Jufan Zhang

Continuous electricity production from leachate in a novel upflow air-cathode membrane-free microbial fuel cell.

In this study, a novel microbial fuel cell, i.e. upflow air-cathode membrane-free microbial fuel cell (UAMMFC) was reported and its performance in electricity generation from original leachate was examined. The experimental results demonstrated that the UAMMFC could continuously generate electricity from leachate (0.3V; REX=150 Omega) for an operational period of time (50 h). The maximum volumetric power reached 12.8 W/m3 at current density of 41 A/m3 (93 Omega). NH4+-N elimination from the leachate was shown to be a consequence of electrochemistry-independent oxidation occurred in the MFC. Increasing organic loading rate from 0.65 to 5.2 kgCOD/m3 d resulted in a decrease of overall Coulombic efficiency (CE) from 14.4% to 1.2%. The low CE obtained here should be attributed to severe oxygen diffusion from the open-to-air cathode.

Effect of ultrasonic and alkaline pretreatment on sludge degradation and electricity generation by microbial fuel cell

Both ultrasonic and alkaline pretreatment of excess sewage sludge were investigated to enhance organic degradation and electricity generation from sludge by the subsequent microbial fuel cell (MFC). The ultrasonic pretreatment showed that the degree of sludge disintegration was directly related to the energy input, ultrasonic density and duration. Alkaline pretreatment demonstrated that more soluble organic matters were released from the sludge with more NaOH dose and longer reaction time, and the degree of sludge disintegration within 30 min accounted for 45-76% of that for 24 h. When ultrasonic and alkaline pretreatment were combined, the released chemical oxygen demand (COD) was higher than those with ultrasonic or alkaline pretreatment alone. Ultrasonic and alkaline (pH=11) pretreatment could enhance electricity generation from sludge by the subsequent MFC, resulting in more degradation of total COD (TCOD) and volatile solids (VS). Slight change in power output from the MFC was observed due to the higher soluble chemical oxygen demand (SCOD) in the pretreated sludge. By using the combined ultrasonic and alkaline pretreatment of sludge, the removal efficiencies of TCOD and VS were increased from 27.1% to 61.0% and 35.2% to 62.9% in comparison with raw sludge, respectively, and the power output in MFC was slightly increased from 10.3 W/m(3) to 12.5 W/m(3).

New development of atmospheric pressure plasma polishing

Atmospheric pressure plasma polishing (APPP) is a precision machining technology used for manufacturing high quality optical surfaces. The changes of surface modulus and hardness after machining prove the distinct improvement of surface mechanical properties. The demonstrated decrease of surface residual stresses testifies the removal of the former deformation layer. And the surface topographies under atomic force microscope (AFM) and scanning electron microscope (SEM) indicate obvious amelioration of the surface status, showing that the 0.926-nm average surface roughness has been achieved.

Numerical Analysis of Delamination Behavior in Laminated Composite with Double Delaminations Embedded in Different Depth Positions

In this article, the finite element method (FEM) using cohesive element is applied to predict the delamination behavior in laminated composite with double delaminations embedded in different depth positions under compressive load. In particular, compared with single delamination composites, the interaction between delaminations and the complicated propagation behavior are discussed. Furthermore, the study is focused on the significant effects of double delaminations on delamination buckling and growth behavior, such as the distance between double delaminations and the delaminations’ depth position.

Process monitoring and analysis of atmospheric pressure plasma polishing method

Atmospheric pressure plasma polishing (APPP) method is a novel non-contact machining technology. It utilizes atmospheric pressure plasma to excite reactive radicals which cause chemical reactions with surface atoms to perform atom-scale removal process. Since the machining process is chemical in nature, APPP method avoids surface/subsurface defects. The removal process is a complicated integrated action which is affected by many factors, such as radio frequency power, gas ratio, temperature, and the like. Hence, it is necessary to monitor and analyze the process from different aspects and by various means. Through the analysis of atomic emission spectroscopy, the impacting rules of the radio frequency power and gas ratio were investigated. The temperature distribution on the workpiece surface was initially established by experiments and the results correspond well with the qualitative analysis conclusion from finite element method. Then, by initial technology optimization, the removal rate of 1.46mm3/min and Ra 0.6nm surface roughness were achieved in subsequent machining operations.