Specific Set Point Research Articles

Assessment of internal and external disturbances on the fuzzy-based thermal control of a sub-scaled building testbed

This experimental study follows on our previous work on the development of robust fuzzy-based thermal control strategies of a multi-room sub-scaled building testbed. In the present analysis, the focus is placed on testing the robustness of the fuzzy controller under internal and external disturbances, as it deals with maintaining specific setpoint values of room temperatures. The testbed has eight rooms, distributed on two floors, with a cooling unit that supplies cool air to each room, and eight 40 W light bulbs serving as heat sources. T-type thermocouples gather the temperature data, and eight dampers deliver the airflow. The controller uses information about the difference between setpoint and actual temperatures, their derivative, and their cumulative integral. The fuzzy sets and if-then rules are built based on experimental data, and a Mamdani inference method is used to provide the inputs to the actuators. Results from experimental tests show that the fuzzy control strategy can handle the different types of disturbances while maintaining the room setpoints.

Production Capacity Prediction and Optimization in the Glycerin Purification Process: A Simulation-Assisted Few-Shot Learning Approach

Chemical process control relies on a tightly controlled, narrow range of margins for critical variables, ensuring process stability and safeguarding equipment from potential accidents. The availability of historical process data is limited to a specific setpoint of operation. This challenge raises issues for process monitoring in predicting and adjusting to deviations outside of the range of operational parameters. Therefore, this paper proposes simulation-assisted deep transfer learning for predicting and optimizing the final purity and production capacity of the glycerin purification process. The proposed network is trained by the simulation domain to generate a base feature extractor, which is then fine-tuned using few-shot learning techniques on the target learner to extend the working domain of the model beyond historical practice. The result shows that the proposed model improved prediction performance by 24.22% in predicting water content and 79.72% in glycerin prediction over the conventional deep learning model. Additionally, the implementation of the proposed model identified production and product quality improvements for enhancing the glycerin purification process.

Sports teams as collective homeostatic systems: Exploiting self-organising tendencies in competition

This paper proposes theoretical insights on how sports teams, conceptualised as homeostatic regulatory systems, can continually self-organise their ongoing interactions to maintain team functioning and organization during competitive performance. In the model, team performance is co-regulated as coordinated behaviours emerge through synergy (re)formation between performers to adapt efficiently and effectively to satisfy emerging dynamical constraints of competitive environments. Understanding collective homeostasis in interpreting the self-organising dynamics of sports teams facilitates the identification and analysis of adaptive behavioural responses of teams, sub-groups, and individual players. As a starting point, a biological model of collective homeostasis is composed of four critical components: a) players, b) set point, c) identifier, and d), adapter. Understanding the interrelated functions of model components is fundamental to designing effective training sessions and programmes for development of self-regulating team performance. In terms of performance analysis, identification and disruption of specific set points will provide insights for studying how to negotiate critical moments of competitive game play.

Current and future pharmacotherapies for obesity in children and adolescents.

Obesity is a common chronic disease in children and adolescents and its prevalence is increasing worldwide. The causes are multifactorial but involve biological predisposition towards a specific body-weight set point and defended adipose tissue mass converging with an obesogenic environment. Comprehensive treatment of paediatric obesity includes lifestyle modification therapy, anti-obesity medications (AOMs) and/or metabolic surgery. Lifestyle modification therapy used alone produces fairly modest weight loss for most youth with obesity. The emergence of new AOMs has changed the landscape of paediatric weight management, improving the outlook for youth with obesity. This Review briefly highlights obesity development pathways in youth and the role that pharmacotherapy can play in counteracting these pathophysiological forces. Here, results from adolescent AOM clinical trials published since 2020 are reviewed, including the safety, efficacy and tolerability of the newest treatments (glucagon-like peptide 1 receptor agonists and phentermine-topiramate). The importance of a comprehensive and chronic care model, including both lifestyle modification and ongoing pharmacotherapy, will be discussed in the context of maximizing long-term health outcomes. Finally, insight will be provided into the emerging pipeline of AOMs (for example, incretin receptor co-agonists and tri-agonists) and how future therapies might fundamentally change the prognosis for youth with obesity.

