Improved transient simulation of salient-pole synchronous generators with internal and ground faults in the stator winding

An improved model for simulating the transient behavior of salient-pole synchronous generators with internal and ground faults in the stator winding is established using the multi-loop circuit method. The model caters for faults under different ground conditions for the neutral, and accounts for the distributed capacitances of the windings to ground. Predictions from the model are validated by experiments, and it is shown that the model accurately predicts the voltage and current waveforms under fault conditions. Hence, it can be used to analyze important features of faults and to design appropriate protection schemes

Inhibitory effect of rhubarb on intestinal α-glucosidase activity in type 1 diabetic rats

Purpose: To investigate the inhibitory effect of rhubarb on α-glucosidase activity in the small intestine of rats with type 1 diabetes.Methods: Type 1 diabetic rat model was established by intraperitoneally injecting 30 male SD rats with 1 % streptozocin (STZ). Rats with fasting blood glucose > 11 mmol/L (24) were used for the study. The rats were randomly divided into three equal groups including control, acarbose and rhubarb groups. Arcabose® (20 mg/kg /day) and rhubarb (100 mg/kg /day) were given by intra-gastric route via insertion of the cannula through the esophagus. Daily fasting blood glucose and daily postprandial glucose levels were assayed for all groups. On day 6, postprandial blood glucose, blood levels of C-peptide and insulin, and intestinal α-glucosidase were also determined.Results: There were no significant differences in levels of C-peptide, insulin and fasting blood glucose between control, Acarbose® and rhubarb groups (p > 0.05). However, α-glucosidase activity at 0, 30, 60 and 120 min in the rhubarb group was 1759.2, 1812.8, 1379.8 and 772.1 U, respectively,) while in the Acarbose® group it was 178.6, 1260.1, 1126.5, 599.2 U, respectively. α-Glucosidase activity in both groups initially showed an increase (p < 0.05), followed by a decline from 60 to 120 min (p ˂ 0.05). After 120 min, α-glucosidase activity in each of the two groups was significantly decreased compared with untreated control (1200 U) (p ˂ 0.05).Conclusion: The inhibitory effect of rhubarb on intestinal α-glucosidase activity of Type 1 diabetic rats is comparable to that of Arcabose®.This suggests that this plant may have clinically potent anti-diabetic properties.Keywords: Type 1 diabetes, α-Glucosidase activity, Acarbose®, Rhubarb, Postprandial glucose leve

Centrifuge Simulation of the Thermal Response of a Dry Sand-Embedded Diaphragm Wall

Geothermal heat exchangers buried in diaphragm walls as an alternative of renewable energy sources can be quite competitive with shallow geothermal resources. The thermal response of a diaphragm wall embedded in the sand foundation under thermomechanical coupling conditions was followed in laboratory centrifuge tests. The model of exchanger tubes enclosed in the diaphragm wall embedded in the sand foundation accounts for lateral loading on the wall simulated by 1 and 50 g acceleration conditions in the centrifuge. Thermal loading, mechanical unloading, and thermomechanical coupling tests were carried out separately. The temperature, deformation, and soil pressure on the wall were monitored. The deformation and thermal stress along the cantilever wall were verified by numerical simulation. The thermal stress on the wall was revealed to be larger than the excavation-induced one. The maximum thermal stress was observed near the bottom of the wall. Though the wall was embedded in surrounding soil, heating caused accumulation of thermal stresses induced by temperature variations, which should be seriously considered in the heat exchanger design for cantilever walls of building structures.Геотермальные теплообменники, встроенные в стенку диафрагмы, являются альтернативным видом использования возобновляемой энергии, которая может быть получена из неглубоких геотермальных ресурсов. Исследован тепловой отклик стенки диафрагмы, вставленной в песочное основание, в условиях термомеханической связи путем лабораторных испытаний в центрифуге. Моделирование теплообменных трубок, встроенных в стенку диафрагмы, вставленную в песочное основание, включало поперечное нагружение стенки и осуществлялось в средах 1 и 50g в центрифуге. Испытания в условиях теплового нагружения, механической разгрузки и термомеханической связи проводились отдельно. Контролировались температура, деформация и давление грунта на стенку. Деформация и тепловое напряжение вдоль консольной стенки контролировались путем численного моделирования в каждом случае. Результаты испытаний показывают, что тепловое напряжение на стенке превышает напряжение, вызванное выемкой грунта. Максимальное тепловое напряжение наблюдалось вблизи основания стенки. Хотя стенка была связана окружающим грунтом, тепловое напряжение накапливалось в процессе нагрева в результате изменения температуры, что необходимо учитывать при конструировании теплообменника в консольной стене зданий.Геотермальні теплообмінники, вбудовані в стінку діафрагми, є альтернативним видом використання відновлюваної енергії, яка може бути отримана з неглибоких геотермальних ресурсів. Досліджено тепловий відгук стінки діафрагми, вставленої в пісочне підставу, в умовах термомеханічної зв'язку шляхом лабораторних випробувань в центрифузі. Моделювання теплообмінних трубок, вбудованих в стінку діафрагми, вставлену в пісочну основину, включало поперечне навантаження стінки і здійснювалося в середовищах 1 і 50g в центрифузі. Випробування в умовах теплового навантаження, механічного розвантаження і термомеханічного зв'язку проводились окремо. Контролювалися температура, деформація і тиск грунту на стінку. Деформація і теплову напругу вздовж консоль¬ной стінки контролювалися шляхом чисельного моделювання в кожному випадку. Результати випробувань показують, що теплове напруга на стінці перевищує напругу, викликану виїмкою грунту. Максимальна теплове напруга спостерігалося поблизу підстави стінки. Хоча стінка була пов'язана навколишнім грунтом, теплову напругу накопичувалося в процесі нагрівання в результаті зміни температури, що необхідно враховувати при конструюванні теплообмінника в консольної стіні будівель

