Advanced Materials Research Vols. 468-471

Abstract: Thermal conductivity (k) of nanofluids has been a hot area of interest. However, controversy exists in majority of the reported results make the thermophysical property of nanofluids remains vague. Dose this disagreement come from different methodologies used by different groups or any other factors Results on k of the nanofluids, prepared by dispersing 22nm-diameter spherical Fe₃O₄ in Polymeric α-olefin (PAO), were presented using transient-hot-wire method and 3ω method to determine the consistency of two experimental methodologies. Within the uncertainty of both methods, the obtained data showed good agreement, which confirmed that the experiment technique was not the chief factor causing the discrepancy of reported results. Thermal conductivity of Fe3O4 nanofluids can not be predicted by existing model.

Abstract: Vehicle routing optimization problem is one of the major research topics in logistics distribution field. Suitable vehicle routing selection is vital to reduce the logistics cost. The paper presents a hybrid optimization method to solve the vehicle routing problem with time windows. In the hybrid optimization method, discrete particle swarm optimization algorithm is used to assign the customers on routes and simulated annealing (SA) algorithm to avoid becoming trapped in local optimum. The simulation results have shown that the proposed method is feasible and effective for the vehicle routing problem with time windows.

Abstract: In this paper, bagasse (de-pithed bagasse) and bagasse pith were treated respectively, the process of hemicelluloses extraction was optimized, and some parameters which may affect the hemicelluloses yield were discussed, such as alkali charge, temperature and time of extraction. The results showed that the hemicelluloses yield of bagasse was obviously affected by the alkali charge and temperature of extraction increasing at the same liquid-to-solid ratio and time, and the maximum reached 18.47% (base on o.d.) . To bagasse pith, it could obtain hemicelluloses of 15.37% by the same treatment with bagasse. Therefore, both bagasse and bagasse pith were the good materials for hemicelluloses extraction.

Abstract: In the fields of transparent liquid impurity detection based on machine vision technology, how to detect and identify a variety of impurities effectively in the liquid is a difficult problem which has not yet been solved, mainly in the low recognition rate, the slow recognition speed, and the phenomenon of error detection and undetected. Therefore, a new impurity detection method based on machine vision is presented in this paper. The experiments show that this method can decrease the recognition speed to 100ms for impurities’ diameter greater than 1mm and achieved a 99% recognition rate.

Abstract: In this work, several millimeter sized micro whistles have been tested as potential frequency analog gas flow sensors. The characteristic curves of the whistles were systematically investigated as a function of geometrical dimensions, the kind of gas applied, and temperature. Both a micro¬phone and a PVDF foil were employed to record the frequencies. The relation be¬tween oscillation frequency and volume flow rate only shows a weak function of fluid properties and temperature. At a given flow rate, the difference of argon and nitrogen is 120 Hz on average, which is corresponding to 1.4 %. For air flow at a given flow rate, frequency rises approximately 380 Hz (2.73 %) per 10 °C. This kind of micro whistle could be employed as gas flow sensor which is insensitive to fluid properties.

Abstract: This paper mainly surveys the different groups of college students to investigate the different aspects of impressions mobile operators made on them. The questionnaire survey shows that students of different gender have significant differences in market impression and technology impression (P<.001); Students of different family residences have no different impressions in mobile operators; Students of different grades have significant differences in market impression, employee impression and total score (*P< .05); Students of different majors have significant differences in all impression dimensions except technology impression. And after multiple comparison analysis, the impressions of different professional students differ mainly between the liberal arts students and science and engineering students. Through this investigation, the study aims to improve the capability of mobile operators in making appropriate impression management when they are in the face of college students, the potential high-end users.

Abstract: In order to detect and locate the water-jet target by the reflected sound signal generated while high pressure water-jet impacted the target, a variety of relevant parameters should be optimized to make microphone acquiring the effective reflected sound signal. The basic principle of high pressure water-jet target detection theory and the parameters needed set were introduced. The experimental device was set up to acquire the reflected sound signal. The wavelet denoising and signal decomposition software was programmed by using MATLAB. The communication between LabVIEW and MATLAB was realized by calling the Math script node which processes the reflected sound signal denoising and decomposition. The optimal parameters are selected based on the voltage amplitude level and stability of the reflected sound signal eigenvalues on the mutation point which is produced on the edges of the target.

Abstract: Ti-6Al-4V alloy was prepared by gelcasting. Plasma rotating electrode and hydrogenation-dehydrogenation Ti-6Al-4V powders were mixed used to meet both high performance and low cost objectives. The morphological properties were investigated by SEM. The results showed that the gelcasting green body with mixed powders has advantages of high solids loading and excellent sinterability. After sintered at 1400°C for 2h, the relative density reached 98%. The bending strength and hardness were 313MPa and 49.8(HRC).

Abstract: . In order to study the environmental impact of coal washing and separating industry, took Beize coal separating plant as an example to analyze its pollution. According to the requirements of Chinese environmental assessment and its project situation, analyzed its features of technological process and possible pollution such as noise, dust, smoke, SO2, waste water and waste solid etc. during construction and operating period. Accident risk analysis was also done. As a result, the intensity of polluting source were confirmed as 0.47 t/a of dust, 2.60t/a of SO2, 2.38t/a of soot and 40.52t/a of coal gangue respectively. Finally, precaution measures for above mentioned pollutions were proponed. This would lay a sound foundation for the following environmental impact assessment.

Abstract: Abstract. Relief Amplitude is a quantitative index that describes topographic features and reflects the degree of relief amplitude. It is widely used in the field of topographic mapping and resource environment assessment. In the present study, the relief amplitudes in different neighborhood-scale units in east mountainous area of Tibetan Plateau were calculated based on the high space-resolution ASTER GDEM data by calling the Focal Function used for neighborhood analysis by means of AML language program. The results revealed that the size of the unit of neighborhood scale affected crucially the relief amplitude. The value of relief amplitude increased rapidly with increasing area of the statistic unit of neighborhood at first. Whereas when the area of neighborhood-scale unit was close to some threshold value, the increasing rate started to slow down and became stable, and during the process in which the increasing rate started to decline, there was a prominent turning point, namely the optimal unit of neighborhood scale. The optimal unit of neighborhood scale was 5.06km2 based on the significance test of elevation difference. A classification map of relief amplitude was established based on the optimal unit of neighborhood scale and it was found that, in the study area, the relief amplitude increased gradually northwestward-southeastwardly.