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Multiphase machine drives are advantageous over three-phase ones in features such as tolerance to open-phase faults (OPFs). Six-phase (6P) ones offer an excellent compromise between complexity and fault tolerance. In particular, those with a symmetrical arrangement of the stator phase windings and a single neutral point provide superior postfault capability. To ensure high reliability and performance, the stator resistance should be monitored. This can be attained with good robustness to uncertainties by dc-signal injection. This article proposes a dc-based resistance estimation method for symmetrical 6P induction machines that achieves the following main characteristics simultaneously for the first time: estimation of individual stator phase resistances and suitability for either healthy or OPF conditions. The dc injection is performed so that no torque ripple is produced and so that the increase in loss, peak current, and braking torque is relatively small. The method is designed so that it is robust to the deviation in the stator neutral-point voltage due to resistance asymmetry. Experimental results are provided.

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Loads affect the stability of grid-forming (GFM) converters, both in stand-alone and grid-connected modes. This has motivated the development of methods that study the stability of GFM converters using an impedance-based analysis. AC impedance-based stability analyses usually study the stability of GFM converters by applying the Nyquist criterion to an impedance ratio denoted as minor loop gain. A limitation of the previous approach when applied to GFM converters, which is not always clearly stated, is that the output impedance of a GFM converter depends on the impedance seen by the converter. This loading effect is not accurately modeled in the literature. This article proposes an impedance model that accounts for this loading effect on the GFM converter output impedance, without introducing approximations. As a direct consequence of the presented impedance model, the stability of the GFM converter when connected to different loads can be determined by checking the stability of a single transfer function, the sensitivity function. Using the sensitivity function, the impedance model presented also reveals a clear link between the voltage controller characteristics and the converter output impedance, which has been reported as a limitation of prior impedance-based analysis methods.

The superior canal dehiscence syndrome is a pathology that affects the arcuate eminence creating a “third window” between the inner ear and the middle fossa. This condition can lead to symptoms such as hearing loss, autophony, or sound-induced vertigo. Traditionally, surgical treatment has been performed by microscope-assisted temporal craniotomy, but when the dehiscence is in the medial part of the arcuate eminence the bone defect may not be seen.

A buyer wishes to purchase a durable good from a seller who in each period chooses a mechanism under limited commitment. The buyer's value is binary and fully persistent. We show that posted prices implement all equilibrium outcomes of an infinite‐horizon, mechanism‐selection game. Despite being able to choose mechanisms, the seller can do no better and no worse than if he chose prices in each period, so that he is subject to Coase's conjecture. Our analysis marries insights from information and mechanism design with those from the literature on durable goods. We do so by relying on the revelation principle in Doval and Skreta (2022).

El Registro Español de Investigación en Dermatitis de Contacto y Alergia Cutánea tiene entre sus objetivos la vigilancia epidemiológica de la dermatitis de contacto. Para ello es importante conocer si se producen alteraciones en el tiempo de las prevalencias de las positividades a los distintos alérgenos.

The findings of this study suggest that menopausal hormone therapy could be a viable treatment alternative for breast cancer survivors experiencing menopausal symptoms, especially those with hormone receptor–negative tumors. Personalized management is recommended for each peri/postmenopausal woman facing a diminished quality of life because of menopause symptoms.

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Multiphase machines are a promising alternative for high-reliability applications. In these applications, overmodulation (OVM) is important since it allows attaining higher modulation indices by injecting, besides zero-sequence voltage harmonics, current-producing ones. In general, the existing techniques are able to limit to some extent the current total harmonic distortion (THD). However, most do not ensure the minimum current THD, thereby not guaranteeing the minimum harmonic stator copper loss. Furthermore, most are intended just for particular phase numbers $n$, symmetrical/asymmetrical winding arrangements and neutral-point (NP) configurations. OVM with low THD remains unaddressed in most types of multiphase motors. This article overcomes these limitations by proposing a generalized OVM strategy that attains the minimum current THD in induction motors with any $n$, winding arrangement, and NP configurations. Two techniques are outlined. One of them injects only non-torque-related harmonics, while the other technique exploits torque-producing harmonics to further reduce the current THD and to attain modulation indices up to square waveform. The superiority of the proposal in terms of current THD is substantiated through studies for multiple kinds of multiphase machines. The experiments are performed by using two six-phase induction motors with symmetrical/asymmetrical windings when 1 and 2 NPs are set.

