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[en] A method is proposed for calculating the limiting deviation and group tolerances when group interchangeability (selective assembly) is used. The example considered is increase in precision of the gap in the joint between a hydraulic cylinder and the piston rod.
[en] The flexibility in radiotherapy can be improved if a patient can be moved between any one of the Department's medical linear accelerators without the need to change anything in the patient's treatment plan. For this to be possible, the dosimetric characteristics of the various accelerators must be the same, or nearly the same i.e. the accelerators must be beam-matched. During a period of nine months, eight Varian iX accelerators with 6 and 15 MV photon beams and 6-18 MeV electron beams (only four of the eight) were installed at our clinic. All accelerators fulfilled the vendor-defined 'fine beam-match' criteria, and a more extensive set of measurements was carried out during commissioning. The measured absorbed dose data for each accelerator were compared with the first accelerator, chosen as reference, and the TPS calculations. Two of the eight accelerators showed a larger discrepancy for the 15 MV beam not revealed by the vendor-defined acceptance criteria, whereas the other six accelerators were satisfactorily matched. The beam-matching acceptance criteria defined by the vendor are not strict enough to guarantee optimal beam-match. Deviations related to dose calculations and to beam-matched accelerators may add up. The safest and most practical way to ensure that all accelerators are within clinical acceptable accuracy is to include TPS calculations in the evaluation. Further, comparisons between measurements and calculations should be done in absolute dose terms
[en] Universal gear reducers are quite simple products, so today there are many manufacturers around the world that produce this kind of reducers. Their connecting dimensions and shape are not defined by the standard, so there is a large number of solutions. The most of manufacturers produce gear reducers with connecting dimensions and axis height, usually the same like the biggest manufacturers do (mainly company SEW), because they want to provide interchangeability of their gear reducers. It is interesting to note that most manufacturers are trying to adopt such a form of reducer that will be different from competing solutions in order to avoid an accusation of coping with someone else’s solution, although manufacturers have almost identical shape and competing (copied) solutions. The paper presents, due to the volume of matter, only the analisys of forms of the housing of modern single-stage universal gear reducers in order to point out the expected directions of their further development. (paper)
[en] The special aim has been stability of the thresholds and standardized pulses under variations of temperature, and also interchangeability of transistors. The selector has the following specifications. Input dynamic, 100 mV to 10 V; adjustable channel width, 100 mV to 1 V; minimum resolving time, 5 μs; maximum storage of capacitor, 100000cps; linearity of capacitor, ± 1%; stability of capacitor: final information is retained to 1% after 24 hours. Tests of the selector under variations of temperature were carried out between -20o and + 55o. The following was observed: threshold variation of + 2% for a threshold of 100 mV; channel-width variation of ± 2% for a width of 100mV; stored information variation in the capacitor of ± 2%. The selector is wired on a plate of dimensions 196 x 96 mm. Consumption is 20 mA at -18V and 30 mA at + 18 V. (author)
[fr]On a plus particulierement recherche la stabilite des seuils et des signaux standardises en fonction de la temperature, ainsi que l'interchangeabilite des transistors. Le selecteur presente les performances suivantes. Dynamique d'entree, 100 mV a 10 V; largeur du canal ajustable, 100 mV a 1 V; temps de resolution minimum, 5μs; capacite maximum de la memoire, 100000 chocs; linearite de la memoire, ± 1%; stabilite de la memoire: l'information finale est conservee a 1% au bout de 24 heures. Les essais du selecteur en fonction de la temperature ont ete effectues entre -20o et +55o. On a observe: une variation de seuil de + 2% pour un seuil de 100 mV; une variation de la largeur du canal de ± 2% pour une largeur de 100mV; une variation de l'information stockee sur la memoire de ± 2%. Le selecteur est cable sur une plaquette de 196 mm de long sur 96 mm de large. Il consomme 20 mA sous -18 V et 30 mA sous +18 V. (author)
