Abstract:Polyhydroxyalkanoates (PHA) are biopolymers which can be accumulated by prokaryotic microorganism as intracellular reserve carbon source in the absence of nutrients resource. PHA, being the potential substitute of the conventional plastics due to their similar physical and chemical properties as those petroleum-based traditional plastic as well as good degradability and biocompatibility, would save fossil resources and hence became a hotspot in the biosynthesis of degradable materials research field. Numerous studies in recent years proved that the activated sludge with mixed microbial culture can significantly reduce the costs of PHA synthesis, and further beneficial to the industrialization of PHA synthesis and wastes reclamation. This paper systematically summarized the research progress of activated sludge-based PHA synthesis in the enrichment and accumulation phase, illustrated the PHA enrichment bacteria selection process (from AN/AE mode to aerobic dynamic discharge mode) and accumulation phase (from fed-batch to continuous feeding mode), and emphasized the feeding mode optimization on the PHA enrichment and accumulation phase. Meanwhile, new ideas of research on PHA synthesis and the dynamic model of PHA synthesis were summarized. The paper also proposed some suggestions for the future research focus on the PHA production based on recent research progress on PHA synthesis with mix culture method.

Abstract:In order to investigate the impact of organic matter type on the efficiency and microbial community structure during anaerobic digestion operation, an expanded granular sludge bed (EGSB) was applied to treat brewery spent grain hydrolysates (BSGH) and pig manure hydrolysates (PMH) that were pre-hydrolyzed by specific enzymes under thermophilic conditions. Results showed that after the organic matter of BSGH was altered by PMH, a series decrease of 40%, 75% and 25% was observed for the bulk COD removal, methane production and organic biomethanation rate, respectively. Meanwhile, the acetic acid concentration in the effluent increased from 50 mg/L to 3 700 mg/L. For the microbial community, the abundance of Firmicutes doubled after the substrate type changing, while Bacteroidetes decreased 50% instead. The quantity of methanogens dropped by 61% and the previously most abundant genus Methanosaeta was replaced by Methanobacterium.

Abstract:The composition, abundance and diversity of anodic microbial communities in three parallel-operated MFCs, which inoculated with activated sludge, were investigated by 16S rDNA based high-throughput sequencing. The relationship between the microbial populations and MFC efficiency was evaluated. The efficiency of MFCs was markedly different even if these MFCs were started up and operated under the same conditions. Two of them (named after Mfc-1 and Mfc-3)arrived at the maximum voltage of 220 to 240 mV with power density of 1.85 to 2.33 W/m³. However, the maximum voltage of MFC Mfc-2 was relative low and kept at about 120 mV. Microbial community composition and abundance were significantly different even if they were enriched by the same substrate. Highly abundant bacteria, such as Anaeromusa, Dechloromonas, Geobacter, that are capable of producing electricity were enriched in Mfc-1 and Mfc-3. However, the genus Acinetobacter, a non-electrogen, existed at high abundance in the Mfc-2. This study concluded that divergence of dominant anodic microbial groups in MFCs, due to possible mismanagement and reactor design drawbacks, resulted in the difference of electricity-producing efficiency. To improve the reliability of experimental results during investigating the MFC function and its influencing factors, at least three parallel-operated MFCs were preferred.

Abstract:Effect of starch on the granulation of sludge which is rich in PAOs was comparably studied with two reactors:without starch addition(1#), and with starch addition(2#). The granulation of the sludge granulars within the reactors, as well as the removal efficiency of COD, TP was investigated via the using of scanning electron microscopy, ultraviolet spectrophotometer and particle instrument. The granulation was fulfilled in 24 days during the operation of the 2# reactor, and was 25% shorter than that of 1#. A higher content of protein observed from the sludge EPS in the 2# reactor suggested that the existence of starch led to a higher production of amylase, and consequently to a fast granulation. In comparing with 1#, 2# exhibited a higher biomass concentration and need more O₂ in aerobic unit, thus resulted in a denser granule sludge structure, which maintain a stable operation of the reactor. The additive of starch as 30% of the COD in the 2# system showed no negative effect on the bulk removal of phosphorus, with an average TP and COD removal efficiency of 95% and 90% respectively. The efficiency system changed insignificantly even if the starch additive was stopped.

