Search

Top-down approaches often fail to involve, collaborate with, and consider social actors in the process of planning, design, and maintenance of public spaces (PDMPS). This research addresses how social participation is included in PDMPS in the Mexican case, by identifying the actors, the level of communication achieved, and their authority and power in the PDMPS process. The paper employs a case study approach, informed by semi-structured interviews. We use a democracy diagram to uncover the diversity of involved actors and how they are involved in the process. We show how government could provide support for social participation to implement participatory processes in PDMPS. [ABSTRACT FROM AUTHOR]

Rationale: Pregnant women are especially vulnerable to mental health problems, including stress, anxiety, and depression. This risk has been increased during the COVID-19 pandemic and differences in psychological symptoms in pregnancy and postpartum before and during COVID-19 exists. Mental health problems can have adverse effects on both the woman, and the neonate, including miscarriages, premature births, low birth weight, and higher rates of cesarean sections and instrument-assisted deliveries. Aim: To evaluate the prevalence of psychological symptoms of pregnant women before and during the COVID-19 pandemic. Method: A cross-sectional study was carried out to assess the psychological profile in a sample of pregnant women selected before the pandemic and a sample of women studied during the first wave of the pandemic. A total of 122 women were selected prior to the pandemic and 181 women during the COVID-19 outbreak. The Symptom Checklist-90 Revised (SCL-90-R) was used to assess depression and anxiety during pregnancy and in the postpartum period. Results: The prevalence of symptoms of depression and anxiety during pregnancy were higher in the sample of women studied during the pandemic (SCL-90-R: M = 54.6 vs. 42.6 and M = 62.6 vs. 51.7 respectively). In the postpartum the difference between both samples of women was even higher for depression and anxiety (SCL-90-R: M = 50.4 vs. 35.0 and M = 51.3 vs. 36.0 respectively). Being a pregnant woman at the COVID-19 outbreak was directly associated with a higher score of depression symptoms (aOR = 8.67, 95% CI [3.26, 23.02], p <.001). Anxiety during childbirth was more frequently reported by women before the pandemic (aOR = 5.13, 95% CI [2.53, 10.44], p <.001). The variable stage (before /during pandemic) was also associated with having a clinical SCL-90-R score above 70 (aOR = 7.61, 95% CI [2.7, 21.47], p <.001). Conclusion: During the pandemic, pregnancy and postpartum were associated with the presence of anxiety and depression. The main factor associated with postpartum depression was maternal age. These finding highlights the vulnerability of pregnant in front of the pandemic, in which psychological health and mental well-being are affected, not only during pregnancy, but also in the postpartum. [ABSTRACT FROM AUTHOR]

Recent research indicates that information and communication technologies (ICTs) can support social participation in the planning, design and maintenance of public spaces (PDMPS), specifically to create comprehensive knowledge among different stakeholders. However, critics point out that the use of ICTs by planners and decision-makers often ignores the needs of local residents. For this research, we inquired how ICTs can support social participation in PDMPS. Our case study combines a literature review and 21 semi-structured interviews with government officials, non-governmental organisations, academics and architecture/urban planning consultancy companies in Mexico to understand how different stakeholders use ICTs to improve the quality of public spaces. We developed an approach that facilitates the analysis of ICT aspects related to hardware and software supporting social participation in PDMPS. The findings show that Mexico has a base of digital tools requiring technical capacities and spatial literacy at various stages of PDMPS, and ICTs are seen as an opportunity to engage with residents. However, in practice, our interviewees mentioned that ICTs are rarely implemented to support participatory processes due to high costs, a lack of political support and the insufficient technical expertise of technical staff to engage with residents using ICTs. The paper closes with recommendations and suggestions for future research on how ICTs can better support participatory processes in PDMPS. [ABSTRACT FROM AUTHOR]

The coronavirus SARS-CoV-2 generated an alert that became a state of emergency in health issues worldwide, a situation that affected the entire population, including pregnant women. The present study aims to understand the effect of the psychopathological profile of a sample of pregnant women at the time of the COVID-19 pandemic on themselves during childbirth (Phase 1) and after childbirth and the anthropometric measures of the neonate at birth (Phase 2). The total sample comprises 81 pregnant women aged 32.07 years (SD = 5.45) and their neonates. Sociodemographic and obstetric data of the sample were collected. During pregnancy, psychopathology was measured by means of the SCL-90, as well as other psychological measures on stress and social support. Cluster k-means techniques were used to uncover the heterogeneous profiles of psychopathology in Phase 1. Two main psychopathological profiles were found (Cluster 1: High psychopathological symptoms; Cluster 2: Low psychopathological symptoms). The clusters generated show significant differences in all the SCL-90-R subscales used and in the general index at Phase 1. After childbirth, high psychopathology profile membership was associated with a greater probability of having a non-eutocic delivery. On the other hand, the low psychopathological symptoms cluster shows higher levels of depressive symptoms, hostility, paranoid ideation, and psychotic symptoms in Phase 2. In conclusion, there seemed to exist two heterogeneous profiles of psychopathology in pregnant women during the pandemic; the stress related to the pandemic seemed uninfluential on the development of a profile of high psychopathological symptoms and the psychopathology profile may influence delivery and postpartum outcomes. [ABSTRACT FROM AUTHOR]

In this article a finite control set model predictive control, is used to track a current reference in a power converter connected to an $RL$ load. An artificial intelligence approach is presented for real-time determination of the weighting factor that regulates the average switching frequency, independently of the operating point. The article focuses on the design, training, and digital implementation of an artificial neural network (ANN) that can be developed in a low-cost control platform. It is presented a sampling and offline ANN training procedure, together with a low-cost hardware implementation based on integer quantization of the ANN. The abovementioned approach provides a standalone application, serving as a framework for the development of ANN applications for power-converters. The main advantage of the presented approach is that the ANN inference is executed in real time. In this way, the weighting factor is automatically updated in real-time, allowing the system to quickly adapt to any reference step changes, and consequently provide the desired behavior. Executing the setup in laboratory prototype confirmed the theoretical analysis and successful tracking of the reference frequency. [ABSTRACT FROM AUTHOR]

