Regulation of oxygen on properties of moderately boron-doped diamond films is fully investigated. Results show that, with adding a small amount of oxygen (oxygen-to-carbon ratio < 5.0%), the crystal quality of diamond is improved, and a suppression effect of residual nitrogen is observed. With increasing ratio of O/C from 2.5% to 20.0%, the hole concentration is firstly increased then reduced. This change of hole concentration is also explained. Moreover, the results of Hall effect measurement with temperatures from 300 K to 825 K show that, with adding a small amount of oxygen, boron and oxygen complex structures (especially B3O and B4O) are formed and exhibit as shallow donor in diamond, which results in increase of donor concentration. With further increase of ratio of O/C, the inhibitory behaviors of oxygen on boron leads to decrease of acceptor concentration (the optical emission spectroscopy has shown that it is decreased with ratio of O/C more than 10.0%). This work demonstrates that oxygen-doping induced increasement of the crystalline and surface quality could be restored by the co-doping with oxygen. The technique could achieve boron-doped diamond films with both high quality and acceptable hole concentration, which is applicable to electronic level of usage. 相似文献
Today, analyzing of sound pressure level and frequency is considered as an important index in human society. Sound experts believe that analyzing of these parameters can help us to better understanding of work environments. Sound measurements and frequency analysis did to fix the harmful frequency in all sections in Shiraz gas power plant with sound analyzer model BSWA 308. The sound pressure levels (LP) and the one and one-third octave band were continuously measured in A and C weighting networks and slow mode for time response. Excel 2013 and Minitab 18.1 software used for statistical calculations. Results analyzed by Minitab 18.1 software. The highest harmful frequency in Shiraz Gas Power Plant (SGPP) was 50 Hz with 115 dB. The sound pressure level (SPL) ranged from 45 dB to 120 dB in one-third octave band and weighting network C. The maximum sound pressure level was in Craft electricity generator with 105.3 dB and 67 Hz. Sound pressure level in surrounded environment was 120 dB. According to the results, in this industry the sound pressure level exceeded the Occupational Exposure Level of Iran (OEL). The value of sound pressure level were higher than the Standard of occupational health. SGPP consumes 47000 cubic meters of natural gas per hour to produce 100 MW (Mega Watt) of electricity. It is very high and it is not economical and cost effective. These numbers indicate that the power plant’s efficiency is low. It could be concluded that the noise pollution is an important issue in these industries. Moreover, SGPP produce noise with loss energy. Frequencies rotation at high sound pressure levels toward low frequencies were happened. 相似文献
We have developed a simple assessment method for the overlap between spheroidal particles, which neither requires the complex manipulation of vectors and matrices that is indispensable in the ordinary methods, nor is based on a model potential. Moreover, we have developed an evaluation method for the interaction energy arising from the overlap of the steric layer coating spheroidal particles. This is based on a sphere-connected particle model, but some modifications are introduced in order to express an appropriate repulsive interaction energy at the deepest overlapping position. We have investigated the phase change in a magnetic spheroidal particle suspension for a two-dimensional system by means of Monte Carlo simulations. In the case of no external magnetic field, if the magnetic particle-particle interaction is sufficiently strong to favour cluster formation, long raft-like clusters tend to be formed in a dilute situation. With decreasing values of area fraction, a chain-like structure in a dense situation transforms into a raft-like structure within a narrow range of the particle area fraction. Similarly, the raft-like clusters are preferred in a weak applied magnetic field, but an increase in the field strength induces a phase change from a raft-like into a chain-like structure.Highlights of the present paper:
A simple assessment method has been proposed for the overlap between two spheroidal particles.
The particle overlap assessment is free from a complex mathematical manipulation regarding vectors and matrices.
A modified sphere-connected model has been proposed in order to more accurately evaluate a repulsive interaction due to the overlap of the steric layers coating spheroidal particles.
2D Monte Carlo simulations have been performed to elucidate the phenomenon of a phase change by magnetic spheroidal particles on a material plane surface.
A phase change between a raft-like and a chain-like aggregate structure is able to be controlled by the area fraction of particles and an external magnetic field.
The effects of moderate thermosonication (MTS) on the quality quartet: physico-chemical, microbial, nutritional and sensory qualities of orange juice (OJ) inoculated with Alicyclobacillus acidoterrestris (AAT) were studied during 24 days of storage at ambient and refrigerated temperatures. The bioactive compounds and antioxidant activity of OJ decreased with storage, while the pectin methyl esterase (PME) increased. Nonetheless, noticeable changes were observed from the 12th day of storage. There was no obvious (p > 0.05) variation in pH and total soluble solids. To determine the nutritional and microbial quality characteristics of OJ during storage, non-linear kinetic curves were successfully fitted with least square fitting polynomial and four-parameter log-logistic distribution models. The E-nose sensors succeeded in discriminating between the aroma of non-treated and treated OJ based on linear discriminant analysis (LDA). Furthermore, terpenes, alcohol and partially aromatic compounds were the main spoilage indicators of OJ during storage based on E-nose analysis and confirmed by HS-SPME-GC/MS analysis. Thus, MTS significantly extended the shelf life of the quality quartet of natural OJ at 4 °C. E-nose-GC/MS fusion offered odor fingerprints to AAT microorganisms that can be used as spoilage index without using traditional food analysis techniques. The proposed approach can be used as an alternative tool for rapid detection of spoilage microorganisms in OJ. 相似文献
A simple and rapid analytical method for the detection of trifloxystrobin, trifloxystrobin acid and tebuconazole in soil, brown rice, paddy plants and rice hulls was established and validated by liquid chromatography with tandem mass spectrometry. Acceptable linearity (R2 > 0.99), accuracy (average recoveries of 74.3–108.5%) and precision (intra- and inter-day relative standard deviations of 0.9–8.8%) were obtained using the developed determination approach. In the field trial, the half-lives of trifloxystrobin and tebuconazole in paddy plants were 5.7–8.3 days in three locations throughout China, and the terminal residue concentrations of trifloxystrobin and tebuconazole were <100 and 500 μg/kg (maximum residue limits set by China), respectively, at harvest, which indicated that, based on the recommended application procedure, trifloxystrobin and tebuconazole are safe for use on rice. The risk assessment results demonstrated that, owing to risk quotient values of both fungicides being <100%, the potential risk of trifloxystrobin and tebuconazole on rice was acceptable for Chinese consumers. These data could provide supporting information for the proper use and safety evaluation of trifloxystrobin and tebuconazole in rice. 相似文献
Energy storage system powered by renewable energies is a viable option to meet energy requirement without addition of carbon footprints to the environment. This study involves development of theoretical and computational models for a solar photovoltaic (PV) system coupled with a lead acid battery. The study commenced with selection of most appropriate lead acid battery and PV system for installation in a representative location in Riyadh, Kingdom of Saudi Arabia. Various technical and economic parameters were assessed and calculated by computational approach. The optimized lead acid battery was integrated with low concentration solar PV panels (CPV) followed by a feasibility study. Theoretical model was developed for the integrated system to calculate various parameters of the CPV and lead acid battery. Technical and economic assessment of this coupled unit was calculated using a theoretical approach. The developed model was then subjected to computational approach for verification and validation analysis of the integrated system. The detailed assessment of batteries and integrated system show the applicability of this system in Riyadh region. The research will be extended to develop energy storage systems for remote areas using lead acid batteries. 相似文献
This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main drawback is the lack of standard procedures. Telemonitoring is another approach to air monitoring, which offers some interesting opportunities, such as ease of coverage of large or remote areas, constituting a complementary approach to traditional strategies; however, it requires huge costs. 相似文献