Apparatus for in situ measurement of light scattering during heat‐treatment.

A fully automated apparatus is described for the in situ measurement of light scattering in glass forming systems during heat treatment. Its furnace and regulator provide high‐temperature change rates of the order of several K/s. Additionally the sample temperature can be kept constant to within 0.1 K for several days in ranges up to 900 °C. A He–Ne laser provides linearly polarized light and the light scattered under 90° (or 15°) is detected using photodiodes and lock‐in amplifiers

Robust Non-Permanent Magnet Motors for Vehicle Propulsion

There has been growing interest in electrical machines that reduce or eliminate rare-earth material content. Traction applications are among the key applications where reducing cost and hence reduction or elimination of rare-earth materials is a key requirement. This paper will assess the potential of three non-permanent magnet options in the context of vehicle propulsion applications: 1) a conventional Switched Reluctance Machine (SRM), 2) a DC-biased Reluctance Machine (DCRM) and, 3) a Wound Field Flux Switching Machine (WFFSM). The three machines were designed to achieve the hybrid vehicle traction requirements of 55kW peak and 30kW continuous over a speed range going from 2800rpm to 14000rpm. Their performance will be compared and the key opportunities and challenges will be highlighted. Preliminary experimental results for the DCRM will be presented

Evaluation of strand-to-strand capacitance and dissipation factor in thermally aged enamelled coils for low-voltage electrical machines

© The Institution of Engineering and Technology 2019. The dissipation factor (i.e. tanδ) and insulation capacitance (IC) measurements are conventional monitoring methods for assessing the aging level of insulation systems. These quantities provide an invaluable indication of the dielectric losses within the insulating materials. However, how these values are affected by the aging processes due to thermal stresses have until today never been investigated fully. Thus, this study exhibits the influence of thermal aging on tanδ and IC of windings for electrical machines (EMs). The work is performed for class 200, round enamelled magnet wire specimens. The study aims at improving the design process of EMs for short duty cycle applications; hence, its outcome might be included at the design stage for enhancing reliability and lifetime. Random wound coils are chosen in the performed study, because they are the most common winding arrangement for low-voltage EMs, which are employed in a wide range of applications (e.g. from home appliances to aerospace motors). Based on the collected data, considerations regarding the impact of relative humidity on both the dissipation factor and IC are presented. Finally, the correlation between the partial discharge inception voltage and the diagnostic measurements is experimentally verified

Turn-turn short circuit fault management in permanent magnet machines

This paper presents a systematic study on turn-turn short circuit fault and ways to manage them to provide a basis for comparison of the various options available. The possible methods to reduce the likelihood of the winding SC fault and the fault mitigation techniques related to such faults are discussed. A Finite Element (FE) analysis of a surface-mount Permanent Magnet (PM) machine under application of different mitigation techniques during a turn-turn fault is presented. Both machine and drive structural adaptations for different fault mitigation techniques are addressed. Amongst the investigated fault mitigation techniques, the most promising solution is identified and validated experimentally. It is shown that the shorting terminal method adopting vertical winding arrangement is an effective method in terms of the implementation, reliability and weight

Detection and classification of turn fault and high-resistance connection fault in inverter-fed permanent magnet machines based on high-frequency signals

Winding turn fault and high-resistance connection (HRC) fault will lead to different consequences and require different mitigation actions. In this study, the differentiating features between a turn fault and HRC fault are analysed and compared in a three-phase surface-mounted permanent magnet machine fed by the inverter with pulse-width-modulation voltages. The resultant high-frequency components in both voltages and currents are utilised for the fault detection and classification based on the high-frequency impedance and ripple current, without requiring modifications to the machine or interface design. Extensive simulations show that this method is capable of fault detection and classification in both transient and steady-state operations

Condition monitoring approach for permanent magnet synchronous motor drives based on the INFORM method

This paper proposes a monitoring scheme based on saliency tracking to assess the health condition of PMSM drives operating under non stationary conditions. The evaluated scheme is based on the INFORM methodology, which is associated to the accurate sensorless control of PM drives without zero speed limitation. The result is a monitoring scheme that is able to detect faults that would be very difficult to evaluate under nonstationary conditions. A relevant aspect of the proposed scheme is that it remains valid for full speed range, and can be used for standstill operation. Additionally, the approach is insensitive to the inverter nonlinearities which enhance the detection capabilities further respect to similar topologies. In this work the proposed approach is evaluated numerically and experimentally in the presence of incipient winding faults and inter-turn short circuits in a PM conventional drive. The obtained results show quick response and excellent detection capabilities not only in the detection of faults, but to determine their magnitude which is vital to avoid further degradation

