This paper deals with the basic dynamical model of electromotor whose creation motivated by problems of electromotor vibrations and its subsequent fatigue. The model is chaacrterized by a flexible shaft with mounted padket of sheet metals that are equipped with parallel copper bars connected by end shortcircuit rings. Finite element analysis is used for the disretization of the shaft, while the sheet metal packet of cylindrical shape is modelled as a set of rigid bodies joined using chosen viscoelastic forces and torques. The shortcircuit rings are supposed to be rigid in this basic dynamical model and the pieces of copper bars are substituted by massless springs of calculated properties. Problematic model parameters are identified by means of performed experimental modal analysis. and Obsahuje seznam literatury
The aim of this article is to inform reader about the development steps and practices which were used during the development of a control system of a fuel metering pump. The aim of this development was to design a cntrol system for a BLDC motor in accordance with rigid aviation standards and verify new development practices and tools alowing faster and simpler certification. The development covers such steps as definition of first requirements, preliminary design, system modelling and simulation, detailed deisgn, verification and testing. Given description intruduces reader to mandatory practices and procedures which are obligatory for successful certification of developed control systems. In addition, the first results measured on an evaluation sample are presented. and Obsahuje seznam literatury
The modern Serbian state (the Principality/Kingdom of Serbia) was created and its territory enlarged gradually during the 19th and early 20th century, in a process of emancipation from the Ottoman Empire, where specific agrarian relations existed based on Ottoman feudalism. Consequently the development of the modern Serbian state proceeded parallel to the replacement of Ottoman agrarian relations with a new type of land ownership, with formerly dependent peasants becoming private owners of the land that they had farmed under Ottoman rule. This led to deep-rooted social changes and even changes in the national culture. For this purpose the paper presents an overview of the creation and the territorial expansion of the modern Serbian state, in the context of the change in the international position of the Ottoman Empire and its social structure. A thorough analysis of the Ottoman agrarian relations in the Balkan regions of the Ottoman Empire is carried out, specifying the changes that occurred during the armed springs of the Serbian peasants - the First and Second Serbian Uprising (1804-1813, 1815). The process of abolishing Ottoman agrarian relations (with the constitution of private land ownership) is treated in detail in the territory of the Principality of Serbia, following the attainment of formal autonomy within the Ottoman Empire (1830) and after gaining independence (1878), including all the international implications.
Philometra overstreeti Moravec et de Buron, 2006 and Philometroides paralichthydis Moravec et de Buron, 2006 are common parasites of the southern flounder, Paralichthys lethostigma Jordan et Gilbert. Because the life cycles of these parasites are unknown, our goal was to assess whether species of copepod commonly found in our estuaries could serve as intermediate hosts for these philometrids. Individuals of five species of copepods were collected and exposed to L1 larvae of each philometrid species. The cyclopoid Oithona colcarva Bowman was the only species to become successfully in-fected. Successive moulting of philometrid larvae in the haemocoel of the copepods was studied using transmission electron microscopy. At 23°C the moult from L1 to L2 was observed for both species as early as 24 h post exposure to L1 larvae. The moult from L2 to L3 was initiated within 2 days post exposure and completed by 6-7 days post exposure. Some parasite-induced tissue damage occurred in the copepod but no cellular response against larval philometrids was observed.
The vibrodiagnostic system VDS-UT2 was developed for the investigation of a tram wheel operational vibration and deformation. The system consists of measuring, acquisition and processing tools for monitoring of tram wheels and their operational parameters, e.g. static and dynamic deformation, displacement, velocity, acceleration and temperature. The measuring on a rotating wheel is realized both by telemetric and by top-timing system. Measured data can be remote-observed via Internet connection with the control PC. The acquisition system by Starmans Electronics s.r.o. provides continuous analog and digital data logging. The control PC processes digital logical signals and evaluates time intervals representing circumferential turning angles between disk and rim.. In the contribution, the diagnostic system is described and the measured data including damage analysis are presented. and Obsahuje seznam literatury
Chrysanthemum plantlets were cultivated in vitro on media with 2.0, 0.3, or 0 % sucrose, or photoautotrophically without an organic carbon source but with supplementation of the culture vessel atmosphere with 2 % CO2. The photoautotrophically cultivated plantlets showed a better growth and multiplication, higher contents of chlorophyll (Chl) and carotenoids, higher Chl a/b ratio, net photosynthetic rate and ribulose-1,5-bisphosphate carboxylase/oxygenase and phosphoenolpyruvate carboxylase activities than plantlets grown on the medium with sucrose. and C. Cristea, F. Dalla Vecchia, N. la Rocca.
