Despite the remarkable theoretical accomplishments and successful applications of adaptive control, this field is not mature enough to solve challenging problems where strict performance and ...robustness guarantees are required. The needs of an approach that explicitly accounts for robust performance and stability specifications is a critical to the design of practical adaptive control systems. Towards this goal, this study extends the robust adaptive controller using multiple models, switching and tuning to multiple input multiple output and non-linear systems. The use of ‘extended superstability’, instead of superstability, allows us to establish overall performance guarantees and reduce the conservativeness of the resulting closed-loop system. The authors show that under the proposed framework, the output and states remain bounded for bounded disturbances, as a direct consequence of the passivation properties of superstability. The effectiveness of the proposed algorithm is demonstrated in numerical simulations of a non-linear continuous stirred tank reactor.
Geothermal energy is becoming more attractive nowadays. Compared with enhanced geothermal recovery method, developing geothermal energy using a closed loop heat exchanger possesses unique advantages, ...such as no fluid exchange with the geothermal reservoir. U-shaped closed loop geothermal energy development system was proposed in recent years with high energy efficiency. In this paper, we reviewed the U-shaped closed loop geothermal energy development system from literature and, then, conducted a case study based on previous models. It is found that: (a) the effective heating distance is an important parameter that can be used for economic analysis; (b) the effective heating distance grows with producer number; (c) the wellbore starting from the turning point to well-head should be insulated; (d) a higher temperature can be obtained not only from by increasing the effective heating distance, but also by decreasing mass flow rate to a reasonable level; (e) the turning point will come earlier when the mass flow rate is smaller, while it will come later when the mass flow rate is larger.
For a linear autonomous system of neutral type with commensurable delays, an algorithm is given for solving the modal controllability problem (in particular, the finite spectrum assignment problem), ...which provides a closed-loop system with a given characteristic quasipolynomial. A procedure for editing the finite part of the spectrum is proposed. A criterion for exponential stabilization of the system under study is constructively justified. When the criterion is met, the closed-loop system can be made exponentially stable according to the proposed spectral reduction algorithm. The obtained statements and spectrum assignment algorithms are illustrated with examples.
This study proposes an adaptive interval type-2 Takagi–Sugeno–Kang (IT2 TSK) fuzzy system with a supervisory mode to control and stabilise a certain class of non-linear fractional order systems. In ...this study, a fractional order adaptation law is derived which adjusts the free parameters and bounds them by utilising a projection algorithm. The global Mittag–Leffler stability of the closed-loop system is proved in the sense that all the involved signals are uniformly bounded. Moreover, if the non-linear system tends to be unstable, a supervisory controller starts cooperating with the adaptive IT2 TSK fuzzy controller to guarantee the stability of the closed-loop system. In addition, a new inference mechanism for the adaptive IT2 TSK fuzzy system is introduced for which the antecedent part is chosen as a type-2 fuzzy set and the consequent parameters are represented as interval sets. According to the practical nature of the proposed inference equation, it would be applicable in online and real-time applications. Numerical simulations show the validity and effectiveness of the introduced control strategy for stabilisation and control of a general class of non-linear fractional order systems perturbed by disturbance and uncertainty.
The MiniMed 670 G insulin pump system is the first commercially available hybrid closed-loop (HCL) insulin delivery system and clinical studies have shown that this device is associated with ...incremental benefits in glycemic control relative to continuous subcutaneous insulin infusion (CSII) with or without continuous glucose monitoring (CGM). The aim was to evaluate the long-term cost-effectiveness of the MiniMed 670 G system versus CSII alone in people with type 1 diabetes (T1D) in the UK.
Cost-effectiveness analysis was performed using the IQVIA CORE Diabetes Model. Clinical input data were sourced from a clinical trial of the MiniMed 670 G system in 124 adults and adolescents with T1D. The analysis was performed over a lifetime time horizon and both future costs and clinical outcomes were discounted at 3.5% per annum. The analysis was performed from a healthcare payer perspective.
The use of the MiniMed 670 G system led to an improvement in quality-adjusted life expectancy of 1.73 quality-adjusted life years (QALYs), relative to CSII. Total lifetime direct costs were GBP 35,425 higher with the MiniMed 670 G system than with CSII resulting in an incremental cost-effectiveness ratio (ICER) of GBP 20,421 per QALY gained. Sensitivity analyses revealed that the ICER was sensitive to assumptions around glycemic control and assumptions relating to the quality-of-life benefit associated with a reduction in fear of hypoglycemia.
Long-term projections from short-term data are inherently associated with uncertainty but represent arguably the best available evidence in lieu of long-term clinical trials.
In the UK, over patient lifetimes, the incremental clinical benefits associated with the use of MiniMed 670 G system means that it is likely to be cost-effective relative to the continued use of CSII in people with T1D, particularly for those with a fear of hypoglycemia or poor baseline glycemic control.