Data Gained from Smart Services in SMEs–Pilot Study

Nowadays, manufacturing companies increasingly invest in servitization by adopting ‘smart services’ enabled by connected product-service systems enabling data exchange between the customer and the service provider. Managing the transition toward smart services is not easy, especially among SMEs as many businesses struggle with lack of money, insufficient digital technologies, unskilled employees or gathering and using the proper data. The research presented in this paper is divided into two parts. The quantitative part focuses on researching possible correlations between business performance and the use of company IT systems among sixty Czech electrotechnical SMEs. The other part consists of a qualitative multi-case study and was conducted among seven Czech electrotechnical SMEs which have already started with smart service development. The findings indicate that companies gather and use the data in very different ways. They provide information to their customers, but also use information for themselves. The study is unique in highlighting the problems of smart services in small and medium manufacturers. Moreover, it investigates the gathering and the data usage gained from smart services in SMEs.Nowadays, manufacturing companies increasingly invest in servitization by adopting ‘smart services’ enabled by connected product-service systems enabling data exchange between the customer and the service provider. Managing the transition toward smart services is not easy, especially among SMEs as many businesses struggle with lack of money, insufficient digital technologies, unskilled employees or gathering and using the proper data. The research presented in this paper is divided into two parts. The quantitative part focuses on researching possible correlations between business performance and the use of company IT systems among sixty Czech electrotechnical SMEs. The other part consists of a qualitative multi-case study and was conducted among seven Czech electrotechnical SMEs which have already started with smart service development. The findings indicate that companies gather and use the data in very different ways. They provide information to their customers, but also use information for themselves. The study is unique in highlighting the problems of smart services in small and medium manufacturers. Moreover, it investigates the gathering and the data usage gained from smart services in SMEs

Relationship of metabolic syndrome and its components with -844 G/A and HindIII C/G PAI-1 gene polymorphisms in Mexican children

<p>Abstract</p> <p>Background</p> <p>Several association studies have shown that -844 G/A and <it>HindIII </it>C/G <it>PAI-1 </it>polymorphisms are related with increase of PAI-1 levels, obesity, insulin resistance, glucose intolerance, hypertension and dyslipidemia, which are components of metabolic syndrome. The aim of this study was to analyze the allele and genotype frequencies of these polymorphisms in <it>PAI-1 </it>gene and its association with metabolic syndrome and its components in a sample of Mexican mestizo children.</p> <p>Methods</p> <p>This study included 100 children with an age range between 6-11 years divided in two groups: a) 48 children diagnosed with metabolic syndrome and b) 52 children metabolically healthy without any clinical and biochemical alteration. Metabolic syndrome was defined as the presence of three or more of the following criteria: fasting glucose levels ≥ 100 mg/dL, triglycerides ≥ 150 mg/dL, HDL-cholesterol < 40 mg/dL, obesity BMI ≥ 95^thpercentile, systolic blood pressure (SBP) and diastolic blood pressure (DBP) ≥ 95^thpercentile and insulin resistance HOMA-IR ≥ 2.4. The -844 G/A and <it>HindIII </it>C/G <it>PAI-1 </it>polymorphisms were analyzed by PCR-RFLP.</p> <p>Results</p> <p>For the -844 G/A polymorphism, the G/A genotype (OR = 2.79; 95% CI, 1.11-7.08; <it>p </it>= 0.015) and the A allele (OR = 2.2; 95% CI, 1.10-4.43; <it>p </it>= 0.015) were associated with metabolic syndrome. The -844 G/A and A/A genotypes were associated with increase in plasma triglycerides levels (OR = 2.6; 95% CI, 1.16 to 6.04; <it>p </it>= 0.02), decrease in plasma HDL-cholesterol levels (OR = 2.4; 95% CI, 1.06 to 5.42; <it>p </it>= 0.03) and obesity (OR = 2.6; 95% CI, 1.17-5.92; <it>p </it>= 0.01). The C/G and G/G genotypes of the <it>HindIII </it>C/G polymorphism contributed to a significant increase in plasma total cholesterol levels (179 vs. 165 mg/dL; <it>p </it>= 0.02) in comparison with C/C genotype.</p> <p>Conclusions</p> <p>The -844 G/A <it>PAI-1 </it>polymorphism is related with the risk of developing metabolic syndrome, obesity and atherogenic dyslipidemia, and the <it>HindIII </it>C/G <it>PAI-1 </it>polymorphism was associated with the increase of total cholesterol levels in Mexican children.</p