Search Results

You are looking at 1 - 10 of 24 items for

  • Author: Min Zhang x
Clear All Modify Search
Open access

Min Huang, Weiyan Zhao, Qingguo Wang, Min Zhang and Qibing Zhu

Abstract

Moisture content uniformity is one of critical parameters to evaluate the quality of dried products and the drying technique. The potential of the hyperspectral imaging technique for evaluating the moisture content uniformity of maize kernels during the drying process was investigated. Predicting models were established using the partial least squares regression method. Two methods, using the prediction value of moisture content to calculate the uniformity (indirect) and predicting the moisture content uniformity directly, were investigated. Better prediction results were achieved using the direct method (with correlation coefficients RP = 0.848 and root-mean-square error of prediction RMSEP = 2.73) than the indirect method (RP = 0.521 and RMSEP = 10.96). The hyperspectral imaging technique showed significant potential in evaluating moisture content uniformity of maize kernels during the drying process.

Open access

Peng Zhang, Min Zhang, Shaojin Wang and Zhishuang Wu

Abstract

Green asparagus was treated with 1-methylcyclopropene at three concentration levels at room temperature for 24 h after harvest to evaluate the postharvest quality during cold storage at 4°C. Comparing with the controls, the loss of vitamin C, decomposition of chlorophyll, and accumulation of the malonydiadehyde under treatments of 1-methylcyclopropene were reduced during storage. The enzyme activities in asparagus including peroxidase and phenylalanine ammonia lyase were inhibited by 1-methylcyclopropene treatments, while the activity of superoxide dismutase was enhanced. Based on non-significant difference of the treated samples with 6 ìl l-1, 1-methylcyclopropene treatments at 4 ìl l-1 could be selected to maintain postharvest quality of green asparagus and provide long storage life.

Open access

Min Zhang, Yun-hua Zhou, Shaojin Wang and Juming Tang

Effects of thermal treatment on colour and texture of Typha latifolia L.

Through the analysis of the residual activity of peroxidase (POD), chromatic aberration, shear intensity and shear power, the effects of different thermal treatment times at 100°C on the POD, surface colour and texture of Typha latifolia L. were evaluated. The results showed that the activity of POD decreased with the increasing thermal treatment time at 100°C. The regeneration amount of POD increased first for some time and then started to decrease with the treatment time. Thermal treatment times 1.0 and 1.5 min at 100°C exhibited maximum regeneration of POD for the samples stored at 20 and 37°C, respectively. The sample had acceptable texture and surface colour when they were treated at 100°C for 4 min because the POD in the sample was inactivated to an acceptable level.

Open access

Tian Gao, Min Zhang, Zhongxiang Fang and Qifeng Zhong

Abstract

A central composite design combined with response surface methodology was utilized to optimise microwave-assisted extraction of flavonoids from young barley leaves. The results showed that using water as solvent, the optimum conditions of microwave-assisted extraction were extracted twice at 1.27 W g−1 microwave power and liquid-solid ratio 34.02 ml g−1 for 11.12 min. The maximum extraction yield of flavonoids (rutin equivalents) was 80.78±0.52%. Compared with conventional extraction method, the microwave-assisted extraction was more efficient as the extraction time was only 6.18% of conventional extraction, but the extraction yield of flavonoids was increased by 5.47%. The main flavonoid components from the young barley leaf extract were probably 33.36% of isoorientin-7-O-glueoside and 54.17% of isovitexin-7-O-glucoside, based on the HPLC-MS analysis. The barley leaf extract exhibited strong reducing power as well as the DPPH radical scavenging capacity.

Open access

Ran Hu, Min Zhang, Benu Adhikari and Yaping Liu

Abstract

Wheat bran is rich in dietary fibre and its annual output is abundant, but underutilized. Insoluble dietary fibre often influences food quality negatively; therefore, how to improve the physical and chemical properties of insoluble dietary fibre of wheat bran for post processing is a challenge. Insoluble dietary fibre was obtained from wheat bran and micronized using high-pressure homogenization, high-intensity sonication, and a combination of these two methods. The high-pressure homogenization and high-pressure homogenization+high-intensity sonication treatments significantly (p<0.05) improved the solubility, swelling, water-holding, oil-holding, and cation exchange capacities. The improvement of the above properties by high-intensity sonication alone was marginal. In most cases, the high-pressure homogenization process was as good as the high-pressure homogenization+high-intensity sonication process in improving the above-mentioned properties; hence, the contribution of high-`intensity sonication in the high-pressure homogenization+high-intensity sonication process was minimal. The best results show that the minimum particle size of wheat bran can reach 9 μm, and the solubility, swelling, water-holding, oil-holding, cation exchange capacities change significantly.

