一效蒸发器主要制作工艺

介绍了一效蒸发器的主要制作工艺,将设备的整体热处理改为局部热处理和胀紧率的确定,为强度胀接大口径管子积累了经验。     

3D ECT reconstruction by an improved Landweber iteration algorithm

Electrical capacitance tomography (ECT) is a relatively mature non-invasive imaging technique that attempts to map dielectric permittivity of materials. Recently, 3D ECT has gained interest because of its potential to generate volumetric images. The study of a fast and accurate image reconstruction algorithm is a challenge task, especially for 3D reconstruction. In this paper, we propose an improved Landweber iteration algorithm. We incorporate an additional acceleration term into the cost function and apply an adaptive threshold operation to the image obtained in each iteration for reducing artefacts. The algorithm proposed is tested by the noise-free and noise-contaminated capacitance data. Sensitivity matrixes and capacitance data of a 3D ECT sensor are obtained by using the finite element (FE) method. Extensive simulations in 3D reconstruction are carried out. The results verify the effectiveness of these improvements. Both the reconstruction time and the artefacts in the reconstructed image are reduced obviously. The experimental results of 3D reconstruction of objects in the shape of letters U and L confirm the effectiveness of the proposed algorithm further.     

Fine and ultrafine particle emissions from microwave popcorn

This study characterized fine (PM_2.5) and ultrafine particle (UFP, diameter < 100 nm) emissions from microwave popcorn and analyzed influential factors. Each pre‐packed popcorn bag was cooked in a microwave oven enclosed in a stainless steel chamber for 3 min. The number concentration and size distribution of UFPs and PM_2.5 mass concentration were measured inside the chamber repeatedly for five different flavors under four increasing power settings using either the foil‐lined original package or a brown paper bag. UFPs and PM_2.5 generated by microwaving popcorn were 150–560 and 350–800 times higher than the emissions from microwaving water, respectively. About 90% of the total particles emitted were in the ultrafine size range. The emitted PM concentrations varied significantly with flavor. Replacing the foil‐lined original package with a brown paper bag significantly reduced the peak concentration by 24–87% for total particle number and 36–70% for PM_2.5. A positive relationship was observed between both UFP number and PM_2.5 mass and power setting. The emission rates of microwave popcorn ranged from 1.9 × 10¹⁰ to 8.0 × 10¹⁰ No./min for total particle number and from 134 to 249 μg/min for PM_2.5.     

Effect of abruptly changing withdrawal rate on solidification microstructure in directionally solidified Al-4.5wt%Cu alloy简

Al-4.5wt.%Cu alloy has been directionally solidified at constant and abruptly changing withdrawal rates, respectively. The effects of the withdrawal rate on solidification microstructure, primary dendrite arm spacing(PDAS) and liquid solute distribution in front of the solid-liquid interface were investigated. The experimental results for the PDAS at a constant withdrawal rate agree well with the values calculated by the Hunt, Trivedi and Hunt-Lu models. At an abrupt change in the withdrawal rate, the maximum to minimum ratio of the PDAS at a given solidification parameter, i.e. λ1max/λ1min, is more than 2, and the PDAS values are remarkably history-dependent. Further, the liquid-solute distribution curve based on theoretical calculation shows that the larger the initial withdrawal rate is, the smaller the minimum of liquid solute concentration in front of the solid-liquid interface is after the abrupt change in withdrawal rate.     

加热速度对冷轧双相钢组织性能的影响

通过模拟连续退火研究了不同加热速度对冷轧双相钢组织性能的影响。研究发现,快速加热可以明显地细化晶粒,但组织的遗传性导致微观组织中有不同程度的带状组织,材料的加热速度不宜超过100℃/s;材料的加工硬化速率及加工硬化指数对冷速的增加呈规律变化。     

The characteristics of voltage degradation of a proton exchange membrane fuel cell under a road operating environment

A real-life testing experiment of a proton exchange membrane fuel cell (PEMFC) and the basic characteristics of its voltage degradation are presented. A general package radio system (GPRS)-based remote monitoring system was used as the data acquisition method, and the non-linear regression method was used to estimate PEMFC's polarization curve within specific iso-interval periods. The voltage degradation rate was calculated using the differential method, and its average level was also analyzed. The experimental results indicated that the voltage degradation rate at a specific current density featured a bathtub-like curve, exhibiting 1) infant degradation, 2) steady degradation, 3) and accelerated degradation.     

