Reduced chatter sliding mode control for hydraulic manipulators based on continuous–time state dependent parameter models

Sliding Mode Control (SMC) systems are developed for a hydraulic manipulator. The control model is obtained via state-dependent parameter (SDP) system identification. In contrast to previous research using discrete-time SDP models, in which the model coefficients are functions of the sampling interval, the present work develops a new continuous-time approach. It is well known that for conventional SMC there is a trade-off between chattering and robust performance. Hence, a recently developed approach to address this problem is investigated, in which the controller is designed via a fractional exponent of the sliding surface. The approach is developed for both conventional and Nonsingular Terminal SMC (NTSMC). The new continuous version of the NTSMC algorithm successfully reduces chattering and provides the best overall performance of various SMC designs. However, for the preliminary experiments reported in this article, a PID lead-lag controller yields the lowest absolute errors, albeit at the cost of a higher control effort. Hence, given that dead-zone and other uncertainties provide the main motivation for use of SMC in this application, further research into the robustness of the new algorithm is required

Optimization of CO2 Laser Cutting Parameters Using Adaptive Neuro-Fuzzy Inference System (ANFIS)

Laser cutting is a manufacturing technology that uses laser light to cut almost any materials. This type of cutting technology has been applied in many industrial applications. Problems seen with a laser is the cutting efficiency and the quality wherein these two parameters are both affected by the laser power and its process speed. This study presents the modelling and simulation of an intelligent system for predicting and optimising the process parameters of CO2 laser cutting. The developed model was trained and tested using actual data gathered from actual laser cut runs. For the system parameters, two inputs were used: the type of material used and the material thickness (mm). For the desired response, the output is the process speed or cutting rate (mm/min). Adaptive neuro-fuzzy inference system (ANFIS) was the tool used to model the optimisation cutting process. Moreover, grid partition (GP) and subtractive clustering were both used in designing the fuzzy inference system (FIS). Among the training models used, GP Gaussian bell membership function (Gbellmf) provided the highest performance with an accuracy of 99.66%

Staphylococcus aureus enterotoxin b down-regulates the expression of transforming growth factor-beta (TGF-β) signaling transducers in human glioblastoma

Background: It has been revealed that Staphylococcus aureus enterotoxin B (SEB) may feature anti-cancer and anti-metastatic advantages due to its ability to modify cell immunity processes and signaling pathways. Glioblastoma is one of the most aggressive human cancers; it has a high mortality nature, which makes it an attractive area for the development of novel therapies. Objectives: We examined whether the SEB could exert its growth inhibitory effects on glioblastoma cells partially through the manipulation of a key tumor growth factor termed transforming growth factor-beta (TGF-β). Materials and Methods: A human primary glioblastoma cell line, U87, was treated with different concentrations of SEB. The cell quantity was measured by the MTT assay at different exposure times. For molecular assessments, total ribonucleic acid (RNA) was extracted from either non-treated or SEB-treated cells. Subsequently, the gene expression of TGF-β transducers, smad2/3, at the messenger RNA (mRNA) level, was analyzed via a quantitative real-time polymerase chain reaction (qPCR) using the SYBR Green method. Significant differences between cell viability and gene expression levels were determined (Prism 5.0 software) using a one-way analysis of variance (ANOVA) test. Results: We reported that SEB could effectively down-regulate smad2/3 expression in glioblastoma cells at concentrations as quantity as 1 µg/mL and 2 µg/mL (P < 0.05 and P < 0.01, respectively). The SEB concentrations effective at regulating smad2/3 expression were correlated with those used to inhibit the proliferation of glioblastoma cells. Our results also showed that SEB was able to decrease smad2/3 expression at the mRNA level in a concentration- and time-dependent manner. Conclusions: We suggested that SEB could represent an agent that can significantly decrease smad2/3 expression in glioblastoma cells, leading to moderate TGF-β growth signaling and the reduction of tumor cell proliferation. © 2016, Ahvaz Jundishapur University of Medical Sciences

Sialoglycan recognition is a common connection linking acidosis, zinc, and HMGB1 in sepsis

© 2021 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY). https://creativecommons.org/licenses/by/4.0/Blood pH is tightly maintained between 7.35 and 7.45, and acidosis (pH <7.3) indicates poor prognosis in sepsis, wherein lactic acid from anoxic tissues overwhelms the buffering capacity of blood. Poor sepsis prognosis is also associated with low zinc levels and the release of High mobility group box 1 (HMGB1) from activated and/or necrotic cells. HMGB1 added to whole blood at physiological pH did not bind leukocyte receptors, but lowering pH with lactic acid to mimic sepsis conditions allowed binding, implying the presence of natural inhibitor(s) preventing binding at normal pH. Testing micromolar concentrations of divalent cations showed that zinc supported the robust binding of sialylated glycoproteins with HMGB1. Further characterizing HMGB1 as a sialic acid-binding lectin, we found that optimal binding takes place at normal blood pH and is markedly reduced when pH is adjusted with lactic acid to levels found in sepsis. Glycan array studies confirmed the binding of HMGB1 to sialylated glycan sequences typically found on plasma glycoproteins, with binding again being dependent on zinc and normal blood pH. Thus, HMGB1-mediated hyperactivation of innate immunity in sepsis requires acidosis, and micromolar zinc concentrations are protective. We suggest that the potent inflammatory effects of HMGB1 are kept in check via sequestration by plasma sialoglycoproteins at physiological pH and triggered when pH and zinc levels fall in late stages of sepsis. Current clinical trials independently studying zinc supplementation, HMGB1 inhibition, or pH normalization may be more successful if these approaches are combined and perhaps supplemented by infusions of heavily sialylated molecules.Peer reviewe

