The operating region of the modular multilevel converter (MMC) is limited by the maximum-allowable voltage ripple of cells, which is associated with the arm energy variation. Injecting the controlled ...second-order harmonic component into the circulating current can reduce energy variation of the arm and, thus, extend the operating region of MMC. Care must be taken, however, that the second-order circulating current affects the arm current, and inappropriately injected harmonic current may cause an undesirable arm current polarity change. Therefore, this paper first investigates and proposes the maximum-allowable second-order circulating current for extending the operating region reliably and efficiently. The active and reactive power capability of MMC is further elaborated and illustrated in line with the maximum excess energy capability for two cases, running with: 1) the original operating region and 2) the extended operating region. Finally, the P- Q diagrams for contingent operating conditions with faulty or disabled submodules are presented. Understanding the unique shape and change of P- Q capability with credible submodule failure contingency should be crucial for planning MMC-HVDC lines, and determining the energy requirements and the level of redundancy in submodules properly in order to achieve the envisioned benefits of the new HVDC. The efficacy and accuracy of the research findings are validated for the MMC-HVDC system using PSCAD/EMTDC.
In this paper, a novel calculation method of references on current amplitude and current angle of a vector inverter for an interior permanent magnet synchronous motor is proposed using FEM. For a ...vehicle application, the current information should be calculated effectively within the driving range while satisfying limitation value of battery voltage. Moreover, the parameters related to current and voltage information have nonlinear characteristics because of high power density of traction motor. FEM is used to calculate exact solution considering nonlinear characteristics. The proposed method for current references only uses several load angle curves of traction motor by FEM according to specified current values. By using load angle curves, the driving currents information for vector inverter can be calculated and interpolated effectively including field weakening region as well as constant torque region satisfying limitation of battery voltage.
This paper presents the optimal rotor design method in a single-phase line-start permanent magnet motor (LSPM) considering the starting torque and efficiency. To consider nonlinear characteristics, ...the design process is comprised of the FEM and analytical method. During this study, permanent-magnets and cage bars were designed using the magnetic equivalent circuit method and the barriers that control all magnetic flux were designed using the FEM, and the tradeoff of starting torque and efficiency is controlled by weight function in Taguchi method simulation. Finally, the performance of the optimal model is compared with those of conventional models.
The most common type of electric vehicle traction motor is the interior permanent magnet synchronous motor (IPMSM). For IPMSM designs, engineers make use of the magnetic equivalent circuit method, ...which is a lumped constant circuit method, and the finite element method, which is a distributed constant circuit method. The magnetic equivalent circuit method is useful for simple design through fast and intuitive parameters, but it cannot derive the distribution of the magnetic field. The finite element method can derive an accurate magnetic field distribution, but it takes a long time and is difficult to use for analysis of intuitive design parameters. In this study, the magnetic equivalent circuit method and Carter’s coefficient were combined for rotor structure design and accurate identification and analysis of circuit constants. In this paper, this design method is called the hybrid magnetic equivalent circuit method. Intuitive design parameters are derived through this hybrid magnetic equivalent circuit method. The air gap flux density distribution according to rotor shape, no-load-induced voltage, and cogging torque was analyzed and compared to results of the finite element method. The proposed method was found to achieve a short solving time and acceptably accurate results.
Autism spectrum disorder (ASD) is a heterogeneously pervasive developmental disorder in which various genetic and environmental factors are believed to underlie its development. Recently, epigenetics ...has been suggested as a novel concept for ASD aetiology with a proposition that epigenetic marks can be transgenerationally inherited. Based on this assumption of epigenetics, we investigated the transgenerational inheritance of ASD-like behaviours and their related synaptic changes in the VPA animal model of ASD. The first generation (F1) VPA-exposed offspring exhibited autistic-like impaired sociability and increased marble burying. They also showed increased seizure susceptibility, hyperactivity and decreased anxiety. We mated the VPA-exposed F1 male offspring with naïve females to produce the second generation (F2), and then similarly mated the F2 to deliver the third generation (F3). Remarkably, the autism-like behavioural phenotypes found in F1 persisted to the F2 and F3. Additionally, the frontal cortices of F1 and F3 showed some imbalanced expressions of excitatory/inhibitory synaptic markers, suggesting a transgenerational epigenetic inheritance. These results open the idea that E/I imbalance and ASD-like behavioural changes induced by environmental insults in mice can be epigenetically transmitted, at least, to the third generation. This study could help explain the unprecedented increase in ASD prevalence.