Model-Free Feedback Control Synthesis From Expert Demonstration

We show how it is possible to synthesize a stabilizing feedback control, in the complete absence of a model, starting from the open-loop control generated by an expert operator, capable of driving a system to a specific set-point. We assume that the system is linear and discrete time. We propose two different controls: a linear dynamic and a static, piecewise linear, one. We show the performance of the proposed controllers on a ship steering problem.

Practical Assessment of an Interdisciplinary Bacteriophage Delivery Pipeline for Personalized Therapy of Gram-Negative Bacterial Infections.

Despite numerous advances in personalized phage therapy, smooth logistics are challenging, particularly for multidrug-resistant Gram-negative bacterial infections requiring high numbers of specific lytic phages. We conducted this study to pave the way for efficient logistics for critically ill patients by (1) closely examining and improving a current pipeline under realistic conditions, (2) offering guidelines for each step, leading to safe and high-quality phage supplies, and (3) providing a tool to evaluate the pipeline’s efficiency. Due to varying stipulations for quality and safety in different countries, we focused the pipeline on all steps up to a required phage product by a cell-free extract system. The first of three study runs included patients with respiratory bacterial infections from four intensive care units, and it revealed a cumulative time of up to 23 days. Ultimately, adjustment of specific set points of the vulnerable components of the pipeline, phage isolation, and titration increased the pipeline’s efficiency by 15% and decreased the maximum required time to 13 days. We present a site-independent practical approach to establish and optimize pipelines for personalized phage delivery, the co-organization of pipeline components between different institutions, non-binding guidelines for every step, and an efficiency check for phage laboratories.

PID Power Controller to a Setpoint of Fluid Level Height in a Reservoir for Unattended Human Monitoring

This paper provides a novel approach of a power control system of a fluid tank pump to reach a specific setpoint of fluid level height. The system enables users to fill a tank to any desired height within a chosen time interval. The system is equipped with a timer that allows the user to fill the tank to the desired level within the desired time. The system is based on utilizing a Proportional Integral and Derivative (PID) controller to adjust the pump's power to satisfy the us-er-defined setups (time and fluid level height). This approach has the potential to be applied for domestic purposes for unattended human monitoring. This approach has been demonstrated using LabVIEW coding to apply the fluid and hydrodynamic design and control principles. The results have illustrated the code's capability to achieve the desired tank fluid level height for a variable range of fluid level height setpoints and time intervals

In Silico Screening To Achieve Fast Lab-Scale Nitroxide-Mediated Polymerization of n-Butyl Acrylate with Maximal Control over Macromolecular Properties

Nitroxide-mediated polymerization (NMP) allows one to synthesize well-defined polymers with narrow molar mass distribution (MMD) and latent functionality. For acrylates, however, side reactions, such as backbiting and β-scission and increases in viscosity, can complicate the molecular control, affecting the MMD dispersity, the double bound content, and the degree of livingness. On top of this, acrylate polymerizations are highly exothermic and thus dedicated temperature control is recommended, even under general lab-scale NMP conditions. In the present work, we account for both side reactions, diffusional limitations and nonisothermicity, so that a detailed model-based design for NMP of n-butyl acrylate can be performed in view of a better evaluation of its commercial potential. The relevance of temperature control and semibatch feeding strategies is particularly explored, benefiting from (i) a successful benchmark to NMP lab-scale batch literature data and (ii) a previous successful benchmark under various lab-scale free radical polymerization (FRP) conditions. It is showcased that specific set points of NMP characteristics, e.g., polymerization time, number average molar mass, and unsaturation level, can be achieved for a high monomer conversion by realizing less conventional thus nonlinear number average molar mass profiles, which is highly relevant for the polymer synthesis and reaction engineering community. The current work, which puts forward a dedicated research strategy from FRP to NMP to minimize error on kinetic parameter determination steps, opens the pathway to maximize the potential of reversible deactivation radical polymerization techniques for their more elegant implementation and appreciation in the society.

