Sixth-harmonic back-EMF based sensorless control for switched-flux permanent magnet machine

In switched-flux permanent magnet (SFPM) machines, the 6th-harmonic back electromotive force (EMF) is dominant, whilst the 3rd-harmonic back-EMF is much smaller. This paper proposes several new position estimation methods for sensorless control based on the 6th-harmonic back-EMF. Firstly, by detecting the zero-crossings of the 6th-harmonic back-EMF with/without eliminating the influence of the 3rd-harmonic back EMF, the related rotor positions can be determined precisely at these zero-crossings. However, since the intermediate rotor positions need to be determined by linear interpretation between two zero-crossings, it only exhibits excellent performance under steady state. Furthermore, the continuous rotor position can be estimated from the proposed new observer by utilizing the combined signals of 6th-harmonic back-EMF and flux-linkage, together with a synchronous reference frame filter (SRFF) and harmonic elimination. Experimental validation show that (a) by eliminating the 3rd-harmonic back-EMF effect, the accuracy of the proposed 6th-harmonic back-EMF zero-crossings detection method can be improved, (b) SRFF is effective to minimize the influence of non-constant amplitudes of the 6th-harmonic backEMF and flux-linkage, (c) the comparison between the fundamental, the 3rd-harmonic back-EMF and the proposed method are presented in order to highlight the effectiveness of proposed control strategy under different operating conditions

Improved high-frequency carrier voltage measurement for position estimation of switched-flux permanent magnet machines

The conventional 12/10 stator/rotor poles switched-flux permanent magnet (SFPM) machine is usually based on all poles wound topology, each phase comprising four winding coils in series connection. However, alternate coils of the same phase have different machine saliency characteristics. Moreover, in order to measure the high-frequency (HF) carrier voltage, the mid-tapered winding wires can be utilized. Consequently, the machine saliencies can be measured separately from two parts of winding coil connections. This paper investigates the influences of machine saliencies on the sensorless rotor position estimations based on different sequence of winding coil connections, in which the primary saliency may contain some additional harmonics referring to the secondary saliency that will degrade the overall sensorless control operations. Furthermore, a simple compensation method is proposed to reduce the influence of multiple saliencies to achieve more accurate sensorless rotor position estimation. By comparing with rotor positon estimations without the proposed compensation and HF carrier current based method, the effectiveness of improved sensorless rotor position estimation has been demonstrated experimentally, as well as the application to dual 3-phase SFPM machines

Corneal dendritic cells in diabetes mellitus: A narrative review

Diabetes mellitus is a global public health problem with both macrovascular and microvascular complications, such as diabetic corneal neuropathy (DCN). Using in-vivo confocal microscopy, corneal nerve changes in DCN patients can be examined. Additionally, changes in the morphology and quantity of corneal dendritic cells (DCs) in diabetic corneas have also been observed. DCs are bone marrow-derived antigen-presenting cells that serve both immunological and non-immunological roles in human corneas. However, the role and pathogenesis of corneal DC in diabetic corneas have not been well understood. In this article, we provide a comprehensive review of both animal and clinical studies that report changes in DCs, including the DC density, maturation stages, as well as relationships between the corneal DCs, corneal nerves, and corneal epithelium, in diabetic corneas. We have also discussed the associations between the changes in corneal DCs and various clinical or imaging parameters, including age, corneal nerve status, and blood metabolic parameters. Such information would provide valuable insight into the development of diagnostic, preventive, and therapeutic strategies for DM-associated ocular surface complications

WORKPLACE ORGANIZATION AND HUMAN RESOURCE PRACTICES: THE RETAIL FOOD INDUSTRY

Most retail food firms adhere to traditional human resources management practices, with employees enjoying little involvement in decision-making and little participation in company financial returns. More than one tenth of non-food firms have innovative human resources systems, with much individual and group involvement in decision-making and financial returns, but only a minuscule proportion of food firms have such systems. At the other end of the spectrum, more than one-fifth of food stores and eating and drinking places (and nearly one-third of food wholesale firms) have traditional systems, as compared to only one-tenth of non-food firms. The tasks and the human resource practices typical of retail food firms are consistent with each other. Core employees in these firms perform tasks that are generally simpler and less variable than those in other industries, and the firms' human resource practices generally give workers less autonomy and incentives than those in other industries. Whether the structure and variability of tasks are the result of a particular business strategy or adoption of a certain technology is not known. Which came first, these simple tasks, the workers who perform them, or these human resource policies is similarly unknown. We arrive at these conclusions through analysis of an original data set composed of 806 Minnesota firms, including 211 food firms, which allows us to characterize the change in human resource practices since the early 1980s, and to examine differences in the organization of work across companies. Work organization and human resource practices in the retail food industry have changed substantially, although the change has been less pronounced than in most other industries.Labor and Human Capital, Marketing,

Effects of epidural compression on stellate neurons and thalamocortical afferent fibers in the rat primary somatosensory cortex