Finite control set model predictive control (FCS-MPC) strategies for power conversion devices benefit from extending the prediction horizon length. Solving this problem relies on the definition of the underlying integer least-squares problem. Sphere decoding algorithm (SDA) has been extensively used in previous works as an approach to solve this problem. In this article, a parallel and fully scalable K-best SDA hardware design is proposed as an alternative. The K-best SDA establishes a different breadth-first search strategy, which addresses some of the main drawbacks of the SDA. Through experimental tests based on an uninterruptible power supply, the K-best SDA performance for long prediction horizon FCS-MPC is assessed and verified. Results demonstrate key beneficial aspects through which the K-best SDA is capable of rendering an improved control performance when compared to the conventional SDA. [ABSTRACT FROM AUTHOR]

This article proposes a sliding-mode-observer (SMO)-based control strategy to regulate the dc-link voltage for a three-phase two-level active front end (AFE). The SMO is designed for the voltage control loop to estimate the external load which is abruptly connected to the AFE dc-link and consequently causes the dc-link voltage fluctuation. The estimated load value is used to compensate the voltage loop controller, therefore, the voltage loop gains more robustness against the load perturbation and its disturbing effect is greatly reduced. The effectiveness and advantage of the proposed control strategy has been verified through theoretical analysis, simulations, and the real-application experiments conducted on a 5 KVA laboratory AFE. The results show that the proposed control strategy provides obvious improvement of the dc-link voltage control performance comparing with the conventional PI controller and demonstrates stronger robustness against the operating point variations caused by the changes in external load and dc-link capacitance. [ABSTRACT FROM AUTHOR]

This paper discusses the opportunities and challenges of public space management (PSM) in the Mexican context by analysing the perspectives of different governance actors. Issues in the PSM literature include ineffective political decisions, prevalence of the private sector, lack of coordination between government institutions, and a need for more effective social participation. While most PSM studies focus on European cities, empirical PSM knowledge in the Latin American context is scarce. To address this gap, this research elucidates the Mexican context by investigating and adapting a PSM framework in Mexico City and Puebla. The case study research is based on qualitative document research and interview analysis from four groups of governance actors: government officials, academics, NGOs, and architecture/urban planning firms. We found multiple PSM challenges: uncoordinated efforts in the maintenance of public space, lack of and polarisation of investment, and privatisation of public space. At the intra-governmental level, the research identified a lack of coordination between government institutions, increasing reliance on the private sector, and limited opportunities for residents to participate in PSM processes. The paper highlights missing links between existing governance actors involved in PSM and wider residents, in the pursuit of the ambitious role of achieving public space quality. • Public Space Management theory contrasts with the reality in the Mexican context. • Governments rely on the private sector for the development of public spaces. • Limited opportunities for local residents to participate in Public Space Management processes • Awareness is needed among governance actors on the management of public spaces. • Lack of transparency in publicly available data affects how public spaces are managed. [ABSTRACT FROM AUTHOR]

This article proposes a novel robust control strategy for three-phase power converters operated under unbalanced grid conditions. A consolidated control objective is obtained in the stationary $\alpha \beta$ frame, which can be flexibly adjusted according to the degree of oscillation in the active and reactive powers and the balance of the three-phase current. Based on the dynamics of the converter and control objective, a control scheme in a cascaded framework is presented, in which an adaptive observer is applied to estimate the positive and negative sequences of the grid voltage. In the current tracking loop, a super-twisting algorithm current controller coupled with a super-twisting differentiator is implemented to track the current references, featuring rapid dynamics, and improved robustness. Additionally, in the voltage regulation loop, an effective composite controller is developed to regulate the dc-link voltage, where a super-twisting observer is used to estimate the load disturbance, thereby improving the performance of the converter. The experimental results are provided to confirm the effectiveness and superiority of the proposed control strategy. [ABSTRACT FROM AUTHOR]

A finite control set model predictive control (FCS-MPC) strategy consists of a prediction model, a cost function and an optimization algorithm. Consequently, the performance of the FCS-MPC depends on the proper design of these three elements. This article assesses the influence of the prediction model of an uninterruptible power supply (UPS). Since the load connected to the voltage source inverter (VSI) affects the dynamic of the system state variables, the load dynamic should be included in the system model. This makes the design of the prediction model a challenge because the load connected to the VSI is generally unknown. To deal with this uncertainty, this work proposes an augmented prediction model based on a state observer that includes as many harmonic components as necessary to accurately represent the output current. The performance of the FCS-MPC for a UPS is evaluated in a laboratory prototype using the proposed and the conventional prediction models. Experimental results show that the proposed solution provides a more accurate representation of the output current, improving the system performance. [ABSTRACT FROM AUTHOR]

Grid-connected photovoltaic (PV) systems can provide grid support features by implementing flexible power point tracking (FPPT) strategies. Conventionally, the FPPT algorithms are based on linear search algorithms, such as perturb and observe. These solutions offer good practical results but usually lead to oscillations around the steady-state operating point. The main contribution of this article is to propose a binary search based FPPT (BNS-FPPT) algorithm. BNS is a computer-science-based searching algorithm that performs a logarithmic search within a sorted data array until the target voltage value is found. Compared to sequential searching algorithms, the proposed BNS-FPPT algorithm conducts a nonlinear search and avoids waving around the final value, reducing the steady-state error. In this article, the basics of the BNS-FPPT are described in detail. In addition, experimental results are conducted on a laboratory setup to compare the BNS-FPPT performance against a state-of-the-art solution. The results show that compared to linear search-based FPPT algorithms, the proposed BNS-FPPT is able to provide the required grid support functionalities, and avoid waving around the final operation point. [ABSTRACT FROM AUTHOR]

