99 research outputs found
Исследование влияния динамических режимов нагружения на вибрационные характеристики узлов трения вращательного и возвратно-вращательного действия
Цель работы – определение влияния вибрационной составляющей на точность воспроизведения динамических законов нагружения и триботехнические характеристики узла трения при его испытании на автоматизированном триботехническом комплексе. В процессе исследования проводились: аналитический обзор существующих методов и аппаратно-программного обеспечение для исследования и анализа виброакустических сигналов, построение математической модели узла скоростного динамического нагружения, разработка комплекса контрольно-измерительного оборудования, разработка программного обеспечения, определение способов крепления и мест установки первичных вибропреобразователей, а также анализ виброакустических сигналов.During the process of writing the graduate qualification work, the following tasks have been achived: 1.Integrated instrument development for the investigation of vibroacoustics; 2. Compiling a numerical scheme; 3. Software development for the imagery of vibroacoustics; 4. Investigation of vibroacoustics
Recommended from our members
Assessment of Commercial Building Lighting as a Frequency Regulation Resource
This paper evaluates the potential for automated lighting control as a resource for frequency regulation of the electric grid system in the context of current energy policies, economic incentives, and technological trends. The growing prevalence of renewable energy has increased the need for ancillary services to maintain grid frequency and stability. While demand side resources like heating, ventilating, and air-conditioning systems, as well as water treatment plants are already evaluated as regulation service providers, the potential application to electrical lighting systems has largely been ignored. Yet, aggregations of lighting systems that are retrofitted with intelligent controls could conceivably contribute to frequency regulation services with little impact on user comfort. To further explore the feasibility of lighting potential, this paper explores (1) how lighting control systems are limited by visual comfort perception and acceptability, (2) how such limitations impact the performance of the lighting system as an frequency regulation resource, and (3) how the market potential of lighting systems as demand side resources compares in different regional transmission organizations. Finally, the impact of developing technologies on the application of lighting systems for frequency regulation is discussed.</div
Forty-five minutes of physical activity at school each day? Curricular promotion of physical activity in grades one to four
Aim: According to the US Department of Health and Human Services (2008) and the World Health Organization (2008), regular physical activity is essential to the healthy development of children and contributes to the reduction of chronic diseases throughout their life span. However, coordinated comprehensive national and international programs to promote physical activity and sports participation are lacking. According to the German Sports Federation (2006), physical education (PE) classes at German schools are increasingly being canceled or taught outside the school. "fit for pisa" is a German intervention developed in response to the demand for scientific evaluation of interventions like daily physical education. Its goal is to provide quality management-secured, structured and standardized PE instruction by qualified instructors. Subjects and methods: The "fit for pisa" intervention has been implemented at five primary schools in Göttingen, Germany, since 2003. This daily physical education intervention is based on quality standards. At the five primary schools participating in "fit for pisa," students receive a supplementary 3 class hours of PE/week in addition to the mandatory 2 class hours/week for the entire school term. In other words, the children now receive one 45-min session of PE each school day. Daily physical education is now a part of their mandatory school curriculum. The curriculum content and teaching methods have been continuously developed and optimized based on the state guidelines for Lower Saxony. Results: Teacher training is held at the participating schools once a month to promote standardized implementation and quality management of the intervention program. Additional monthly meetings are held so that the teachers can discuss any problems, deviations or other issues occurring in the classes. Checklists are provided for the teachers and external trainers to document the content and objectives of each lesson. Supervisors evaluate the checklists at regular intervals. Using these instruments, the results of the 4-year intervention program were evaluated at the five participating primary schools. Conclusions: This study provides important data for recommendations to implement additional physical education in primary schools, for the corresponding quality assurance instruments and for the optimization of physical education guidelines for primary schools
Swift detection of the super-swift switch-on of the super-soft phase in nova V745 Sco (2014)
V745 Sco is a recurrent nova, with the most recent eruption occurring in
February 2014. V745 Sco was first observed by Swift a mere 3.7 hr after the
announcement of the optical discovery, with the super-soft X-ray emission being
detected around four days later and lasting for only ~two days, making it both
the fastest follow-up of a nova by Swift and the earliest switch-on of
super-soft emission yet detected. Such an early switch-on time suggests a
combination of a very high velocity outflow and low ejected mass and, together
with the high effective temperature reached by the super-soft emission, a high
mass white dwarf (>1.3 M_sun). The X-ray spectral evolution was followed from
an early epoch where shocked emission was evident, through the entirety of the
super-soft phase, showing evolving column density, emission lines, absorption
edges and thermal continuum temperature. UV grism data were also obtained
throughout the super-soft interval, with the spectra showing mainly emission
lines from lower ionization transitions and the Balmer continuum in emission.