A number of neurological disorders such as epidural hematoma can cause compression of cerebral cortex. We here tested the hypothesis that sustained compression of primary somatosensory cortex may affect stellate neurons and thalamocortical afferent (TCA) fibers. A rat model with barrel cortex subjected to bead epidural compression was used. Golgi‑Cox staining analyses showed the shrinkage of dendritic arbors and the stripping of dendritic spines of stellate neurons for at least 3 months post‑lesion. Anterograde tracing analyses exhibited a progressive decline of TCA fiber density in barrel field for 6 months post‑lesion. Due to the abrupt decrease of TCA fiber density at 3 days after compression, we further used electron microscopy to investigate the ultrastructure of TCA fibers at this time. Some TCA fiber terminal profiles with dissolved or darkened mitochondria and fewer synaptic vesicles were distorted and broken. Furthermore, the disruption of mitochondria and myelin sheath was observed in some myelinated TCA fibers. In addition, expressions of oxidative markers 3‑nitrotyrosine and 4‑hydroxynonenal were elevated in barrel field post‑lesion. Treatment of antioxidant ascorbic acid or apocynin was able to reverse the increase of oxidative stress and the decline of TCA fiber density, rather than the shrinkage of dendrites and the stripping of dendritic spines of stellate neurons post‑lesion. Together, these results indicate that sustained epidural compression of primary somatosensory cortex affects the TCA fibers and the dendrites of stellate neurons for a prolonged period. In addition, oxidative stress is responsible for the reduction of TCA fiber density in barrels rather than the shrinkage of dendrites and the stripping of dendritic spines of stellate neurons

Patient-oriented simulation based on Monte Carlo algorithm by using MRI data

<p>Abstract</p> <p>Background</p> <p>Although Monte Carlo simulations of light propagation in full segmented three-dimensional MRI based anatomical models of the human head have been reported in many articles. To our knowledge, there is no patient-oriented simulation for individualized calibration with NIRS measurement. Thus, we offer an approach for brain modeling based on image segmentation process with <it>in vivo </it>MRI T1 three-dimensional image to investigate the individualized calibration for NIRS measurement with Monte Carlo simulation.</p> <p>Methods</p> <p>In this study, an individualized brain is modeled based on <it>in vivo </it>MRI 3D image as five layers structure. The behavior of photon migration was studied for this individualized brain detections based on three-dimensional time-resolved Monte Carlo algorithm. During the Monte Carlo iteration, all photon paths were traced with various source-detector separations for characterization of brain structure to provide helpful information for individualized design of NIRS system.</p> <p>Results</p> <p>Our results indicate that the patient-oriented simulation can provide significant characteristics on the optimal choice of source-detector separation within 3.3 cm of individualized design in this case. Significant distortions were observed around the cerebral cortex folding. The spatial sensitivity profile penetrated deeper to the brain in the case of expanded CSF. This finding suggests that the optical method may provide not only functional signal from brain activation but also structural information of brain atrophy with the expanded CSF layer. The proposed modeling method also provides multi-wavelength for NIRS simulation to approach the practical NIRS measurement.</p> <p>Conclusions</p> <p>In this study, the three-dimensional time-resolved brain modeling method approaches the realistic human brain that provides useful information for NIRS systematic design and calibration for individualized case with prior MRI data.</p

Novel G9 rotavirus strains co-circulate in children and pigs, Taiwan

Molecular epidemiologic studies collecting information of the spatiotemporal distribution of rotavirus VP7 (G) and VP4 (P) genotypes have shown evidence for the increasing global importance of genotype G9 rotaviruses in humans and pigs. Sequence comparison of the VP7 gene of G9 strains identified different lineages to prevail in the respective host species although some of these lineages appear to be shared among heterologous hosts providing evidence of interspecies transmission events. The majority of these events indicates the pig-to-human spillover, although a reverse route of transmission cannot be excluded either. In this study, new variants of G9 rotaviruses were identified in two children with diarrhea and numerous pigs in Taiwan. Whole genome sequence and phylogenetic analyses of selected strains showed close genetic relationship among porcine and human strains suggesting zoonotic origin of Taiwanese human G9 strains detected in 2014–2015. Although the identified human G9P[19] and G9P[13] rotaviruses represented minority strains, the repeated detection of porcine-like rotavirus strains in Taiwanese children over time justifies the continuation of synchronized strain surveillance in humans and domestic animals

Percutaneous transhepatic techniques for retrieving fractured and intrahepatically dislodged percutaneous transhepatic biliary drainage catheters

Dislodged intrabiliary drainage devices, including catheters, endoprostheses, and stents, may further impair drainage and cause various local reactions, vascular and gastrointestinal tract complications. Endoscopic approaches for management of plastic biliary endoprostheses have been extensively discussed. However, in rare cases of fracture of percutaneous transhepatic biliary drainage (PTBD) catheters, only a percutaneous transhepatic technique for retrieving should be applied to avoid further damage by its rigid fragment. We present the adjusted techniques using either a goose neck snare, over-the-wire balloon catheter, or biopsy forceps with image demonstration and reviews. We encountered two patients with PTBD tube fracture and intrahepatic dislodgment. In both patients, percutaneous approaches were used for successfully retrieving and removing the fractured catheter through transhepatic tract: one with the use of a biopsy forceps, another with an inflatable balloon catheter