In recent years, different advanced control methods have been successfully proposed as alternatives to conventional cascaded linear controllers for power converters in distributed generation systems and microgrids. The prime movers of this research are strong capabilities of advanced controllers to improve the dynamic performance and robustness of power electronic converters in these applications. This article first introduces the key roles and functionalities of voltage source converters in distributed generation systems and microgrids. Then, it describes how these functionalities are traditionally achieved by using linear controllers, and addresses their fundamental dynamic performance limitations. Afterward, the most prominent advanced control methods are overviewed. In this context, the implementation principles, advantages, and disadvantages of prominent model- and data-based advanced control methods are critically discussed and experimentally compared. This article ends with a discussion about promising research directions in the area of advanced control for power electronic converters. [ABSTRACT FROM AUTHOR]

Glucocorticoids are steroid hormones that have systemic effects that are mediated by the glucocorticoid receptor. Environmental chemicals that disrupt glucocorticoid receptor signaling and/or glucocorticoid homeostasis could adversely affect the health of human and nonhuman vertebrates. A major challenge in identifying environmental chemicals that alter glucocorticoid receptor signaling and/or glucocorticoid homeostasis is a lack of adequate screening methods. We developed a cell‐based bioassay to measure total glucocorticogenic activity (TGA) of environmental chemicals and human serum. Human MDA‐MB‐231 breast cancer cells were stably transfected with a luciferase reporter gene driven by 3 tandem glucocorticoid‐response elements. Dose–response curves for 6 glucocorticoids and 4 non‐glucocorticoid steroid hormones were generated to evaluate the specificity of the bioassay. Cells were also optimized to measure TGA of 176 structurally diverse environmental chemicals and human serum samples in a high‐throughput format. Reporter activity was glucocorticoid‐specific and induced 400‐fold by 1 μM dexamethasone. Furthermore, 3 of the screened chemicals (3,4,4′‐trichlorocarbanilide, isopropyl‐N‐phenylcarbamate, and benzothiazole derivative 2‐[4‐chlorophenyl]‐benzothiazole) potentiated cortisol‐induced glucocorticoid receptor activity. Serum TGA estimates from the bioassay were highly correlated with a cortisol enzyme‐linked immunosorbent assay. The present study establishes an in vitro method to rapidly screen environmental chemicals and human serum for altered glucocorticogenic activity. Future studies can utilize this tool to quantify the joint effect of endogenous glucocorticoids and environmental chemicals. Environ Toxicol Chem 2021;40:177–186. © 2020 SETAC [ABSTRACT FROM AUTHOR]

In this article, a model predictive control (MPC) strategy based on the optimal switching sequence (OSS) concept for a single-phase grid-connected H-bridge neutral-point-clamped (H-NPC) power converter is presented. The proposed OSS-MPC algorithm considers both the grid current tracking error and the dc-link capacitor voltage balance. Special emphasis is placed on the power converter control region in order to design suitable switching sequence candidates for this multiobjective control problem. Additionally, based on an analysis of the weighting factor effect over closed-loop performance, it is possible to demonstrate that this controller parameter is relatively easy to adjust. In fact, the weighting factor only affects the peak current during transients, with no effect over the steady-state performance. As a result, the proposed OSS-MPC provides a fast closed-loop dynamic to the H-NPC converter, which operates with a fixed switching frequency at all times. This predictive control strategy is experimentally validated in a 3.5-kVA laboratory setup. [ABSTRACT FROM AUTHOR]

Background: Rheumatoid arthritis (RA) in elderly population represents a challenge for physicians in terms of therapeutic management. Methotrexate (MTX) is the first-line treatment among conventional synthetic-disease-modifying anti-rheumatic drugs (cs-DMARDs); however, it is often associated with adverse events (AEs). Therefore, the objective of this study was to identify the incidence and risk factors of MTX discontinuation due to AEs in elderly patients with RA in a long-term retrospective cohort study. Methods: Clinical sheets from elderly RA patients taking MTX from an outpatient rheumatology consult in a university centre were reviewed. To assess MTX persistence, we used Kaplan–Meir curves and Cox regression models to identify the risk of withdrawing MTX due to adverse events. Results: In total, 198 elderly RA patients who reported using MTX were included. Of them, the rates of definitive suspension of MTX due to AEs were 23.0% at 5 years, 35.6% at 10 years and 51.7% at 15 years. The main organs and system involved were gastrointestinal (15.7%) and mucocutaneous (3.0%). Factors associated with withdrawing MTX due to AEs were MTX dose ≥ 15 mg/wk (adjusted HR: 2.46, 95% CI: 1.22–4.96, p = 0.012); instead, the folic acid supplementation was protective for withdrawal (adjusted HR: 0.28, 95% CI: 0.16–0.49, p < 0.001). Conclusions: Higher doses of MTX increase the risk of withdrawals in elderly RA, while folic acid supplementation reduces the risk. Therefore, physicians working in therapeutic management for elderly patients using MTX must focus on using lower MTX doses together with the concomitant prescription of folic acid. [ABSTRACT FROM AUTHOR]