Abstract:To solve the existing problems, such as sludge volume increasing, high consumption of chemical reagent and energy during the sludge treatment and disposal, a sludge conditioning method, called self-flocculation, was proposed. This approach enhanced the dewatering efficiency of sludge via the utilization of the self-flocculation function of the extracellular polymeric substance (EPS). By orthogonal and single factor experiments, the impacts of sludge concentration, stirring intensity and stirring time on the sludge self-flocculation were investigated. Meanwhile, the corresponding variation of the capillary suction time (t_CST), sludge volume index (SVI), particle size and Zeta potential were also analyzed. Experimental results indicated that self-flocculation could enlarge the particle size of sludge and decrease the effect of flocs Zeta potential. Therefore, hydrophobicity, dewaterability and settleability of sludge were improved. Under the optimal self-flocculation conditions (sludge concentration, 18 g/L, stirring intensity, 200 r/min, stirring time, 3.5 min), the particle size and Zeta potential of the sludge increased 11.4% and 19%, respectively, while the t_CST and SVI could be respectively reduced by 17.1% and 8.1%. In addition, the significant effects of operational parameters on self-flocculation showed a decreased trend of sludge concentration > stirring intensity > stirring time. A higher sludge concentration, stirring intensity and stirring time was beneficial to the sludge self-flocculation. However, once each of the three parameters was higher than that at the optimal condition, sludge self-flocculation would weaken gradually. This study provided a new approach for sludge conditioning by using the sludge self-characteristics.

Abstract:To verify the effectiveness of pressure declination monitoring for assessing physical damage of ultrafiltration (UF) membrane, the changes of water qualities in UF permeate and the pressure declination behavior of the UF membrane were systematically investigated. Medical probe was used to induce the breakage points on UF membrane (the damage rate of single breakage point:A=5.46×10^-6). It was found that as damage percentage increased from 0 to 5A, the DOC and UV₂₅₄ in permeate only increased by 24% and 26%, respectively; although the permeate turbidity increased form 0.100 NTU to 0.290 NTU, the absolute value is still too low to reflect the degree of membrane damage properly. On the other hand, a sharp decreasing trend of the pressure inside the membrane fibers was observed for the damaged UF membrane even at the damage percentage of A, the pressure of 55 kPa was demonstrated to decrease to zero in only 66 s. Therefore, monitoring the pressure declination behavior can be considered as a fast, efficient and sensitive method for evaluating the damages on UF membrane. Furthermore, exposure tests showed that the contact of UF membrane with powdered activated carbon (PAC) in a short-term time (45 d) would not cause physical damage on the UF membrane, and the water quality of the UF permeate would be adversely affected by the short-term PAC contact.

Abstract:The purpose of this article was to investigate the effectiveness and mechanism for the oxidation of estrone by aqueous potassium permanganate. Experiments were conducted to examine the reaction kinetics of potassium permanganate with estrone under the condition with potassium permanganate in excess over a wide pH range. Then, reaction products of estrone with potassium permanganate were identified with liquid chromatography tandem mass spectrometry (LC-MS/MS). The results showed that the loss of estrone followed the pseudo-first-order kinetics with potassium permanganate, suggesting that the reaction is first-order with respect to estrone. The pseudo-first-order rate constant (K_obs, s^-1) increased linearly with the increase of potassium permanganate concentration. The degradation of estrone of the second-order rate constants (k, L·mol^-1·s^-1) increased with the increase of pH. Estrone was shown to exhibit similarly appreciable reactivity toward potassium permanganate with the second-order rate constant at near neutral pH comparable to chlorine but much lower than that of ozone. In comparison with these oxidants, however, potassium permanganate was much more effective for the oxidative removal of estrone in real waters, mainly due to the relatively high stability of potassium permanganate therein. Identification of oxidation products suggested the initial attack of potassium permanganate at the hydroxyl group in the aromatic ring of estrone, leading to the formation of a series of quinone-like and aromatic ring-opening products and thus the elimination of its estrogenic activity.

