On the Use of High-resolution Time-frequency Distribution Based on a Polynomial Compact Support Kernel for Fault Detection in a Two-level Inverter

Quadratic Time-Frequency Distributions (TFDs) become a standard tool in many fields producing nonstationary signatures. However, these representations suffer from two drawbacks: First, bad time-frequency localization of the signal's autoterms due to the unavoidable crossterms generated by the bilinear form of these distributions. This results on bad estimation of the Instantaneous Frequency (IF) laws and decreases, in our case, the ability to precisely decide the existence of a motor fault. Secondly, the TFD's parameterization is not always straightforward. This paper deals with faults' detection in two-level inverter feeding induction motors, in particular open-circuit Insulated Gate Bipolar Transistor (IGBT) faults. For this purpose, we propose the use of a recent high-resolution TFD, referred as PCBD for Polynomial Cheriet-Belouchrani Distribution. The latter is adjusted using only a single integer that is automatically optimized using the Stankovic concentration measure, otherwise, no external windows are needed to perform the highest time-frequency resolution. The performance of the PCBD is compared to the best-known quadratic representations using a test bench. Experimental results show that the frequency components characterizing open-circuit faults are best detected using the PCBD thanks to its ability to suppress interferences while maintaining the signal's proper terms.

Zero-Leverage in European Firms

This study analyzes the zero-leverage phenomenon in a sample of European listed firms for the period 2001-2016, with a focus on the role played by the corporate governance mechanisms on the explanation of the phenomenon. Considering a set of internal and external corporate governance variables, it is rejected that firms with poor internal mechanisms of corporate governance have a greater propensity to adopt zero-leverage policies. Nonetheless, a great ownership concentration—measure for external corporate governance mechanisms—decreases the firm's propensity to be debt-free, indicating that the presence of large shareholders reduces managers' opportunistic actions. Results that partially validate that zero-leverage policies are driven by entrenched managers avoiding the disciplinary power of debt, especially in the presence of small shareholders without incentives and power to control managers' actions. Additionally, zero-leverage firms seem to substitute debt by internal sources of liquidity. Results are robust to different zero-leverage classifications and econometric methods.

Pengaruh Penerapan Model Problem Based Learning terhadap Kemampuan Pemecahan Masalah Matematika Siswa

AbstrakPenelitian bertujuan untuk mengetahui bagaimana pengaruh penerapan model problem based learning terhadap kemampuan pemecahan masalah matematika siswa kelas VII SMP Negeri 3 Palembayan berdasarkan tingkat Kemampuan Awal Matematis (KAM) siswa. Dimana siswa dibagi menjadi 3 kategori yaitu KAM Tinggi, KAM Sedang dan KAM rendah. Jenis penelitian yang digunakan dalam penelitian ini adalah penelitian pre-eksperimen, dengan rancangan penelitian one shot case study. Subjek pada penelitian ini siswa kelas VII.3 yang dipilih secara secara acak. Instrumen yang digunakan pada penelitian ini adalah tes akhir. Tes yang digunakan adalah berbentuk essay. Penelitian ini menggunakan teknik analisis data deksriptif kualitatif. Berdasarkan analisis data secara keseluruhan, model PBL dapat membuat kemampuan pemecahan masalah matematika siswa lebih baik. Terlebih lagi untuk siswa yang termasuk ke dalam kategori KAM tinggi. Ini terlihat dari ukuran pemusatan dimana rata-rata untuk siswa pada kategori sedang 52,86 dengan simpangan baku 11,31 sehingga disimpulkan bahwa model ini dapat memberikan pengaruh terhadap kemampuan pemecahan masalah siswa. The Effect of Application of the Problem Based Learning Model on Mathematical Problem Solving StudentsAbstractThis study aimed to determine how the effect of problem-based learning model implementation toward student mathematic problem-solving abilities at Class VII SMPN 3 Palembayan based on the basic level of Mathematical Ability. Students were divided into 3 categories such as the low, medium and high ability. It was pre-experimental research using one shot case research study design. The research subject was class VII.3 students who were randomly selected. The instrument was a final test in the form of an essay. It used a qualitative descriptive data analysis technique. Based on the data analysis, the Problem-solving learning model can make students' mathematics problem-solving abilities better. Moreover, those students are categorized into high ability. It is seen from the concentration measure for students in the medium category are 52.86 with a standard deviation i.e. 11.31. It is concluded that problem-solving model can affect the students' problem-solving abilities.

Ethnic Networks and Language Proficiency Among Immigrants

Recent research on the linguistic adjustment of minority-language-speaking immigrants in several destinations has found that acquisition of destination language skills is inhibited by living in an area where many others speak the same minority language. This chapter uses a unique data set for Australia (1988) that includes a variety of ethnic network variables to analyze the role of the language concentration measure. These ethnic variables, in particular, ethnic press, relatives in Australia, and spouse's origin language, are highly statistically significant. Their inclusion in the equation eliminates the effect of the minority-language concentration variable. The model for analyzing the determinants of English reading and English writing skills in Australia is also shown to be very similar to the model for speaking fluency, including the effect of the ethnic network variables.

Is severe hypocalcemia immediately life threatening?

Objective Severe hypocalcemia (Ca <1.9 mmol/L) is often considered an emergency because of a potential risk of cardiac arrest or seizures. However, there is little evidence to support this. The aim of our study was to assess whether severe hypocalcemia was associated with immediately life-threatening cardiac arrhythmias or neurological complications. Methods A retrospective observational study was carried out over a 2-year period in the Adult Emergency Department (ED) of Nantes University Hospital. All patients who had a protein-corrected calcium concentration measure were eligible for inclusion. Patients with multiple myeloma were excluded. The primary outcome was the number of life-threatening cardiac arrhythmias and/or neurological complications during the stay in the ED. Results A total of 41,823 patients had protein-corrected calcium (pcCa) concentrations measured, 155 had severe hypocalcemia, 22 were excluded because of myeloma leaving 133 for analysis. Median pcCa concentration was 1.73 mmol/L (1.57–1.84). Seventeen (12.8%) patients presented a life-threatening condition, 14 (10.5%) neurological and 3 (2.2%) cardiac during ED stay. However, these complications could be explained by the presence of underlying co-morbidities and or electrolyte disturbances other than hypocalcemia. Overall, 24 (18%) patients died in hospital. Vitamin D deficiency, chronic kidney disease and hypoparathyroidism were the most frequently found causes of hypocalcemia. Conclusion Thirteen percent of patients with severe hypocalcemia presented a life-threatening cardiac or neurological complication on the ED. However, a perfectly valid alternative cause could account for these complications. Further research is warranted to define the precise role of hypocalcemia.

Individual peculiarities in pharmacokinetics of antiblastomic drugs in healthy volunteers

The data of inter-individual variations in pharmacokinetics of antiblastomic drugs from the group of tyrosine proteinkinase inhibitors (imatinib, gefitinib and nilotinib) and antiblastomic immune modulator lenalidomide in healthy volunteers by meams of HPLC-MS/MS were represented in the article. The concentrations of the drugs studied were measured in the volunteer blood serum. The indeces Cmax (maximal concentration and time reaching), Tmax (time covering maximal concentration measure), AUC0-t (squire under pharmaceutical curve) were processed by trapetias method, Cmax/AUC0-t as well as Kel (elimination constant) and T1/2 (period of semielimination) according to individual signs. The significant individual variability revealed for imatinib, gefitinib and nilotinib in healthy volunteers indicates on necessity of therapeutic drug monitoring in patients treated with them to aim optimal dosing.