Point-spread Analysis of γ-ray/depth Spectra for Borehole Monitoring Applications

An approach to the analysis of γ-ray spectra that might arise as depth profiles from the characterization of radioactivity in boreholes is described. A borehole logging probe, ‘ABACUS’, has been designed and constructed which comprises a cerium bromide detector and a built-in multichannel analyzer. This has been tested in a bespoke, laboratory-based testbed built to replicate the borehole environment. An established, semi-empirical model has been applied data arising from the cerium bromide scintillation detector to extract the number of counts under the photopeak from each of the resulting γ-ray spectra (in this case the 662 keV line from 137 Cs) associated with each depth position, and which also enables this information to be isolated from other contributions such as background and the Compton continuum. A complementary approach has been adopted to process the asymmetric and non-Gaussian trend that concerns the photopeak count as a function of depth in the borehole testbed for a given depth profile, when the testbed is subject to the activity provided by a sealed, 137 Cs source. This comprises a modified, Moffat point-spread function. The Moffat function is a continuous probability distribution based upon the Lorentzian distribution. Its particular importance is due to its ability to reconstruct point spread functions that comprise wings that cannot be reproduced accurately by either a Gaussian or Lorentzian function. This application of the Moffat formalism to radioactive contamination assessment profiles enables an effective and accurate assessment to be made of the position of localized radioactivity in the testbed wall

COTS vision system, radiation sensor and 6 DoF robot for use in identifying radiologically uncharacterised objects

A novel, semi-autonomous radiological scanning system for inspecting uncharacterised objects is presented. The research utilises commercially available off-the-shelf (COTS) electronic components, intended for use in relatively low radioactive dose environments. To illustrate the concept, a Microsoft Kinect, a Universal Robots UR3 (6 degree of freedom) manipulator and a Kromek RadAngel gamma radiation spectrometer are utilised. The new control software allows the remote operator to select the required object, before the robot arm autonomously scans it, enabling the generation of various radiological spectra shapes. These data inform the operator of any likely radioisotopes present and where they are located in the object

A Low-Cost and Semi-Autonomous Robotic Scanning System for Characterising Radiological Waste

A novel, semi-autonomous radiological scanning system for inspecting irregularly shaped and radiologically uncharacterised objects in various orientations is presented. The system utilises relatively low cost, commercial-off-the-shelf (COTS) electronic components, and is intended for use within relatively low to medium radioactive dose environments. To illustrate the generic concepts, the combination of a low-cost COTS vision system, a six DoF manipulator and a gam-ma radiation spectrometer are investigated. Three modes of vision have been developed, al-lowing a remote operator to choose the most appropriate algorithm for the task. The robot arm subsequently scans autonomously across the selected object, determines the scan positions and enables the generation of radiological spectra using the gamma spectrometer. These data inform the operator of any likely radioisotopes present, where in the object they are located and thus whether the object should be treated as LLW, ILW or HLW

Hyperspectral Imaging based Characterization and Identification of Sintered UO2 Fuel Pellets

Hyperspectral Imaging (HSI) is a well-established technology able to capture the same spatial scene or image in hundreds of different wavelengths across the electromagnetic spectrum, covering not only the visible but also the shortwave infrared range (1000-2500nm), potentially revealing information otherwise invisible to the human eye. In this work, we explored whether HIS technology can be used for the fast-non-invasive characterization and identification of sintered UO2 fuel pellets. Preliminary experiments included the imaging of the pellets, revealing their spectral responses. These show promising features that could be used for their identification, where two different groups of pellets, pure and doped, seem to be easily recognized based on their spectral response. The experiments included a pixel-wise classification map generated via the Spectral Angle Mapper (SAM) technique in which the pure and doped pellets are successfully identified

Stormwater reuse, a viable option: Fact or fiction?

The increasing spread of urbanization is a common phenomenon witnessed in most parts of the world due to the perceived benefits of urban living. A compounding issue is the growing shortage of safe and reliable water sources. Perennial water shortages are becoming a common feature in many parts of the world. It is important to recognize stormwater reuse as a key resource for securing adequate future water supplies based on the concept of ‘water fit for purpose’. These require careful prioritization of vulnerabilities, identification of the areas requiring adaptation and provide certainty of outcomes. Given the increasing inevitability of climate change it should be viewed as an opportunity to take advantage of new opportunities which stormwater reuse presents. This study identified key barriers to stormwater reuse and the difficulties in removing them