Selective harmonic elimination method for wide range of modulation indexes in multilevel inverters using ICA

Selective harmonic elimination（SHE） in multilevel inverters is an intricate optimization problem that involves a set of nonlinear transcendental equations which have multiple local minima. A new advanced objective function with proper weighting is proposed and also its efficiency is compared with the objective function which is more similar to the proposed one. To enhance the ability of the SHE in eliminating high number of selected harmonics, at each level of the output voltage, one slot is created. The SHE problem is solved by imperialist competitive algorithm（ICA）. The conventional SHE methods cannot eliminate the selected harmonics and satisfy the fundamental component in some ranges of modulation indexes. So, to surmount the SHE defect, a DC-DC converter is applied. Theoretical results are substantiated by simulations and experimental results for a 9-level multilevel inverter. The obtained results illustrate that the proposed method successfully minimizes a large number of identified harmonics which consequences very low total harmonic distortion of output voltage.     

Study on pharyngeal and uvular consonants in foreign accented Arabic for ASR

This paper investigates the unique pharyngeal and uvular consonants of Arabic from the point of view of automatic speech recognition (ASR). Comparisons of the recognition error rates for these phonemes are analyzed in five experiments that involve different combinations of native and non-native Arabic speakers. The most three confusing consonants for every investigated consonant are discussed. All experiments use the Hidden Markov Model Toolkit (HTK) and the Language Data Consortium (LDC) WestPoint Modern Standard Arabic (MSA) database. Results confirm that these Arabic distinct consonants are a major source of difficulty for Arabic ASR. While the recognition rate for certain of these unique consonants such as // can drop below 35% when uttered by non-native speakers, there is advantage to include non-native speakers in ASR. Besides, regional differences in pronunciation of MSA by native Arabic speakers require the attention of Arabic ASR research.     

Waterpipe smoking: construction and validation of the Lebanon Waterpipe Dependence Scale (LWDS-11).

Waterpipe smoking is becoming fashionable in Lebanon, but no studies have studied nicotine dependence related to waterpipe smoking. A score was constructed from 21 items and subsequently submitted to two factor analyses, which led to the extraction of four factors. Reliability and test-retest reproducibility were measured. Convergent construct validity and discriminant validity also were assessed for different smokers' samples. The Lebanon Waterpipe Dependence Scale-11 (LWDS-11) was composed of four subscales, the first representing nicotine dependence, the second negative reinforcement, the third psychological craving, and the fourth positive reinforcement. Internal consistency and test-retest reproducibility were adequate, and the subscales correlated adequately with measurements of nicotine metabolites, exhaled carbon monoxide levels, and the frequency of waterpipe smoking. The LWDS-11 discriminated between mild, moderate, and heavy waterpipe smokers, based on a threshold score of 10. Results were biologically and psychologically sound. This is the first scale to characterize waterpipe dependence. With further improvement and confirmation, it could become a useful clinical and epidemiological tool.     

Asphalt Works Subcontracting Disputes in Large Construction Programs

Subcontracting is a common, and sometimes warranted, practice on large construction projects. However, it is also well recognized that disputes are likely to develop between subcontractors and general contractors in trying to achieve target objectives of cost, quality, and time. This paper tackles quality- and time-related disputes that are peculiar to the case of subcontracting asphalt works under a large construction program, such as that of a new airport construction. In particular, it reports on disagreements regarding the achieved thickness and surface smoothness of the constructed asphalt concrete layer, and on activity-interfacing and delay-attribution issues resulting from improper contractual and scheduling practices. Factors believed to be relevant to both classes of disputes are identified, and analyses are offered to pinpoint significant anomalies. Finally, arguments are developed and recommendations given, that reflect best industry practices whose application could help minimize the likelihood of facing such disputes in the future.     

