Simplified Design Methodology for a Slotless Brushless DC Motor

The paper presents a simplified analytical method to design a small two-pole slotless brushless dc motor. Using only a few approximations, the motor analytical model is formulated to generate a system of equations. The system can be solved analytically, producing a motor design for given specifications. The method is used to design a motor with the specifications 150 W, 10 000 rpm, and 18 V     

Treatment options in Western hepatocellular carcinoma: a prospective study of 224 patients

BACKGROUND/AIMS: Though hepatocellular carcinoma (HCC) is one of the most frequent malignant tumors in the world, the optimal therapeutic strategy is still poorly defined. This is mainly due to geographic differences in HCC which may affect the validity of treatment regimens in differents areas of the world. The aim of the present study was to analyze the natural course of the disease as well as to assess the efficacy of different therapeutical schemes in HCC observed in Ljubljana (Slovenia) and Trieste (Italy), two cities in Western Europe situated close to each other. METHODS: During the period from January 1988 to December 1993, 224 consecutive patients (132 in Trieste and 92 in Ljubljana) with HCC were enrolled in the study. Patients were treated with the following 3 schemes: surgery 39 (17.4%), transcatheter chemoembolization (TACE) 116 (51.8%), and no treatment 69 (30.8%). The tumor was classified by Okuda staging and the liver disease by Child-Pugh score. Patients were followed up for 12-60 months, with an average of 40 months. The response rate to TACE and recurrence following surgery were evaluated. Comparative analysis of survival between different treatment groups was performed. RESULTS: The natural course of the disease, and other characteristics of the HCC, showed a typical Western type of tumor. Liver disease was scored as Child A in 58%, Child B in 30% and Child C in 12%, and the tumor was staged as Okuda I in 52%, Okuda II in 37% and Okuda III in 11%, respectively. Treatment with TACE was followed by an objective response in 27%, with a median survival of 31 months. Surgery was followed by a recurrence rate of 77% within 19.5 months and median survival of 49 months. The overall median survival of nontreated patients was 8 months. Survival in each group of patients differed significantly between all three consecutive stages of Okuda (p<0.001). In contrast, the differences in survival were significant only between Child A and B (p<0.02). The differences between Child B and C were not significant. CONCLUSIONS: This study emphasizes the importance of staging in the choice of treatment modality and diffusion of HCC in affecting an overall response to treatment and survival. Surgery is highly effective in monofocal HCC of Okuda I and II without cirrhosis. TACE is effective in Okuda I and II and Child A cirrhosis only. The treatment of HCC in Child B cirrhosis needs further studies. In Child C and/or Okuda stage III of HCC, any treatment except pure symptomatic relief is detrimental and should not be used.     

Influence of degree of deformation in rolling on anneal hardening effect of a cast copper alloy

This paper reports results of investigations carried out on a cast copper alloy containing 8 at.% Al. The alloy, and pure copper for the sake of comparison, were subjected to cold rolling with a final reduction of 30, 50 or 70%. The cold rolled copper and copper alloy samples were isochronally and isothermally annealed up to the recrystallization temperature. The hardness, strength and electrical conductivity were measured and X-ray and DSC analyses performed. Anneal hardening effect was observed in the alloy in the temperature range 180–300°C, followed by an increase in the electrical conductivity. The amount of strengthening increases with increasing degree of prior cold work. The X-ray analysis shows a change in the lattice parameter during annealing when anneal hardening effect was observed. The DSC analysis shows the exothermic character of this effect.     

Analytical Solution for Rotor Eddy-Current Losses in a Slotless Permanent-Magnet Motor: The Case of Current Sheet Excitation

We present an analytical solution for the magnetic field, induced eddy currents, and the corresponding losses generated in the rotor of a slotless permanent-magnet (PM) motor. The field excitation is a current sheet placed at the stator interior surface. The solution is based on an analytical solution of the diffusion equation using double Fourier series and in the complex domain. The first and the second Fourier series correspond to the time and space harmonics, respectively. We have analyzed the effect of each time harmonic in detail, and verified the results with FEM software.     