We investigated seasonal patterns of photosynthetic responses to CO2 concentrations in Spartina alterniflora Loisel, an aerenchymous halophyte grass, from a salt marsh of the Bay of Fundy (NB, Canada), and from plants grown from rhizome in controlled-environment chambers. From late May to August, CO2 compensation concentrations (Γ) of field-grown leaves varied between 2.5-10.7 cm3(CO2) m-3, with a mean of 5.4 cm3(CO2) m-3. From September onwards field leaves showed CO2 compensation concentrations from 6.6-21.1 cm3(CO2) m-3, with a mean of 13.1 cm3 m-3 well into the C3-C4 intermediate range. The seasonal variability in Γ did not result from changing respiration, but rather from a sigmoidal response of net photosynthetic rate (PN) to applied CO2 concentration, found in all tested leaves but which became more pronounced late in the season. One explanation for the sigmoidal response of PN to external CO2 concentration could be internal delivery of CO2 from roots and rhizomes to bundle sheath cells via the aerenchyma, but the sigmoidal responses in S. alterniflora persisted out to the tips of leaves, while the aerenchyma extend only to mid-leaf. The sigmoidicity persisted when CO2 response curves were measured from low to high CO2, or from high to low CO2, and even when prolonged acclimation times were used at each CO2 concentration. and M. O. Bärlocher ... [et al.].
We studied the developmental changes in photosynthetic and respiration rates and thermal dissipation processes connected with chloroplasts and mitochondria activity in etiolated wheat (Triticum aestivum L., var. Irgina) seedlings during the greening process. Etioplasts gradually developed into mature chloroplasts under continuous light [190 μmol(photon) m-2 s-1] for 48 h in 5-day-dark-grown seedlings. The net photosynthetic rate of irradiated leaves became positive after 6 h of illumination and increased further. The first two hours of de-etiolation were characterized by low values of maximum (Fv/Fm) and actual photochemical efficiency of photosystem II (PSII) and by a coefficient of photochemical quenching in leaves. Fv/Fm reached 0.8 by the end of 24 h-light period. During greening, energy-dependent component of nonphotochemical quenching of chlorophyll fluorescence, violaxanthin cycle (VXC) operation, and lipoperoxidation activity changed in a similar way. Values of these parameters were the highest at the later phase of de-etiolation (4-12 h of illumination). The respiration rate increased significantly after 2 h of greening and it was the highest after 4-6 h of illumination. It was caused by an increase in alternative respiration (AP) capacity. The strong, positive linear correlation was revealed between AP capacity and heat production in greening tissues. These results indicated that VXC in chloroplasts and AP in mitochondria were intensified as energy-dissipating systems at the later stage of greening (after 4 h), when most of prolamellar bodies converted into thylakoids, and they showed the greatest activity until the photosynthetic machinery was almost completely developed. and E. V. Garmash ... [et al.].
Developmental changes of plant in the regulation of photosynthate distribution of leaves were studied in hydroponically cultivated rice by the 14CO2 tracer technique and analysis of the activity of the regulatory enzymes, sucrose phosphate synthase (SPS), phosphoenolpyruvate carboxylase (PEPC), and pyruvate kinase (PK). The distribution of primary photosynthates into sugars, amino acids, organic acids, sugar phosphates, proteins, and polysaccharides was determined by column chromatography. The relative primary photosynthate distribution to the sugar phosphate fraction was significantly larger in the 5th leaf than in the 6th one. Correspondingly, the Vmax of PEPC was significantly higher in the 5th than in the 6th leaf, while no significant differences between leaves were detected in the other enzymes. As a consequence, the ratio of the Vmax of SPS and PEPC was lower in the 5th than in the 6th leaf. As the 5th leaf develops before panicle initiation in rice, it predominantly supports vegetative growth, while the 6th leaf develops after panicle initiation and thus contributes mainly to reproductive growth. We conclude that the physiological properties of each leaf are regulated developmentally. When the 6th leaf became fully expanded (corresponding to the panicle initiation stage of plant), the distribution pattern of 14C was transiently changed in the 5th leaf, indicating that individual organs that are mainly involved in vegetative development are affected to some extent by the whole-plant-level physiological transformation that occurs at the transition from the vegetative to the reproductive stage. and T. Shinano ... [et al.].
Alterations in photosynthetic capacity of primary leaves of wheat seedlings in response to ultraviolet-B (UV-B; 280-320 nm; 60 µmol m-2 s-1) exposure alone and in combination with photosynthetically active radiation (PAR; 400-800 nm; 200 µmol m-2 s-1) during different phases of leaf growth and development were assessed. UV-B exposure resulted in a phase-dependent differential loss in photosynthetic pigments, photochemical potential, photosystem 2 (PS2) quantum yield, and in vivo O2 evolution. UV-B exposure induced maximum damage to the photosynthetic apparatus during senescence phase of development. The damages were partially alleviated when UV-B exposure was accompanied by PAR. UV-B induced an enhancement in accumulation of flavonoids during all phases of development while it caused a decline in anthocyanin content during senescence. The differential changes in these parameters demonstrated the adaptation ability of leaves to UV-B stress during all phases of development and the ability was modified in UV-B+ PAR exposed samples. and M. K. Pradhan ... [et al.].