This study presents an attractive closed-loop system of multiphase switched-capacitor coupled-inductor (MSCCI) converter as well as its relevant analysis and design to fulfill the task of high-gain ...DC-DC conversion/regulation. The power part of MSCCI is structurally composed of a three-stage switched-capacitor (SC) booster and a turn-ratio-n coupled inductor. Under multiphase operation, the step-up gain can be uplifted into
just by using fewer circuit elements, where
is the duty cycle. When
,
, it can lift the output into 44 times voltage of supply theoretically. While raising n or
, a bigger gain will be realised but it may result in the serious volume size or magnetic bias of coupled inductor. Here, the stage number of SC booster can be extendable for an additional gain to reduce these tensions. The control part is constructed by a non-overlapping circuit, phase generator, and pulse-width-modulation (PWM) compensator, so as to execute the topological multiphase operation and also increase the output regulation/robustness. Some theoretical analysis and control design are discussed. Finally, the validity of the analysis/design is examined via simulation results, and the practicality of this proposed converter is confirmed via experiments on the prototype circuit.
Compared with single-input multiple-output (SIMO) radar, colocated multiple-input multiple-output (MIMO) radar can detect moving targets better by adopting waveform diversity. When the colocated MIMO ...radar transmits a set of orthogonal waveforms, the transmit weights are usually set equal to one, and the receive weights are adaptively adjusted to suppress clutter based on space-time adaptive processing technology. This paper proposes the joint design of space-time transmit and receive weights for colocated MIMO radar. The approach is based on the premise that all possible moving targets are detected by setting a lower threshold. In each direction where there may be moving targets, the space-time transmit and receive weights can be iteratively updated by using the proposed approach to improve the output signal-to-interference-plus-noise ratio (SINR), which is helpful to improve the precision of target detection. Simulation results demonstrate that the proposed method improves the output SINR by greater than 13 dB.
Parameter convergence is desirable in adaptive control as it brings several attractive features, including accurate online modelling, exponential tracking, and robust adaptation without parameter ...drift. However, a strong persistent-excitation (PE) condition must be satisfied to guarantee parameter convergence in the conventional adaptive control. This study proposes a model reference composite learning control strategy to guarantee parameter convergence without the PE condition. In the composite learning, an integral at a moving-time window is applied to construct a prediction error, an integral transformation is derived for avoiding the time derivation of plant states in the calculation of the prediction error, and both the tracking error and the prediction error are applied to update parametric estimates. Global exponential stability of the closed-loop system is established under an interval-excitation condition which is much weaker than the PE condition. Compared with a concurrent learning technique that has the same aim as this study, the proposed composite learning technique avoids the usage of singular value maximisation and fixed-point smoothing resulting in a considerable reduction of computational cost. Numerical results have verified effectiveness and superiority of the proposed control strategy.
Recent advances in biosensor design and sensing efficacy need to be amalgamated with research in responsive drug delivery systems for building superior health or illness regimes and ensuring good ...patient compliance. A variety of illnesses require continuous monitoring in order to have efficient illness intervention. Physicochemical changes in the body can signify the occurrence of an illness before it manifests. Even with the usage of sensors that allow diagnosis and prognosis of the illness, medical intervention still has its downfalls. Late detection of illness can reduce the efficacy of therapeutics. Furthermore, the conventional modes of treatment can cause side-effects such as tissue damage (chemotherapy and rhabdomyolysis) and induce other forms of illness (hepatotoxicity). The use of drug delivery systems enables the lowering of side-effects with subsequent improvement in patient compliance. Chronic illnesses require continuous monitoring and medical intervention for efficient treatment to be achieved. Therefore, designing a responsive system that will reciprocate to the physicochemical changes may offer superior therapeutic activity. In this respect, integration of biosensors and drug delivery is a proficient approach and requires designing an implantable system that has a closed loop system. This offers regulation of the changes by means of releasing a therapeutic agent whenever illness biomarkers prevail. Proper selection of biomarkers is vital as this is key for diagnosis and a stimulation factor for responsive drug delivery. By detecting an illness before it manifests by means of biomarkers levels, therapeutic dosing would relate to the severity of such changes. In this review various biosensors and drug delivery systems are discussed in order to assess the challenges and future perspectives of integrating biosensors and drug delivery systems for detection and management of chronic illness.
Thermoacoustic instabilities present in the combustor of power producing devices are having adverse effects on the performance. To avoid thermoacoustic instabilities, design of control method is very ...much essential. Design and development of a closed loop control method is a real challenge for combustor. Active control methods are advantageous than passive methods. The characterization of thermoacoustic instability is essential for effective design of control method. The selection of appropriate controller and it's design depends on characterization of thermoacoustic instabilities. In this method the feedback signal acquired from microphone is used to control the flow rate of radial micro-jets. The developed method is implemented effectively to suppress thermoacoustic instabilities in a one dimensional combustor (Rijke tube). The airflow to the radial micro-jets injector was controlled using a control unit which consist of a stepper motor coupled with a needle valve, and an airflow sensor. Radial micro-jets are used to break a coupling and act as an active closed-loop method. The control method used radial jets effectively to control the thermoacoustic instability and reduces sound pressure level to background level (100 dB to 44 dB) in short span of time (10 Second).•LabVIEW Interface for Arduino (LIFA), LabVIEW, and DAQ are very useful in developed closedloop active control method.•Developed closed loop active control method is very effective for suppression of thermoacoustic instability.•Developed closed loop active control method used air in the form micro jets to control thermoacoustic instabilities.
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