Semi-active vibration control of the motorized spindle using a self-powered SSDV technique: simulation and experimental study

SSD (synchronized switch damping) is used for vibration control of the motorized spindle based on piezoelectric stack. Moreover, inspired by self-powered SSDI, a self-powered SSDV circuit was designed to overcome the disadvantages of requiring readjusting control parameters and sensor re-positioning of SSDI (synchronized switch damping on inductor) and SSDV (synchronized switch damping on voltage source). A simulation and an experimental were built, and the results show vibration control performance of self-powered SSDV is better than self-powered SSDI and is more flexible and effective than self-powered SSDI by adjusting the DC voltage to adapt to different speeds of the motorized spindle

Thermal performance of finned-tube thermoacoustic heat exchangers in oscillatory flow conditions

Heat exchangers play a key role in the overall performance of thermoacoustic devices. Due to the complex nature of oscillatory flows, the underlying mechanism of heat transfer in oscillatory flows is still not fully understood. This work investigates the effect of fin length and fin spacing on the thermal performance of finned-tube heat exchangers. The heat transfer rate between two finned-tube heat exchangers arranged side-by-side in an oscillatory flow was measured over a range of testing conditions. The results are presented in terms of heat transfer coefficient and heat transfer effectiveness. Comparisons are made between experimental results of this work and a number of models, such as, the Time-Average Steady-Flow Equivalent (TASFE) model, the Root Mean Square Reynolds Number (RMS-Re) model and the boundary layer conduction model, as well as several empirical correlations in literature. A new empirical correlation is proposed to be used for the prediction of thermal performance for finned-tube heat exchangers in oscillatory flows. The uncertainties associated with the measurement of heat flux are estimated

Genetic Characterization of Animal Brucella Isolates from Northwest Region in China

Animal brucellosis is a reemerging disease in China, particular in northwest China. The Brucella species (even genus) are highly conserved; therefore the use of Multilocus sequencing typing (MLST: based on conserved housekeeping loci) is more suitable for discrimination at species or biovar level on Brucella. In this study, MLST was used to analyze the characterization of Brucella from sheep and yaks during 2015 and 2016. All 66 isolates were collected from northwest China, including Inner Mongolia, Xinjiang, Qinghai, and Gansu provinces. Isolates were cultured on Brucella agar medium and identified by MLST. MLST identified five ST types: ST8 (n=55), ST7 (n=2), ST3 (n=5), ST1 (n=2), and ST14 (n=2). This analysis revealed that B. melitensis isolates exhibited high single genotypes (ST8) in the most northwest China. MLST of isolates provides helpful information on understanding genetic characterization of Brucella in northwest China

Studies of the Cataluminescence of Benzene Homologues onNanosized γ–Al2O3/Eu2O3 and the Development of a Gas Sensorfor Benzene Homologue Vapors

The cataluminescence (CTL) of benzene and the benzene homologues tolueneand xylene on nanosized γ–Al2O3 doped with Eu2O3 (γ–Al2O3/Eu2O3) was studied and asensor of determining these gases was designed. The proposed sensor showed highsensitivity and selectivity at an optimal temperature of 432 ºC, a wavelength of 425 nm anda flow rate of 400 mL/min. Quantitative analysis was performed at the optimal conditions.The linear ranges of CTL intensity versus concentration of the benzene homologues were asfollows: benzene 2.4~5000 mL/m3, toluene 4.0~5000 mL/m3 and xylene 6.8~5000 mL/m3,with detection limits (3Ã) of 1.8 mL/m3, 3.0 mL/m3 and 3.4 mL/m3 for each one,respectively. The response time of this system was less than 3 s. The coexistence of othergases, such as SO2, CO and NH3, caused interference at levels around 11.7%, 5.8% and8.9% respectively. The technique is a convenient and fast way of determining the vapors ofbenzene homologues in air