Optimization of biogas from chicken droppings with Cymbopogon citratus

Optimization of biogas production and quality from chicken droppings by anaerobic co-digestion with Cymbopogon citratus was investigated. The anaerobic digestions of chicken droppings, chicken droppings with C. citratus as well as C. citratus alone were carried out for a period of 30 days at an average ambient temperature of 33.1 ± 2 °C using identical reactors (A–C) respectively. Results obtained indicate that chicken droppings produced on the average 1.8 L/kg/day of biogas, co-digestion of chicken droppings and C. citratus produced 1.3 L/kg/day of biogas while C. citratus alone produced 1.0 L/kg/day with estimated average methane content of 41.71%, 66.20% and 71.95% for reactors A–C respectively. The water boiling rates of biogas from chicken droppings, chicken droppings with C. citratus, and C. citratus alone were 0.079 L/min, 0.091 L/min and 0.12 L/min respectively, after the gases were scrubbed with water and slaked lime. It was observed that notwithstanding the higher biogas volumetric yield from chicken droppings digested alone, the co-digestion of chicken droppings with C. citratus had better gas quality with respect to the methane content present and cooking rate. This study has shown that the methane content of biogas from animal manure substrates could be improved by co-digestion with energy plants.     

Prediction of fracture in a dual-phase steel subjected to non-linear straining

In this work, selected fracture criteria are applied to predict the fracture of dual-phase steel subjected to non-linear strain paths. Furthermore, the effects of manufacturing history are studied. Four fracture criteria were calibrated in three tests using standard specimens. The fracture criteria were first validated in the circular Nakajima test. A second validation test case was included in order to validate fracture prediction for non-linear strain paths. In this test a sheet metal component was manufactured and subsequently stretched until it fractured. All fracture criteria included in this study predict fracture during the Nakajima test with reasonable accuracy. In the second validation test however, the different fracture criteria show considerable diversity in accumulated damage during manufacturing which caused substantial scatter of the fracture prediction in the subsequent stretching. This shows that manufacturing history influences the prediction of fracture.     

Dissolution rate enhancement of the anti-inflammatory drug diflunisal by coprecipitation with a biocompatible polymer using carbon dioxide as a supercritical fluid antisolvent

Dissolution rate enhancement of the anti-inflammatory drug diflunisal was achieved using for the first time a supercritical fluid technology. The supercritical fluid antisolvent (SAS) method was applied to precipitate diflunisal alone and to coprecipitate the drug together with the biocompatible polymer polyvinylpyrrolidone (PVP K-30 and K-10). The untreated and SAS processed diflunisal, and the coprecipitates were characterized in terms of size, morphology, crystallinity, compositions, drug-polymer interactions, and drug release. SAS processed diflunisal exhibited a polymorphic form different from that of the untreated drug. Diflunisal crystallinity disappeared in the coprecipitates. Three different drug: polymer mass ratios were studied: 75:25, 50:50, and 25:75. Microparticle size decreased and aggregation disappeared as the relative amount of polymer increased. The 25:75 coprecipitate consisted of loose spherical particles exhibiting mean particle size of 410 nm while the 75:25 coprecipitate consisted of bigger aggregated particles. The SAS method was shown to be a suitable technology to form solid dispersions of a poorly soluble drug.     

Microstructure evolution of spray-formed hypereutectic Al-Si alloys in semisolid reheating process

The Al-27%Si alloy was prepared by the spray forming process, and its microstructure evolution during the semisolid reheating process was investigated. The results show that, the primary Si phase coarsens during the reheating process and the coarsening rate increases with the increase of reheating temperature. The eutectic phase is produced in the molten region when quenched in the cold water. The microstructure evolution in the semisolid state can be divided into three stages. The remarkable characteristic of the first stage is only a solid-state phase transformation process. However, the region around the α(Al) matrix gradually melts in the second stage. The primary Si in the liquid phase coarsens obviously, and the eutectic phase is produced in the molten region when the specimens are quenched in cold water. In the last stage, the same thing as that in the second stage happens except that all the α(Al) matrixes are melted.