Solution-processable single-material molecular emitters for organic light-emitting devices

This tutorial review presents some recent developments in the design, synthesis and implementation of organic solution-processable molecular fluorophores for non-doped electroluminescent light-emitting devices. After a brief presentation of the basic principles of operation and main characteristics of electroluminescent devices, some examples of active emitters representative of the main classes of non-doped molecular electrofluorophores will be discussed. Emphasis is placed on the relationships between the molecular structure and the electronic properties of molecular emitters, in which high photoluminescence efficiency, synthetic accessibility and processability are combined by design with additional functions such as hole and/or electron injection and transport

Structure-properties relationships in solution-processable single-material molecular emitters for efficient green organic light-emitting diodes

The electroluminescent properties of a series of solution-processable fluorescent molecular emitters have been systematically investigated. While the introduction of the electron-deficient benzothiadiazole unit in the structure confers efficient electron-injection on the emitter materials, they exhibit different hole-transport properties. The device characteristics of the OLEDs based on these various emitters are discussed on the basis of (i) the energy levels of their HOMO and LUMO and (ii) their hole-transport properties in relation with the charge-transport and blocking properties of the electron- and hole-transport layers. (C) 2012 Elsevier B.V. All rights reserved

The quantum cryptographic switch

We illustrate using a quantum system the principle of a cryptographic switch, in which a third party (Charlie) can control to a continuously varying degree the amount of information the receiver (Bob) receives, after the sender (Alice) has sent her information. Suppose Charlie transmits a Bell state to Alice and Bob. Alice uses dense coding to transmit two bits to Bob. Only if the 2-bit information corresponding to choice of Bell state is made available by Charlie to Bob can the latter recover Alice's information. By varying the information he gives, Charlie can continuously vary the information recovered by Bob. The performance of the protocol subjected to the squeezed generalized amplitude damping channel is considered. We also present a number of practical situations where a cryptographic switch would be of use.Comment: 7 pages, 4 Figure

Electromagnetically induced transparency in multi-level cascade scheme of cold rubidium atoms

We report an experimental investigation of electromagnetically induced transparency in a multi-level cascade system of cold atoms. The absorption spectral profiles of the probe light in the multi-level cascade system were observed in cold Rb-85 atoms confined in a magneto-optical trap, and the dependence of the spectral profile on the intensity of the coupling laser was investigated. The experimental measurements agree with the theoretical calculations based on the density matrix equations of the rubidium cascade system.Comment: 9 pages, 5 figure

A Dithienylbenzothiadiazole Pure Red Molecular Emitter with Electron Transport and Exciton Self-Confinement for Nondoped Organic Red-Light-Emitting Diodes

An amorphous photoluminescent material based on a dithienylbenzothiadiazole structure has been used for the fabrication of organic red-light-emitting diodes. The synergistic effects of the electron-transport ability and exciton confinement of the emitting material allow for the fabrication of efficient pure-red-light-emitting devices without a hole blocker

The littlest Higgs model and Higgs boson associated production with top quark pair at high energy linear e+e−e^{+}e^{-} collider

In the parameter space allowed by the electroweak precision measurement data, we consider the contributions of the new particles predicted by the littlest Higgs($LH$) model to the Higgs boson associated production with top quark pair in the future high energy linear $e^{+}e^{-}$ collider($ILC$). We find that the contributions mainly come from the new gauge bosons $Z_{H}$ and $B_{H}$. For reasonable values of the free parameters, the absolute value of the relative correction parameter $\delta\sigma/\sigma^{SM}$ can be significanly large, which might be observed in the future $ILC$ experiment with $\sqrt{S}=800GeV$.Comment: latex files, 13 pages, 3 figure