In this paper we present the application of an input-output inversion technique for the open-loop control of an overhead crane modelled as a double pendulum. The method is mathematically derived, ...obtaining a parametric trajectory that ensures reduced residual oscillations. Then, it is shown that the postactuation can be neglected so that the method can be implemented with standard industrial drives. The robustness of the method is evaluated by means of simulations, and the performance of the method is experimentally compared with the well-known input shaping technique. The advantages of using a double pendulum model instead of a simple pendulum one are also shown.
In this paper we propose a design methodology for a cascade control system where the two controllers are of fractional-order-proportional-integral-derivative type. The tuning of the inner (secondary) ...controller aims to achieve a high performance (in terms of the integrated absolute error) in the load disturbance rejection task by exploiting the fractional-order derivative action. Then, a fractional-first-order-plus-dead-time transfer function of the inner feedback system in series with the primary process is estimated and the outer (primary) controller is tuned to maintain performance in rejecting load disturbances while achieving a satisfactory set-point response. Simulation results show the effectiveness of the methodology and the key role played by the additional flexibility in the design introduced by the fractional-order controllers.
Poor prognosis in lung cancer has been attributed to the presence of lung cancer stem cells (CSCs) which resist chemotherapy and cause disease recurrence. Hence, the strong need to identify ...mechanisms of chemoresistance and to develop new combination therapies. We have previously shown that Stearoyl-CoA-desaturase 1 (SCD1), the enzyme responsible for the conversion of saturated to monounsaturated fatty acids is upregulated in 3D lung cancer spheroids and is an upstream activator of key proliferation pathways β-catenin and YAP/TAZ. Here we first show that SCD1 expression, either alone or in combination with a variety of CSCs markers, correlates with poor prognosis in adenocarcinoma (ADC) of the lung. Treatment of lung ADC cell cultures with cisplatin enhances the formation of larger 3D tumor spheroids and upregulates CSCs markers. In contrast, co-treatment with cisplatin and the SCD1 inhibitor MF-438 reverts upregulation of CSCs markers, strongly synergizes in the inhibition of 3D spheroids formation and induces CSCs apoptosis. Mechanistically, SCD1 inhibition activates endoplasmic reticulum stress response and enhances autophagy. These data all together support the use of combination therapy with SCD1 inhibitors to achieve better control of lung cancer.
•SCD1 upregulation combined with CSC markers predicts outcome in lung ADC at early stage.•Resistance to CDDP is reverted by SCD1 inhibition in lung CSC.•MF-438 combined with chemotherapy results in activation of UPR response and cell and apoptosis.
This paper presents a new direct digital design method for discrete proportional integral derivative PID + filter (PIDF) controllers employed in DC-DC buck converters. The considered controller ...structure results in a proper transfer function which has the advantage of being directly implementable by a microcontroller algorithm. Secondly, it can be written as an Infinite Impulse Response (IIR) digital filter. Thirdly, the further degree of freedom introduced by the low pass filter of the transfer function can be used to satisfy additional specifications. A new design procedure is proposed, which consists of the conjunction of the pole-zero cancellation method with an analytical design control methodology based on inversion formulae. These two methods are employed to reduce the negative effects introduced by the complex poles in the transfer function of the buck converter while exactly satisfying steady-state specifications on the tracking error and frequency domain requirements on the phase margin and on the gain crossover frequency. The proposed approach allows the designer to assign a closed-loop bandwidth without constraints imposed by the resonance frequency of the buck converter. The response under step variation of the reference value, and the disturbance rejection capability of the proposed control technique under load variations are also evaluated in real-time implementation by using the Arduino DUE board, and compared with other methods.
The majority of cancer patients experience dramatic weight loss, due to cachexia and consisting of skeletal muscle and fat tissue wasting. Cachexia is a negative prognostic factor, interferes with ...therapy and worsens the patients' quality of life by affecting muscle function. Mice bearing ectopically-implanted C26 colon carcinoma are widely used as an experimental model of cancer cachexia. As part of the search for novel clinical and basic research applications for this experimental model, we characterized novel cellular and molecular features of C26-bearing mice.
A fragment of C26 tumor was subcutaneously grafted in isogenic BALB/c mice. The mass growth and proliferation rate of the tumor were analyzed. Histological and cytofluorometric analyses were used to assess cell death, ploidy and differentiation of the tumor cells. The main features of skeletal muscle atrophy, which were highlighted by immunohistochemical and electron microscopy analyses, correlated with biochemical alterations. Muscle force and resistance to fatigue were measured and analyzed as major functional deficits of the cachectic musculature.