Objective: To determine the association between different pelvic floor disorders and the presence of sexual dysfunction in women. Method: An observational study of non‐pregnant women was carried out in Spain in 2021 and 2022. To assess the presence of pelvic floor problems, the Pelvic Floor Distress Inventory (PFDI‐20) was used, consisting of the subscales Pelvic Organ Prolapse Distress Inventory‐6 (POPDI‐6; prolapse symptoms), Colorectal‐Anal Distress Inventory (CRADI‐8; colorectal symptoms), and Urinary Distress Inventory‐6 (UDI‐6; urinary symptoms). The validated tool, Female Sexual Function (FSF), was used to evaluate female sexual function. Results: In total, 1008 women participated. Of these, 288 (28.6%) had some type of sexual dysfunction. Regarding symptoms, 52 (5.2%) stated that they do not reach orgasm and 172 (17.1%) said they had never or occasionally felt sexual desire in the last month. Women with sexual dysfunctions had higher mean scores on the POPDI‐6, CRADI‐8, and UDI‐6 subscales than those who did not have sexual dysfunction (P ≤ 0.005). Risk factors identified included being postmenopausal, with an adjusted odds ratio (aOR) of 2.98 (95% confidence interval [CI] 2.12–4.18), and a greater impact of the symptoms of pelvic floor problems as assessed by the PFDI‐20 scale, in such a way that for each point increase the probability of sexual dysfunction increases with an aOR of 1.008 (95% CI 1.005–1.011). Conclusion: Women with pelvic floor disorders and postmenopausal women present sexual dysfunction more frequently. Synopsis: The high prevalence of sexual dysfunction in women associated with pelvic floor disorders is an important public health problem. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including smart grids, equalization of a high-voltage battery, and management of lithium ion batteries.

Model predictive control (MPC) is a very attractive solution for controlling power electronic converters. The aim of this paper is to present and discuss the latest developments in MPC for power converters and drives, describing the current state of this control strategy and analyzing the new trends and challenges it presents when applied to power electronic systems. The paper revisits the operating principle of MPC and identifies three key elements in the MPC strategies, namely the prediction model, the cost function, and the optimization algorithm. This paper summarizes the most recent research concerning these elements, providing details about the different solutions proposed by the academic and industrial communities. [ABSTRACT FROM AUTHOR]

This paper proposes an extended state observer (ESO) based second-order sliding-mode (SOSM) control for three-phase two-level grid-connected power converters. The proposed control technique forces the input currents to track the desired values, which can indirectly regulate the output voltage while achieving a user-defined power factor. The presented approach has two control loops. A current control loop based on an SOSM and a dc-link voltage regulation loop which consists of an ESO plus SOSM. In this work, the load connected to the dc-link capacitor is considered as an external disturbance. An ESO is used to asymptotically reject this external disturbance. Therefore, its design is considered in the control law derivation to achieve a high performance. Theoretical analysis is given to show the closed-loop behavior of the proposed controller and experimental results are presented to validate the control algorithm under a real power converter prototype. [ABSTRACT FROM PUBLISHER]

In this paper, a model predictive control (MPC) based on optimal switching sequences (OSSs) for a single-phase grid-connected full-bridge neutral-point-clampled (NPC) power converter is presented. The predictive control algorithm is formulated in terms of OSSs, which was originally proposed to govern three-phase power converters. In this paper, the OSS concept is extended to control single-phase power converters. The proposed MPC algorithm belongs to the continuous control set MPC and is able to provide fixed switching frequency while handling system constraints. The proposed algorithm has been experimentally tested in an NPC power converter prototype. Experimental results show the desired fixed switching behavior in the steady-state condition and the intrinsic fast dynamic provided by MPC during transients. Furthermore, the test outcomes demonstrate the robustness of the proposed controller under large system parameter deviations. [ABSTRACT FROM AUTHOR]

Grid-connected power converters play a key role in several applications such as the integration of renewable energy sources and motor drives. For this reason, the development of high performance control strategies for this particular class of power converters has increasingly attracted the interest of both academic and industry researchers. This paper presents the predictive optimal switching sequence (OSS) direct power control (DPC) (OSS-DPC) algorithm for grid-connected converters. The OSS-DPC method belongs to the predictive-DPC family and provides the desired power references by calculating globally OSSs. To address computational and implementation issues, an efficient control algorithm, named reduced OSS-DPC, is introduced. The implementation of the proposed control strategy in a standard DSP is evaluated on a two-level power converter prototype working as a STATCOM. Experimental results show the algorithm's potential to provide high performance during both transient and steady states. [ABSTRACT FROM PUBLISHER]

This paper presents a new synchronization scheme for detecting multiple positive-/negative-sequence frequency harmonics in three-phase systems for grid-connected power converters. The proposed technique is called MAVF-FLL because it is based on the use of multiple adaptive vectorial filters (AVFs) working together inside a harmonic decoupling network, resting on a frequency-locked loop (FLL) which makes the system frequency adaptive. The method uses the vectorial properties of the three-phase input signal in the \alpha \beta reference frame in order to obtain the different harmonic components. The MAVF-FLL is fully designed and analyzed, addressing the tuning procedure in order to obtain the desired and predefined performance. The proposed algorithm is evaluated by both simulation and experimental results, demonstrating its ability to perform as required for detecting different harmonic components under a highly unbalanced and distorted input grid voltage. [ABSTRACT FROM PUBLISHER]

Energy storage systems (ESSs) are enabling technologies for well-established and new applications such as power peak shaving, electric vehicles, integration of renewable energies, etc. This paper presents a review of ESSs for transport and grid applications, covering several aspects as the storage technology, the main applications, and the power converters used to operate some of the energy storage technologies. Special attention is given to the different applications, providing a deep description of the system and addressing the most suitable storage technology. The main objective of this paper is to introduce the subject and to give an updated reference to nonspecialist, academic, and engineers in the field of power electronics. [ABSTRACT FROM PUBLISHER]

Multilevel cascaded H-bridge (CHB) converters have been presented as a good solution for high-power applications. In this way, several control and modulation techniques have been proposed for this power converter topology. In this paper, the steady-state power balance in the cells of a single-phase two-cell CHB is studied. The capability to be supplied with active power from the grid or to deliver active power to the grid in each cell is analyzed according to the dc-link voltages and the desired ac output voltage value. The limits of the maximum and minimum input active powers for a stable operation of the CHB are addressed. Simulation results are shown to validate the presented analysis. [ABSTRACT FROM AUTHOR]

