Analysis of optimal operating modes of the induction traction drives for establishing a control algorithm over a semiconductor transducer

Оптимізовано режими роботи тягового асинхронного приводу тепловоза за критерієм ефективності. Ідентифіковано оптимальні режими керування автономного інвертору напруги при різних температурах обмоток тягових двигунів. Проаналізовано оптимальні режими роботи тягового приводу тепловоза та трамваю, що дозволило встановити відмінності розташування точки переходу з просторово-векторної до однократної ШІМ від температури двигуна

Аналіз теплового стану індуктора електромагнітного млина з охолодженням оливою у стаціонарних режимах роботи

Introduction. An electromagnetic mill (EMM) for the technological processing of various substances, which is based on the stator of a three-phase induction motor, is being studied. The stator winding has an increased current density, so the mill is provided with a system of forced cooling with transformer oil. Problem. Currently, there are no works on the thermal state calculation of the EMM with the given design and oil cooling. Therefore, the study of such EMMs thermal state is relevant, as it will contribute to increasing the reliability and efficiency of their work. Goal. Formation of a mathematical model of the thermal state of the electromagnetic mill inductor and the analysis of its heating in stationary modes of operation with cooling by transformer oil. Methodology. The problem of calculating the thermal state, namely the temperature distribution in the main parts of the electromagnetic mill, is solved by the equivalent thermal resistance circuit method. The design of the EMM is provided in a sufficiently complete volume, and on this basis, a corresponding equivalent thermal replacement circuit is formed, which is supplemented by an equivalent hydraulic circuit of oil passageways. An explanation is provided for the composition and solution of the equations algebraic system that describes the distribution of temperatures by the constituent elements of the EMM. Results. The thermal calculation results of the electromagnetic mill showed that the maximum heating temperature is much lower than the allowable one for the selected insulation class. According to the hydraulic scheme, the necessary oil consumption, its average speed and the corresponding pressure at the inlet of the intake pipe are determined, which are at an acceptable level. It is noted that the rather moderate temperature state of the inductor and the hydraulic parameters of the oil path are facilitated by such innovations in the design of the EMM as the loop double layer short chorded winding and axial ventilation channels in the stator core. Originality. Now EMM thermal equivalent circuits with air cooling only have been presented. Therefore, the developed thermal circuit of the oil-cooled inductor is new and makes it possible to evaluate the operating modes of the EMM. Practical value. The proposed technical solutions can be recommended for practical implementation in other EMMs. Taking into account the identified reserves of the EMM temperature state, a forecast was made regarding the transition from its oil cooling to air cooling. But the use of air cooling requires a change in the design of the EMM.Проблема. Досліджується електромагнітний млин (ЕММ) для технологічної обробки різних речовин, який виконано на базі статора трифазного асинхронного двигуна. Обмотка статора має підвищену густину струму, тому для млина передбачена система примусового охолодження трансформаторною оливою. Наразі робіт з розрахунку теплового стану ЕММ з наданою конструкцією і охолодженням оливою не представлено. Тому дослідження теплового стану таких ЕММ є актуальним, бо сприятиме підвищенню надійності та ефективності їх роботи. Метою статті є формування математичної моделі теплового стану індуктора електромагнітного млина та аналіз його нагріву у стаціонарних режимах роботи з охолодженням трансформаторною оливою. Задача розрахунку теплового стану, а саме – розподілу температури в основних частинах індуктора електромагнітного млина, розв’язується методом еквівалентних теплових схем. Конструкція ЕММ надана у достатньо повному обсязі і на цій основі сформована відповідна еквівалентна теплова схема заміщення, яка доповнена еквівалентною гідравлічною схемою шляхів проходження оливи. Надано пояснення щодо складання та розв’язання алгебраїчної системи рівнянь, які описують розподіл температур по складовим елементам індуктора ЕММ. Результати теплового розрахунку індуктора ЕММ показали, що максимальна температура нагріву значно менша за допустиму для обраного класу нагрівостійкості ізоляції. За гідравлічною схемою індуктора визначено необхідні витрати оливи, її середню швидкість і відповідний тиск на вході у впускний патрубок, які знаходяться на допустимому рівні. Зазначено, що досить помірному температурному стану індуктора і гідравлічним параметрам тракту оливи сприяють такі нововведення в конструкцію ЕММ, як двошарова скорочена петльова обмотка статора і аксіальні вентиляційні канали в осерді статора. Натепер були представлені теплові еквівалентні схеми ЕММ лише з повітряним охолодженням. Тому розроблена теплова схема індуктора з охолодженням оливою є новою і дає можливість оцінки режимів роботи ЕММ

