1,840 research outputs found

    State Nonpoint Source Programs

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    Funding Nonpoint Control Projects in Missouri (p. 69) State of Maryland Nonpoint Source Control Implementation Program (p. 71) The Wisconsin Nonpoint Source Program (p. 76

    Reduction of internal friction in silica glass with high OH content

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    The aim of this article is to investigate processes occurring during annealing of silica glass classified as being of type III1. This is an inexpensive silica glass produced by many manufacturers across the globe. However, it can be successfully used for fabrication of high-Q mechanical resonators. The relationship between residual internal stress and internal friction is elucidated. Quantitative analysis of the structural relaxation kinetics is presented. The influence of the cooling process for structural transformation is also discussed. Based on our results, we suggest optimal annealing conditions for minimizing internal friction type III silica glass. The results will be useful for further improvement of the Q-factor of mechanical resonators, including the test masses of the next generation of gravitational wave detectors. Our approach might, in addition, be used for studying the modification of atomic structure in multicomponent glasses

    Phase synchronization of autonomous AC grid system with passivity-based control

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    This paper discusses a ring‐coupled buck‐type inverter system to harness energy from direct current (DC) sources of electricity. The DC‐DC buck converter circuit is modified with an H‐bridge to convert the DC input voltage to a usable alternating current (AC) output voltage. Passivity‐based control (PBC) with port‐controlled Hamiltonian modelling (PCHM) is a method where the system is controlled by considering not only the energy properties of the system but also the inherent physical structure. PBC is applied to achieve stabilization of the AC output voltage to a desired amplitude and frequency. Unsynchronized output voltages in terms of phase angle or frequency can cause detrimental effects on the system. Phase‐locked loop (PLL) is employed in the ring structure to maintain synchronization of the AC output voltage of all inverter units in the ring‐coupled system

    Adaptive Estimation for Uncertain Nonlinear Systems with Measurement Noise: A Sliding-Mode Observer Approach

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    International audienceThis paper deals with the problem of adaptive estimation, i.e. the simultaneous estimation of the state and time-varying parameters, in the presence of measurement noise and state disturbances, for a class of uncertain nonlinear systems. An adap-tive observer is proposed based on a nonlinear time-varying parameter identification algorithm and a sliding-mode observer. The nonlinear time-varying parameter identification algorithm provides a fixed-time rate of convergence, to a neighborhood of the origin, while the sliding-mode observer ensures ultimate boundedness for the state estimation error attenuating the effects of the external disturbances. Linear matrix inequalities are provided for the synthesis of the adaptive observer while the convergence proofs are given based on the Lyapunov and Input-to-State Stability theory. Finally, some simulation results show the feasibility of the proposed approach

    Fractional modeling dynamics of HIV and CD4+ T-cells during primary infection

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    In this paper, we introduce fractional-order into a model of HIV-1 infection of CD4+ T cells. We study the effect of the changing the average number of viral particles N with different sets of initial conditions on the dynamics of the presented model. Generalized Euler method (GEM) will be used to find a numerical solution of the HIV-1 infection fractional order model

    Performance and application of an open source automated magnetic optical density meter for analyzing magnetotactic bacteria

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    We present a spectrophotometer (optical density meter) combined with electromagnets dedicated to the analysis of magnetotactic bacteria. We have ensured that our system, called MagOD, can be easily reproduced by providing the source of the 3D prints for the housing, electronic designs, circuit board layouts, and microcontroller software. We compare the performance of this novel system to existing adapted commercial spectrophotometers. In addition, we demonstrate its use by analyzing the absorbance of magnetotactic bacteria as a function of their orientation with respect to the light path and their speed of reorientation after the field has been rotated by 90o. We continuously monitored the development of a culture of magnetotactic bacteria over a period of five days, and measured the development of their velocity distribution over a period of one hour. Even though this dedicated spectrophotometer is relatively simple to construct and cost-effective, a range of magnetic field-dependent parameters can be extracted from suspensions of magnetotactic bacteria. Therefore, this instrument will help the magnetotactic research community to understand and apply this intriguing micro-organism

    Parenting a child with congenital cytomegalovirus infection: a qualitative study.

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    Background: Congenital cytomegalovirus (CMV) is the most common infectious cause of congenital disability, which can cause lifelong impairments including sensorineural hearing loss and developmental delay. This study aimed to explore the experiences of parenting a child with congenital CMV and the impact this has on families. Methods: Ten parents living with a child with congenital CMV in the UK participated in semistructured interviews and data were analysed using thematic analysis. Results: The findings illustrate that delays in making the diagnosis of congenital CMV are associated with parental distress and lack of knowledge about CMV among medical professionals can exacerbate this distress. Parents expressed frustration about not knowing about CMV infection during their pregnancies and therefore not having the opportunity to take measures to reduce their risk of acquiring CMV while pregnant. The uncertainty about the long-term outcomes of children with congenital CMV adds additional emotional burden for parents. Family and wider societal networks have the potential to facilitate coping and alleviate stress, but the lack of awareness of CMV acts as a barrier to receiving support from family and friends. Conclusions: There is a need to increase awareness of CMV among medical professionals, pregnant women and wider society to improve the diagnostic process and to provide better support for families caring for children with congenital CMV infection
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