring Weight Coefficient of Intelligent Home Care Service Quality Evaluation Index Based on G1 and Entropy Methods

As aging people is growing quickly in many countries, the fall problem is formed a curial public health and clinical problem among elderly persons. As an important pension model, the wisdom of the elderly at home in solving the pension problem has played a huge role. How to reasonably determine the weight of the evaluation indicators of the quality of home care services is a difficult problem in practice. Based on the SERVQUAL model, this paper develops five dimensions of reliability, ease of use, tangibility, responsiveness and empathy. First, the subjective weight of evaluation index is determined by G1 method. Secondly, the entropy weight method is used to determine the objective weight of the evaluation index. Finally, the subjective weight and the objective weight are reasonably integrated based on the ideal scheme method. This paper will help the follow-up research on the evaluation of the service quality of the intelligent home-aged care, with strong practical significance and theoretical value. Keywords: Weight Coefficient; Evaluation Index; Intelligent Home Care; Care Servic

Current Situation and Future Development of Activity Theory in China

The cultural-historical activity theory was developed by the Russian psychologist Vygotsky and his colleagues in the 1920s and 1930s. Since then, it has been expanded globally and rapidly, particularly during the past 15 years. However, there has been little interaction between the broader international community and China with respect to the development of the theory and its applications in China, which has taken place along a path of its own. This paper aims to examine this development, focusing on 1) the general situation and background of the research, 2) the basic understanding, theoretical construction and unique features of development; 3) the focal areas in and limitations of the application; and 4) idea evolution in terms of different generation theories. At the end of the paper, emerging trends and future prospects of activity theoretical research in China will be suggested and discussed

Testing Higher-order Clusterability on graphs

Analysis of higher-order organizations, usually small connected subgraphs called motifs, is a fundamental task on complex networks. This paper studies a new problem of testing higher-order clusterability: given query access to an undirected graph, can we judge whether this graph can be partitioned into a few clusters of highly-connected motifs? This problem is an extension of the former work proposed by Czumaj et al. (STOC' 15), who recognized cluster structure on graphs using the framework of property testing. In this paper, a good graph cluster on high dimensions is first defined for higher-order clustering. Then, query lower bound is given for testing whether this kind of good cluster exists. Finally, an optimal sublinear-time algorithm is developed for testing clusterability based on triangles