Open access

Camel Lagnika, Min Zhang, John Nsor-Atindana and Fatoumata Tounkara

Abstract

Effects of ultrasound, high pressure argon, and treatments comprising their combinations on physicochemical and microbiological characteristics of white mushrooms were studied during 9 days of storage at 4°C. High pressure argon treatments were relatively effective in retaining firmness and were found to maintain the cell integrity. White mushrooms firmness after 9 days of storage was increased from 2.79 N for untreated mushrooms up to 3.01, 3.24, 3.58 N for ultrasound, treatments comprising ultrasound and high pressure argon, high pressure argon, respectively. Similarly, the loss of water, ascorbic acid and total soluble solid in fresh mushroom was also greatly reduced by the high pressure argon treatment. The ultrasound treatment followed by treatments comprising ultrasound and high pressure argon and high pressure argon, respectively exhibited a pronounced effect on retarding browning and in delaying mesophilic and psychrotrophic bacteria, yeasts and moulds growth in white mushroom, compared to the control during 9 days of cold storage. Treatments comprising ultrasound and high pressure argon treatment delayed pseudomonas growth, implying that it could extend shelf life of white mushrooms to 9 days at 4°C.

Open access

Zhenyu Jiang, Min Xiang, Mingdong Lin, Weihua Zhang and Shuai Zhang

ABSTRACT

Annular cavitator with water injection is one of the key parts of the long-range supercavitating vehicle powered by water ramjet. In this paper, hydrodynamic properties of annular cavitator are studied numerically. The standard k ~ ε turbulence model is coupled with the Reynolds Averaged Navier-Stokes (RANS) equations to model the natural supercavitation process. The multiphase flow is considered as a mixture of varying density and modeled by the mass exchange equations. To fully understand this process, numerical simulations were performed for different annular cavitators. Computational Fluid Dynamics (CFD) results, including the pressure distribution and forces acting on the cavitator surface, mass flow and pressure loss of water injection, various supercavity sizes, were obtained and analyzed. The pressure distribution on the cavitator surface was significantly changed which resulted in 4 ~ 6% increase of the total drag of the vehicle. The results show that the mass flow and velocity of the injection water is mainly dependent on the tube size, while the total pressure loss of the water injection is mostly related to the outlet pressure. Supercavity generated by annular cavitator is smaller than that of the discal one. Based on the correlation analysis of the supercavity size and other factors, it could be concluded that the contraction of the cavity size is mainly caused by the diffluent mass flow of the water injection.

Open access

Peng-He Zhang, Jun-Jia He, Dan-Dan Zhang and Lan-Min Wu

A Fault Diagnosis Method for Substation Grounding Grid Based on the Square-Wave Frequency Domain Model

Current methods of fault diagnosis for the grounding grid using DC or AC are limited in accuracy and cannot be used to identify the locations of the faults. In this study, a new method of fault diagnosis for substation grounding grids is proposed using a square-wave. A frequency model of the grounding system is constructed by analyzing the frequency characteristics of the soil and the grounding conductors into which two different frequency square-wave sources are injected. By analyzing and comparing the corresponding information of the surface potentials of the output signals, the faults of the grounding grid can be diagnosed and located. Our method is verified by software simulation, scale model experiments and field experiments.

Open access

Jia Tian-Rang, Zhang Zi-Min, Tang Chun-An and Zhang Yong-Jun

Field test and laboratory analog model test on the stress-relief effects of protective layer extraction are time-consuming and laborious. In this paper, on the basis of full consideration of rock heterogeinity and in combination with gas geology at Pingdingshan Mine 5, a numerical model was estalished with the gas-solid coupling rock failure process analysis system RFPA-Gas to simulate the stress variation law, roof and floor deformation, fracture evolution law, displacement in the protected seam, change in gas permeability and gas migration law during protective layer extraction. The simulation results repoduced stress variations in coal and rock strata, roof and floor deformation and fracture evolution process during protective layer extraction. The movement of rock strata were characterized by upper three zones and lower two zones: caving zone, fracture zone and bending subsidence zone in the vertical direction in the overlying strata; floor deformation and failure zone and elasto-plastic deformation zone in the vertical direction in the underlying strata. It showed that stress relief occurred in the protected seam, which led to vertical and horizontal displacements, significant increase in gas permeability, gas desorption and migration. Hence, the outburst threat in the protected seam was eliminated. Meanwhile, with comprehensive analysis of variaition of stress state, deformation characteristics and fracture distribution in coal seam and with consideration of changes in gas leakage rate, gas pressure and permeability, according to gas leakage rate, the floor strata of the protecive layer were divided into four leakage zones. They corresponded to four zones with different stress states and fracture development: original leakage zone - slow reducing leakage zone - dramatic increasing leakage zone- steady increasing leakage zone. This classification provides a clear direction for gas control in the protective layer. The simulation results are in good agreement with the stress-relief effects in field.

Open access

Xiping Liu, Dong Chen, Liang Yi, Chao Zhang and Min Wang

Abstract

Magnetic-geared permanent magnet (MGPM) electrical machine is a new type of machine by incorporating magnetic gear into PM electrical machine, and it may be in operation with low-speed, high-torque and direct-driven. In this paper, three types of MGPM machines are present, and a quantitative comparison among them is performed by finite element analysis (FEA). The magnetic field distribution, stable torque and back EMF are obtained at no-load. The results show that three types of MGPM machine are suitable for different application fields respectively according to their own advantages, such as high torque and back EMF, which form an important foundation for MGPM electrical machine research.