Space-vector modulation (SVM) is a well-suited technique to be applied to multilevel converters and is an important research focus in the last 25 years. Recently, a single-phase multilevel modulator has been introduced, showing its conceptual simplicity and its very low computational cost. In this paper, some of the most conventional multilevel SVM techniques have been chosen to compare their results with those obtained with single-phase multilevel modulators. The obtained results demonstrate that the single-phase multilevel modulators applied to each phase are equivalent with the chosen well-known multilevel SVM techniques. In this way, single-phase multilevel modulators can be applied to a converter with any number of levels and phases, avoiding the use of conceptually and mathematically complex SVM strategies. Analytical calculations and experimental results are shown, validating the proposed concepts. [ABSTRACT FROM AUTHOR]

This paper presents a simple and low-computational-cost modulation technique for multilevel cascaded H-bridge converters. The technique is based on geometrical considerations considering a unidimensional control region to determine the switching sequence and the corresponding switching times. In addition, a simple strategy to control the dc-voltage ratio between the H-bridges of the multilevel cascaded converter is presented. Examples for the two-cell topology are shown, but the proposed technique can be applied to develop modulation methods for a higher number of H-bridges. Experimental results are presented to validate the proposed technique. [ABSTRACT FROM AUTHOR]

Recently, a multilevel cascaded converter fed with a single dc source has been presented. An analysis of the steady-state working limits of this type of converter is presented in this paper. Limits of the maximum output voltage and the minimum and maximum loading conditions for stable operation of the converter are addressed. In this paper, a way to achieve any dc voltage ratio (inside the stable operation area of the converter) between the H-bridges of the single-dc-source cascaded H-bridge converter is presented. The proposed dc-voltage-ratio control is based on a time-domain modulation strategy that avoids the use of inappropriate states to achieve the dc-voltage-ratio control. The proposed technique is a feedforward-modulation technique which takes into account the actual dc voltage of each H-bridge of the converter, leading to output waveforms with low distortion. In this way, the dc voltage of the floating H-bridge can be controlled while the output voltage has low distortion independently of the desired dc voltage ratio. Experimental results from a two-cell cascaded converter are presented in order to validate the proposed dc-voltage-ratio control strategy and the introduced concepts. [ABSTRACT FROM AUTHOR]

Modulation techniques for multilevel converters can create distorted output voltages and currents if the dc-link voltages are unbalanced. This situation can be avoided if the instantaneous dc voltage error is not taken into account in the modulation process. This paper proposes a feed-forward space vector modulation method for a single-phase multilevel cascade converter. Using this modulation technique, the modulated output voltage of the power converter always generates the reference determined by the controller, even in worst case voltage unbalance conditions. In addition, the possibility of optimizing the dc voltage ratio between the H-bridges of the power converter is introduced. Experimental results from a 5-kVA prototype are presented in order to validate the proposed modulation technique. [ABSTRACT FROM AUTHOR]

Simplified space vector modulation (SVM) techniques for multilevel converters are being developed to improve factors such as the computational cost, number of commutations, and voltage distortion. The feedforward SVM presented in this paper takes into account the actual dc capacitor voltage unbalance of the multilevel power converter. The resulting technique is a low-cost generalized feedforward 3-D SVM method and is particularized for three-phase multilevel diode-clamped converters. This new modulation technique can be applied to topologies where the gamma component may not be zero. The computational cost of the proposed method is similar to those of comparable methods and it is independent of the number of levels of the power converter. Experimental results using a three-level diode-clamped converter are presented to validate the proposed modulation technique. [ABSTRACT FROM AUTHOR]

The direct power control (DPC) technique has been widely used as a control strategy for three-phase power rectifiers due to its simplicity and good performance. DPC uses the instantaneous active and reactive power to control the power converter. The controller design has been proposed as a direct control with a lookup table and, in recent works, as an indirect control with an inner control loop with proportional-plus-integral controllers for the instantaneous active and reactive power errors. In this paper, a model-based DPC for three-phase power converters is designed, obtaining expressions for the input control signal, which allow the design of an adaptive control law that minimizes the errors introduced by parameter uncertainties as the smoothing inductor value or the grid frequency. A controller design process, a stability study of the system, and experimental results for a synchronous three-phase power rectifier prototype are presented to validate the proposed controller. [ABSTRACT FROM AUTHOR]

Abstract Background : A phase II multicentric trial of paclitaxel and cisplatin was conducted in previously untreated patients, with locally advanced transitional-cell carcinoma (TCC) of the bladder, to assess its toxicity and efficiency in preserving the bladder. Methods : Forty-four patients with locally advanced TCC of the bladder (seven with T3a, 27 with T3b, and eight with T4a) were treated with paclitaxel 175 mg/m 2 over 3 h, and cisplatin 75 mg/m 2 over 30 min, on the first day of each 21-day treatment cycle. Therapy was continued for three cycles. Patients were re-evaluated and scheduled for radiotheraphy or radical surgery depending on tumoral response. Tumoral response was measured by citology, computed tomographical scans, and deep randomized biopsies of the bladder. Results : Thirty-two out of 42 patients (76%; 95% confidence interval 45–93%) showed a major response (22 complete, and 10 partial). Response times ranged from 18 to 54 months. Three patients with T4 bladder primary tumors experienced a pathological CR. At a median follow-up of three years, 20 patients remain free of disease (47.6%), six patients are alive with disease (14.3%), 12 patients died of disease (28.5%), and four others died of unrelated causes (9.5%). Hematological toxicity included anemia, thrombocytopenia, and neutropenia. No grade four febrile neutropenia was observed. Non-hematological toxicity included alopecia (93.2%), diarrhea (11.4%), vomiting (18.5%) mucosytis (4.6%), and neuropathy (4.6%). Drug omissions or dose delay for adverse events were only necessary in one patient (2.2%), and three patients (6.8%), respectively. Conclusions : Paclitaxel and cisplatin is an active and well-tolerated neo-adjuvant regimen for previously untreated patients with pure TCC of the bladder, achieving a vesical preservation rate of 52%. [ABSTRACT FROM AUTHOR]