Activation of Smad2/3 signaling by low fluid shear stress mediates artery inward remodeling

Endothelial cell (EC) sensing of wall fluid shear stress (FSS) from blood flow governs vessel remodeling to maintain FSS at a specific magnitude or set point in healthy vessels. Low FSS triggers inward remodeling to restore normal FSS but the regulatory mechanisms are unknown. In this paper, we describe the signaling network that governs inward artery remodeling. FSS induces Smad2/3 phosphorylation through the type I transforming growth factor (TGF)-β family receptor Alk5 and the transmembrane protein Neuropilin-1, which together increase sensitivity to circulating bone morphogenetic protein (BMP)-9. Smad2/3 nuclear translocation and target gene expression but not phosphorylation are maximal at low FSS and suppressed at physiological high shear. Reducing flow by carotid ligation in rodents increases Smad2/3 nuclear localization, while the resultant inward remodeling is blocked by the EC-specific deletion of Alk5. The flow-activated MEKK3/Klf2 pathway mediates the suppression of Smad2/3 nuclear translocation at high FSS, mainly through the cyclin-dependent kinase (CDK)-2-dependent phosphosphorylation of the Smad linker region. Thus, low FSS activates Smad2/3, while higher FSS blocks nuclear translocation to induce inward artery remodeling, specifically at low FSS. These results are likely relevant to inward remodeling in atherosclerotic vessels, in which Smad2/3 is activated through TGF-β signaling.

Learning points, lines, and plane geometry with Hawgent dynamic mathematics software

Geometry is any shape seen as a set of specific set points, while a plane means a collection of all lines. In mathematics, points, line, and planes geometry is complicated for students to understand a basic concept. This research aims to help teachers explain the concepts of points, lines, and planes and help students understand the basic concepts of points, lines, and planes with Hawgent dynamic mathematics software. The method used in this research is Analysis, Design, Development, Implementation, and Evaluation. The evaluation results of media expert were 82.77%, and material expert was 84.17%. The result of the implementation is a positive response from students when learning mathematics uses Hawgent dynamic mathematics software in the classroom and also a positive response from the teacher towards learning media of Hawgent dynamic mathematics software. In further research, elementary school materials can be developed using Hawgent dynamic mathematics software or other dynamic mathematics software to increase students’ interest in learning and make students more active in teaching and learning activities.

Sensitivity analysis of household factors and energy consumption in residential houses: A multi-dimensional hybrid approach using energy monitoring and modeling

The energy forecast modeling has long been referred to as the function of estimating the energy consumption of a building and providing sustainable design options for energy-efficient policies. In addition to the existing conventional schemes for energy performance and energy simulation, there is the potential to connect steady-state energy modeling to energy monitoring data, along with household factors such as family size, housing design, and occupancy ratio to better understand hard-to-measure energy-related behaviors. This paper introduces a multi-dimensional hybrid approach that combines multiple interactions between observation-based and simulation-based data using energy modeling’s graphical interface software. Compared to the observed energy consumption, the model samples show an average Pearson coefficient of determination in the range of 72% to 76% probability of the energy model data. Accordingly, research has carried out specific air conditioning set points and schedules within each household. Finally, the variation of simulated household models illustrates the greatest effect of air conditioning setpoint on savings of 20% to 60%, compared to the baseline usage. Sensitivity analysis shows that larger household size, higher occupancy ratio, lower thermal resistance for wall insulation, and slighter airflow rate can reduce the end-use and the gross site or source energy. The study underlines the diverse interactions among household characteristics, occupant schedules, and energy monitoring data, which are prospective to stimulate the application of building energy modeling in the early design stage and the optimization of energy efficiency in the operational phases.