Synonymous Codon Usages as an Evolutionary Dynamic for <i>Chlamydiaceae</i>

The family of Chlamydiaceae contains a group of obligate intracellular bacteria that can infect a wide range of hosts. The evolutionary trend of members in this family is a hot topic, which benefits our understanding of the cross-infection of these pathogens. In this study, 14 whole genomes of 12 Chlamydia species were used to investigate the nucleotide, codon, and amino acid usage bias by synonymous codon usage value and information entropy method. The results showed that all the studied Chlamydia spp. had A/T rich genes with over-represented A or T at the third positions and G or C under-represented at these positions, suggesting that nucleotide usages influenced synonymous codon usages. The overall codon usage trend from synonymous codon usage variations divides the Chlamydia spp. into four separate clusters, while amino acid usage divides the Chlamydia spp. into two clusters with some exceptions, which reflected the genetic diversity of the Chlamydiaceae family members. The overall codon usage pattern represented by the effective number of codons (ENC) was significantly positively correlated to gene GC3 content. A negative correlation exists between ENC and the codon adaptation index for some Chlamydia species. These results suggested that mutation pressure caused by nucleotide composition constraint played an important role in shaping synonymous codon usage patterns. Furthermore, codon usage of T3ss and Pmps gene families adapted to that of the corresponding genome. Taken together, analyses help our understanding of evolutionary interactions between nucleotide, synonymous codon, and amino acid usages in genes of Chlamydiaceae family members

Isolates from Yaks in Qinghai, China

Recently, the yak population has exhibited reproductive disorders, which are considered to be associated with Chlamydia abortus (C. abortus) in Qinghai, China. In this study, a total of 9 aborted fetuses (each from a different herd) and 126 vaginal swab samples from the 9 herds were collected and analyzed. C. abortus DNA was detected from all of the 9 aborted fetuses and 30 of the 126 vaginal swab samples (23.81%) from yak cows in the selected herds. Four C. abortus strains were isolated from embryonated egg yolk sacs inoculated with foetal organ suspensions. The isolated C. abortus strains were further identified, which showed identical restriction profiles with the C. abortus reference strain using AluI restriction enzyme in the RFLP test. Moreover, the isolated C. abortus strains and C. abortus-positive vaginal swab samples were genotyped by multiple loci variable number tandem repeat analysis and all belonged to the genotype 2 group. These findings suggested that C. abortus played a substantial role in yak abortion in Qinghai, China

Calibration of Ultrasonic Transducer Based on Ultrasonic Logging Instrument for Shaft Sinking

High-precision logging equipment is critical for measuring the borehole diameter and drilling offset in coal mining and petroleum drilling. We propose a module composition and positioning principle for an ultrasonic transducer based on an ultrasonic logging instrument for shaft sinking by drilling (ULISSD) for calculating the reflection distance. The logging distance, which is the primary performance index of a logging system, is determined by using the self-reception sensitivity and error of the ultrasonic transducer in a downhole system. To measure the error between the piezoelectric element of the transducer and the rubber seal of the borehole logging system, we developed an ultrasonic-transducer error-calibration device and a calibration method for a central-air-return-shaft-drilling project. This calibration device can eliminate the inherent error of the transducer and calculate the rate of propagation with high accuracy. The measurement error is reduced by approximately 1.5 mm; thus, the ULISSD measurement accuracy can be effectively improved in central-air-return-shaft drilling

Identification and Characterization of Chlamydia abortus Isolates from Yaks in Qinghai, China

Recently, the yak population has exhibited reproductive disorders, which are considered to be associated with Chlamydia abortus (C. abortus) in Qinghai, China. In this study, a total of 9 aborted fetuses (each from a different herd) and 126 vaginal swab samples from the 9 herds were collected and analyzed. C. abortus DNA was detected from all of the 9 aborted fetuses and 30 of the 126 vaginal swab samples (23.81%) from yak cows in the selected herds. Four C. abortus strains were isolated from embryonated egg yolk sacs inoculated with foetal organ suspensions. The isolated C. abortus strains were further identified, which showed identical restriction profiles with the C. abortus reference strain using AluI restriction enzyme in the RFLP test. Moreover, the isolated C. abortus strains and C. abortus-positive vaginal swab samples were genotyped by multiple loci variable number tandem repeat analysis and all belonged to the genotype 2 group. These findings suggested that C. abortus played a substantial role in yak abortion in Qinghai, China