Measurement of oxygen reduction activities via the rotating disc electrode method: From Pt model surfaces to carbon-supported high surface area catalysts

The aim of this report is to scrutinize the thin-film rotating disc electrode (TF-RDE) method for investigating the electrocatalytic activity of high surface area catalysts. Special emphasis is given to the oxygen reduction reaction (ORR) on carbon-supported platinum catalysts. On the basis of measurements on four different Pt catalyst samples with various average particle sizes, it is demonstrated in detail how the intrinsic properties of the catalyst, i.e., the mass activity (A/g_Pt) and the specific activity (A/m²_Pt), are evaluated. The potential sources of error are critically discussed and guidelines for the measurements are given. Furthermore, the specific ORR activities determined for the different catalyst samples are analyzed and compared to polycrystalline Pt. The previously reported effect of the particle size on the specific activity for the ORR is interpreted on the basis of the shift in the potential of zero total charge and the concomitant alteration of the adsorption properties.     

Synthesis and Structure of 1,5-Di-(Ethylphenyl)-1,5-Dimethyl-3,3,7,7-Tetraphenylcycloterasiloxane: a Novel Cyclotetramer

Herein we report the first synthesis of 1,5- di-(ethylphenyl)-1,5-dimethyl-3,3,7,7-tetraphenylcyclotetrasiloxane using a new ‘One Pot’ procedure as recently reported for the preparation of strictly alternating 1,1,5,5-tetramethyl-3,3,7,7-tetraphenylcyclotetrasiloxane by the heterofunctional condensation of diphenylsilanediol with (phenylethyl)methyldichlorosilane in the presence of the ter tiary amine, triethylamine (Nguyen et al. Silicon 6:21–26 2014). The prepared 1,5-di-(ethylphenyl)-1,5-dimethyl-3,3,7,7-tetraphenylcyclotetrasi loxane was fully characterized by single-crystal X-ray diffraction, ¹H, ¹³C and ²⁹Si nuclear magnetic resonance spectroscopy, elemental analysis, mass spectroscopy, thermogravimetric analysis and differential scanning calori metric studies.     

Robust LPC parameter estimation in standard CELP 4800 bit/s speechcoder

In order to decrease LPC spectral degradation in the USA FED STD 1016 4.8 kbit/s CELP speech coder, application of a robust LPC parameter estimation is proposed. Robust LPC methods, based on Huber's M-estimation theory and a heuristic sample-selective two-stage robust procedure, are considered. Comparative experimental analysis is carried out based on the cepstral distance, as an objective spectral measure. Presented experimental analyses justify the use of the robust LPC methods in the standard CELP 4800 bit/s speech coder, showing that the best results are obtained by using the combined sample-selective robust LPC procedure     

Some chemical bases for gypsy moth,Lymantria dispar,larval rejection of green ash,Fraxinus pennsylvanica,foliage as food

Green ash is one of the few tree species rejected as food by larvae of the generalist gypsy moth,Lymantria dispar L. (Lepidoptera: Lymantriidae). Such rejection is based especially on chemicals present in green ash foliage. The gypsy moth larval feeding-inhibitory activity is contained in the ethyl acetate extractables of green ash foliage. Three representative columnchromatographed fractions of the extractables contained antifeedant activity. Individual fractions showed weaker antifeedant activity compared to the total ethyl acetate extractables. Acid hydrolysis of the extractables destroyed antifeedant activity and yielded feeding stimulant activity at higher concentrations. The aqueous extractables were not feeding-inhibitory. Compounds in the green ash extractables were separated by TLC, HPLC, CC, and GC.     

A proposal of a traffic information signalling compatible withAM-MF broadcasting

The possibilities for information signaling through two additional tones, coherent with the usual AM stereo pilot tone used in the present USA AM stereo systems, are investigated. Two criteria are defined: an objective one, based on US Federal Communications Commission rules, and a subjective one, based on average human audio perception levels. On the basis of these criteria, the width of the injection gap (to inject desired two tones) is evaluated. The signaling method includes two signals besides the pilot tone: one for program identification and the other for message-in-progress. The primary intention of the signaling is coupled to the traffic radio information service, but without any modification the proposed system could be used for other purposes (paging, alert signaling, exact time distribution, etc.)