Resistance to MPTP-Neurotoxicity in α-Synuclein Knockout Mice Is Complemented by Human α-Synuclein and Associated with Increased β-Synuclein and Akt Activation

Genetic and biochemical abnormalities of α-synuclein are associated with the pathogenesis of Parkinson's disease. In the present study we investigated the in vivo interaction of mouse and human α-synuclein with the potent parkinsonian neurotoxin, MPTP. We find that while lack of mouse α-synuclein in mice is associated with reduced vulnerability to MPTP, increased levels of human α-synuclein expression is not associated with obvious changes in the vulnerability of dopaminergic neurons to MPTP. However, expressing human α-synuclein variants (human wild type or A53T) in the α-synuclein null mice completely restores the vulnerability of nigral dopaminergic neurons to MPTP. These results indicate that human α-synuclein can functionally replace mouse α-synuclein in regard to vulnerability of dopaminergic neurons to MPTP-toxicity. Significantly, α-synuclein null mice and wild type mice were equally sensitive to neurodegeneration induced by 2′NH2-MPTP, a MPTP analog that is selective for serotoninergic and noradrenergic neurons. These results suggest that effects of α-synuclein on MPTP like compounds are selective for nigral dopaminergic neurons. Immunoblot analysis of β-synuclein and Akt levels in the mice reveals selective increases in β-synuclein and phosphorylated Akt levels in ventral midbrain, but not in other brain regions, of α-synuclein null mice, implicating the α-synuclein-level dependent regulation of β-synuclein expression in modulation of MPTP-toxicity by α-synuclein. Together these findings provide new mechanistic insights on the role α-synuclein in modulating neurodegenerative phenotypes by regulation of Akt-mediated cell survival signaling in vivo

Impact of water, exposed to a static magnetic field, on the diapausing artemia cysts

Биологическим эффектам взаимодействия физических полей с биологическими объектами уделяется достаточно много внимания вследствие их широкого применения в различных областях деятельности человека. Исследовали влияние воды, подвергнутой действию постоянного магнитного поля (0,108 Тл и 0,208 Тл) с учетом северного (N-группа) и южного (S-группа) полюсов, на вылупление науплиев из цист артемии и хемилюминесценцию (ХЛ) их экстрактов. Не установлено существенных различий значений вылупления науплиев во всех опытных вариантах, за исключением достоверного увеличения этого показателя в намагниченной при большей индукции ИМИ у северного полюса воде. Значения ХЛ экстрактов вылупившихся в намагниченной воде (0,108 Тл) науплиев были достоверно ниже контроля, тогда как при увеличении индукции ИМИ до 0,208 Тл обнаружена противоположная зависимость. Обсуждаются возможные механизмы опосредованного влияния ИМИ на активацию вылупления и ХЛ науплиев артемии.Physical fields play an important role in human activity. The influence of water exposed to 0.108 Т and 0.208 T static magnetic field (SMF), including north (N-group) and south (S-group) poles on Artemia cysts hatching rate and chemiluminescence (ChL) parameters of nauplia extracts was studied. No significant differences were observed in hatching rate values in all experimental groups with the exception of a considerable increase of this parameter in N-group exposed to a higher strength SMF. ChL values of the nauplia extracts in experimental groups with water exposed to 0.108 T were significantly lower as compared with the control, while at the higher SMF strength the ChL values were larger. Possible mechanisms of indirect impact of SMF on hatching stimulation and ChL of Artemia are discussed

Analysis of Optimal Operating Modes of the Induction Traction Drives for Establishing a Control Algorithm Over a Semiconductor Transducer

The study addresses determining optimal operating modes of the induction traction drive. We identified optimal operating modes of the autonomous voltage inverter at different temperatures of windings of the traction motors for a tram carriage and a diesel locomotive.The identification is carried out of optimal parameters in the operating modes of autonomous voltage inverter of the traction drive of a tram and a diesel locomotive. We obtained dependences of performance efficiency and electromagnetic torque of the induction traction motor on the rotation frequency and temperature of the windings for the following modes: acceleration, recuperative braking, and maintaining preset speed.We determined operating modes of induction traction drive of the tram Tatra T3 VPA and the diesel locomotive 2TE25A over the entire range of motors' rotation frequency at spatial-vector and one-time pulse-width modulation of the semiconductor inverter for different values of temperature of the motor's windings. A technique was devised for this purpose, which is based on solving a problem on the optimization of parameters of the traction drive using a combined method that employs genetic algorithms and the Nelder–Mead method.It was established that dependences of change in the transition point from the spatial-vector to the one-time PWM on the temperature of traction motor for a tram and a diesel locomotive are not similar. Different level of the location of this point is predetermined by the different load in magnetic circle of the motor, by different level of saturation coefficient. The difference in saturation coefficient is 0.15‒0.4 r.u