A faulty node detection scheme for wireless sensor networks that use data aggregation for transport

This paper presents a faulty node detection approach for wireless sensor networks that aggregate measurement data on their way toward the sink (base station). The approach is based on the idea of commanding sensor nodes on the aggregation paths to temporarily stop including their readings in the received aggregated readings from their upstream neighbors. The scheme is dependent on the ability of the sink to detect faulty nodes through changes in the received aggregated readings at the sink using a Markov Chain Controller (MCC). The algorithm that is run in the sink uses the MCC to assign a state to each sensor node based on transitions that are triggered by receiving aggregated path readings, and accordingly deduces the nodes that may be faulty. The experimental results show at least 98% detection rate at the cost of reasonable detection delays and generated wireless network traffic. Copyright © 2016 John Wiley & Sons, Ltd.     

Vacuum Technology Considerations For Mass Metrology

Vacuum weighing of mass artifacts eliminates the necessity of air buoyancy correction and its contribution to the measurement uncertainty. Vacuum weighing is also an important process in the experiments currently underway for the redefinition of the SI mass unit, the kilogram. Creating the optimum vacuum environment for mass metrology requires careful design and selection of construction materials, plumbing components, pumping, and pressure gauging technologies. We review the vacuum technology¹ required for mass metrology and suggest procedures and hardware for successful and reproducible operation.     

Formation of OTS self-assembled monolayers at chemically treated titanium surfaces

Enhanced biocompatibility of titanium implants highly depends on the possibility of achieving high degrees of surface functionalization for a low immune response and/or enhanced mineralization of bioactive minerals, such as hydroxyapatite. In this respect, surface modification with Self Assembled Monolayers (SAMs) has a great potential in delivering artificial surfaces of improved biocompatibility. Herein, the effectiveness of common chemical pre-treatments, i.e. hydrogen peroxide (H₂O₂) and Piranha (H₂SO₄ + H₂O₂), in facilitating surface decontamination and hydroxylation of titanium surfaces to promote further surface functionalization by SAMs is investigated. The quality of the octadecyltrichlorosilane (OTS) based SAM appeared to strongly depend upon the surface morphology, the density and nature of surface hydroxyl sites resulting from the oxidative pre-treatments. Contrary to common belief, no further hydroxylation of the titanium substrate was observed after the selected chemical pre-treatments, but the number of hydroxyl groups available on the surface was decreased as a result of the formation of a titanium oxide layer with a gel-type structure. Further examinations by atomic force microscopy, infrared spectroscopy and X-ray photoelectron spectroscopy also revealed that mild oxidizing conditions were sufficient to remove surface contamination without detrimental effects on surface hydroxylation state and surface roughness. Furthermore, the adsorption of the alkylsiloxane molecules forming the SAM film is believed to proceed through hydrolysis at surface acidic hydroxyl groups rather than randomly. This site dependent adsorption process has significant implications for further functionalization of titanium based implants. It also highlights the difficulty of achieving an OTS based SAM at the surface of titanium and question the quality of SAMs reported at titanium surfaces so far.     

Study of ethanol-induced conformational changes of holo and apo alpha-lactalbumin by spectroscopy and limited proteolysis

This study was performed to contribute to the analysis of alpha-lactalbumin "molten globule" state by using spectral and proteolysis techniques. Samples of holo and apo alpha-lactalbumin in the presence of different concentrations of ethanol were analyzed. Results of fluorescence spectroscopy of both forms showed that as ethanol concentration increased, the tryptophanyl residues became more accessible to the solvent. Near circular dichroism spectra of holo alpha-lactalbumin indicated that its tertiary structure was maintained in 20% ethanol whereas it was altered in 30 and 40% ethanol. For apo alpha-lactalbumin, spectra were similar in all samples studied. Holo alpha-lactalbumin was resistant to trypsinolysis in 0% ethanol, whereas it was easily hydrolyzed in 20 and 30% ethanol. In the case of the apo form and in the absence of ethanol, 70% of the protein was degraded after 1 h. However, in the presence of 20 and 30% ethanol, the overall reaction rate was lowered. Peptides obtained after tryptic hydrolysis were identified by reversed-phase high-performance liquid chromatography coupled to mass spectrometry. Differences in population of produced peptides indicate the changes of folding intermediates present in the studied alpha-lactalbumin solutions. This study demonstrated that proteolytic enzymes are suitable tools to determine protein structure complementing physico-chemical studies.