[es]Los autores han procurado en particular lograr la estabilidad de los umbrales y de las senales normalizadas en funcion de la temperatura, asi como la intercambiabilidad de los transistores. Las caracteristicas del selector son las siguientes: Margen de entrada, de 100 mV a 10 V; amplitud del canal ajustable, de 100 mV a 1 V; tiempo de resolucion minimo, 5 μs; capacidad maxima de la memoria, 100000 impulsos; linealidad de la memoria, ± 1%; estabilidad de la memoria: a las 24 horas, la informacion final se conserva al 1%. Los ensayos del selector en funcion de la temperatura se han efectuado entre -20o y +55o. Se han observado los siguientes resultados: Variacion del umbral de + 2% para un umbral de 100 mV; variacion de la anchura del canal de ± 2% para una anchura de 100 mV; variacion de ± 2% de la informacion almacenada por la memoria. El selector esta conectado a una placa de 196 mm de longitud y 96 mm de ancho. Consumo: 20 mA a -18 V y 30 mA a +18 V. (author)
[ru]Avtory osobenno stremilis' k stabil'nosti porogov i unifikatsii signalov v zavisimosti ot temperatury, a takzhe k vzaimozamenyaemosti tranzistorov. Selektor imeet sleduyushchie kharakteristiki. Vkhodnoj dinamik: 100mV-10V; shirina reguliruemogo kanala: 100mV-1 V; minimal'noe razreshayushchee vremya - 5μs; maksimal'naya emkost' zapominayushchego ustrojstva - 100000 otschetov; linejnost' zapominayushchego ustrojstva ± 1%; stabil'nost' zapominayushchego ustrojstva: okonchatel'naya informatsiya sokhranyaetsya s tochnost'yu do 1% posle 24 chasov. Temperaturnoe ispytanie selektora provodilos' v predelakh ot -20o do +55o. Pri ispytaniyakh nablyudalis': kolebaniya poroga v + 2% dlya poroga v 100mV; kolebanie shiriny kanala dlya shiriny v 100mV; oshibka informatsii, khranimoj zapominayushchim ustrojstvom, v ± 2%. Selektor smontirovan na plastine dlinoj v 196 millimetrov i shirinoj v 96 millimetrov. On potreblyaet 20 mA pri -18 vol'takh i 30 mA pri +18 vol'takh. (author)
[en] The practicality of three armature designs for tractional electric motors (power 560–755 kW, tractional force 5326 kgf) is analyzed. The use of an armature shaft of variable (reinforced) cross section in place of the armature with a sleeve is proposed, and suggestions are made regarding the assembly of the bearings. Reinforcement of the working shaft by smoothing may be recommended.
[en] Nuclear utilities are embarking on innovative approaches for reducing costs in all aspects of engineering, operation, maintenance, and procurement to produce power cheaply and efficiently and remain competitive with other power producers. In the area of procurement, utilities are increasingly obtaining commercial-grade items for use in safety-related applications. This trend is occurring because of lack of suppliers capable or willing to meet 10 CFR 21 and 10 CFR 50 App. B requirements and because of the absence of original equipment suppliers or the spiraling cost associated with procuring items' basic components safety-related from original suppliers. Utilities have been looking at ways to reduce procurement costs. One promising means to reduce costs is to utilize information provided in other nonnuclear industry standards regarding the specification, control, manufacture, and acceptance of the critical characteristics required of the item to perform its design function. A task force was instituted under the sponsorship of the Electric Power Research Institute to investigate the feasibility of using items manufactured to other industry standards in nuclear safety-related applications. This investigation looked at a broad spectrum of available industry standards pertaining to the design, function, manufacture, and testing of items and determined that some standards are more useful than others. This paper discusses the results of this investigation and how credit from the controls exercised for items manufactured to certain existing industry standards can be taken to minimize dedication costs
