scholarly journals Therapeutic cell engineering: designing programmable synthetic genetic circuits in mammalian cells

2021 ◽  
Author(s):  
Maysam Mansouri ◽  
Martin Fussenegger
Keyword(s):  
Mammalian Cells ◽  
Closed Loop ◽  
Control Cell ◽  
Open Loop ◽  
Proof Of Concept ◽  
Genetic Circuits ◽  
Cell Behaviors ◽  
Digital Devices ◽  
Closed Loop Systems ◽  
Therapeutic Cell

AbstractCell therapy approaches that employ engineered mammalian cells for on-demand production of therapeutic agents in the patient’s body are moving beyond proof-of-concept in translational medicine. The therapeutic cells can be customized to sense user-defined signals, process them, and respond in a programmable and predictable way. In this paper, we introduce the available tools and strategies employed to design therapeutic cells. Then, various approaches to control cell behaviors, including open-loop and closed-loop systems, are discussed. We also highlight therapeutic applications of engineered cells for early diagnosis and treatment of various diseases in the clinic and in experimental disease models. Finally, we consider emerging technologies such as digital devices and their potential for incorporation into future cell-based therapies.

Impedance Reduction Controller Design for Mechanical Systems

2013 ◽  
Author(s):  
Hanseung Woo ◽  
Kyoungchul Kong
Keyword(s):  
Case Studies ◽  
Closed Loop ◽  
Controller Design ◽  
Mechanical Impedance ◽  
Open Loop ◽  
Mechatronic Systems ◽  
Closed Loop Systems ◽  
Guaranteed Stability ◽  
Reaction Forces ◽  
Definition Of

Safety is one of important factors in control of mechatronic systems interacting with humans. In order to evaluate the safety of such systems, mechanical impedance is often utilized as it indicates the magnitude of reaction forces when the systems are subjected to motions. Namely, the mechatronic systems should have low mechanical impedance for improved safety. In this paper, a methodology to design controllers for reduction of mechanical impedance is proposed. For the proposed controller design, the mathematical definition of the mechanical impedance for open-loop and closed-loop systems is introduced. Then the controllers are designed for stable and unstable systems such that they effectively lower the magnitude of mechanical impedance with guaranteed stability. The proposed method is verified through case studies including simulations.

scholarly journals Equivalence of Open-Loop and Closed-Loop Operation of SAW Resonators and Delay Lines

Sensors ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 185 ◽  
Author(s):  
Phillip Durdaut ◽  
Michael Höft ◽  
Jean-Michel Friedt ◽  
Enrico Rubiola
Keyword(s):  
Closed Loop ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Noise Analysis ◽  
Open Loop ◽  
Sensor System ◽  
Electronic Systems ◽  
Delay Lines ◽  
Resonant Sensors ◽  
Closed Loop Systems

Surface acoustic wave (SAW) sensors in the form of two-port resonators or delay lines are widely used in various fields of application. The readout of such sensors is achieved by electronic systems operating either in an open-loop or in a closed-loop configuration. The mode of operation of the sensor system is usually chosen based on requirements like, e.g., bandwidth, dynamic range, linearity, costs, and immunity against environmental influences. Because the limit of detection (LOD) at the output of a sensor system is often one of the most important figures of merit, both readout structures, i.e., open-loop and closed-loop systems, are analyzed in terms of the minimum achievable LOD. Based on a comprehensive phase noise analysis of these structures for both resonant sensors and delay line sensors, expressions for the various limits of detection are derived. Under generally valid conditions, the equivalence of open-loop and closed-loop operation is shown for both types of sensors. These results are not only valid for SAW devices, but are also applicable to all kinds of phase-sensitive sensors.

scholarly journals Formulation and Simulations of the Conserving Algorithm for Feedback Stabilization on Rigid Body Rotations

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Yong-Ren Pu ◽  
Thomas A. Posbergh
Keyword(s):  
Rigid Body ◽  
Closed Loop ◽  
Numerical Algorithms ◽  
Open Loop ◽  
Rigid Bodies ◽  
Feedback Stabilization ◽  
Conserved Quantities ◽  
Control Laws ◽  
Loop Control ◽  
Closed Loop Systems

