Control of systems with sector-bounded nonlinearities: robust stability and command effort minimization by disturbance rejection

The paper shows that a control strategy with disturbance rejection is able to reduce the control effort to a minimum, ensuring at the same time a desired performance level. The disturbance to be rejected is completely unknown except for a sectorial bound. The control unit is endowed with an extended state observer which includes a disturbance dynamics, whose state tracks the unknown disturbance to be rejected. In summary, the novel contributions of the paper are the following. First, we derive a robust stability condition for the proposed control scheme, holding for all the nonlinearities that are bounded by a known (or estimated) maximum slope. Second, we propose a novel approach for designing the observer and state feedback gains, which guarantee robust closed-loop stability. Third, we show that the designed control system yields, with a minimum control effort, the same control performance as a robust state feedback control, which on the contrary may require a larger command activity. Two simulated case studies are presented to show the effectiveness of the proposed approach

Productivity and quality of different tomato cultivars under intercropping system with maize and dry farming conditions in Southern Italy

This research, carried out in a typical Mediterranean environment of Southern Italy, reports some quantitative and qualitative traits of three local tomato cultivars (‘Arsicolo’, ‘Crovarese’, and ‘San Marzano’) plus a commercial one (‘Datterino’) cultivated without irrigation and intercropped with maize. For each cultivar, in addition to the determination of fruit production, tomato paste and “conserva” paste were prepared using a traditional technique of the Tanagro Valley (province of Salerno, Southern Italy). Results highlighted that ‘Arsicolo’ showed the best fruit yield (32.2 metric tons ha-1) and tomato paste production (92.9% paste return by tomato fruits weight) due to its ancient peculiar adaptability to cultivation in dry conditions, while ‘Datterino’, ‘Crovarese’, and ‘San Marzano’ had 19, 16.7, 10.5 tons ha-1 of fruit yield and 85.7, 83.9, 76.2% of tomato paste return, respectively. Conversely, for the qualitative traits, such as total solids, soluble solids, titratable acidity, and ascorbic acid, ‘Crovarese’ showed the best results (9.1%, 6.6 °Brix, 0.93%, and 39.7 mg per 100 g of fresh weight, respectively). The two components extracted by the principal components analysis (PCA) explained 84.9% of the total variance in the morphological, quantitative and qualitative traits and the dendrogram obtained by hierarchical cluster analysis allowed to divide the cultivars into three groups. Our findings highlighted that local tomato cultivars, intercropped with maize, can be cultivated adopting only few sustainable field operations and with no irrigation

Right ventricular restoration during pulmonary valve implantation in adults with congenital heart disease☆

n/

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Robust stability and control effort minimization by disturbance rejection

A goal of the paper is to proof that a control strategy with unknown disturbance rejection reduces the control effort to a minimum. A similar statement appeared in the literature, but without any formal proof. The disturbance to be rejected is completely unknown except for a sectorial bound. The control unit is endowed with a state observer which includes a disturbance dynamics whose state tracks the unknown disturbance to be rejected. Observers of this kind are commonly referred to as extended state observers. The novel contributions of the paper are the following. First, we derive a robust stability condition for the proposed control scheme, holding for all the nonlinearities that are bounded by an estimated maximum slope. Second, we compute bounds on the closed-loop bandwidth of the extended state predictor and of the state feedback. Third we propose a novel approach for designing observer and state feedback gains, which guarantee robust closed-loop stability. Fourth, we show that the designed control system yields, with a minimum control effort, the same control performance as a robust state feedback control, which on the contrary may require a larger command activity. A simulated multivariate case study is presente

Robust stability and control effort minimization by disturbance rejection

A goal of the paper is to proof that a control strategy with unknown disturbance rejection reduces the control effort to a minimum. A similar statement appeared in the literature, but without any formal proof. The disturbance to be rejected is completely unknown except for a sectorial bound. The control unit is endowed with a state observer which includes a disturbance dynamics whose state tracks the unknown disturbance to be rejected. Observers of this kind are commonly referred to as extended state observers. The novel contributions of the paper are the following. First, we derive a robust stability condition for the proposed control scheme, holding for all the nonlinearities that are bounded by an estimated maximum slope. Second, we compute bounds on the closed-loop bandwidth of the extended state predictor and of the state feedback. Third we propose a novel approach for designing observer and state feedback gains, which guarantee robust closed-loop stability. Fourth, we show that the designed control system yields, with a minimum control effort, the same control performance as a robust state feedback control, which on the contrary may require a larger command activity. A simulated multivariate case study is presented

Streptomyces albidoflavus Strain CARA17 as a Biocontrol Agent against Fungal Soil-Borne Pathogens of Fennel Plants

Fennel crop is a horticultural plant susceptible to several soil-borne fungal pathogens responsible for yield losses. The control of fungal diseases occurring on fennel crops is very difficult with conventional and/or integrated means; although several chemical fungicides are able to contain specific fungal diseases, they are not registered for fennel crops. The intensive use of some fungicides causes public concern over the environment and human health. The main aims of this study were to assess the ability of a strain of Streptomyces albidoflavus CARA17 to inhibit the growth of fungal soil-borne pathogens, and to protect fennel plants against severe fungal soil-borne pathogens such as Athelia rolfsii, Fusarium oxysporum, Plectosphaerella ramiseptata, Sclerotinia sclerotiorum and Verticillium dahliae. This study confirmed that the CARA17 strain has been able to inhibit the mycelium growth of pathogens in vitro conditions with significant inhibition degrees, where S. sclerotiorum resulted in being the most controlled. The strain CARA17 was also able to significantly protect the fennel seedlings against fungal soil-borne pathogens used in vivo conditions, where the treatment with an antagonist strain by dipping resulted in being more effective at limiting the disease severity of each fungal soil-borne pathogen. Moreover, any treatment with the CARA17 strain, carried out by dipping or after transplanting, produced benefits for the biomass of fennel seedlings, showing significant effects as a promoter of plant growth. Finally, the results obtained showed that CARA17 is a valid strain as a biocontrol agent (BCA) against relevant fungal soil-borne pathogens, although further studies are recommended to confirm these preliminary results. Finally, this study allowed for first time worldwide the association of Plectosphaerella ramiseptata with fennel plants as a severe pathogen

CAD TOOLS FOR POWER OPTIMIZATION - Advanced Clock Gating

CGCap (Clock Gating Capture), is a tool for dynamic power management that implements a solution for the automatic instantiation of clock gating circuitry in an RTL netlist. CGCap is largely based on the PowerChecker design flow. More precisely, CGCap can only be invoked once the PowerChecker database has been created on the design under consideration. As in the case of PowerChecker, CGCap also requires the possibility to interface with an RTL simulator; it can be customized to any existing simulator that supports the VCD (Value Change Dump

CAD TOOLS FOR POWER OPTIMIZATION - Advanced Clock Gating

CGCap (Clock Gating Capture), is a tool for dynamic power management that implements a solution for the automatic instantiation of clock gating circuitry in an RTL netlist. CGCap is largely based on the PowerChecker design flow. More precisely, CGCap can only be invoked once the PowerChecker database has been created on the design under consideration. As in the case of PowerChecker, CGCap also requires the possibility to interface with an RTL simulator; it can be customized to any existing simulator that supports the VCD (Value Change Dump