V745 Sco is compared with both V2491 Cyg (another nova with a very short
super-soft phase) and M31N 2008-12a (the most rapidly recurring nova yet
discovered). The longer recurrence time compared to M31N 2008-12a could be due
to a lower mass accretion rate, although inclination of the system may also
play a part. Nova V745 Sco (2014) revealed the fastest evolving super-soft
source phase yet discovered, providing a detailed and informative dataset for
study.Comment: 14 pages, 11 figures (4 in colour), accepted for publication in MNRA
Isoforms of Retinol binding protein 4 (RBP4) are increased in chronic diseases of the kidney but not of the liver
<p>Abstract</p> <p>Background</p> <p>The levels of retinol-binding protein 4 (RBP4) – the carrier protein for Vitamin A in plasma – are tightly regulated under healthy circumstances. The kidney, the main site of RBP4 catabolism, contributes to an elevation of RBP4 levels during chronic kidney disease (CKD) whereas during chronic liver disease (CLD) RBP4 levels decrease. Little is known about RBP4 isoforms including apo-RBP4, holo-RBP4 as well as RBP4 truncated at the C-terminus (RBP4-L and RBP4-LL) except that RBP4 isoforms have been reported to be increased in hemodialysis patients. Since it is not known whether CLD influence RBP4 isoforms, we investigated RBP4 levels, apo- and holo-RBP4 as well as RBP4-L and RBP4-LL in plasma of 36 patients suffering from CKD, in 55 CLD patients and in 50 control subjects. RBP4 was determined by ELISA and apo- and holo-RBP4 by native polyacrylamide gel electrophoresis (PAGE). RBP4-L and RBP4-LL were analyzed after immunoprecipitation by mass spectrometry (MALDI-TOF-MS).</p> <p>Results</p> <p>RBP4 isoforms and levels were highly increased in CKD patients compared to controls (P < 0.05) whereas in CLD patients RBP4 isoforms were not different from controls. In addition, in hepatic dysfunction RBP4 levels were decreased whereas the amount of isoforms was not affected.</p> <p>Conclusion</p> <p>The occurrence of RBP4 isoforms is not influenced by liver function but seems to be strongly related to kidney function and may therefore be important in investigating kidney function and related disorders.</p
Systematic Analysis of Parameter Identifiability for Improved Fitting of a Biological Wastewater Model to Experimental Data
Protein biomarkers in blood reflect the interrelationships between stroke outcome, inflammation, coagulation, adhesion, senescence and cancer
The most important predictors for outcomes after ischemic stroke, that is, for health deterioration and death, are chronological age and stroke severity; gender, genetics and lifestyle/environmental factors also play a role. Of all these, only the latter can be influenced after the event. Recurrent stroke may be prevented by antiaggregant/anticoagulant therapy, angioplasty of high-grade stenoses, and treatment of cardiovascular risk factors. Blood cell composition and protein biomarkers such as C-reactive protein or interleukins in serum are frequently considered as biomarkers of outcome. Here we aim to provide an up-to-date protein biomarker signature that allows a maximum of mechanistic understanding, to predict health deterioration following stroke. We thus surveyed protein biomarkers that were reported to be predictive for outcome after ischemic stroke, specifically considering biomarkers that predict long-term outcome (≥ 3 months) and that are measured over the first days following the event. We classified the protein biomarkers as immune‑inflammatory, coagulation-related, and adhesion-related biomarkers. Some of these biomarkers are closely related to cellular senescence and, in particular, to the inflammatory processes that can be triggered by senescent cells. Moreover, the processes that underlie inflammation, hypercoagulation and cellular senescence connect stroke to cancer, and biomarkers of cancer-associated thromboembolism, as well as of sarcopenia, overlap strongly with the biomarkers discussed here. Finally, we demonstrate that most of the outcome-predicting protein biomarkers form a close-meshed functional interaction network, suggesting that the outcome after stroke is partially determined by an interplay of molecular processes relating to inflammation, coagulation, cell adhesion and cellular senescence