Abstract:Phthalate acid esters (PAEs) are widely used in building materials, such as paints. In order to determine the pollution characteristics and exposure levels of PAEs to painters, 10 urine samples from painters and other 10 urine samples from general individuals were collected in Harbin, China. 14 phthalate metabolites in the urine samples were comparably analyzed. Urinary concentrations of metabolites with painters were higher than those with general population, in which the mMP, mBP and miBP are major metabolites. Furthermore, the concentrations of low molecular weight metabolites within the urine of the painters were significantly higher than those within the general individuals, indicating that painters exposed to low molecular weight PAEs during their working time. Finally, the daily intakes of PAEs were estimated, which were all lower than the reference dose by U.S. EPA, indicating that the exposure risk with PAEs for both painters and general population were in safe level.

Abstract:In order to improve the separability of powdered activated carbon, a new type of magnetic activated carbon was prepared using chemical co-precipitation.Using methylene blue as target pollutants, performance of the powdered magnetic activated carbon was studied under varied conditions of pH, contact time and initial methylene blue concentrations, via the comparison with powdered activated carbon. The results showed that the adsorption capacity of synthetic magnetic powdered activated carbon was higher than that of the powdered activated carbon, and an alkaline pH value and adequate contact time were favorable for the pollutants removal. Under the condition of 100 mg/L methylene blue concentration, 0.4 g/L magnetic activated carbon dosage of, pH 9 and a reaction time of 300 minutes, the removal rate of methylene blue reached 98.9%. The adsorption behavior of methylene blue on magnetic activated carbon fitted the Langmuir isotherm and Elovich dynamics model. Thermodynamic analysis indicated that the adsorption was spontaneous endothermic reaction of single molecule layer, and the chemical adsorption played an important role during the adsorption process. The magnetic activated carbon had a good recyclable performance, it could complete precipitation in 10 minutes under natural condition, and could be quickly separated in 30 seconds under the action of outside magnetic field.

Abstract:In order to get a fully understanding of non-point pollution problem in rotation agricultural watershed at the central United States Illinois, USA, Principal component analysis (PCA) was used to do the water quality evaluation of the Little Vermilion River watershed. The PCA approach divided various factors that influence phosphorus transport into three principal components. The first component, botanical component, contained air temperature, cover phenotype, evapotranspiration, cover factor and dry mass factors. The second component contained precipitation and flow, which was defined as hydrologic component. The third component included tillage practices and nitrogen application, and was termed as anthropogenic component. The result showed that the hydrologic component impact phosphorus loss most than other components, especially for subsurface drainage water.

Abstract:Fularji district of Qiqihar is a typical heavy industry district in China. Gas and particle phases air samples were collected using active air sampler at upwind and downwind of the district in order to study the occurrence, pollution characteristic, and gas/particle partitioning of polybrominated diphenyl ethers (PBDEs). The results indicated that the total concentration (gas plus particle phases) of PBDEs ranged from 13.9 to 102 pg·m^-3 with the mean concentration of 53.6 pg·m^-3, and BDE-209 was the dominant congener. According to the results of source analysis, PBDEs in air were mainly originated from Commercial Deca-BDEs and Commercial Penta-BDEs. The slopes obtained from the linear regression between log K_P and log p_L^o were lower than the theoretical value of -1, suggesting the non-equilibrium between gas and particle phases. The particle bound fraction (φ) values were modeled using the Junge-Pankow Adsorption Model and the Harner-Bidleman Absorption Model. The values of φ from both the two models were overestimate compared to those obtained from field measurement.

Abstract:Effect of different organic substrate concentration on nitrogen removal in SNAD and the application of this process to treat domestic wastewater were investigated in a MBR, with gradually increased glucose as a source of organic matter. Besides, changes of microbial communities were observed by PCR-DGGE techniques. Experimental results and DGGE profiles showed that the increase of organic carbon concentration did not inhibited the activity and category species of AOB and Anammox bacteria when the C/N ration was ranged 0 to 2.0. Meanwhile, a significantly improvement of nitrogen removal was observed via effective denitrification, with a total nitrogen removal efficiency of 67% and nitrogen removal rate of 0.34 kg/(m³·d), respectively. Under the C/N of 3-4 condition, the anammox bacteria in the system changed insignificantly, but AOB was inhibited and the category species reduced, resulting a decreasing of nitrogen removal efficiency.Total nitrogen removal efficiency and nitrogen removal rate were about 73% and 0.17 kg/(m³·d), respectively.Nitrosomonas and Candidatus Kuenenia stuttgartiensis were the predominant microorganisms in the SNAD reactor and played a major role in autotrophic nitrogen removal.

