Faulty automotive systems significantly degrade the performance and efficiency of vehicles and are often major contributors of vehicle breakdown; they result in large expenditures for repair and ...maintenance. Therefore, intelligent vehicle health-monitoring schemes are needed for effective fault diagnosis in automotive systems. Previously, we developed a data-driven approach using a data-reduction technique, coupled with a variety of classifiers, for fault diagnosis in automotive systems. In this paper, we consider the problem of fusing classifier decisions to reduce diagnostic errors. Specifically, we develop three novel classifier fusion approaches: 1. class-specific Bayesian fusion; 2. joint optimization of the fusion center and individual classifiers; and 3. dynamic fusion. We evaluate the efficacies of these fusion approaches on an automotive engine data. The results demonstrate that the proposed fusion techniques outperform traditional fusion approaches. We also show that learning the parameters of individual classifiers as part of the fusion architecture can provide better classification performance.
Imperfect test outcomes, due to factors such as unreliable sensors, electromagnetic interference, and environmental conditions, manifest themselves as missed detections and false alarms. This paper ...develops near-optimal algorithms for dynamic multiple fault diagnosis (DMFD) problems in the presence of imperfect test outcomes. The DMFD problem is to determine the most likely evolution of component states, the one that best explains the observed test outcomes. Here, we discuss four formulations of the DMFD problem. These include the deterministic situation corresponding to perfectly observed coupled Markov decision processes to several partially observed factorial hidden Markov models ranging from the case where the imperfect test outcomes are functions of tests only to the case where the test outcomes are functions of faults and tests, as well as the case where the false alarms are associated with the nominal (fault free) case only. All these formulations are intractable NP-hard combinatorial optimization problems. Our solution scheme can be viewed as a two-level coordinated solution framework for the DMFD problem. At the top (coordination) level, we update the Lagrange multipliers (coordination variables, dual variables) using the subgradient method. At the bottom level, we use a dynamic programming technique (specifically, the Viterbi decoding or Max-sum algorithm) to solve each of the subproblems, one for each component state sequence. The key advantage of our approach is that it provides an approximate duality gap, which is a measure of the suboptimality of the DMFD solution. Computational results on real-world problems are presented. A detailed performance analysis of the proposed algorithm is also discussed.
The authors have performed numerical modeling and have analyzed, from the results of calculation, distinctive features of two-phase flow in a channel of constant cross section upon traverse injection ...of a reactive liquid through spray injectors. A model hydrocarbon fuel with thermophysical properties similar to TS-1 kerosene has been considered as the reactive liquid. The characteristics of spraying and evaporation of liquid droplets in a high-enthalpy subsonic air flow have been obtained by mathematical modeling, and an analysis has been made of the quality of mixing and the intensity of combustion of a two-phase mixture. Also, the regularities of the influence of the number of injectors and the pressure difference in them and of the mass flow rate of the reactive liquid on the intensity of processes occurring in the channel have been obtained.
Dwarf spheroidal galaxy satellites of the Milky Way are prime targets for indirect detection of dark matter with gamma rays due to their proximity, high dark matter content, and absence of nonthermal ...emission processes. Recently, the Dark Energy Survey (DES) revealed the existence of new ultrafaint dwarf spheroidal galaxies in the southern-hemisphere sky, therefore ideally located for ground-based observations with the imaging atmospheric Cherenkov telescope array H.E.S.S. We present a search for very-high-energy ( E ≳ 100 GeV ) gamma-ray emission using H.E.S.S. observations carried out recently towards Reticulum II, Tucana II, Tucana III, Tucana IV, and Grus II satellites. No significant very-high-energy gamma-ray excess is found from the observations on any individual object nor in the combined analysis of all the datasets. Using the most recent modeling of the dark matter distribution in the dwarf galaxy halo, we compute for the first time on DES satellites individual and combined constraints from Cherenkov telescope observations on the annihilation cross section of dark matter particles in the form of Weakly Interacting Massive Particles. The combined 95% C.L. observed upper limits reach ⟨ σ v ⟩ ≃ 1 × 10−23 cm3 s−1 in the W+W− channel and 4 × 10−26 cm3 s−1 in the γ γ channels for a dark matter mass of 1.5 TeV. The H.E.S.S. constraints well complement the results from Fermi-LAT, HAWC, MAGIC, and VERITAS and are currently the most stringent in the γγ channels in the multi-GeV/multi-TeV mass range.
Background and Objectives
As a measure of nicotine dependence among adolescent smokers, the modified Fagerström Tolerance Questionnaire (mFTQ; seven items), has been successfully used in the United ...States (USA). Nonetheless, the validity and reliability of mFTQ at the international level is still needed. The current study is the first to test the validity and reliability of mFTQ in four countries: Thailand, Spain, the USA, and Russia.