Postpartum post-traumatic stress disorder (PTSD) is not a specific process but can last for months and may manifest itself during any subsequent pregnancies or even become chronic. This study aimed to determine the factors associated with long-term PTSD symptoms one year after delivery. A cross-sectional study was conducted on 1301 Spanish puerperal women. Data were collected on sociodemographic, obstetric, and neonatal variables. The Perinatal Post-Traumatic Stress Disorder Questionnaire (PPQ) was administered online through midwives' associations across Spain. Crude odds ratio (OR) and adjusted odds ratio (aOR) and their 95% confidence intervals were calculated. A PPQ score ≥ 19 (high-risk) was recorded for 13.1% (171) of the participants. Identified risk factors were not respecting a birth plan (aOR = 1.89 (95% CI 1.21–2.94)), formula-feeding of the baby at discharge (aOR = 2.50 (95% CI 1.20–5.17)), postpartum surgical intervention (aOR = 2.23 (95% CI 1.02–4.85)), hospital readmission (aOR = 3.45 (95% CI 1.21–9.84)), as well as verbal obstetric violence (aOR = 3.73 (95% CI 2.52–5.53)) and psycho-affective obstetric violence (aOR = 3.98 (95% CI 2.48–6.39)). During childbirth, some clinical practices, such as formula-feeding of the newborn at discharge or types of obstetric violence towards the mother, were associated with a higher risk of PTSD symptoms one year after delivery. [ABSTRACT FROM AUTHOR]

This work describes an efficient implementation in terms of computation time and resource usage in a Field-Programmable System-On-Chip (FPSoC) of a Finite Control Set Model Predictive Control (FCS-MPC) algorithm. As an example, the FCS-MPC implementation is used for the current reference tracking of a two-level three-phase power converter. The proposed solution is an enabler for using both complex control algorithms and digital controllers for high switching frequency semiconductor technologies. An original HW/SW (hardware and software) system architecture for an FPSoC is designed to take advantage of a modern operating system, while removing time uncertainty in real-time software tasks, and exploiting dedicated FPGA fabric for the most complex computations. In addition, two different architectures for the FPGA-implemented functionality are proposed and compared in order to study the area-speed trade-off. Experimental results show the feasibility of the proposed implementation, which achieves a speed hundreds of times faster than the conventional Digital Signal Processor (DSP)-based control platform. [ABSTRACT FROM AUTHOR]

Low-speed drive is one of the challenges for modular multilevel converters (MMCs) due to large capacitor voltage fluctuation. In this article, a cascaded MMC and cycloconverter (CCV) based machine drive system is proposed to ensure stable operation of medium-voltage and low-speed machine. The MMC provides medium-frequency ac voltage for the CCV, and the CCV converts the medium-frequency ac input to low-frequency ac output required by the machine. Detailed analysis about MMC's operation frequency, device current stress, and submodule (SM) capacitance are given in this article. Proposed drive system can operate at zero/low frequency under rated load torque, while the SM capacitance is much smaller than that in existing methods. Simulation and experimental studies are conducted, and the results verify the effectiveness of the proposed system. [ABSTRACT FROM AUTHOR]

In this article, a low computational burden model predictive control (MPC) strategy without weighting factor is proposed for the single-phase cascaded H-bridge CHB converters. To reduce the switching state candidates, a hierarchy control algorithm is proposed. The grid current is controlled by selecting a subregion from the designed 2-D control plane, instead of the entire area. Two vectors are chosen in one sampling period for more accurate tracking. Then, the voltage balancing is achieved by selecting the optimal switching state from the subregion candidates to form the above two vectors. The cost function can be constructed of one variable: load voltage. Therefore, the weighting factor can be eliminated. No tuning or retuning processes are required in the proposed method. To reduce the computational time further, the principle of eliminating the switching state candidates operating the same voltage balancing performance is proposed. Conventional and proposed MPC methods are verified by experimental tests via a laboratory setup of a three-cell connected CHB converter. Steady-state and transient operations demonstrate that the proposed method guarantees less distortion grid current and shorter execution time (reduced from 15 to 3 $\mu s$). Fast response speed to variations in voltage reference and load resistance can be achieved t. [ABSTRACT FROM AUTHOR]

Multilevel cascaded H-bridge converters have become a mature technology for applications where high-power medium ac voltages are required. Normal operation of multilevel cascaded H-bridge converters assumes that all power cells have the same dc voltage, and each power cell generates the same voltage averaged over a sampling period using a conventional phase-shifted pulse width modulation (PWM) technique. However, this modulation method does not achieve good results under unbalanced operation per H-bridge in the power converter, which may happen in grid-connected applications such as photovoltaic or battery energy storage systems. In the paper, a simplified mathematical analysis of the phase-shifted PWM technique is presented. In addition, a modification of this conventional modulation method using variable shift angles between the power cells is introduced. This modification leads to the elimination of harmonic distortion of low-order harmonics due to the switching (triangular carrier frequency and its multiples) even under unbalanced operational conditions. The analysis is particularized for a three-cell cascaded H-bridge converter, and experimental results are presented to demonstrate the good performance of the proposed modulation method. [ABSTRACT FROM PUBLISHER]

Due to the high-performance requirements of power converters in industrial applications, sliding-mode control has drawn extensive research attention for its insensitivity against external disturbances. In order to ensure this advantage while suppressing the chattering problem caused by discontinuous switching functions, in this article, a fuzzy sliding-mode control (FSMC) strategy consisting of three control loops is proposed for three-phase three-level neutral-point-clamped active front-end rectifiers. In the power tracking loop, an improved super-twisting algorithm is proposed to enforce the tracking errors of active power and reactive power to bounded regions in finite time and guarantee the transient performance. Next, in the dc-link voltage regulation loop, the regulation error of dc-link voltage converges to a bounded region with a super-twisting extended state observer-based FSMC strategy. A simple but efficient proportional-integral controller is employed in dc-link voltage balancing loop to reduce the voltage difference between two dc-link capacitors. The proposed controller is characterized by attenuated chattering phenomenon and improved the dc-link voltage regulation performance, disturbance rejection ability, and power tracking performance. Experimental results are provided to verify the effectiveness and superiority of the proposed strategy. [ABSTRACT FROM AUTHOR]