A framework for designing data-driven optimization systems for neural modulation

Objective. Neural modulation is a fundamental tool for understanding and treating neurological and psychiatric diseases. However, due to the high-dimensional space, subject-specific responses, and variability within each subject, it is a major challenge to select the stimulation parameters that have the desired effect. Data-driven optimization provides a range of different algorithms and tools for addressing this challenge, but each of these algorithms has specific strengths and limitations, and therefore must be carefully designed for a given neural modulation problem. Here we present a framework for designing data-driven optimization algorithms for neural modulation. Approach. We develop this framework using an optogenetic medial septum stimulation model, where the goal is to find the stimulation parameters that modulate hippocampal gamma power to a desired value. This framework proceeds in four steps: (a) collecting stimulation data, (b) creating high-throughput simulation models, (c) prototyping a range of different data-driven optimization algorithms and evaluating their performance, and (d) deploying the best performing algorithm in vivo. Main results. Following this framework, we prototype and design an algorithm specifically for finding the medial septum optogenetic stimulation parameters that maximize hippocampal gamma power. Building on this, we then change our objective function to find the stimulation parameters that modulate gamma to a specific setpoint, use the framework to understand and anticipate the results before deploying in vivo. Significance. We show that this framework can be used to design an effective optimization solution for a specific neural modulation problem, and discuss how it can potentially be applied beyond the optogenetic medial septum stimulation model.

Towards Fossil Free Cities—A Supermarket, Greenhouse & Dwelling Integrated Energy System as an Alternative to District Heating: Amsterdam Case Study

The municipality of Amsterdam has set stringent carbon emission reduction targets: 55% by 2030 and 95% by 2050 for the entire metropolitan area. One of the key strategies to achieve these goals entails a disconnection of all households from the natural gas supply by 2040 and connecting them to the existing city-wide heat grid. This paper aims to demonstrate the value of considering local energy potentials at the city block level by exploring the potential of a rooftop greenhouse solar collector as a renewable alternative to centralized district heating. An existing supermarket and an ATES component complete this local energy synergy. The thermal energy balance of the three urban functions were determined and integrated into hourly energy profiles to locate and quantify the simultaneous and mismatched discrepancies between energy excess and demand. The excess thermal energy extracted from one 850 m2 greenhouse can sustain up to 47 dwellings, provided it is kept under specific interior climate set points. Carbon accounting was applied to evaluate the system performance of the business-as-usual situation, the district heating option and the local system. The avoided emissions due to the substitution of natural gas by solar thermal energy do not outweigh the additional emissions consequential to the fossil-based electricity consumption of the greenhouse’s crop growing lights, but when the daily photoperiod is reduced from 16 h to 12 h, the system performs equally to the business-as-usual situation. Deactivating growth lighting completely does make this local energy solution carbon competitive with district heating. This study points out that rooftop greenhouses applied as solar collectors can be a suitable alternative energy solution to conventional district heating, but the absence of growing lights will lead to diminished agricultural yields.

Heterosynaptic Plasticity Determines the Set Point for Cortical Excitatory-Inhibitory Balance

Excitation in neural circuits must be carefully controlled by inhibition to regulate information processing and network excitability. During development, cortical inhibitory and excitatory inputs are initially mismatched but become co-tuned or balanced with experience. However, little is known about how excitatory-inhibitory balance is defined at most synapses or about the mechanisms for establishing or maintaining this balance at specific set points. Here we show how coordinated long-term plasticity calibrates populations of excitatory-inhibitory inputs onto mouse auditory cortical pyramidal neurons. Pairing pre- and postsynaptic activity induced plasticity at paired inputs and different forms of heterosynaptic plasticity at the strongest unpaired synapses, which required minutes of activity and dendritic Ca2+ signaling to be computed. Theoretical analyses demonstrated how the relative rate of heterosynaptic plasticity could normalize and stabilize synaptic strengths to achieve any possible excitatory-inhibitory correlation. Thus, excitatory-inhibitory balance is dynamic and cell specific, determined by distinct plasticity rules across multiple excitatory and inhibitory synapses.