[en] The task of modernizing the wheel-motor blocks of locomotives with a wheel diameter of 1050 mm with asynchronous and collector traction motors is considered. As a result of the analysis, it was found that the design of the traverse suspension of the collector engines is outdated and contains wearing surfaces that are difficult to protect from contamination, while due to the limited dimensions the attempt to use a hinged suspension of the “Earring” type, the silent blocks on the axes were stuck. For drives with asynchronous motors, an increase in the rotational speed is limited by the cantilever location of the gear, at which the gear rotates and the end of the motor shaft can be turned. An engine suspension design with three spherical silent blocks, a liquid with ferromagnetic nanoparticles and a permanent magnet is proposed. It eliminates jamming of the silent blocks on the axes during transverse movements of the engine and ensures interchangeability of the wheel-motor blocks for upgraded and non-upgraded trolleys. To improve the reliability of traction transmission, it is proposed to position the gear between the rotary bearings. To reduce the wear of traction gear teeth, the design of an elastic gear wheel with chevron teeth was proposed. A patent for an invention and a patent for a utility model have been obtained for the proposed technical solutions. (paper)
[en] Long exposure to radiation from fluoroscopy-guided interventions (FGIs) can be detrimental to both patients and radiologists. The effective doses received by the interventional radiology staff after performing 230 FGIs in a year were assessed by using double dosimetry and five various algorithms. The Shapiro-Wilk test revealed normally-distributed data (p < 0.01), while the significant correlation coefficients between the effective doses ranged between 0.88 and 1.00. As for the Bland-Altman analysis, both Niklason and Boetticher algorithms strongly supported the absence of statistical significance between the estimated effective doses. This portrays that the occupational doses received by the interventional radiology staff during FGIs fall within the acceptable limit regardless of the varied algorithms applied. In short, the Niklason and Boetticher algorithms appeared to be the more interchangeable ones for effective evaluation of doses. This is in view of their strong mutual correlations and excellent agreement. (authors)
[en] This work presents the evaluation of pulse rate variability (PRV) obtained from pulse onsets of photoplethysmographic (PPG) signals. Three published algorithms were used to determine the pulse onsets: diastolic point, maximum second derivative and tangent intersection. Temporal series of pulse onsets were obtained for each method, and several variability indices were derived from these series. Simultaneous ECG and PPG records were acquired from 37 healthy volunteers to evaluate the interchangeability between PRV indices and heart rate variability (HRV) indices by the Bland–Altman method. Furthermore, the concordance correlation coefficient was used to correlate the indices. In all the cases, PRV indices obtained through the tangent intersection method showed better accuracy and precision (Bland–Altman analysis, bias ± 1.96 standard deviation: low frequency, LF_m_s"2 = −28.06 ± 72.68; high frequency, HF_m_s"2 = −68.23 ± 192.85; high frequency in normalized units, HF_n_u =−2.02 ± 7.08; LF/HF = 0.17 ± 0.71) and higher correlation (concordance correlation coefficients: low frequency, LF_m_s"2 = 0.99; high frequency, HF_m_s"2 = 0.98; high frequency in normalized units, HF_n_u = 0.97; LF/HF = 0.90) with HRV indices than other methods, and could be used as a good surrogate of HRV. (paper)
[en] In this work, we present a structural, morphology and magnetic study of the Li0.5Fe2.5-xCrxO4 spinel nanoparticles (x = 0, 0.5, 0.75, 1, and 1.25) with mean particle size of 20-30 nm prepared by sol-gel method. The lattice constants and the size of particle decrease with increasing Cr concentration. In these samples, the preference of Cr''3''+ and Li''+ ions in the octahedral sites and a small degree of site-interchange between Li''+ in the octahedral sites and Fe''3''+ in the tetrahedral sites were found which increases with increasing the Cr content. A decrease of magnetization due to the spin disorder in the surface layer of the particles was observed. The spontaneous magnetization at 5K suggests the Néel type of magnetic ordering in these samples. The magnetic coercivity is discussed in terms of particle size, morphology and chromium substitution. (author)