Background Improving the identification of people who inject drugs (PWID) in electronic medical records can improve clinical decision making, risk assessment and mitigation, and health service research. Identification of PWID currently consists of heterogeneous, nonspecific International Classification of Diseases (ICD) codes as proxies. Natural language processing (NLP) and machine learning (ML) methods may have better diagnostic metrics than nonspecific ICD codes for identifying PWID. Methods We manually reviewed 1000 records of patients diagnosed with Staphylococcus aureus bacteremia admitted to Veterans Health Administration hospitals from 2003 through 2014. The manual review was the reference standard. We developed and trained NLP/ML algorithms with and without regular expression filters for negation (NegEx) and compared these with 11 proxy combinations of ICD codes to identify PWID. Data were split 70% for training and 30% for testing. We calculated diagnostic metrics and estimated 95% confidence intervals (CIs) by bootstrapping the hold-out test set. Best models were determined by best F-score, a summary of sensitivity and positive predictive value. Results Random forest with and without NegEx were the best-performing NLP/ML algorithms in the training set. Random forest with NegEx outperformed all ICD -based algorithms. F-score for the best NLP/ML algorithm was 0.905 (95% CI,.786–.967) and 0.592 (95% CI,.550–.632) for the best ICD -based algorithm. The NLP/ML algorithm had a sensitivity of 92.6% and specificity of 95.4%. Conclusions NLP/ML outperformed ICD -based coding algorithms at identifying PWID in electronic health records. NLP/ML models should be considered in identifying cohorts of PWID to improve clinical decision making, health services research, and administrative surveillance. [ABSTRACT FROM AUTHOR]

Background: Myostatin is a regulator of muscle size. To date, there have been no published studies focusing on the relation between myostin levels and myopenia in rheumatoid arthritis (RA).Objective: Evaluate the value of serum myostatin as a biomarker of cachexia and low skeletal muscle mass (LSMM) in RA patients, along with whether high serum myostatin is associated to these conditions after adjusting for potential confounders.Methods: This cross-sectional study included 161 female RA patients and 72 female controls. In the RA group, we assessed several potential risk factors for LSMM and rheumatoid cachexia. Dual-energy X-ray absorptiometry was used to quantify the skeletal muscle mass index (SMMI) (considering LSMM ≤ 5.5 kg/m2) and the presence of rheumatoid cachexia (a fat-free mass index ≤ 10 percentile and fat mass index ≥ 25 percentile of the reference population). Serum myostatin concentrations were determined by ELISA. To identify a cut-off for high serum myostatin levels, we performed ROC curve analysis. Multivariable logistic regression analysis was used to identify the risk factors for LSMM and rheumatoid cachexia. The risk was expressed as odds ratios (ORs) and their 95% confidence intervals (95% CIs).Results: Compared to the controls, the RA group had a higher proportion of LSMM and exhibited high serum myostatin levels (p < 0.001). ROC curve analysis showed that a myostatin level ≥ 17 ng/mL was the most efficient cut-off for identifying rheumatoid cachexia (sensitivity: 53%, specificity: 71%) and LSMM (sensitivity: 43%, specificity: 77%). In the multivariable logistic regression, RA with high myostatin levels (≥17 ng/mL) was found to increase the risk of cachexia (OR = 2.79, 95% CI: 1.24-6.29; p = 0.01) and LSMM (OR = 3.04, 95% CI: 1.17-7.89; p = 0.02).Conclusions: High serum myostatin levels increase the risk of LSMM and rheumatoid cachexia. We propose that high myostatin levels are useful biomarkers for the identification of patients in risk of rheumatoid cachexia and myopenia. [ABSTRACT FROM AUTHOR]

In this article, a nonlinear high-gain observer (NHGO)-based second-order sliding mode (SOSM) control strategy is proposed for the three-phase three-level neutral-point-clamped (NPC) converter. This controller applies the advanced SOSM algorithm both in the voltage regulation loop and in the power tracking loop, which provides a fast dynamic for the dc-link voltage, and also assures a good steady-state behavior for the NPC converter. Additionally, an NHGO technique is implemented in the voltage regulator combining with the SOSM algorithm. The conventional observer-based controllers suffer from the destructive effects of measurement noise, and it can only be addressed by diminishing the observer gain, which sacrifices the observer property. The NHGO technique adopts a time varying gain, that is, high gain in transient while low gain in steady state, which minimizes the adverse influence of measurement noise. The tuning method of the proposed NHGO-based SOSM controller is given to simplify the implementation process. Finally, the simulation and experimental results of the proposed control scheme for the NPC converter are given and compared with the conventional PI controller as well as the well-known linear extended state observer-based control method, which validates the feasibility and superiority of the proposed controller. [ABSTRACT FROM AUTHOR]

Modular multilevel converters have become the prominent topology for medium- and high-voltage applications. The performance of these converters highly depends on the accuracy of the used modulation approach, for which the capacitor voltage of submodules (SM) are usually assumed to be equal. This article exhibits that ignoring the capacitor voltage differences among SMs adversely affects the system performance. This becomes more obvious the larger the capacitor voltage differences are. Hence, this article proposes a more accurate feedforward modulation approach that takes into account either the instantaneous capacitor voltage value and the real output voltage in the modulation stage. As a result, in applications where larger SM voltage differences are expected, the current distortion and control performance are improved. Particularly, switching–saving approaches benefit from this method as it enables their operation with reduced switching losses without the downsides of increased distortion due to capacitor voltage differences. The proposed approach is analyzed and compared with the nearest-level modulation and with the level-shift PWM. Simulations and experimental validation are presented to confirm the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]

