190 research outputs found

    The Influence of Puritanism on the Sin and Punishment in The Scarlet Letter

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    “The Scarlet Letter”, written by 19th century American novelist Nathaniel Hawthorne, tells the story of the triangle love affairs of heroine Hester Prynne, her husband Roger Chillingworth, and her lover Arthur Dimmesdale.” This paper attempts to interpret The Scarlet Letter from the aspects of sin and punishment. It discusses how Hawthorne arranges the fate of each character and the influence of Puritanism on people's thoughts and life. Under the influence of Puritanism, the three characters pay a heavy price for their sins and receive emotional and moral punishment, and finally each has a different way to get salvation of the soul. Keywords: “The Scarlet Letter”,; Puritanism; Sin and Punishment; Salvation

    Robust Control Design of Gain-scheduled Controllers for Nonlinear Processes

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    In the chemical or biochemical industry most processes are modeled by nonlinear equations. It is of a great significance to design high-performance nonlinear controllers for efficient control of these nonlinear processes to achieve closed-loop system's stability and high performance. However, there are many difficulties which hinder the design of such controllers due mainly to the process nonlinearity. In this work, comprehensive design procedures based on robust control have been proposed to efficiently deal with the design of gain-scheduled controllers for nonlinear systems. Since all the design procedures proposed in this work rely strongly on the process model, the first difficulty addressed in this thesis is the identification of a relatively simple model of the nonlinear processes under study. The nonlinearity of the processes makes it often difficult to obtain a first-principles model which can be used for analysis and design of the controller. As a result, relatively simple empirical models, Volterra series model and state-affine model, are chosen in this work to represent the nonlinear process for the design of controllers. The second major difficulty is that although the nonlinear models used in this thesis are easy to identify, the analysis of stability and performance for such models using nonlinear control theory is not straightforward. Instead, it is proposed in this study to investigate the stability and performance using a robust control approach. In this approach, the nonlinear model is approximated by a nominal linear model combined with a mathematical description of model error to be referred to, in this work, as model uncertainty. In the current work it was assumed that the main source of uncertainty with respect to the nominal linear model is due to the system nonlinearity. Then, in this study, robust control theoretical tools have been especially developed and applied for the design of gain-scheduled Proportional-Integral (PI) control and gain-scheduled Model Predictive Control (MPC). Gain-scheduled controllers are chosen because for nonlinear processes operated over a wide range of operation, gain-scheduling has proven to be a successful control design technique (Bequette, 1997) for nonlinear processes. To guarantee the closed-loop system's robust stability and performance with the designed controllers, a systematic approach has been proposed for the design of robust gain-scheduled controllers for nonlinear processes. The design procedure is based on robust stability and performance conditions proposed in this work. For time-varying uncertain parameters, robust stability and performance conditions using fixed Lyapunov functions and parameter-dependent Lyapunov functions, were used. Then, comprehensive procedures for the design and optimization of robust gain-scheduled PI and MPC controllers tuning parameters based on the robust stability and performance tests are then proposed. Since the closed-loop system represented by the combination of a state-affine process model and the gain-scheduled controller is found to have an affine dependence on the uncertain parameters, robust stability and performance conditions can be tested by a finite number of Linear Matrix Inequalities (LMIs). Thus, the final problems are numerically solvable. One of the inherent problems with robust control is that the design is conservative. Two approaches have been proposed in this work to reduce the conservatism. The first one is based on parameter-dependent Lyapunov functions, and it is applied when the rate of change of the time-varying uncertainty parameters is a priori available. The second one is based on the relaxation of an input-saturation factor defined in the thesis to deal with the issue of actuator saturation. Finally, to illustrate the techniques discussed in the thesis, robust gain-scheduled PI and MPC controllers are designed for a continuous stirred tank reactor (CSTR) process. A simple MIMO example with two inputs and two outputs controlled by a multivariable gain-scheduled MPC controller is also discussed to illustrate the applicability of the methods to multivariable situations. All the designed controllers are simulated and the simulations show that the proposed design procedures are efficient in designing and comparing robust gain-scheduled controllers for nonlinear processes

    Factors Leading to Students’ Satisfaction in the Higher Learning Institutions

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    There is an increasing need to understand factors that affect satisfaction of students with learning. This study will explore the relationship between student satisfaction and teacher-student relationship, teacher preparedness, campus support facilities and experiences provided by the institute to the students. Study is a necessary activity that most people must engage in for much of their lives to support themselves and their families; however, motivation and student satisfaction vary for students. Some students are motivated by a sense of accomplishment, some by helping others, and others by personal fulfillment. Some students get satisfied by personality grooming, personal values, and psychological needs fulfillment. The data was collected through questionnaire from the students of selected universities. This study focuses on factors that influence student satisfaction for the purpose of improving quality and thereby better performance. Keywords: Student satisfaction, Student-teacher relationship, Faculty preparedness, Campus facilities, Higher educatio

    Characterization of the Interface Roughness of Coatings Based on Ultrasonic Reflection Coefficient Amplitude Spectrum

