Torque Ripple Minimization for a Permanent Magnet Synchronous Motor Using a Modified Quasi-Z-Source Inverter

This paper presents a torque ripple minimization method for a permanent magnet synchronous motor (PMSM) drive system that utilizes a modified quasi-Z-source (qZS) inverter. The proposed modified qZS network is designed by adding an extra switching device to the conventional qZS topology and provides a wider range of capabilities for inverter input voltage control, e.g., both step-up and step-down operations. It also allows for modification of the traditional switching sequence selection scheme when using the space vector modulation (SVM) for switching. The provided flexibilities are leveraged to develop a control system that minimizes the torque ripples during PMSM operation while satisfying conventional control objectives such as shaft speed control. The control system is comprised of an input voltage optimization subsystem with the goal of torque ripple minimization, which provides the reference for a cascaded modulated model predictive control subsystem for the modified qZS network control, and a motor side predictive control subsystem. The control system employs a new switching sequence selection scheme for SVM modulation to further reduce PMSM torque ripples. Experimental results are provided to validate the theoretical outcomes

Utjecaj toplinskog stresa i različita vremena osjemenjivanja na postotak steonosti muznih krava

The objective of this study was to evaluate three synchronization fix timed-AI protocols throughout the year on one commercial dairy farm in a semi-arid zone. Mean temperature-humidity indices (THI) were 77.5, 84.9, 70.8 and 58.8 in spring, summer, autumn and winter, respectively. Insemination was synchronized in 3 groups of healthy Holstein Friesian dairy cows (Body Condition Score 2.25-3; scale 1-5) using controlled intravaginal drug release (CIDR) +E2 (n = 99), CIDR+GnRH (n = 38), or Select-Ovsynch (n = 181). Pregnancy diagnosis was done by rectal palpation 45-50 days after one AI. Pregnancy rate did not differ between the three methods, but was lower (P0.05), but rates were lower in spring than in winter (P0,05), ali je u proljeće postotak bio niži nego zimi (P<0,05). U navedenoj polusušnoj zoni visoki THI ima negativan učinak na plodnost muznih krava te se nijedan od triju primijenjenih protokola nije pokazao dobrim za plodnost u ljetnom razdoblju. Prema tome, trebalo bi uvesti sezonsko planiranje teljenja u kojem bi životinje bile osjemenjivane u hladnije doba godine

Comparative cervical cytology and conception rate in postpartum dairy cows

During the early postpartum period, multiple bacterial species invade the uterus of cows. Phagocytosis by polymorphonuclear cells is a primary mechanism involved in the elimination of bacteria and improvement of conception rate. Therefore, a relationship could exist between endometrial cytology and conception rate of postpartum dairy cows. In this study 50 postpartum healthy Holstein Frisian dairy cows were selected. They had a normal parturition history and had no mucopurulent discharge from vulva or abnormality in rectal palpation. Cervical mucosal discharge was collected from all cows on days 25 to 30 and 55 to 60 postpartum. Blood progesterone levels were determined in all cows by radioimmunoassay (RIA). Differential cellular counts were carried out from a Giemsa-stained smear of the mucosa. Data were analyzed by Independent T test, one-way ANOVA, and Duncan’s multiple range tests. There was no significant difference between cell percentages at different times or in number of postpartum artificial inseminations (P≥0.05). However, when cows were divided into two groups to progesterone above 1 ng/mL and below 1 ng/mL, there were significant differences (P<0.05) between neutrophil percentages at different times after parturition and artificial insemination number (1 and 2 or 3). The result of this study showed that cytological evaluation of cervical smear is helpful for diagnosis and treatment of subclinical endometritis and prognosis of postpartum fertility

Fault-Tolerant Space Vector Modulation for Modular Multilevel Converters With Bypassed Faulty Submodules

This paper develops a modulation based fault-tolerant (FT) strategy for restoring the operation of three-phase modular multilevel converters (MMCs) with faulty switches. This FT strategy is based on a proposed modified space vector modulation (SVM) technique that generates balanced line-to-line (line) voltages even in the case of a fault occurrence. In the postfault operation, the proposed strategy is able to restore the fundamental amplitude of the line to the neutral (load) voltages to that of the normal operation condition with a slightly increased voltage stress over the switches in the faulty phase. In this paper, first a brief background about MMCs and SVM technique is provided. Then, the proposed FT strategy and the modified SVM technique are presented. Finally, several simulation and experimental results are provided to validate operation of the proposed strategy

Demographics of Fall-Related trauma among the Elderly Presenting to Emergency Department; a Cross-Sectional Study