The problem of stabilization of rigid bodies has received a great deal of attention for many years. People have developed a variety of feedback control laws to meet their design requirements and have formulated various but mostly open loop numerical algorithms for the dynamics of the corresponding closed loop systems. Since the conserved quantities such as energy, momentum, and symmetry play an important role in the dynamics, we investigate the conserved quantities for the closed loop control systems which formally or asymptotically stabilize rigid body rotation and modify the open loop numerical algorithms so that they preserve these important properties. Using several examples, the authors first use the open loop algorithm to simulate the tumbling rigid body actions and then use the resulting closed loop one to stabilize them.

Modeling and Simulation of Closed Loop Controlled Parallel Cascaded Buck Boost Converter Inverter Based Solar System

2015 ◽  
Vol 6 (3) ◽  
pp. 648 ◽  
Author(s):  
T. Sundar ◽  
S. Sankar
Keyword(s):  
Solar System ◽  
Modeling And Simulation ◽  
Single Phase ◽  
Closed Loop ◽  
Boost Converter ◽  
Open Loop ◽  
Boost Converters ◽  
Closed Loop Systems ◽  
Simulink Model ◽  
Simulation Results

<p>This Work deals with design, modeling and simulation of parallel cascaded buck boost converter inverter based closed loop controlled solar system. Two buck boost converters are cascaded in parallel to reduce the ripple in DC output. The DC from the solar cell is stepped up using boost converter. The output of the boost converter is converted to 50Hz AC using single phase full bridge inverter. The simulation results of open loop and closed loop systems are compared. This paper has presented a simulink model for closed loop controlled solar system.  Parallel cascaded buck boost converter is proposed for solar system.</p>

Water Hammer Pressure Transients in a Closed Loop System

Volume 3 ◽  
2004 ◽  
Author(s):  
Robert A. Leishear ◽  
Jeffrey H. Morehouse
Keyword(s):  
Method Of Characteristics ◽  
Closed Loop ◽  
Water Hammer ◽  
Open Loop ◽  
Loop System ◽  
Closed Loop System ◽  
Open Loop System ◽  
Trapped Air ◽  
Closed Loop Systems ◽  
Fluid Transients

The effects of fluid transients, or water hammer, in closed loop systems are somewhat different than those observed in open ended systems. The open loop system has received much attention in the literature, not so for the closed system. The generally accepted method of characteristics (MOC) technique was applied herein to investigate closed loop systems. The magnitudes of the pressures during fluid transients were investigated for examples of rapid valve closures, and the operations of parallel pumps. The effects of trapped air in the system were also considered for these examples. To reduce the pressures caused by the transients, the installation of slow closing valves were evaluated for different conditions.

A reliable, straightforward technique for generating Bode and Nyquist diagrams

SIMULATION ◽  
1967 ◽  
Vol 8 (5) ◽  
pp. 255-257 ◽  
Author(s):  
Willard A. Gilly
Keyword(s):  
Input Signal ◽  
Closed Loop ◽  
Analog Computer ◽  
Open Loop ◽  
Closed Loop System ◽  
Closed Loop Systems ◽  
Graphical Comparison ◽  
Analog Logic ◽  
Computer Operator ◽  
Chart Recording

Several methods have been devised for generating Bode diagrams on an analog computer. All of them, or at least all of them that we are familiar with, are either imprecise or they are excessively laborious. And the method most commonly used by analog pro grammers -graphical comparison of variables on a strip chart recording-combines both disadvantages. These can be largely avoided by a method we have found quite convenient, using analog logic and memory equipment. Our method yields phase and gain information directly and requires no manual adjustments by the computer operator other than to change the frequency of the input signal and to adjust the abscissa of the X-Y plotter. The method can be used for both open-loop and closed-loop systems and is especially useful for obtaining the open-loop response of a closed-loop system, as in figure 1. Here is how it works:

Not too Far from the Tree

2018 ◽  
Vol 140 (02) ◽  
pp. 28-33
Author(s):  
John H. Tibbets
Keyword(s):  
Artificial Intelligence ◽  
Closed Loop ◽  
Open Loop ◽  
Loop System ◽  
Strong Wind ◽  
Israel Institute ◽  
Closed Loop Systems ◽  
Institute Of Technology ◽  
Robotic Harvesting ◽  
Technion Israel Institute