Features of a choice of magnetic systems materials for aviation electric motors

В работе выполнен сравнительный анализ различных сталей, применяемых для изготовления магнитопроводов электродвигателей авиационных агрегатов. Предложены рекомендации по выбору марки сталей для сердечников, которые разработаны на основании испытаний, проведенных на созданном экспериментальном стенде.У роботі проведено порівняльний аналіз різних сталей і технологій виготовлення магнітопроводів електродвигунів авіаційних агрегатів. Рекомендації по вибору марки сталей для осердь розроблено на підставі випробувань на створеному експериментальному стенді.A comparative analysis of various steels and technologies for manufacturing the magnetic cores of electric engines of aircraft assemblies was carried out in. Recommendations for the selection of steel grades for cores were developed on the basis of tests on the experimental stand created by the authors

Simulating the Traction Electric Drive Operation of A Trolleybus Equipped with Mixed Excitation Motors and A DC-DC Converter

Switching to the new type of a traction drive, from direct to alternating current, cannot be performed instantly in public transportation. The reason is the large fleet of vehicles and associated costs. In most countries in Europe and Asia, this process takes years.Therefore, the fleet of trolleybuses develops in two directions simultaneously. The first is the purchase of new trolleybuses, that is, the renewal of fleet with modern machines with an alternating current traction motor. The second is the overhaul and modernization of "outdated" machines, in order to improve their performance. Most "obsolete" trolleybuses are equipped with direct current traction motors of serial or mixed excitation. It is possible to achieve substantial energy savings and to improve the characteristics of the traction electric drive with such engines by using a pulse control system and by optimizing control algorithms.The goal of this study is to increase energy efficiency and to improve the characteristics of the trolleybus traction electric drive, equipped with a direct current motor of mixed excitation. This is accomplished by improving this drive's control system based on the pulse control system via DC-DC.The feasibility of the tractive electric drive has been tested through imitation and physical modeling. A mathematical model of the DC motor with mixed excitation has also been improved. A special feature of this model is taking into consideration the saturation of the elements of a magnetic wire of the traction motor based on the preliminary performed calculations of a magnetic field using a finite element method. By combining these components, the improved mathematical model of the entire trolleybus electric drive has been built.The operation of the trolleybus electric drive under a start mode has been simulated. The results have confirmed the increase in the energy efficiency of the traction electric drive by reducing the loss for excitation. The comparison has proven that the losses of energy decreased from 0.587 MJ (0.163 kWh) to 0.531 (0.1475 kWh) MJ, by 9.54 %

Three-year experience of a dedicated prostate mpMRI pre-biopsy programme and effect on timed cancer diagnostic pathways.

AIM: To evaluate the effect of pre-biopsy magnetic resonance imaging (MRI) on cancer diagnostic times, and to report MRI-directed pathology outcomes. MATERIALS AND METHODS: In total, 1483 patients were referred with prostate cancer suspicion during a 30-month period. Upfront MRI was performed in 745 patients: 332 MRIs in the 15 months prior to dedicated scanning slots (group 1), and 413 in the 15 months post-introduction (group 2). A further 88 patients had initial MRI following clinical assessment. Biopsy via the transrectal (TR) or transperineal (TP) approach was performed, with MRI/ultrasound fusion for MRI targets. Clinically significant cancer (csPCa) was defined as Gleason ≥3+4. Negative MRIs were defined as Likert 1-2. Per-case clinical decisions were taken to biopsy or not. RESULTS: 44.4% of patients avoided biopsy. 484/833 (58.1%) MRIs were negative; 37.4% of these patients had biopsy with a negative predictive value (NPV) of 92.8% for Gleason ≥3+4 and 98.3% for ≥4+3. Overall prostate cancer prevalence was 34.3% (24.6% csPCa). In 323 MRI-positive cases, any cancer was present in 78.9% (csPCa 60.4%). Of the 1483 patients, 1232 (83.1%) completed all diagnostic tests within 28 days. Upfront MRI patients met this standard in 621/833 (74.5%), improving from 66.9% to 81.1% with reserved slots (group 2) with a reduced diagnostic time from median 25.5 to 20.9 days. Biopsy scheduling delayed the pathway in 69.7%, with MRI responsible in 22.3%, reducing to 10.3% in group 2. TP biopsies met the 28-day standard in significantly less cases (29.7%), compared to TR (67.4%, p<0.0001). CONCLUSION: Reserved MRI slots reduces time-to-diagnosis, and upfront MRI safely avoids biopsy in a significant proportion of men, whilst maintaining expected csPCa detection rates