Common algorithm of static stability estimation and computation of steady states of power systems

Generators with automatic control of excitation at studying static stability of electric system modes have been considered by transfer functions. Free number match conditions of the characteristic equation and matrix of Jacobi used in steady state calculations by the Newton method for various generator idealized models are analyzed. Features of using practical criteria of stability are examined

Generalized static characteristics of electric power subsystems and their steepness factors

Representation of parts of electric power systems by generalized static characteristics has been considered. The design procedure of steepness factors of generalized static characteristics depending on features of equivalent subsystems is discussed. The generalized static characteristics and their steepness factors give the equivalent information on power subsystems and can be used at estimation of static aperiodic stability of power supply systems

Consideration of Raft and Soil Interaction in Piled-Rafts Design

Based on the analysis of the piled-raft foundations, as well as experimental investigations of the geotechnical engineers, it is stated that the load of a piled-raft foundation is transferred both to a raft and a pile. When a piled-raft foundation design, the account of this factor allows the significant decrease of the foundation cost. To work out the method of a piled-raft foundation design, the experimental and numerical investigations have been carried out.The paper gives some results of the experimental and numerical investigations of piled-raft foundations. A method of the evaluation of a load part transferred to a raft and the piles is suggested. The conditions of the load transfer to a raft when a foundation loading are determined

Wavelet analysis of epileptic spikes

Interictal spikes and sharp waves in human EEG are characteristic signatures of epilepsy. These potentials originate as a result of synchronous, pathological discharge of many neurons. The reliable detection of such potentials has been the long standing problem in EEG analysis, especially after long-term monitoring became common in investigation of epileptic patients. The traditional definition of a spike is based on its amplitude, duration, sharpness, and emergence from its background. However, spike detection systems built solely around this definition are not reliable due to the presence of numerous transients and artifacts. We use wavelet transform to analyze the properties of EEG manifestations of epilepsy. We demonstrate that the behavior of wavelet transform of epileptic spikes across scales can constitute the foundation of a relatively simple yet effective detection algorithm.Comment: 4 pages, 3 figure

Drug Loaded Biodegradable Load-Bearing Nanocomposites for Damaged Bone Repair

In this paper we present a short review-scientific report on processing and properties, including in vitro degradation, of load bearing biodegradable nanocomposites as well as of macroporous 3D scaffolds for bone ingrowth. Biodegradable implantable devices should slowly degrade over time and disappear with ingrown of natural bone replacing the synthetic graft. Compared to low strength biodegradable polymers, and brittle CaP ceramics, biodegradable CaP-polymer and CaP-metal nanocomposites, mimicking structure of natural bone, as well as strong and ductile metal nanocomposites can provide to implantable devices both strengths and toughness. Nanostructuring of biodegradable [beta]- TCP (tricalcium phosphate)-polymer (PCL and PLA), [beta]-TCP-metal (FeMg and FeAg) and of Fe-Ag composites was achieved employing high energy attrition milling of powder blends. Nanocomposite powders were consolidated to densities close to theoretical by high pressure consolidation at ambient temperature-cold sintering, with retention of nanoscale structure. The strength of developed nanocomposites was significantly higher as compared with microscale composites of the same or similar composition. Heat treatment at moderate temperatures in hydrogen flow resulted in retention of nanoscale structure and higher ductility. Degradation of developed biodegradable [beta]-TCP-polymer, [beta]-TCPmetal and of Fe-Ag nanocomposites was studied in physiological solutions. Immersion tests in Ringer's and saline solution for 4 weeks resulted in 4 to 10% weight loss and less than 50% decrease in compression or bending strength, the remaining strength being significantly higher than the values reported for other biodegradable materials. Nanostructuring of Fe-Ag based materials resulted also in an increase of degradation rate because of creation on galvanic Fe-Ag nanocouples. In cell culture experiments, the developed nanocomposites supported the attachment the human osteoblast cells and exhibited no signs of cytotoxicity. Interconnected system of nanopores formed during processing of nanocomposites was used for incorporation of drugs, including antibiotics and anticancer drugs, and can be used for loading of bioactive molecules enhancing bone ingrowth

Improving the surface characteristics of Ti-6Al-4V and Timetal 834 using PIRAC nitriding treatments

