Based on the rolling bearing vibration measurement principle in ISO standard, a nonlinear dynamic model of ball bearing is built and motion equations of the inner ring, outer ring, and rolling elements are derived by using Lagrange’s equation. The ball bearing model includes the influence of waviness, rotational speed, external load, arbor supporting stiffness and arbor eccentricity. Ball bearing high-speed vibration tests are performed and used to verify the theoretical results. Simulated results showed that specific waviness orders produced the principal frequencies that were proportional to rotational speed. Rotational speed mainly affected the value of the natural frequency of the bearing system, and RMS (Root Mean Square) of the full band had a great fluctuation with the increase of rotational speed. In the experiment, spectrum and RMS of 2fs-30 kHz (fs: the rotational frequency of inner ring/arbor) under high speed could include not only the influence of rotational speed but also principal frequencies produced by waviness, which could cover the part of requirements of the standard bearing vibration measurement.
The public transport service is highly essential to meet the demand due to a rapidly growing population and mobility. Thus providing public service and improve its service becomes an urgent need in recent years. In Iraq, the Bus system represents the backbone in public transportation, which is based mainly on highway infrastructure. To meet the growing mobility needs, enhancing public service provided only by bus routes is essential. Measuring bus route performance represents one of the crucial transit research topics in the last recent years. The current study tries to investigate the urban public route's efficiency utilizing the "data envelopment analysis (DEA)" technique. To analyze route performance, DEA is using, and performance measures include route design, cost, service, operation, and comfort efficiency are selected and calculated for different routes. Efficiency and effectiveness are the output of this process. Bus company owners can also use the results of this study to improve their services, attract new customers, and better manage their resources.
Several recent earthquakes have indicated that the design and construction of bridges based on former seismic design provisions are susceptible to fatal collapse triggered by the failure of reinforced concrete columns. This paper incorporates an experimental investigation into the seismic response of nonductile bridge piers strengthened with low-cost glass fiber reinforced polymers (LC-GFRP). Three full-scale bridge piers were tested under lateral cyclic loading. A control bridge pier was tested in the as-built condition and the other two bridge piers were experimentally tested after strengthening them with LC-GFRP jacketing. The LC-GFRP strengthening was performed using two different configurations. The control bridge pier showed poor seismic response with the progress of significant cracks at very low drift levels. Test results indicated the efficiency of the tested strengthening configurations to improve the performance of the strengthened bridge piers including crack pattern, yield, and ultimate cyclic load capacities, ductility ratio, dissipated energy capacity, initial stiffness degradation, and fracture mode.
To study the difference in seismic vulnerability of multiple typical structures in multiple intensity zones, the seismic damage of 7099 buildings of Dujiangyan masonry structure (MS), reinforced concrete structure (RC) and bottom frame seismic wall masonry (BFM) in the 2008 Wenchuan earthquake in China is summarized and analysed. First, a statistical analysis of the data is carried out, the empirical seismic vulnerability matrix and model curves are established by considering the number of storeys, the age and the fortification factors.The vulnerability curves of the cumulative exceeding probability of the empirical seismic damage and the grade of the seismic damage in multiple intensity zones are shown. The mean damage index vulnerability matrix model is proposed and verified using the empirical seismic damage matrix of typical structures.
In recent years, GaN-based light-emitting diode (LED) has been widely used in various applications, such as RGB lighting system, full-colour display and visible-light communication. However, the internal quantum efficiency (IQE) of green LEDs is significantly lower than that of other visible spectrum LED. This phenomenon is called “green gap”. This paper briefly describes the physical mechanism of the low IQE for InGaN/GaN multiple quantum well (MQW) green LED at first. The IQE of green LED is limited by the defects and the internal electric field in MQW. Subsequently, we discuss the recent progress in improving the IQE of green LED in detail. These strategies can be divided into two categories. Some of these methods were proposed to enhance crystal quality of InGaN/GaN MQW with high In composition and low density of defects by modifying the growth conditions. Other methods focused on increasing electron-hole wave function overlap by eliminating the polarization effect.
Composition effect on electro-optic (EO) properties of a LiNbO3 (LN) single-crystal has been investigated in a Li2O-content range of 47.0–49.95 mol%. Some non-congruent LN crystals with different Li2O-contents were prepared by performing Li-deficient or Li-rich vapour transport equilibration treatments on as-grown congruent LN crystals. Unclamped EO coefficients γ13 and γ33 of these samples were measured by a Mach–Zehnder interferometric method. The measurements show that in the Li-deficient regime both γ13 and γ33 increase by ∼8% as Li2O-content decreases from the congruent 48.6 mol% to the 47.0 mol% in the Li-deficient regime. The feature is desired for the EO application of the Li-deficient crystal. In the near-stoichiometric regime, both γ13 and γ33 reveal a non-monotonic dependence. As the Li2O-content increases from the 48.6 mol%, the EO coefficient decreases. Around Li2O-content 49.5 mol%, a minimum is reached. After that, the EO coefficient recovers slowly. At the stoichiometric composition, it recovers to a value close to that at the congruent point. Comparison shows that different crystal growth methods give rise to different defect structure features and hence different composition effects.