This article explores the concept of robotic harvesting and use of computer, sensors, and artificial intelligence in the field of harvesting. More powerful computers, better sensors, and improved artificial intelligence promise to make machines competitive with human laborers for picking the apple harvest. Israel-based FFRobotics is one of the two companies racing to commercialize the world’s first mechanical apple picker. FFRobotics plan to test their apple-picking robot on Washington’s 2018 harvest, which runs from mid-August through mid-November. Modern orchard designs also allow engineers to build simpler apple-picking systems, according to Amir Degani, founder of the Civil, Environmental, and Agricultural Robotics Lab at Technion-Israel Institute of Technology in Haifa. Degani advised with FFRobotics on developing its robotic arm. FFRobotics is still struggling with whether to go with open- or closed-loop controller. The open-loop system recognizes a specific fruit and sends the gripper to that location. If a strong wind moves the apple left or right, the gripper does not follow. The closed-loop system tracks the movement of the fruit by distinctive points on the apple’s face as guides and adjusts the arm as it moves closer to the apple. While closed-loop systems are more effective, they are also too expensive.

scholarly journals A synthetic integral feedback controller for robust tunable regulation in bacteria

2017 ◽  
Author(s):  
Gabriele Lillacci ◽  
Stephanie Aoki ◽  
David Schweingruber ◽  
Mustafa Khammash
Keyword(s):  
Closed Loop ◽  
Protein Pair ◽  
General Purpose ◽  
Proof Of Concept ◽  
Feedback Control System ◽  
Genetic Circuits ◽  
Closed Loop System ◽  
The Face ◽  
Integral Controller ◽  
Integral Feedback

AbstractWe report on the first engineered integral feedback control system in a living cell. The controller is based on the recently published antithetic integral feedback motif [1] which has been analytically shown to have favorable regulation properties. It is implemented along with test circuitry in Escherichia coli using seven genes and three small-molecule inducers. The closed-loop system is highly tunable, allowing a regulated protein of interest to be driven to a desired level and maintained there with precision. Realized using a sigma/anti-sigma protein pair, the integral controller ensures that regulation is maintained in the face of perturbations that lead to the regulated protein’s degradation, thus serving as a proof-of-concept prototype of integral feedback implementation in living cells. When suitably optimized, this integral controller may be utilized as a general-purpose robust regulator for genetic circuits with unknown or partially-known topologies and parameters.

scholarly journals Techno-Economic Mapping for the Improvement of Shallow Geothermal Management in Southern Switzerland

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 279 ◽  
Author(s):  
Rodolfo Perego ◽  
Sebastian Pera ◽  
Antonio Galgaro
Keyword(s):  
Closed Loop ◽  
Real Data ◽  
Empirical Method ◽  
Open Loop ◽  
Economic Feasibility ◽  
Economic Potential ◽  
Geothermal Systems ◽  
Continuous Growth ◽  
Closed Loop Systems ◽  
Geothermal Potential

Cantone Ticino, a mountainous region located in the southern part of Switzerland, is greatly affected by the continuous growth of subsurface exploitation through the use of both closed-loop and open-loop geothermal systems. In this study, techno-economic maps for shallow geothermal potential of Cantone Ticino are produced, considering closed-loop systems. The work starts with the identification of the main parameters affecting the techno-economic potential such as GST and thermal conductivity. Maps for different indicators of techno-economic feasibility are created and compared against real data/measurements. An empirical method is tailored to derive a map of the techno-economic geothermal potential, expressed as meters required to provide 1 kW of installed power. The produced map shows an overall discrepancy from real installed length data of approximately ±23%. Moreover, compared with current regulation, the produced maps show an unoptimized management of the shallow geothermal resource, since high potential zones are commonly located where the installation of BHE is not permitted and often closed-loop systems are installed where the estimated potential is lower, mainly in alluvial fans. In light of these considerations, the authorization process in Cantone Ticino for BHE should be revised taking into account the real techno-economic potential.

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