Prediction of starting performance of PM motors by DC decay testingmethod

This paper presents a method to predict the direct- and quadrature-axes operational impedances and starting performance of permanent-magnet (PM) motors by a simple standstill response testing method using a small-capacity DC power supply unit. In this method, not only the starting performance but also the direct- and quadrature-axes synchronous machine constants (synchronous, transient, and subtransient reactances) and equivalent circuit constants are calculated. This proposed strategy, tentatively named the DC decay testing method, is carried out on a 3.7-kW 200-V 22. A 100-Hz four-pole interior PM motor with a damper winding. The results measured by on-load tests and those predicted by the proposed method on starting performance demonstrate the validity and usefulness of the proposed method     

A systematic layout-based method for the modeling of high-powerHBT's using the scaling approach

A systematic scaling approach for the modeling of high-power/large-size HBT's is presented. This approach is based on: 1) identifying and characterizing the elementary cell, and 2) modeling the input/output interconnections using the device's physical layout. The proposed approach reduces the optimization problem for the large-size device to the easier fitting of the lumped equivalent circuit of the elementary cell. It is shown that there is a good agreement between the predicted results, using the developed model, and the available measurements for different bias points. Such a modeling approach is particularly appealing for high-power applications where the large-signal characterization of large-size devices becomes a difficult task, particularly for on-wafer devices     

Diffuse aspiration bronchiolitis (DAB) produced in animals by repeated HCl microaspiration

We recently reported that diffuse aspiration bronchiolitis (DAB) was detected in 1% of autopsied lungs of aged cases of pneumonia. We hypothesized whether repeated HCl micro-aspiration (RHMA) is involved in DAB and established an animal model by administering HCl intratracheally to rats every two days for 2 weeks. Saline was given to control animals in the same fashion. Then, we performed bronchio-alveolar lavage (BAL) or excised lungs for histologic examination. There was no difference in BAL cell counts, TNF alpha-production, elastase-like activity or albumin levels between the HCl and control groups. Histologically, DAB-like findings were observed in the HCl-treated animals. These data suggest that RHMA might be involved in DAB, while neither TNF alpha-production nor elastase-like activity may play a significant role in inducing DAB.     

DSP-based speed adaptive flux observer of induction motor

A method for estimating the rotor flux and speed of an induction motor based on adaptive control theory is presented. The method is applied to a direct field-oriented induction motor control without speed sensors. The influence of the parameter variation on the speed estimation can be removed by the proposed parameter adaptive scheme. The validity of the adaptive flux observer is verified experimentally     

Effect of ZnSe quantum dot concentration on the fluorescence enhancement of polymer P3HT film

The effects of ZnSe quantum dot (Qd) concentration on the fluorescence in Poly(3-hexylthiophene-2,5-diyl) matrix (P3HT) are investigated. The fluorescence spectra were found to be very dependant on the Qd concentration and light emission is significantly enhanced by incorporation of ZnSe Qd in the polymer matrix. Using a theoretical model for hybrid (organic–inorganic) system, interesting numerical results for the light emission and relative quantum efficiency as a function of ZnSe Qd concentration were obtained. The theoretical results were found to be in good agreement with experimental data.     

Quadruped virtual robot simulation in a virtual environment obeying physical laws

In the development of a robot, the validation of that robot with the use of real machinery takes a considerable amount of time and money. In particular, it is difficult to validate a robot’s behavior in an unsafe place. The developers also have to pay attention to virtual debugging. Using a program validated in VR space makes the verification of a real machine’s behavior more efficient. In this research, we make a virtual robot walk on a road autonomously by using a program where the virtual robot tracks a line in a virtual environment.     

High Performance Control of Matrix Converter Fed Induction Motor Drive System

I Introduction Matrix converter(MC)is a modern energyconversion device that has been developed over the lastthree decades[1~5].Matrix converter fed motor drive issuperiorto pulse width modulation(PWM)inverter drivessince it provides bi-directional power f…     

Optoelectronic properties of sexithiophene single crystals

UV—Vis absorption, photoluminescence (PL) and photoconductivity (PC) measurements have been carried out on sexithiophene (6T) single crystals grown from the vapor phase. UV—Vis absorption data were used to determine the absorption coefficient and refraction index under polarized light. The spectrum at polarization perpendicular to the unique axis b is similar to that measured on polycrystalline films, whereas that at light polarized parallel to b presents a weak structured absorption. The refractive index is 1.656, independent of the wavelength, under parallel polarization, and follows the Sellmeier equation, with n_∞ = 1.867, under perpendicular polarization. The PL excitation spectrum with parallel polarization follows exactly the corresponding weak absorption, whereas, at perpendicular polarization, it saturates when the absorption length compares the crystal thickness, and then decreases down to a minimum at 3.5 eV. This lowering mirrors a decrease of the PL yield at higher energies. The PC action spectrum shows an opposite behavior: it presents first a rise at 2.4 eV, parallel to the absorption onset, then a second rise at 3.0 eV up to a maximum at 3.3 eV. The first rise corresponds to the generation of singlet excitons, which then give birth to charges, through either exciton breaking, or more likely charge detrapping. The second rise could correspond to a direct ionization process. The magnetic field effect on PC has been studied. A relative decrease of up to 6% at a field of 4000 G has been detected. The decrease is attributed to the lowering of the triplet—doublet interaction constant R.     

Systematic DC/small-signal/large-signal analysis of heterojunctionbipolar transistors using a new consistent nonlinear model

In this paper, a new systematic approach to heterojunction bipolar transistors (HBT's) characterization and modeling is presented. The proposed approach is based on a new compact HBT nonlinear circuit model which accounts for both self-heating and the temperature dependence effects. The model's parameters are extracted from measured dc-IV characteristics and S-parameters. The power characteristics of the device are then predicted using the extracted model without any further optimizations. The same model is also used for intermodulation distortion analysis. The model has been implemented in a number of commercial nonlinear simulators and in an in-house computer code. Results are presented for two different size devices showing good agreement with measurements