We found that the C26 tumor, ectopically implanted in mice, is an undifferentiated carcinoma, which should be referred to as such and not as adenocarcinoma, a common misconception. The C26 tumor displays aneuploidy and histological features typical of transformed cells, incorporates BrdU and induces severe weight loss in the host, which is largely caused by muscle wasting. The latter appears to be due to proteasome-mediated protein degradation, which disrupts the sarcomeric structure and muscle fiber-extracellular matrix interactions. A pivotal functional deficit of cachectic muscle consists in increased fatigability, while the reported loss of tetanic force is not statistically significant following normalization for decreased muscle fiber size.
We conclude, on the basis of the definition of cachexia, that ectopically-implanted C26 carcinoma represents a well standardized experimental model for research on cancer cachexia. We wish to point out that scientists using the C26 model to study cancer and those using the same model to study cachexia may be unaware of each other's works because they use different keywords; we present strategies to eliminate this gap and discuss the benefits of such an exchange of knowledge.
In this paper we present a set of tuning rules for standard (integer-order) PID and fractional-order PID controllers. Based on a first-order-plus-dead-time model of the process, the tuning rules have ...been devised in order to minimise the integrated absolute error with a constraint on the maximum sensitivity. The achieved performance indexes can also be used for the assessment of the controller performance. Both set-point following and load disturbance rejection tasks are considered. By comparing the results obtained for the two kinds of controllers, it is shown that the use of fractional-order integral action is not advantageous, while the use of a fractional-order derivative action provides a performance improvement.
This paper introduces an electrical drives control architecture combining a fractional-order controller and a setpoint pre-filter. The former is based on a fractional-order proportional-integral(PI) ...unit, with a non-integer order integral action, while the latter can be of integer or non-integer type. To satisfy robustness and dynamic performance specifications, the feedback controller is designed by a loop-shaping technique in the frequency domain. In particular, optimality of the feedback system is pursued to achieve input-output tracking. The setpoint pre-filter is designed by a dynamic inversion technique minimizing the difference between the ideal synthesized command signal(i.e., a smooth monotonic response) and the prefilter step response. Experimental tests validate the methodology and compare the performance of the proposed architecture with well-established control schemes that employ the classical PIbased symmetrical optimum method with a smoothing pre-filter.
This paper deals with the design of a control system based on fractional order models and fractional order proportional-integral-derivative (FOPID) controllers and fractional-order ...proportional-integral (FOPI) controllers. The controller design takes into account the trade-off between robustness and performance as well as the trade-off between the load disturbance rejection and set-point tracking tasks. The fractional order process model is able to represent an extensive range of dynamics, including over-damped and oscillatory behaviors and this simplifies the process modelling. The tuning of the FOPID and FOPI controllers is achieved by using an optimization, as a first step, and in a second step, several fitting functions were used to capture the behavior of the optimal parameters of the controllers. In this way, a new set of tuning rules called FOMCoRoT (Fractional Order Model and Controllers Robust Tuning) is obtained for both FOPID and FOPI controllers. Simulation examples show the effectiveness of the proposed control strategy based on fractional calculus.
This paper investigates the performance achievable with a fractional-order PID regulator controlling the Depth of Hypnosis (measured via the Bispectral Index Scale) through the administration of ...propofol during the maintenance phase of total intravenous anesthesia. In particular, two different methodologies were applied to tune the controller: in the first case, genetic algorithms (GAs) were used to minimize the integrated absolute error, while in the second case, the isodamping approach—a method that targets phase margin invariance with respect to the process dc gain—was employed. In both cases, the performance was extensively analyzed and compared with that of a standard PID controller by simulating multiple patients through a Monte Carlo method. The results demonstrate that a fractional-order PID controller can be effectively used to control the Depth of Hypnosis, but the improvement with respect to a standard PID controller is marginal.
Abstract
A novel transduction pathway for the powerful angiogenic factor VEGF has been recently shown in endothelial cells to operate through NAADP-controlled intracellular release of Ca
2+
. In the ...present report the possible involvement of NAADP-controlled Ca
2+
signaling in tumor vascularization, growth and metastatic dissemination was investigated in a murine model of VEGF-secreting melanoma. Mice implanted with B16 melanoma cells were treated with NAADP inhibitor Ned-19 every second day for 4 weeks and tumor growth, vascularization and metastatization were evaluated. Control specimens developed well vascularized tumors and lung metastases, whereas in Ned-19-treated mice tumor growth and vascularization as well as lung metastases were strongly inhibited.
In vitro
experiments showed that Ned-19 treatment controls the growth of B16 cells
in vitro
, their migratory ability, adhesive properties and VEGFR2 expression, indicating NAADP involvement in intercellular autocrine signaling. To this regard, Ca
2+
imaging experiments showed that the response of B16 cells to VEGF stimulation is NAADP-dependent. The whole of these observations indicate that NAADP-controlled Ca
2+
signaling can be relevant not only for neoangiogenesis but also for direct control of tumor cells.
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