Abstract:Partial nitrification (PN) process was successfully developed in a plug flow reactor fed with low strength sewage at ambient temperature (18-21.5℃). For better detecting the efficiency and mechanism of the partial nitrification process in the PN reactor, ammonia, nitrite, and nitrate were detected firstly, subsequentially the functional bacterial community in the reactor was also investigated at microbial level. The sludge microstructures were detected by scanning electron microscopy (SEM), and the microbial characteristics was studied via fluorescence in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), cloning and sequencing analyzing. The DO concentration was maintained between 0.1 to 0.6 mg/L, to enhance AOB competition superiority. After 80 days continuous operation, PN reactor achieved nitrite accumulation rate of 100% and effluent NO₂^--N to NH₄⁺ -N ratio achieved 1.11. SEM results showed that spherical bacteria were the predominant bacteria in partial nitrifying sludge. FISH results showed the proportion of AOB and NOB were 37.3% and 4.4%, respectively. Bacterial DGGE and sequencing results indicated that six dominant bacteria coexisting in the PN reactor, among which Nitrosomonas sp. were the main AOB species.Those multiple functional bacteria contributed to the nitrogen removal in PN reactor.

Abstract:To study the biological stability of drinking water distribution system and the control strategy of microorganism, this paper, based on the actual water distribution system of the southern city, adopted molecular biological methods to analyze three kinds of proteobacteria in biofilms, discussed the interrelationship between biofilm and bacterial regrowth potential (BRP). The results showed that improvement of water quality led to a transformation from gamma proteobacteria dominate (the proportion was 52.14%-77.34%, 51.02%-77.45%, 51.86%-65.99%, respectively) to alpha proteobacteria dominate (the proportion reached 62.56%-91.36%, 75.27%-96.20%, 73.08%-96.76%, respectively), and the biological stability was improved. In addition, the shedding of biofilm, which makes higher nutrient concentrations of water pipe network, promoted the bacteria regrowth and thus has a certain correlation with BRP.

Abstract:The kinetics and mechanism in the electrochemistry/catalytic hydrogenation (E/C) coupling process, which was employed to remove nitrate (NO₃^--N) from groundwater, was investigated in this paper. The results demonstrated that the NO₃^--N could be rapidly removed by E/C under anoxic conditions, and the degradation efficiency of NO₃^--N followed the increasing current density(I_D) with observed second order reaction rate and the constant(k) value of 0.005 5 cm²·mA^-1·min^-1. The NO₃^--N reductive by E/C with two kinds of reactions, electrochemistry denitrification and catalytic reduction, both of which aggregated by the reaction of brine electrolysis.

Abstract:To explore the pollutants sources and the water quality variation rules of the water source reservoirs, monthly monitoring of water quality from April 2013 to April 2014 was carried out in Zhelin Reservoir, which is the main water source of Jiujiang City. The dynamic variations of water temperature and DO concentrations were measured in situ, while COD_Mn, TOC, TN, TP, Fe and Mn were determined in the laboratory. The results showed that the main pollution source of Zhelin Reservoir was the upstream runoff, and its percentage contribution to the bulk pollutants was 88.3% for COD_Mn, 76.2% for TN and 67.6% for TP, respectively. During the stable stratification period, the maximum concentrations of COD_Mn, TOC, TN, TP, Fe and Mn in the bottom water reached 3.8, 2.4, 1.12, 0.14, 0.42 and 0.34 mg/L, respectively. The algae population and algal species identification results demonstrated that the maximum density of algae was 2.25×10⁶ cells/L, in which green algae was predominated. However, during the mixing period, Mn concentration exceeded the drinking water standard.