Grid-connected converters must remain coupled to the grid during a fault. They have to control the reactive currents injected to the grid because of its limited overload capacity. In particular, grid-forming (GFM) converters ride through the fault either preserving GFM operation or switching from GFM to grid-following (GFL) mode. In the GFM mode, the current cannot be controlled, and therefore, mechanisms as virtual impedances become necessary. This article proposes a converter with GFM and GFL capabilities that demonstrates effective voltage tracking in the GFM mode and current tracking in the GFL mode, good dynamic disturbance rejection response, and wide stability range and robustness in both modes. During a fault, the proposed converter switches from GFM to GFL mode in order to precisely control the injected currents. The current control is able to limit the current at the inception of severe faults. This characteristic is preserved for a wide range of grid impedances, thanks to its good robustness and wide stability margin. As a result, the controller can operate in a stand-alone mode, connected to a weak grid or connected to a stiff grid with a short-circuit ratio of up to 50. The fault ride-through capability of the converter is tested under severe symmetrical and asymmetrical faults.

Multiphase motor drives based on a cascaded H-bridge (CHB) voltage source inverter (VSI) are suitable for fault-tolerant applications because a damaged H-bridge can be safely bypassed without interrupting the drive operation. This bypass has the effect of an undesired dc-link voltage shortage that multiphase motors can be effectively tolerated if appropriate $x$-$y$ components are injected into the stator voltages. These degrees of freedom, which are not available in three-phase motors, permit to reach higher speeds without field weakening nor torque oscillations during the fault. However, no specific strategies exploiting this particular advantage of multilevel multiphase drives have been proposed so far, albeit resorting to strategies devised for three-phase VSIs would reduce the drive performance. This article proposes a postfault strategy for multiphase CHBs with bypassed H-bridges that better uses its dc link by injecting appropriate $x$-$y$ components in the modulation reference signals, without altering the $\alpha$-$\beta$ ones. Experimental results, obtained with a five-level five-phase motor drive, show that the proposed strategy manages to run the motor at rated speed with negligible torque ripple when an H-bridge is bypassed. It is also recognized that the continuous operation in this situation requires using a circulating-current filter to mitigate the extra stator copper losses that arise.

Six-phase induction motor (6PIM) drives offer enhanced fault tolerance and reduced per-phase ratings. Hysteresis current control (HCC) is attractive for 6PIMs because it is simple, robust and fast. HCC is conventionally implemented so that each leg voltage is directly set based on the respective phase-current error. However, this approach does not consider that, in multiphase drives, phase voltages and currents are related through a combination of equivalent impedances corresponding to various subspaces. In general, there is a notable dissimilarity between these impedances, being typically small for secondary ($\bm {xy}$) subspaces. This can cause large current distortion and poor reference tracking. This article proposes an improved HCC for 6PIM drives. Instead of directly inputting the per-phase current error to the hysteresis comparator and directly applying the switching states chosen by it, the input and output components associated with different subspaces are segregated. The input and output $\bm {xy}$ components are nullified in open loop so that the $\bm {xy}$ impedance no longer affects the HCC behavior, even if low. This prevents the disrupting $\bm {xy}$ currents, ensures effective tracking of the torque/flux-producing $\bm {\alpha \beta }$ reference current, and enables reconfiguration-less fault tolerance. Experiments using 6PIMs with different winding configurations corroborate the significant advantages of the proposal.