Bovine parvovirus (BPV), bovine coronavirus (BCoV) and bovine parainfluenza virus (BPIV) are common etiologies causing gastrointestinal and respiratory diseases in dairy herds. However, there are few reports on the synchronous detection of BPV, BCoV and BPIV. The present article aimed to develop a quick and accurate RT-PCR assay to synchronously detect BPV, BCoV and BPIV based on their specific probes. One pair universal primers, one pair specific primers and one specific probe was designed and synthesized. After the concentrations of primer and probe and annealing temperature were strictly optimized, the specificity, sensitivity and repeatability of the established triplex probe qRT-PCR were evaluated, respectively. The results showed the recombinant plasmids of pMD18-T-BPV, pMD18-T-BCoV and pMD18-T-BPIV were 554bp, 699bp and 704bp, respectively. The optimal annealing temperature was set at 45.0°C for triplex qRT-PCR. The triplex probe qRT-PCR can only synchronously detect BPV, BCoV and BPIV. Detection sensitivities were 2.0×102, 2.0×102 and 2.0×101 copies/μL for BPV, BCoV and BPIV, being 1000-fold greater than that in the conventional PCR. Detection of clinical samples demon- strated that triplex probe qRT-PCR had a higher sensitivity and specificity. The intra-assay and inter-assay coefficient of variation were lower than 2.0%. Clinical specimens verified that the triplex qRT-PCR had a higher sensitivity and specificity than universal PCR. In conclusion, this triplex probe qRT-PCR could detect only BPV, BCoV and BPIV. Minimum detection limits were 2.0×102 copies/μL for BPV and BCoV, and 2.0×101 copies/μL for BPIV. The sensitivity of this triplex probe qRT-PCR was 1000-fold greater than that in the conventional PCR. The newly qRT-PCR could be used to monitor or differentially diagnose virus infection.
Phosphorothioate CpG oligodeoxynucleotides (ODN) are reported to be recognized by the membrane-bound TLR9 and trigger the MyD88-dependent up-regulation of Type I interferons and pro-inflammatory cytokines. Whether plasmids containing multiple CpG motifs stimulate the same signaling pathway is yet to be determined. The present results show that the CpG motifs enrich plasmid pUC18-CpG stimulates RAW 264.7 in vitro, mainly through the TBK1-mediated signaling pathway, causing the up-regulation of IFN-β, and pro-inflammatory cytokines TNF-α and IL-6. When pUC18-CpG is co-administered with the recombinant Echinococcus granulosus antigen, the antigen-specific antibody titers are markedly increased compared to the Quil-A adju- vanted group. Antigen specific cytokine quantification shows that cytokine profiles from the pUC18-CpG adjuvanted-group are switched to a Th1-biased immune response.
The perovskites XBiO3 (X = Al, Ga, In) have been studied in terms of mechanical, optical and thermoelectric behavior for energy harvesting application. Density functional theory is applied to study electronic, optical and thermoelectric properties of the studied materials. Structural, mechanical and thermodynamic stabilities are confirmed from the tolerance factor, Born mechanical stability and formation energy/specific heat capacity. Poisson and Plough ratios show the studied materials are ductile and have ability to withstand pressure. Band structure analysis shows the indirect band gap 3.0/2.1/1.0 eV for ABO/GBO/IBO. A complete set of optical spectra is reported by dielectric constants, refractive index, optical conduction, absorption of light and optical loss energy. Shifting of maximum absorption band to visible region increases the potential of perovskites XBiO3. Transport characteristics are also investigated by electrical conductivity, Seebeck coefficient and figure of merit.
The electronic, optical and thermoelectric properties of zirconia-based MgZrO3 oxide have been studied theoretically at a variant pressure up to 25 GPa. Calculations for the formation energy and tolerance factor reveal the thermodynamic and structural stability of MgZrO3. To tune the indirect band gap from to a direct band gap, the optimized structure of MgZrO3 has been subjected to external pressure up to 25 GPa. The optical properties have been discussed in the form of dielectric constant and refraction that brief us about the dispersion, polarization, absorption, and transparency of the MgZrO3. In the end, the thermoelectric parameters have been analyzed at variant pressure against the chemical potential and temperature. The narrow band gap and high absorption in the ultraviolet region increase the demand of the studied oxide for energy harvesting device applications.
A high performance distributed sensor system with multi-intrusions simultaneous detection capability based on phase sensitive OTDR (Φ−OTDR) has been proposed and demonstrated. To improve system performance, three aspects have been investigated. Firstly, a model of one−dimensional impulse response of backscattered light and a Monte Carlo method have been used to study how the laser line width affects the system performance. Theoretical and experimental results show that the performances of the system, especially the signal−noise−ratio (SNR), decrease with the broadening of laser linewidth. Secondly, a temperature−compensated fibre Bragg grating with a 3 dB linewidth of 0.05 nm and a wavelength stability of 0.1 pm has been applied as an optical filter for effective denoising. Thirdly, a novel interrogation method for multi−intrusions simultaneous detection is proposed and applied in data denoising and processing. Consequently, benefiting from the three−in−one improvement, a high performance Φ−OTDR has been realized and four simultaneous applied intrusions have been detected and located at the same time along a 14 km sensing fibre with a spatial resolution of 6 m and a high SNR of 16 dB. To the best of our knowledge, this is the most multifunctional Φ−OTDR up to now and it can be used for perimeter and/or pipeline intrusion real−time monitoring.
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