Energy Flexibility Assessment of a Zone with Radiant Floor Heating System by Means of Experimental Measurements

This article investigates the potential energy flexibility of a thermal zone that contains a hydronic radiant floor heating system embedded in a concrete slab. The energy flexibility of the zone is quantified from experimental measurements for a specific zone air set point change. The experiment was carried out in an experimental perimeter zone test cell (PZTC) designed to simulate the conditions of an office space near a window which has a radiant floor heating system. The PZTC is located inside a controlled environmental chamber (EC). The EC provides the desired exterior conditions. The temperature inside the PZTC is controlled with a thermostat that adjusts the heating power delivered from the hydronic pipes to the slab. It was observed that modulating the zone air temperature setpoint results in significant changes in the heating load, and thus providing a certain amount of energy flexibility. Application of the quantified energy flexibility along with applicable strategies in response to a specific price signal profile are discussed.

Control of specific growth rate for the enhanced production of human interferon α2b in glycoengineered Pichia pastoris: process analytical technology guided approach

AbstractBACKGROUNDProcess variability in bioprocess systems involving genetically engineered strains is a common bottleneck and a real‐time insight of the on‐going process is crucial to achieve the desired product and its quality. In this study, a process analytical technology (PAT) platform was developed for the monitoring and control of specific growth rate during methanol induction phase (μmet) of glycoengineered Pichia pastoris fermentation for human interferon alpha 2b (huIFNα2b) production.RESULTSThe PAT guided approach involves real‐time monitoring of capacitance (ΔC) facilitating online estimation of specific growth rate (μest), which serves as a process input during controller application. Fed‐batch experiments using pulsed‐feeding of methanol at different dosage (20 g and 30 g) did not significantly influence μmet. Exponential methanol feeding was achieved using a modified proportional, integral and derivative (PID) controller for different predefined specific growth rate set point (μsp) values, namely 0.015, 0.03, 0.04 and 0.06 h−1. Exponential feeding strategy during the induction phase resulted in two crucial outcomes: (i) controlled methanol feeding rate (regulated by the developed PID controller) balanced the methanol consumption rate (qs, met) of the P. pastoris; (ii) significant improvement in huIFNα2b titer (1483 mg L−1) and specific productivity(>0.4 mg g−1. h) was achieved by the robust control of μmet at optimal (0.04 h−1) value. The purified huIFNα2b was found to exhibit antiproliferative effect against human breast cancer cell lines.CONCLUSIONSEfficient control of μmet at a very low narrow range was achieved with a long‐term controller stability (>10 h) and the highest titer reported to date for huIFNα2b (at optimal μmet) in the yeast expression platform. © 2019 Society of Chemical Industry

Drosophila anion exchanger 2 is required for proper ovary development and oogenesis

Understanding how cell fate decisions are regulated is a central question in stem cell biology. Recent studies have demonstrated that intracellular pH (pHi) dynamics contribute to this process. Indeed, the pHi of cells within a tissue is not simply a consequence of chemical reactions in the cytoplasm and other cellular activity, but is actively maintained at a specific setpoint in each cell type. We found previously that the pHi of cells in the follicle stem cell (FSC) lineage in the Drosophila ovary increases progressively during differentiation from an average of 6.8 in the FSCs, to 7.0 in newly produced daughter cells, to 7.3 in more differentiated cells. Two major regulators of pHi in this lineage are Drosophila sodium-proton exchanger 2 (dNhe2) and a previously uncharacterized gene, CG8177, that is homologous to mammalian anion exchanger 2 (AE2). Based on this homology, we named the gene anion exchanger 2 (ae2). Here, we generated null alleles of ae2 and found that homozygous mutant flies are viable but have severe defects in ovary development and adult oogenesis. Specifically, we find that ae2 null flies have smaller ovaries, reduced fertility, and impaired follicle formation. In addition, we find that the follicle formation defect can be suppressed by a decrease in dNhe2 copy number and enhanced by the overexpression of dNhe2, suggesting that this phenotype is due to the dysregulation of pHi. These findings support the emerging idea that pHi dynamics regulate cell fate decisions and our studies provide new genetic tools to investigate the mechanisms by which this occurs.