Methods
In a cross‐sectional survey, mFTQ, risk factors of nicotine dependence, and sociodemographic characteristics were assessed. Risk factors included age of first cigarette, frequency of alcohol use, frequency of marijuana use, and number of cigarettes smoked yesterday. Salivary cotinine was also obtained in Thailand and Spain.
Results
For all four countries, mFTQ exhibited a single factor structure, as supported by previous work in the USA. For all studied countries except Thailand, mFTQ presented acceptable internal reliability. Overall, risk factors of nicotine dependence have predicted mFTQ scores across countries. Frequency of alcohol use in the USA and frequency of marijuana use in Thailand and Spain were not associated with mFTQ scores.
Discussion and Conclusions
mFTQ is a single‐factor measure of nicotine dependence that shows acceptable internal consistency and validity across countries. Further work can advance the scale and tailor it to different cultures.
Scientific Significance
mFTQ can be a clinically practical international measure of nicotine dependence. This study provides initial support for the utility of the mFTQ among Thai, Spanish, American, and Russian adolescents. Further research is needed to test and advance mFTQ across cultures. (Am J Addict 2017;26:689–696)
Abstract
Objective
To analyze the register of patients with acute coronary syndrome (ACS) at the clinical cardiological dispensary from september to november 2018–2019 and 2020 during COVID-19.
...Materials and methods
A retrospective study was conducted, the registry included 952 patients with ACS in 2018 and 1033 patients in 2019, as well as 964 patients in 2020 during the COVID-19 pandemic. Statistical analysis of the material was performed using the Statistica 11.0 software.
Results
When analyzing the provision of specialized care to patients with ACS in 2018, the average age of patients was 67 years, the mortality rate was 3.94%. The structure of ACS in 2018 was dominated by patients with ST-segment elevation myocardial infarction (STEMI) - 47%, myocardial infarction without ST-segment elevation (STEMI) occurred in 23%. The proportion of patients with unstable angina pectoris (NS) was 30%. Only 43.6% were registered with coronary heart disease (CHD) before ACS. 12.5% had a history of diabetes mellitus (DM), 31.2% had arterial hypertension (AH). This cardiovascular event recurred in 4% of patients. Average bed-days 9.73. In 2019, the average age of patients was 68 years, the mortality rate was 4.35%. In the structure of ACS in 2019, patients with STEMI were more common 47.5% than with STEMI 28%. The proportion of patients with HC was 24.5%. 52.1% of patients were registered at the dispensary before ACS with a diagnosis of coronary artery disease. A history of diabetes mellitus was in 13.0%, AH in 39.6% of patients. For 3.8% of patients, myocardial infarction in 2019 became recurrent. The average bed-days was 9.92. In 2020, the average age of patients was 66 years, the mortality rate was 6.25%. The structure of patients was dominated by patients with STEMI - 50.5%, STEMI was less common - in 17.5%. The proportion of patients with unstable angina pectoris was 32%. It was revealed that 54.4% were registered in the dispensary before ACS with coronary artery disease. 28.5% had a history of diabetes mellitus, 40.8% - AH. This event was repeated for 4.7% of patients. Average rate, bed-days rate is 8.85.
Conclusions
Initial analysis reveals that the group of patients with ACS in 2020 was younger than the group of patients in 2019–2020. ACS in combination with diabetes during the pandemic occurred 2 times more often than in the same period of 2018–2019. The proportion of patients registered with the dispensary increased over the period 2018–2019–2020, however, the mortality rate in the 2020 group had a clear upward trend, which may be due to various reasons, incl. the COVID-19 pandemic. The average number of bed-days also objectively decreased when comparing the 2020 and 2019–2018 patient cohorts, which may be due to the burden on the healthcare system during the pandemic.
Funding Acknowledgement
Type of funding sources: Public hospital(s). Main funding source(s): Clinical Cardiology Dispensary
Ti/Ta/Hf/Ni/ceramic layered composite materials are produced via the self-propagating high-temperature synthesis (SHS) of prestructured samples using metal foils (Ti, Hf, Ta, Ni) and reaction tapes ...(Ti + 0.65C), (Ti + 1.7B) and (5Ti + 3Si). The reaction tapes are prepared by cold rolling from powder mixtures. The microstructure, and elemental and phase compositions of the synthesized multilayer composite materials are characterized by scanning-electron microscopy (SEM) and X-ray phase analysis. The formation of intermediate layers and modification of the surface of the metal foils is given individual attention. Their flexural strength is determined according to the scheme of three-point loading at temperatures of 25 and 1100°С. Microstructure analysis of the produced materials shows that the joining of the metal foils and reaction tapes in the combustion mode is facilitated due to reaction diffusion, mutual impregnation, and chemical reactions occurring in the reaction tapes and on the surface of metal foils. The formation of thin intermediate layers in the form of cermets and eutectic solutions provides the synthesized multilayer materials with good strength properties (up to 275 MPa at 25°С, up to 72 MPa at 1100°С). These results are of interest for the development of construction materials operating under extreme conditions.
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