Abstract:Extracellular polymeric substances (EPS) in sewage sludge are highly hydrophilic, and the destruction of EPS structure is very essential for the high-performance dewatering process. In this study, the peracetic acid lysis and chemical re-flocculation was used to achieve the volume reduction and dewaterability improvement of waste activated sludge. Moreover, dynamic variations of the floc morphology and EPS properties of sludge were also investigated. The results indicated that PAA treatment had very limited effect on sludge filterability, while filtration drying performance was effectively improved. PAA could effectively solubilize the sludge particle and destroy the protein-like substances, resulting in an efficient releasing of bound water. Sludge dewatering was enhanced under a low pH level after PAA oxiution, ascribing to the higher oxiutive ability of PAA under acid conditions. No integral sludge floc could be observed after PAA treatment at high dosages. Floc reformed after the additive of PAC and ferric chloride, meanwhile both filterability and dewaterability were improved. Furthermore, PAC performed better in improving sludge dewatering performance than ferric chloride due to its high adsorption and bridging abilities.

Abstract:To investigate the deposition and adsorption behavior of BSA on the PVDF surface and the structure of the BSA adsorption layers over a range of ionic strengths, a quartz crystal microbalance with dissipation monitoring (QCM-D) combined with a self-made PVDF-coated sensor crystal was used in this study. These results were combined with those of fouling experiments and the flux recovery rate (at corresponding ionic strengths) to obtain visual insight into the effect of ionic strength on membrane BSA fouling behavior.Results show that when the ionic strength increased from 0 to 1 mmol/L, the adsorption amount of BSA on PVDF surface was increased, and a denser and more compact BSA layer was formed, accompanied by the enhancement of membrane fouling, which was mainly attributed to the decrease of electrostatic repulsion forces. But on the contrary, when ionic strength increased to 10 and 100 mmol/L, the PVDF-BSA and BSA-BSA interaction forces are weakened due to an increase in the hydration repulsion force, which results a decrease in adsorption amount of BSA on PVDF surface, a more nonrigid and soft BSA layer was formed, and membrane fouling decreased significantly. Moreover, the flux recovery rate was increase significantly at high ionic strength.

Abstract:In order to evaluate the feasibility of the fast startup of Anammox process, a lab-scale Anammox baffled biofilm reactor was carried out in this study. The experimental conditions were maintained at temperature (30±2)℃, DO 0.2-0.5 mg/L, pH 7.6-8.0, average ammonia nitrogen load at 0.12 kg/(m³·d) and nitrite nitrogen load at 0.18 kg/(m³·d), respectively. By taking continuous low strength influent, the start-up process was successfully achieved within 83 days. After the fast startup, the average concentration of effluent NH₄⁺ -N, NO₂^--N and TN were 1.5, 1 and 10 mg/L, respectively. Meanwhile, the average removal efficiencies of NH₄⁺ -N, NO₂^--N and TN reached 95%, 95% and 80%, respectively. The effluent could stably meet the first grade A standards of Urban Sewage Disposal Plant Contamination Integrated Discharge Standard of China (GB 18918-2002). Under the stable phase, the removal rate of NO₂^--N in each compartment along the reactor gradually decreased, and the remove of NH₄⁺ -N presented in some delay.

Abstract:The paper is to study the effect of fibroblast growth factor-21 (FGF-21) on lipid metabolism in the monosodium glutamate (MSG) induced obese rats. SD rats were induced by MSG after weaning, and then randomly divided into experimental and vehicle groups. After fed to 20 weeks, the experimental groups were injected with FGF-21 (1 mg/kg) for a continuous 32 d. The rats were detected the body weight, Lee's index, food intake, abdominal and subcutaneous fat content, lipid content, glucose tolerance and the relevant indicators of hepatic and lipid metabolism before and after the injection. As compared to vehicle-treated rats, FGF-21 did not affect the amount of daily food intake in MSG rats, but led to a significant reduction in Lee's index, total body weight and abdominal fat mass (52.8% reduction) at the end of treatment. After FGF-21 treatment, the levels of glucose, triglycerides, cholesterol and LDL-C decreased except HDL-C. The exogenous FGF-21 led to the improvement of the liver weight, hepatic AST, ALT and ALP and the reduction of endogenous FGF-21, PPARα and PPARγ in liver. In summary, FGF-21 could regulate on lipid metabolism and reverse hepatic steatosis in MSG rats.