Objectives: Neurodevelopmental disorders present deficits in executive functions (EFs). Before 36 months old, EFs act as basic abilities that allow adequate executive functioning at later ages. Three basic EFs are assessable before the child reaches 36 months old: working memory, inhibition, and cognitive flexibility. This review aims to provide an overview of the progress and difficulties in assessing these three basic executive functions before children reach 36 months old. Methods: Four databases were systematically searched without time or language limitations. The selection process was done using a PRISMA flowchart for scoping reviews. Sixteen studies were included, all in English and published between 2004 and 2021. Results: Out of 277 studies, 16 met the inclusion criteria. The general data of the studies were summarized, such as sample age, type of study, measurement features, types of EFs assessed, task names, internal structure, reliability, and main contributions. The findings on available tasks and scales, factor structure, biological and environmental factors, and the variables influencing EFs before 36 months old are described. Conclusions: Multiple factors influenced the evolution of EFs. The unidimensional model seems to better explain EFs before 36 months old. Expanding psychometric research with large samples and studying samples of children with symptoms at risk for neurodevelopmental disorders may help to improve the measurement of EFs before 36 months old.

Multiphase machines have significant benefits over their three-phase counterparts. One of them is the possibility of further exploiting the dc-link voltage by injecting non-torque-related voltage harmonics in the $xy$ planes. This allows reaching higher modulation indices in the overmodulation (OVM) region of pulsewidth modulation (PWM) while avoiding torque ripple in motors with negligible space harmonic effects. The most prominent OVM techniques are those based on the instantaneous minimization of the $xy$ voltage. These methods were devised just for five-phase drives and have the drawback that they lack generality. This article overcomes this limitation by proposing an OVM strategy for symmetrical induction motor drives with any odd phase number $n$. The proposal achieves the minimum voltage distortion, and consequently, it greatly mitigates the $xy$ current distortion. Indeed, it attains the lowest current distortion compared with the existing techniques. It relies on carrier-based PWM in its design and implementation stages, and accordingly, it is much simpler than previous methods. Furthermore, the inverter switching frequency (loss) is substantially reduced. Theoretical assessments are given for drives with odd $n$ between 5 and 11. The experiments are performed with a symmetrical nine-phase induction motor with a single neutral point.

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The present study employs the direct integration boundary element method (DIBEM) to analyze the buckling behavior of thin plates. Unlike conventional approaches, this method eliminates the need for domain discretization or specialized solutions. Furthermore, it constitutes a continuation from the previous research in Doval et al. (2013), which employed the radial integration method for the same investigation. To showcase the efficacy of the proposed approach, it is utilized in the stability analysis of both perforated and non-perforated plates. The findings are then compared against analytical responses, in the case of non-perforated plates, and finite element method results, for perforated plates. Moreover, the use of boundary elements reduces the size of the eigenvalue problem involved in stability analysis, as compared to finite elements, provided that only the domain and a few internal points are needed for discretization. Overall, this paper presents a novel and effective approach to the analysis of buckling plates. [ABSTRACT FROM AUTHOR]

The available evidence of hormone therapy interactions with other drugs comes mainly from biological plausibility, the knowledge of extensive concomitant use without reported incidents, and the extrapolation of hormonal contraception. These eligibility criteria can help in the decision process of hormone therapy coadministration with another group of drugs.

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Delayed recall (DR) impairment is one of the most significant predictive factors in defining the progression to Alzheimer’s disease (AD). Changes in brain functional connectivity (FC) could accompany this decline in the DR performance even in a resting state condition from the preclinical stages to the diagnosis of AD itself, so the characterization of the relationship between the two phenomena has attracted increasing interest. Another aspect to contemplate is the potential moderator role of the APOE genotype in this association, considering the evidence about their implication for the disease. 379 subjects (118 mild cognitive impairment (MCI) and 261 cognitively intact (CI) individuals) underwent an extensive evaluation, including MEG recording. Applying cluster-based permutation test, we identified a cluster of differences in FC and studied which connections drove such an effect in DR. The moderation effect of APOE genotype between FC results and delayed recall was evaluated too. Higher FC in beta band in the right occipital region is associated with lower DR scores in both groups. A significant anteroposterior link emerged in the seed-based analysis with higher values in MCI. Moreover, APOEgenotype appeared as a moderator between beta FC and DR performance only in the CI group. An increased beta FC in the anteroposterior brain region appears to be associated with lower memory performance in MCI. This finding could help discriminate the pattern of the progression of healthy aging to MCI and the relation between resting state and memory performance.