The papers in this special section focus on the deployment of predictive control in power converters and electrical drives. [ABSTRACT FROM PUBLISHER]

The papers in this special section focus on predictive control in power converters and electrical drives. With the fast microcontrollers available today, applications of predictive control in power converters and electrical drives are a very powerful and attractive alternative to classical controllers. The use of predictive control offers a number of advantages: very intuitive approach, no need for linear controllers and modulators, easy inclusion of nonlinearities and restrictions, etc. However, predictive control schemes in power converters and electrical drives have not yet been implemented in industrial applications. Nevertheless, after some further progress, it can be expected that the advantages of predictive algorithms will lead to an increased number of industrial applications in the future. [ABSTRACT FROM PUBLISHER]

In this article, a two-stage control scheme consisting of an adaptive-gain second-order sliding mode (SOSM) controller and a switched high-gain observer (HGO) is proposed for the three-level neutral-point-clamped (NPC) converter. The adaptive-gain SOSM control method is applied both in the voltage regulation loop and instantaneous power tracking loop, thus, the boundary of the disturbance derivative does not need to be known a priori. Compared with the fixed-gain SOSM, it provides a faster dynamic and a better steady-state response for the NPC converter. On the other hand, the conventional disturbance compensation observer used in the power system suffers from the adverse effects of measurement noise, which limits the performance of the observer. A switched HGO is combined with the adaptive-gain SOSM controller in the voltage regulation loop to address this issue. By using a switched observer gain, the switched HGO greatly diminishes the performance degradation induced by the inevitable measurement noise. Finally, several experiments between the representative extended state observer-based SOSM control scheme and the proposed control method are carried out for a comparison. The results demonstrate the feasibility and effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Multilevel cascaded H-bridge converters have found industrial application in the medium-voltage high-power range. In this paper, a generalized modulation technique for this type of converter based on a multidimensional control region is presented. Using the multidimensional control region, it is shown that all previous modulation techniques are particularized versions of the proposed method. Several possible solutions to develop a specific implementation of the modulation method are addressed in order to show the potential possibilities and the flexibility of the proposed technique. In addition, a feedforward version of this technique is also introduced to determine the switching sequence and the switching times, avoiding low harmonic distortion with unbalanced dc voltages. Experimental results are shown in order to validate the proposed concepts. [ABSTRACT FROM AUTHOR]

The papers in this special section focus on predictive control in power converters and electrical drives. With the fast microcontrollers available today, applications of predictive control in power converters and electrical drives are a very powerful and attractive alternative to classical controllers. The use of predictive control offers a number of advantages: very intuitive approach, no need for linear controllers and modulators, easy inclusion of nonlinearities and restrictions, etc. However, predictive control schemes in power converters and electrical drives have not yet been implemented in industrial applications. Nevertheless, after some further progress, it can be expected that the advantages of predictive algorithms will lead to an increased number of industrial applications in the future. The focus on this special is on: 1) predictive control applied to power converters; 2) predictive control applied to motor drives; 3) design and implementation issues of predictive control; and 4) applications of predictive control in industrial electronics. [ABSTRACT FROM PUBLISHER]

The papers in this special section on predictive control in power converters and electrical drives focuses on the following topics: 1) predictive control applied to power converters: ac/dc, ac/ac, dc/ac, ac/dc/ac, multilevel converters, etc.; 2) predictive control applied to motor drives: induction machines, permanent-magnet synchronous motors (PMSMs), etc.; and 3) design and implementation issues of predictive control: cost function selection, weighting factor design, delay compensation, model parameters errors, variable switching frequency, etc.; 4) applications of predictive control in industrial electronics. [ABSTRACT FROM PUBLISHER]

Single-phase power converters are widely used in power applications as photovoltaics and fuel-cell power conditioners. In addition, multilevel converters are a well-known solution in order to achieve high-quality output waveforms in power systems. In this paper, a time-domain duty-cycle computation technique for single-phase multilevel converters named IDM is presented. The proposed technique is based on geometrical calculations with outstanding simplicity and generality. The proposed modulation technique can be easily applied to any multilevel converter topology carrying out the necessary calculations. The most common multilevel converter topologies have been studied in this paper as examples to introduce the proposed modulation strategy. Any other multilevel converter topology could be studied, and the corresponding IDM could be easily developed. In addition, the well-known optimized voltage balance strategy for voltage capacitor control using the redundant switching states of the system is applied working with the proposed IDM method, showing that both techniques are compatible. Experimental and simulation results for several single-phase multilevel converters are shown to validate the proposed modulation technique. [ABSTRACT FROM AUTHOR]

A bioeconomic approach was used to evaluate random variation of growth and mortality parameters and feed conversion ratio (FCR) for intensive production of the blue shrimp Litopenaeus stylirostris (Stimpson). Severe mortality problems caused by high impact diseases were not considered in this analysis. For a 50-ha farm, the maximum values of the internal rate of return (IRR=44%) and net revenue above operation costs (NR=US$1 211 000) were obtained for a stocking density of 67 postlarvae (PL) m−2 during winter–spring (cycle 1) and 65 PL m−2 during summer–autumn (cycle 2). Regardless of the density used for cycle 1, stocking at 50 and 65 PL m–2 for cycle 2 sufficed to obtain, respectively, IRRs greater than the minimum attractive IRRs of 15% and 30%. A frequency distribution of IRR, projected for densities of 67 and 65 PL m−2, showed high confidence in obtaining IRR values above 15% and 30% (i.e. confidence >99% and 92% respectively). The frequency distribution of NR showed that the farm could operate without economic losses. Stocking a minimum of 53% of the capacity of the farm would guarantee positive NR. Sensitivity analysis indicated that the IRR and NR were mainly influenced by mortality rate, selling price, density, final weight and FCR. [ABSTRACT FROM AUTHOR]