Abstract:A staple food in China, rice is prone to be hardened, dehydrated, decreased in stickiness in storage, restricting the development of the rice food. Retrogradation of starch, the main component of rice, is the leading cause to rice quality deterioration. The thesis, elaborated on the structure of rice starch and the effects of other rice components on retrogradation, and overviewed the control technologies on retrogradation of rice starch home and abroad, tries to provide ways for improving the quality of rice food and extending their shelf life.

Abstract:The dispersion characteristics of PD is carried out to figure out the accuracy of peridynamics method (PD) and its simulation effects on rock spalling. Firstly, based on the dispersion analyses of the PD discrete equations, it is found that the numerical dispersion is more apparent with increasing the domain size if the space step is fixed; with the number of nodes in the domain fixed, the numerical dispersion becomes weaker when the space step decreases; the numerical dispersion also gets weaker with the increase of the nodes at a fixed domain. Subsequently, by comparing it to the traditional finite difference method, it is pointed out that the PD discrete equations can be written as the combination of a series of differential equations, whose truncation error is the second order infinitesimal of the domain radius (δ); when δ is set as the space step, PD method is equivalent to the central difference method, owning the highest calculational accuracy. Finally, the PD method is used to explore the one-dimensional spalling phenomenon of rock bar. The effects of space step and domain size on computing results are discussed, and the spalling time, spalling locations and damage distribution are further given. The effectiveness of PD method is also verified by contrast with the spalling test. It is shown that PD can be used for rock spalling analysis and high-precision results can be obtained by PD method coupled with FDM, costing less time and owning a clear advantage.

Abstract:In order to explore how to choose the turbulence model of the gas-liquid two phase flow in a horizontal pipe, the guess that the turbulence of the interface of the gas-liquid two phase flow in a horizontal pipe is anisotropic was put forward. The emergence and development mechanism of the turbulence anisotropy in the interface was analyzed. It points out that the turbulence inertial force generated by the turbulence anisotropy in the interface is an important reason for the formation of annular flow in a horizontal tube, which was verified by comparing the simulation results of using the two-equation model and Reynolds stress model (RSM) to simulate the same working condition of annular flow in a horizontal tube. On such basis, the basis of selecting turbulence model in gas-liquid two phase flow was discussed. The results show that the RSM model is adaptive for large gas-liquid shear stress in a horizontal pipe, while the two-equation model and RSM model are both adaptive for other conditions.

Abstract:To predict typhoon design wind speed of buildings in typhoon prone region more efficiently and accurately, probability distributions of typhoon key parameters are first fitted by using the historical typhoon wind data during 1949 and 2012 in southeast china costal region. Then, the empirical typhoon wind field model with new formula for Holland radial pressure profile parameter B is presented. Finally, in conjunction with Monte Carlo simulation method, by using typhoon extreme wind speed analysis method, typhoon extreme wind speeds with different return periods for Hong Kong are obtained. The simulation results are compared with these results obtained by using observed data and Hong Kong wind code. The effectiveness of predicting typhoon extreme wind speed by using this empirical typhoon wind field model is validated.

Abstract:A series of model tests on friction piles in corrosive foundation model were conducted to investigate the settlement characteristics of friction piles (end-bearing friction pile and friction pile) under working load in corrosive foundation. The copper sulfate solution as the corrosive medium was adopted to make the foundation model, which could accelerate surface deterioration speed. Then the settlement law of friction piles with surface deterioration under working load was investigated. The results indicated that the deterioration degree around pile surface increases with time, and the settlements increase with the deterioration degree. The load-settlement curves of end-bearing friction pile and friction pile were different. After 17 360 minutes under working load, the percentage of settlement on end-bearing friction pile reaches 28.5% of pile diameter. The settlement caused by skin deterioration is 10.6% which is larger than the settlement of friction pile with 7%. By the end of the test, the settlements of two types of piles reach the settlements corresponding to the ultimate bearing capacities respectively. Surface deterioration can cause significant incensement of friction pile settlement. This may affect the pile normal function.