Introduction: Falling is reported to be the most common cause of mortality due to trauma in individuals over the age of 75 years. The present study is designed with the aim of determining the demographics of fall-related trauma among the elderly presenting to emergency department (ED). Methods: The present prospective cross-sectional study was carried out on all elderly patients ≥ 60 years old presenting to ED of a major referral trauma center in North West of Iran during 1 year. Demographic data, location and height of falling, duration of hospitalization, trauma severity and in-hospital outcome of the patients were gathered and reported via descriptive statistics. Results: 228 patients with the mean age of 70.96 ± 5.2 years were studied (53.9% female). Most patients were in the 66-70 years age range (32.6%) and had a history of hypertension (22.3%), who had visited following a fall inside the house (69.3%), due to slipping (73.7%), and from a height equal to or less than 2m (71.9%). 6 (2.6%) patients died in the hospital. Mean trauma severity of patients based on ISS, RTS, and TRISS were 10.65 ± 3.95 (3-19), 7.84 ±.21 (1.4-14.5) and 1.66 ±1.31 (-1.49-3.82), respectively. Regarding need for hospitalization, only ISS shows a significant difference between outpatients and inpatients (p = 0.023). Patients who died had a significantly higher trauma severity based on ISS (p &lt; 0.0001) and RTS (p &lt; 0.0001). Conclusion: Based on the findings of the present study, slipping and syncope are the most common causes of  falling in the studied elderly that had mostly happened inside the house and from a height less than 2m. Therefore, most patients were in the mild to moderate range of trauma severity. ISS and RTS were significantly higher in the 6 (2.6%) patients who died

Prognostic investigations of B7-H1 and B7-H4 expression levels as independent predictor markers of renal cell carcinoma.

In order to evaluate the correlation of B7-H4 and B7-H1 with renal cell carcinoma (RCC), we analyzed B7-H1 and B7-H4 expressions and their clinical significance by immunohistochemical method. Our result indicated that B7-H4-positive staining was detected in 58.13 % of RCC tissues (25 tissues tumors), and there were 18 tissues of patients without detectable B7-H4. Furthermore, 21 cases (48.83 %) were B7-H1-positive. Positive tumor expressions of B7-H4 and B7-H1 were markedly related to advanced TNM stage (P = 0.001; P = 0.014), high grade (P = 0.001; P = 002), and larger tumor size (P = 0.002; P = 024) in RCC tissues than patients with B7-H4-negative and B7-H1-negative in RCC tissues. The patients with B7-H1 and B7-H4-positive expressions were found to be markedly correlated with the overall survival of the patients (P < 0.05) and tended to have an increased risk of death when compared with negative expression groups. Univariate analysis showed that B7-H4 and B7-H1 expressions, TNM stage, high grade, and tumor size were significantly related to the prognosis of RCC. Furthermore, multivariate analysis showed that B7-H4 and B7-H1 expressions decreased overall survival. The adjusted HR for B7-H1 was 2.83 (95 % CI 1.210-2.971; P = 0.031) and also was 2.918 (95 % CI 1.243-3.102; P = 0.006) for B7-H4 that showed these markers were independent prognostic factors in RCC patients. The expressions of B7-H1 and B7-H4 in RCC patients indicate that these markers may be as a predictor of tumor development and death risk. Further investigations can be helpful to confirm B7-H1 and B7-H4 roles as an independent predictor of clinical RCC outcome

Dichlorido(6-methyl-2,2′-bipyridine-κ2 N,N′)zinc(II)

In the mol­ecule of the title compound, [ZnCl2(C11H10N2)], the ZnII atom is four-coordinated in a distorted tetra­hedral configuration by two N atoms from the 6-methyl-2,2′-bipyridine ligand and by two Cl atoms. There are π–π contacts between the pyridine ring and the five-membered ring, and also between the pyridine rings, [centroid–centroid distances = 3.685 (3) and 3.757 (3) Å, respectively]

Trichlorido(5,5′-dimethyl-2,2′-bipyridine-κ2 N,N′)(methanol-κO)indium(III)

In the mol­ecule of the title compound, [InCl3(C12H12N2)(CH4O)], the InIII atom is six-coordinated in a distorted octa­hedral configuration by two N atoms from the chelating 5,5′-dimethyl-2,2′-bipyridine ligand, one O atom from a methanol molecule and three Cl atoms. In the crystal structure, inter­molecular O—H⋯Cl hydrogen bonds link the mol­ecules into chains parallel to [001]