Two common defects in induction machines (IMs) are eccentricity and interturn faults, which should be diagnosed to prevent performance degradation and further damage. A popular fault-detection approach is the current signature analysis (CSA), because of its simplicity and nonintrusiveness. Under closed-loop control, it is combined with analogous voltage-reference (VR) signature analysis (VRSA). However, by using these methods in three-phase IMs, it is difficult to discriminate between these faults, which cause similar symptoms. Multiphase machines provide remarkable advantages such as inherent tolerance to open-phase faults. Six-phase IMs are particularly attractive since they allow adopting three-phase converters. Among them, those with symmetrical spatial arrangement of the stator phases offer superior fault tolerance. Nonetheless, the distinction between eccentricity and interturn failures in these IMs has not been addressed so far. This article studies the discrimination between eccentricity and interturn faults in symmetrical six-phase (S6) IMs by CSA or VRSA. It is shown that, conversely to three-phase IMs and most other multiphase IMs, in S6 ones, these two types of failures can be easily distinguished: interturn faults considerably alter the currents or VRs in the so-called $\boldsymbol{x}$-$\boldsymbol{y}$ plane, whereas eccentricity leads to current/voltage symptoms only in the $\boldsymbol{\alpha} _{\mathbf{1}}$-$\boldsymbol{\beta} _{\mathbf{1}}$ plane. Experimental results confirm the theory.

Multiphase drives exhibit remarkable advantages (e.g., fault tolerance) over three-phase ones. Six-phase drives are particularly attractive, given their moderate complexity and suitability for off-the-shelf three-phase converters. Regarding the stator winding arrangement, the symmetrical one offers superior postfault capabilities in most scenarios. On the other hand, resistance asymmetry in the stator phases or connections may arise due to different causes. The conventional full-range minimum-loss strategy (FRMLS) generates stator-current references under open-phase (infinite resistance) faults so that torque ripple is prevented while minimizing the losses for each torque ($\boldsymbol{d}$-$\boldsymbol{q}$ current) value and maximizing the torque range; however, this method is unsuitable for unequal resistances of finite value. This article proposes an FRMLS for setting the current references to reach these goals in symmetrical six-phase drives with any resistance asymmetry. The optimum references are found online depending on the resistances, without lookup tables. The phase currents are individually limited by an iterative algorithm, so that minimum stator copper loss (SCL) is achieved over the maximum admissible torque range. In this manner, unlike the conventional FRMLS, minimum SCL and maximum torque range are attained even for finite resistance imbalance. The currents in phases affected by high resistances are suitably reduced. Experimental results are provided.

The demand for motor drives based on multiphase machines (MMs) is increasing due to their inherent fault-tolerant capabilities. To achieve satisfactory post-fault operation, a proper fault-tolerant controller is needed. Some direct-torque-control (DTC) techniques have been reported for five-phase induction motor (FPIM) drives under an open-phase fault (OPF). DTC offers simplicity, fast response, and less parameter sensitivity. However, the existing fault-tolerant DTC methods were designed for two-level voltage-source inverters (VSIs). A three-level neutral-point-clamped (NPC) VSI allows greater flexibility in the switching states, lower current and torque ripple, and reduced common-mode voltage (CMV). However, the increased number of switching states requires the design of new DTC methods, able to tolerate OPFs while providing satisfactory performance in various aspects. In this article, two fault-tolerant DTC techniques are developed for three-level NPC VSI-fed FPIM drives under an OPF. The possible switching states are synthesized with suitable virtual vectors (VVs), addressing the dc-link voltage balance, ${\text {d}v/\text {d}t}$ , CMV, and dc-link utilization. The two methods are compared under an OPF in these terms, as well as regarding the average switching frequency. Comparative experimental results are provided to assess the viability of the developed DTC schemes at steady-state and dynamic conditions.

This article proposes a finite control set (FCS) current controller for grid-tied converters, specifically tailored to meet the characteristics of ac ship microgrids in all-electric ships (AESs). Contrary to a pulsewidth modulator (PWM)-based design, which often employs an LCL filter, the proposal is able to meet applicable harmonic regulations using an L filter with the same total inductance as the LCL filter and the same switching frequency required by PWM-based solutions. Moreover, the proposed design provides a low sensitivity in a wide frequency range from dc to the switching frequency of the power converter. This low sensitivity permits to quickly attenuate low-order disturbances and it is particularly convenient in marine applications with a weak grid, where the frequent connection and disconnection of high power nonlinear loads can significantly affect the voltage waveform quality.