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    In order to nondestructively characterize the interface roughness of coatings effectively, the ultrasonic reflection coefficient amplitude spectrum (URCAS) involving interface roughness was derived based on the phase screen approximation theory [1]. The interface roughness was determined by a two-parameter inversion combined with a cross-correlation algorithm. For homogeneous coatings, the effects of ultrasonic wavelength λ, beam coverage, and shape variations of the coating on the roughness measurements were analyzed through numerical calculation. A series of simulations indicated that measurement errors were less than 10% when the relationship between interface roughness and wavelength satisfied Rq=1.5%λ~12%λ approximately. For inhomogeneous coatings, the attenuation coefficient shows a non-negligible effect on the URCAS. A new URCAS suited for roughness measurement of inhomogeneous coatings was formulated by considering the relationship of attenuation coefficient α(f) on frequency f, which was determined by simulations. Ultrasonic experiments were carried out on standard roughness specimens and tungsten carbide (WC) coating specimen utilizing delay line transducers. The standard roughness specimens were shown in Fig 1, whose roughness Rq were 8.5μm, 14.2μm, and 28.6μm measured by confocal laser scanning microscope (CLSM), respectively. The WC coating was sprayed on stainless steel by high velocity oxygen fuel (HOVF). Experimental results show that the roughness of standard roughness specimens obtained by the proposed ultrasonic measurement are in good agreement with the LCM observations, and the relative errors are less than 8.5%. For inhomogeneous WC coatings, the absolute error of roughness measurement is less than 2.5μm and the relative error is less than 20% between ultrasonic and metallographic methods

    A Multifunctional Array System Based on Adjustable-Phase Antenna for Wireless communications

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    In this work, an innovative method for controlling the current distribution of the radiating patch by adjusting the input phase is investigated to achieve both pattern and polarization reconfigurable characteristics for the multifunction. A compact and low-profile antenna with four fed ports is designed to implement the proposed method, which can operate linear, right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) with different beam directions in the operating band from 4.0 to 5.0 GHz. Even more, a four-by-four passive planar array is designed and fabricated based on this antenna element, which can scan the coverage of 70{\deg} with low gain fluctuation and low sidelobe with dual-polarization. Meanwhile, it can realize the wide-angle scanning capability up to 60{\deg} with low sidelobe with RHCP and LHCP. More important, the dual- and triple-beam with different directions can be obtained by the proposed array. Good agreement has been shown between measured and simulated results. Therefore, the proposed antenna is a good solution for wireless communication systems because of its simple-configuration, multifunction, and beamforming capability

    Overexpression of N-Myc Downstream-Regulated Gene 2 (NDRG2) Regulates the Proliferation and Invasion of Bladder Cancer Cells In Vitro and In Vivo

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    N-Myc downstream-regulated gene 2 (NDRG2) is a candidate tumor suppressor gene, which plays an important role in controlling tumor growth. The aim of this study was to investigate the expression of NDRG2 gene in bladder cancer (BC) tissues and several bladder cancer cell lines, and to seek its clinical and pathological significance. Ninety-seven bladder carcinoma and 15 normal bladder tissue sections were analyzed retrospectively with immunohistochemistry. The human bladder cancer cell line T24 was infected with LEN-NDRG2 or LEN-LacZ. The effects of NDRG2 overexpression on T24 cells and T24 nude mouse xenografts were measured via cell growth curves, tumor growth curves, flow cytometric analysis, western blot and Transwell assay. NDRG2 was highly expressed in normal bladder tissue, but absent or rarely expressed in cacinomatous tissues (χ2=8.761, p < 0.01). The NDRG2 level was negatively correlated with tumor grade and pathologic stage(r=-0.248, p < 0.05), as well as increased c-myc level (r=-0.454, p< 0.001). The expression of NDRG2 was low in the three BC cell lines. T24 cells infected with LEN-NDRG2 showed inhibition of proliferation both in vitro and in vivo, and NDRG2 overexpression can inhibit tumor growth and invasion in vitro

    Grape Drying: Current Status and Future Trends

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    With high moisture and sugar content, fresh grapes respire and transpire actively after harvest, which contribute to quality loss. Drying can process grapes into raisins for longer shelf-life as well as dehydrated grapes, which can be used for wines or juice production. The pre-treatments, drying method and drying conditions, can significantly influence the quality of final products. In this chapter, firstly, different pre-treatments as a necessary operation previous to the drying of grapes into raisins is introduced. These pre-treatments include chemical pre-treatment, physical pre-treatment, and blanching. In addition, the quality and drying characteristics of different pre-treatments is summarized too. Secondly, the current status of different technologies for grape drying and their effects on drying kinetics and quality attributes of seedless grapes are described to highlight the advantages and disadvantages of each drying method. These drying methods include the traditional open sun drying, shade drying, hot-air drying, freezing drying, microwave drying, as well as the vacuum impulsed drying. Thirdly, influences of drying on bioactive substances (flavonoids, phenolics, anthocyanin, and resveratrol) and antioxidant capacity of grape by-products including seed, skin, stem, and stalk are also examined. Finally, the future research trends of grape and its by-product drying are indentified and discussed
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