This paper presents a study on shape design of permanent magnets that is focused on robustness for cogging torque, sinusoidal back emf, and partial demagnetization of the permanent magnet of the ...outer rotor permanent magnet synchronous motor (PMSM). The simulation method for partial demagnetization is proposed and performed with four kinds of permanent magnet shape models at the fault current and two kinds of load angles corresponding to maximum torque operation and short circuit operation by finite-element method (FEM). The robust shape model of permanent magnets for large-sized hybrid electric vehicles is presented. The characteristics after partial demagnetization are analyzed and compared with experimental results for verification of the partial demagnetization effect
A previous animal study demonstrated that the administration of Omija extract and soybean mixture (OSM) improved glycemic control in the type 2 diabetes model. In this study, we conducted a 12-week, ...randomized, double-blinded, and placebo-controlled clinical trial to determine the effects of OSM in humans with hyperglycemia. Participants with fasting plasma concentrations of 100–140 mg/dL were enrolled (n = 80) and administered either OSM or placebo products for 12 weeks. The outcomes included measurements of efficacy (fasting plasma glucose (FPG), postprandial glucose (PPG), fasting plasma insulin (FPI), postprandial insulin (PPI), hemoglobin A1c (HbA1c), C-peptide, fructosamine, and lipid parameters) and safety at baseline and at 12 weeks. After the intervention, the OSM group showed significantly decreased levels of FPG, PPG (30, 60 min), PPI (60 min), insulin area under the curve (AUC), fructosamine, and low-density-lipoprotein (LDL) cholesterol compared to the placebo group. No clinically significant changes in any safety parameter were observed. Therefore, it is hypothesized that OSM supplementation is an effective and safe functional food supplement for humans with hyperglycemia.
Abstract Introduction Some studies have reported that fracture pattern was also associated with reduction loss after surgery. The purpose of this study was to evaluate various factors that can ...influence reduction loss, including fracture patterns in unicondylar and bicondylar tibial plateau fractures. Materials and methods A total of 138 tibial plateau fractures that underwent open reduction and internal fixation using plates were retrospectively reviewed. The OTA/AO classification, fracture pattern, degree of comminution, and existence of reduction loss were evaluated based on simple radiographs and computed tomography. Patient information, including age, gender, and occupation, were acquired through chart reviews. The effect of each variable on reduction loss was evaluated through multiple logistic regression analysis. Results Of 138 knees, reduction loss was observed in 40 knees (28.9%). Reduction loss was found in 11 (20.4%) of the type B knees (54 knees) and 29 (34.9%) of the type C knees (83 knees), according to the OTA/AO classification. The multiple logistic regression analysis for all cases revealed that the existence of comminution and coronal fracture influenced the occurrence of reduction loss, with odds ratios of 9.148 and 4.823, respectively (P < 0.001 and P = 0.001, respectively). In type B and type C, according to the OTA/AO classification, the existence of comminution and coronal fracture had causal relationships with the occurrence of reduction loss. The odds ratios of comminution and coronal fracture for reduction loss for type B were 9.114 and 9.117, respectively (P = 0.019 and P = 0.031, respectively), and the odds ratios for type C were 8.490 and 4.782, respectively (P = 0.001 and 0.009, respectively). Conclusions When a tibial plateau fracture has a coronal fracture, if it is difficult to fix its fragments rigidly with medial or lateral plate fixation; therefore, buttress plating or direct fixation of fragments through the posteromedial, posterolateral, or posterior approach should be considered.
Autism spectrum disorder (ASD) is a pervasive developmental disorder characterized by three main behavioral symptoms including social deficits, impaired communication, and stereotyped and repetitive ...behaviors. ASD prevalence shows gender bias to male. Prenatal exposure to valproic acid (VPA), a drug used in epilepsy and bipolar disorder, induces autistic symptoms in both human and rodents. As we reported previously, prenatally VPA‐exposed animals at E12 showed impairment in social behavior without any overt reproductive toxicity. Social interactions were not significantly different between male and female rats in control condition. However, VPA‐exposed male offspring showed significantly impaired social interaction while female offspring showed only marginal deficits in social interaction. Similar male inclination was observed in hyperactivity behavior induced by VPA. In addition to the ASD‐like behavioral phenotype, prenatally VPA‐exposed rat offspring shows crooked tail phenotype, which was not different between male and female groups. Both male and female rat showed reduced GABAergic neuronal marker GAD and increased glutamatergic neuronal marker vGluT1 expression. Interestingly, despite of the similar increased expression of vGluT1, post‐synaptic marker proteins such as PSD‐95 and α‐CAMKII expression was significantly elevated only in male offspring. Electron microscopy showed increased number of post‐synapse in male but not in female at 4 weeks of age. These results might suggest that the altered glutamatergic neuronal differentiation leads to deranged post‐synaptic maturation only in male offspring prenatally exposed to VPA. Consistent with the increased post‐synaptic compartment, VPA‐exposed male rats showed higher sensitivity to electric shock than VPA‐exposed female rats. These results suggest that prenatally VPA‐exposed rats show the male preponderance of ASD‐like behaviors including defective social interaction similar to human autistic patients, which might be caused by ectopic increase in glutamatergic synapses in male rats.
Prenatal VPA exposure induces male inclined autistic symptoms including impaired social interactions and seizure susceptibility in rat fetus. These gender‐specific impairments of VPA‐exposed rats, which are similar to human autistic patients, may provide experimental models to elucidate the gender‐dependent symptoms and molecular mechanisms in anti‐social disorders including ASD, especially focusing on the development of excitatory/inhibitory nervous systems and synapses.
This article solves the problem caused by high level current feedback gain setting for fast responsiveness of magnetic levitation systems considering the current dynamics and presents advanced ...nonlinear positioning technology without plant parameter information. The main features of this study are summarized as follows: First, current control demonstrates current ripple reduction and overall performance guarantee through a low feedback gain in the steady state, including a dynamic feedback loop increased by an error variable magnitude in the transient period. Second, the plant parameter information-free velocity observer replaces the observer output error integral action with the disturbance estimation action to improve the closed-loop performance. The simulation results reveal the practical advantages derived from the contributions of this study.
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