This article compares the most prominent overmodulation (OVM) techniques for five-phase induction motor drives with respect to the minimum current distortion (MCD) achievable. To attain a benchmark of the latter, two MCD OVM approaches are devised. Contrarily to previous strategies aimed at voltage distortion reduction/minimization, these MCD methods are focused on minimizing the harmonic stator copper loss (HSCL), thus minimizing the current total harmonic distortion (THD). One of these MCD strategies minimizes the HSCL while injecting only $x$–$y$ harmonics. The other MCD method exploits $\alpha$–$\beta$ harmonic injection to further decrease the HSCL and to cover the whole OVM region. Moreover, the dual-mode OVM, which is one of the three-phase methods with the lowest distortion, is extended here for five-phase drives. The findings provide insight into how close the OVM methods are to the benchmark imposed by the MCD strategies. Notably, these MCD techniques yield a significant reduction of current THD, HSCL, and peak current, especially for machines with negligible third-order space harmonic. The average switching losses are also decreased. Indications for real-time implementation of the MCD solutions are also given.

This article presents a voltage controller designed to operate grid-forming (GFM) converters under different grid impedance scenarios demonstrating good performance in conjunction with external power-synchronization loops (PSLs), e.g., droop control. GFM converters are required to have fast, accurate and stable voltage–frequency response, self-synchronization, power balance, grid supporting and fault ride-through (FRT) capabilities; either they are connected to the grid or to other generators. State-of-the-art voltage controllers are mainly focused on achieving either good voltage tracking and disturbance rejection or wide stability range and robustness. This proposal fulfils both tendencies as, first, it shows fast dynamic response, accurate voltage tracking, and total cancellation of output current disturbances at both positive-and negative-sequences of fundamental frequency because the controller presents zero-output impedance. Second, the controller shows a good sensitivity function and a wide stability range, which permit its operation in grid-connected and stand-alone mode. Finally, the proposed controller exhibits a good performance combined with a PSL under a wide range of grid impedance scenarios, showing seamless transition between grid-connected and stand-alone mode and vice versa, demonstrating also FRT capabilities preserving GFM operation under symmetrical and asymmetrical grid-fault events.

Harmonic content of the line current of mains-connected equipment destined for use in Europe is regulated by IEC 1000-3-2. This standard defines four different classes for electronic equipment (class A, B, C, D). These classes establish different current harmonic limits depending on the use of the electronic equipment. Class A and class D are applied to equipment classified in the field of consumer electronics as: television receivers, personal computers, home electrical appliance, audio equipment, etc. This paper presents the analysis and design procedure of the input section of electronic equipment classified as class A. This novel analysis describes how to select the values for the filter in order to improve the margin of compliance. (1). Index Terms--Harmonic, IEC 1000-3-2 Standard, Power Factor Corrector (PFC).

IMPORTANCE: A clear dosing regimen for methotrexate in psoriasis is lacking, and this might lead to a suboptimal treatment. Because methotrexate is affordable and globally available, a uniform dosing regimen could potentially optimize the treatment of patients with psoriasis worldwide. OBJECTIVE: To reach international consensus among psoriasis experts on a uniform dosing regimen for treatment with methotrexate in adult and pediatric patients with psoriasis and identify potential future research topics. DESIGN, SETTING, AND PARTICIPANTS: Between September 2020 and March 2021, a survey study with a modified eDelphi procedure that was developed and distributed by the Amsterdam University Medical Center and completed by 180 participants worldwide (55 [30.6%] resided in non-Western countries) was conducted in 3 rounds. The proposals on which no consensus was reached were discussed in a conference meeting (June 2021). Participants voted on 21 proposals with a 9-point scale (1-3 disagree, 4-6 neither agree nor disagree, 7-9 agree) and were recruited through the Skin Inflammation and Psoriasis International Network and European Academy of Dermatology and Venereology in June 2020. Apart from being a dermatologist/dermatology resident, there were no specific criteria for participation in the survey. The participants worked mainly at a university hospital (97 [53.9%]) and were experienced in treating patients with psoriasis with methotrexate (163 [91.6%] had more than 10 years of experience). MAIN OUTCOMES AND MEASURES: In a survey with eDelphi procedure, we tried to reach consensus on 21 proposals. Consensus was defined as less than 15% voting disagree (1-3). For the consensus meeting, consensus was defined as less than 30% voting disagree. RESULTS: Of 251 participants, 180 (71.7%) completed all 3 survey rounds, and 58 participants (23.1%) joined the conference meeting. Consensus was achieved on 11 proposals in round 1, 3 proposals in round 2, and 2 proposals in round 3. In the consensus meeting, consensus was achieved on 4 proposals. More research is needed, especially for the proposals on folic acid and the dosing of methotrexate for treating subpopulations such as children and vulnerable patients. CONCLUSIONS AND RELEVANCE: In this eDelphi consensus study, consensus was reached on 20 of 21 proposals involving methotrexate dosing in patients with psoriasis. This consensus may potentially be used to harmonize the treatment with methotrexate in patients with psoriasis.