Evaluation of a liquid crystal based polarization modulator for a space mission thermal environment

The Multi Element Telescope for Imaging and Spectroscopy (METIS) is one of the remote sensing instruments to be onboard the future NASA/ESA Solar Orbiter mission. The science nominal mission orbit will take the spacecraft from 0.28 to 0.95 astronomical units from the Sun, setting challenging and variable thermal conditions to its payload. METIS is an inverted-occultation coronagraph that will image the solar corona in the visible and UV wavelength range. In the visible light path a Polarization Modulation Package (PMP) performs a polarimetric analysis of the incoming solar light. This PMP is based on liquid crystal variable retarders (LCVR) and works under a temporal modulation scheme. The LCVRs behavior has a dependence on temperature and, as a consequence, it is critical to guarantee the PMP performance in the mission thermal environment. Key system specifications are the optical quality and the optical retardance homogeneity. Moreover, the thermally induced elastic deformations of the mechanical mounts and the LCVRs shall not produce any performance degradation. A suitable thermal control is hence required to maintain the system within its allowed limits at any time. The PMP shall also be able to reach specific set-points with the power budget allocated. Consequently, and in order to verify the PMP thermal design, we have experimentally reproduced the expected thermal flight environment. Specifically, a thermal-vacuum cycle test campaign is run at the different mission operational conditions. The purpose is both to check the stability of the thermal conditions and to study the optical quality evolution/degradation. Within this test transmitted wavefront measurements and functional verification tests have been carried out. To do that we adapted an optical interrogation scheme, based on a phase shifting interferometric technique, that allows for inspection of the PMP optical aperture. Finally, measurements obtained at non-operational temperature conditions are also shown. These results demonstrate that the device meets the specifications required to perform its operational role in the space mission environment.

Analysis and synthesis of input strictly passive gain-scheduled controllers

Gain-scheduling within a passive systems framework is considered. A novel input strictly passive gain-scheduled controller is proposed. The scheduling signals, although bounded and square integrable on a finite time interval, are not constrained to be linear, but rather are permitted to be a nonlinear function of external parameters or time. Synthesis of the controller parameters is also considered. In particular, how to include state-feedback or observer gains individually designed about specific set points within the gain-scheduled controller is presented. The number of states associated with the controller is fixed. Adding set points within the scheduling algorithm does not increase the number of controller states numerically integrated online, reducing the computational burden associated with implementation. Although the input strictly passive gain-scheduled controller developed can be used to control any passive plant, the utility of the proposed architecture is highlighted by considering the control of flexible-link robotic manipulators. Numerical simulation results are presented, including a comparison to another passivity-based gain-scheduling algorithm.

Voltage and power control used to stabilise the distributed generation system for stand‐alone or grid‐connected operation

This study presents a control strategy for managing power delivered to, or absorbed from, the grid, independent of local load or grid characteristics. To achieve this objective, the strategy requires the use of three levels of control structures. The first is related to phase-locked loop and grid-tie algorithms, which are employed to minimise disturbances during the grid connection. The second, which produces voltages with reduced harmonics levels at the distributed generation (DG) terminals, comprises the cascade voltage and current control. The third structure is the active and reactive power control mechanisms, which uses the angle of displacement and the adjusting of the DG voltage amplitude to keep the power flow through the grid at a specific set-point, independent of local load characteristics. In addition, the power control structures have to operate in a decoupled operation mode, whereby the active power control has to be faster than the reactive power control, or vice versa. In terms of their physical structure, a passive LCL filter is used to connect the voltage source inverter to the grid. To verify the findings and observations discussed in this study, a set of simulations and experimental results are presented.