Despite the popularity of a number of techniques of thermochemical diffusion for titanium, in many cases the surface engineering processes used may not be economically viable options for industry. This work focuses on the application of Powder Immersion Reaction Assisted Coating (PIRAC), a relatively inexpensive nitriding treatment that can provide a remarkable improvement in the surface characteristics of titanium alloys. The aim of this work was to determine whether PIRAC could be successfully applied to Ti-6Al-4V and the high-performance near-α titanium alloy Timetal 834. In order to study the response of these materials to PIRAC nitriding, techniques such as X-ray diffraction, micro-indentation hardness, surface profilometry, optical and electron microscopy, nano-scratch adhesion testing and ball-on-plate reciprocating-sliding wear testing were employed. These techniques highlighted the markedly different response between the two alloys to the PIRAC treatment; namely, that Ti-6Al-4V forms a thick compound layer, while at the same processing temperature and time Timetal834 does not form any appreciable Ti 2 N phase instead forming a nitrogen-diffusion case with a thin TiN compound layer at the surface. This inherent difference in nitridability influences the metallurgical response of each alloy. Despite this, the surfaces of both alloys were still hardened considerably and their tribological performance in dry sliding conditions improved compared to the untreated alloys

Cognitive Methods in Staff Training

The article examines the impact of cognitive training methods on the effectiveness of training company personnel, touches upon the relevance of the use of effective training methods by companies in modern conditions. The statistics of the distribution of various types of teaching are given, an evaluation characteristic of one of the traditional teaching methods is given, in terms of the result obtained. The conditions for employees to acquire new knowledge that will maximize the effectiveness of all training are identified. Some of the effective methods of training personnel with a cognitive focus, which are less common in Russian companies, are considered, and their characteristics are given in terms of the results obtained. The authors conclude that it is advisable to use cognitive methods in training employees for the successful and faster development of knowledge, skills and abilities of personnel, and, accordingly, to increase the efficiency of companies in general.Рассматривается вопрос влияния когнитивных методов обучения на результативность обучения персонала компаний, затрагивается вопрос актуальности применения компаниями в современных условиях эффективных методов обучения. Приводится статистика распространения различных видов обучения, дается оценочная характеристика одного из традиционных методов обучения с точки зрения получаемого результата. Обозначаются условия получения сотрудниками новых знаний, способствующих максимизации эффективности всего обучения. Рассматриваются некоторые из эффективных методов обучения персонала когнитивной направленности, менее распространенные в российских компаниях, дается их характеристика с точки зрения получаемых результатов. Авторы делают вывод о целесообразности применения когнитивных методов в обучении сотрудников для успешного и более быстрого развития знаний, навыков и умений персонала и для повышения эффективности деятельности компаний в целом

An observation of the f0(1710)f_0(1710) meson in the ωϕ\omega\phi system in the Pion-BeBe Interaction at Momentum of 29 GeV

The charge-exchange reaction $\pi^-p \rightarrow n\,\omega(783)\phi(1020)$, $\omega \rightarrow \pi^+\pi^-\pi^0$, $\phi \rightarrow K^+K^-$ is studied with the upgraded VES facility (U-70, Protvino) in the interaction of a 29 GeV pion beam with a beryllium target. The distribution over the invariant mass of the system $M_{\omega\phi}$ shows a near-threshold signal. A partial wave analysis reveals that the scalar state ($J^{PC}=0^{++}$) dominates in this mass region. The observed signal can be described with a contribution of the known resonance $f_0(1710)$. Using OPE approximation for the reaction $\pi^-p \rightarrow n\, f_0(1710)$ the product of branching fractions is found to be: $Br(f_0(1710)\rightarrow \pi\pi)\cdot Br(f_0(1710)\rightarrow \omega\phi) = (4.8 \pm 1.2) \cdot 10^{-3}$

Electrocerebral Recovery During the Intracarotid Amobarbital Procedure: Influence of Interval Between Injections

Purpose and Methods : During the intracarotid amobarbital procedure (IAP) at the University of Michigan, continuous scalp EEG monitoring guides the timing for presentation of memory items and postinjection testing. Most of our patients have undergone bilateral injections. The interval between injections varied from 22 to 60 min, depending on the test and recovery time, as well as the time to catheterize the second side. After noting a trend toward prolonged electro-graphic recovery following the second injection, we tested our clinical impression that recovery of the second hemisphere may be influenced by (a) the time between injections and (b) which hemisphere is injected first (epileptogenic or nonepileptogenic). To study these questions, we analyzed EEG recovery data from 48 consecutive IAPs. Approximately half the patients had the epileptogenic side injected first. Results : We found that (a) electrographic recovery after the second injection is prolonged if the interval between bilateral injections is less than 40 minutes and (b) electrographic recovery is more rapid after injection of the epileptogenic hemisphere. Conclusions : We now recommend waiting at least 45 min between injections. The pathophysiology of more prolonged amobarbital effect on the nonepileptogenic hemisphere than on the epileptogenic hemisphere remains unclear.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65275/1/j.1528-1157.1997.tb00067.x.pd