I introduce a stability notion, dynamic stability, for two‐sided dynamic matching markets where (i) matching opportunities arrive over time, (ii) matching is one‐to‐one, and (iii) matching is irreversible. The definition addresses two conceptual issues. First, since not all agents are available to match at the same time, one must establish which agents are allowed to form blocking pairs. Second, dynamic matching markets exhibit a form of externality that is not present in static markets: an agent's payoff from remaining unmatched cannot be defined independently of other contemporaneous agents' outcomes. Dynamically stable matchings always exist. Dynamic stability is a necessary condition to ensure timely participation in the economy by ensuring that agents do not strategically delay the time at which they are available to match.

Patients with nonmelanoma skin cancer (NMSC)—ie, basal cell carcinoma (BCC) or squamous cell carcinoma (SCC)—have an increased risk of developing a second skin cancer. The aim of this study was to describe the frequency, incidence per 1000 person-years, and predictors of a second skin cancer in a cohort of patients with NMSC treated with Mohs micrographic surgery (MMS).

The article reports that in the summer of 1628, when Rubens arrived in Madrid for the second time, he met two important people for him as his client and friend Ambrosio de Spínola, Marquis de los Balbases, a Genoese in the service of the Spanish Crown and one of the most important generals important of the Spanish army and the painter had portrayed him on several occasions and, at his service, he had to carry out numerous diplomatic missions.

Copyright of Revista Istmo is the property of Centros Culturales de Mexico, A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hand eczema is common in patients with atopic dermatitis (AD), but few studies have described the characteristics of these patients in large, representative populations from different geographic regions and occupational settings.

La dermatitis de las manos (DM) es frecuente en los pacientes con dermatitis atópica (DA). Pocos estudios describen las características de estos pacientes a partir de poblaciones amplias y representativas de ámbitos geográficos y laborales diferentes.

Finite-set model predictive control (FS-MPC) as predictive current control (PCC) is considered an exciting option for the stator current control of multiphase machines due to their control flexibility and easy inclusion of constraints. The weighting factors (WFs) of PCC must be tuned for the variables of interest, such as the machine losses $x-y$ currents, typically performed by trial-and-error procedure. Tuning methods based on artificial neural network (ANN) or the coefficient of variation were proposed for three-phase inverter and motor drive applications. However, the extension of this concept to the multiphase machine application is not straightforward, and only empirical procedures have been reported. In this context, this article proposes an optimal method to tune the WF of the PCC based on the multiobjective particle swarm optimization (MOPSO) algorithm. A Pareto dominance concept is used for the MOPSO to find the optimal WF values for the PCC, comparing parameters of root-mean-square error of the stator tracking currents. The proposed method offers a systematic approach to the WF selection, with an algorithm of easy implementation with direct control over the size of the search space and the speed of convergence. Simulation and experimental results in steady-state and transient conditions are provided to validate the proposed offline tuning procedure of the PCC of a six-phase induction machine. The improvements of RMSE can be more than 500% for $x-y$ subspace, with minor effect in $\alpha -\beta $ subspace. Finally, the proposed method is extended to a more complex cost function, and the results are compared with an ANN approach.