Swift detection of the super-swift switch-on of the super-soft phase in nova V745 Sco (2014)
V745 Sco is a recurrent nova, with the most recent eruption occurring in February 2014. V745 Sco was first observed by Swift a mere 3.7 hr after the announcement of the optical discovery, with the super-soft X-ray emission being detected around four days later and lasting for only ~two days, making it both the fastest follow-up of a nova by Swift and the earliest switch-on of super-soft emission yet detected. Such an early switch-on time suggests a combination of a very high velocity outflow and low ejected mass and, together with the high effective temperature reached by the super-soft emission, a high mass white dwarf (>1.3 M_sun). The X-ray spectral evolution was followed from an early epoch where shocked emission was evident, through the entirety of the super-soft phase, showing evolving column density, emission lines, absorption edges and thermal continuum temperature. UV grism data were also obtained throughout the super-soft interval, with the spectra showing mainly emission lines from lower ionization transitions and the Balmer continuum in emission. V745 Sco is compared with both V2491 Cyg (another nova with a very short super-soft phase) and M31N 2008-12a (the most rapidly recurring nova yet discovered). The longer recurrence time compared to M31N 2008-12a could be due to a lower mass accretion rate, although inclination of the system may also play a part. Nova V745 Sco (2014) revealed the fastest evolving super-soft source phase yet discovered, providing a detailed and informative dataset for study
Multiwavelength observations of V407 Lupi (ASASSN-16kt) --- a very fast nova erupting in an intermediate polar
We present a detailed study of the 2016 eruption of nova V407 Lupi (ASASSN-16kt), including optical, near-infrared, X-ray, and ultraviolet data from SALT, SMARTS, SOAR, Chandra, Swift, and XMM-Newton. Timing analysis of the multiwavelength light-curves shows that, from 168 days post-eruption and for the duration of the X-ray supersoft source phase, two periods at 565 s and 3.57 h are detected. We suggest that these are the rotational period of the white dwarf and the orbital period of the binary, respectively, and that the system is likely to be an intermediate polar. The optical light-curve decline was very fast ( 2.9 d), suggesting that the white dwarf is likely massive ( M). The optical spectra obtained during the X-ray supersoft source phase exhibit narrow, complex, and moving emission lines of He II, also characteristics of magnetic cataclysmic variables. The optical and X-ray data show evidence for accretion resumption while the X-ray supersoft source is still on, possibly extending its duration
The January 2016 eruption of recurrent nova LMC 1968
We present a comprehensive review of all observations of the eclipsing Recurrent Nova LMC 1968 in the Large Magellanic Cloud which was previously observed in eruption in 1968, 1990, 2002, 2010, and most recently in 2016. We derive a recurrence time of 6.2 +/- 1.2 years and provide the ephemerides of the eclipse. In the ultraviolet-optical-IR photometry the light curve appears with a common decline after discovery with high variability right from the first observation around two days after eruption. Spectra from 2016 and 1990 are very similar and are dominated by H and He lines longward of 2000 A. Interstellar reddening is found to be E(B-V) = 0.07+/-0.01. The super soft X-ray luminosity is lower than the Eddington luminosity and the X-ray spectra suggest the mass of the WD is larger than 1.3 Msun. Eclipses in the light curve suggest that the system is at high orbital inclination. On day four after the eruption a recombination wave was observed in Fe II ultraviolet absorption lines. Narrow line components are seen and explained as being due to reionisation of ejecta from a previous eruption. The UV spectrum varies with orbital phase, and so does a component of the He II 1640 A emission line, which leads us to propose that early-on the inner WD Roche lobe might be filled with a bound opaque medium prior to the re-formation of an accretion disk. Both that medium and the ejecta can cause the delay in the appearance of the soft X-ray source
- …