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Integrating processes with inverse response and time delay are frequently encountered in the level control of a boiler steam drum and are difficult to identify and control. In this paper, a systematic approach for autotuning of a proportional−integral (PI) or proportional−integral−derivative (PID) controller is proposed for this type of process. A single run of a biased relay feedback test is carried out to obtain four parameters of the model without any prior information about the time delay or the steady-state gain. Since the exact limit cycle expressions are derived, accurate parameter estimations are achieved. Then, according to the estimated model, an analytical procedure for PI/PID controller design is developed based on H ∞ optimization and internal model control (IMC) theory. The internal stability of the closed-loop feedback system is guaranteed. Moreover, robust stability analysis for the proposed control scheme is provided in the presence of model mismatches. Hence, the best tradeoff between robust stability and nominal performance of the closed-loop system can be achieved by adjusting the controller parameter λ conveniently. For illustration, simulation examples are given to compare the proposed method with those previously used.

An optimization-based approach to synthesizing plantwide control architectures is discussed. The approach assumes that a dynamic model is available, and it extends earlier work. The plantwide controller is synthesized in three stages involving fast and slow safety variables to be controlled, followed by product variables. In each stage a mixed integer linear program is solved to generate candidate architectures. The objective function involves a tradeoff between manipulated variable moves and transient response area. The integers in the formulation determine the control architecture, and integer cuts are employed to generate second best, third best, etc., candidate solutions. Controlling component balances and adding unit operation controls completes the plantwide control system design. The Tennessee Eastman process is used to illustrate the synthesis procedure.

Current molecular analysis of cells and tissues routinely relies on separation, enrichment, and subsequent measurements by various assays. Here we demonstrate a platform of hyperspectral stimulated Raman scattering microscopy for fast, quantitative and label-free imaging of biomolecules in intact tissues using spectroscopic fingerprints as the contrast mechanism.

The Neoproterozoic Datangpo Formation of the Nanhua Basin in South China records interglacial sedimentation between the ~720-660-Ma Sturtian and ~654-635-Ma Marinoan glaciations. The lower part (1 st Member) of this formation contains manganese-rich deposits that represent a mixture of two main components, Mn-carbonates and Mn-bearing aluminosilicates (clay minerals). The Mn-carbonate component is characterized by high La/Sc ratios, high initial 87 Sr/ 86 Sr ratios, and low initial εNd(t) values, and the siliciclastic component by low La/Sc ratios, low initial 87 Sr/ 86 Sr ratios, and high initial εNd(t) values. The likely source of the non-radiogenic

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Video games have been found to have positive influences on executive function in older adults; however, the underlying neural basis of the benefits from video games has been unclear. Adopting a task-based functional magnetic resonance imaging (fMRI) study targeted at the flanker task, the present study aims to explore the neural basis of the improved executive function in older adults with video game experiences. Twenty video game players (VGPs) and twenty non-video game players (NVGPs) of 60 years of age or older participated in the present study, and there are no significant differences in age (t = 0.62, p = 0.536), gender ratio (t = 1.29, p = 0.206) and years of education (t = 1.92, p = 0.062) between VGPs and NVGPs. The results show that older VGPs present significantly better behavioral performance than NVGPs. Older VGPs activate greater than NVGPs in brain regions, mainly in frontal-parietal areas, including the right dorsolateral prefrontal cortex, the left supramarginal gyrus, the right angular gyrus, the right precuneus and the left paracentral lobule. The present study reveals that video game experiences may have positive influences on older adults in behavioral performance and the underlying brain activation. These results imply the potential role that video games can play as an effective tool to improve cognitive ability in older adults.