Abstract:This paper presents a model for solving interface crack with arbitrary crack traction based on the Scaled boundary finite element method to study the significant influence of the traction acting on the crack faces on the stability of a crack. The order of stress singularity is complex for an interface crack. With the existence of crack traction, the stress singularity is more complicated. Base on the proposed model, stress and displacement are solved analytically in the radial direction, and the stress singularity at crack tip is obtained with high precision without refined mesh. The arbitrary crack traction is firstly decomposed to one component parallel to the crack and the other one perpendicular to the crack, then both the two components are expressed as the sum of a limited number of power functions respectively. The effect of each power function is solved analytically. According to the Linear superposition principle, the solution of a structure with arbitrary crack traction can be obtained. The proposed model is effective for both anisotropic and isotropic materials. The model is verified by several plates with crack tractions, in which stress intensity factors are calculated. Sensitivity analysis is also performed concerning the plate geometry and material properties. Finally the model is applied to solve the stress intensity factors of an interface crack of a gravity dam filled with water.

Abstract:This paper investigates a new type of secondary beam through type concrete girder-steel secondary beam connection. In the core zone, the steel beam fully crosses through the concrete girder with an end plate welded at steel beam end. Static test was conducted on the 1/2 scale specimen to study the mechanical behavior and failure process of this type of joint during bending moments. Tests results indicate that the bending failure of steel secondary beam occurs, and the strength of steel secondary beam can be fully used. Test capacity value is slightly higher than theoretical calculation value. Steel beam was anchored well and no slippage failure occurred during load process. The specimen showed excellent deformation capability and ductility coefficient can reach 5.11.

Abstract:This study aims to determine the key factors that influence the application of roof-mounted solar energy harvesting systems in cold regions. Based on a questionnaire survey involving 9 indexes including energy efficiency, performance, cost, power consumption, damage of roof structure, visual pollution, ease of installation, proneness of falling and anti-freezing from 80 interviewees in more than 30 solar equipment communities in Harbin, a city in the cold regions of China, it has been revealed that the high cost (70%), visual pollution (82.5%) and poor anti-freezing (66.25%) are major concerns to residents. As such, the above three emergent problems (>50%) were highly desired to be overcome for the application of solar equipment in cold regions. After exploring the main technical problems and their potential solutions, it is proposed that, in order to rationalize the design of the solar roofs, it would be of necessity to design the roof by optimizing factors through a multi-objective function approach. This integrated design would refer to technology of multi-disciplines involving architectonics, structural engineering, industrial design, et al.

Abstract:Intensity discontinuity and high computational complexity are drawbacks in some existing methods of image inpainting. To tackle these problems, a method based on PDE model(Isophote-TV-H^-1 model) and improved Criminisi algorithm is proposed in this paper. Firstly, the damaged image is decomposed into cartoon and texture with the TV-H^-1 model. Secondly, the Isophote-TV-H^-1 model and the improved Criminisi algorithm are used to recover the cartoon and texture of the damaged image, respectively. Finally the recovered texture is superimposed on the recovered cartoon to get the result image. The experimental results demonstrate that the proposed model recovers the texture of the damaged region better than the TV model. Comparing with Criminisi algorithm, the proposed model suppresses the error propagation through improving the similarity measurement method, as well as improves the efficiency by employing the local search.

Abstract:In order to accurately calculate the result of gust load, a mathematical model of nonlinear system for helicopter flight dynamics is developed with the consideration of both temporal derivative and spatial gradient of variable wind velocity. The gust load for helicopter is analyzed through the time-domain overload coefficients simulation, which is compared with the result from engineering estimation formula. By consideing the influences of helicopter rotor, tail rotor, fu selage, vertical stabilizer and horizontal stabilizer on gust load, this method provides more accurate result of gust load in a forward flight with small advanced ratios. The comparison result shows that the vertical gust load has more significant influences on helicopter structural strength than gust in other directions. Moreover, the relationship between gust load and gust velocity strength is linear under the same advanced ratio. Numerical results indicate that the proposed method can be applied to analyze gust load in different flight states and variable gust fields.

Abstract:In order to simulate the hull piping transient response subjected to an impact load, a discrete-time precise transfer matrix method was applied to write a program and simulate the shock response of naval piping system. By comparing the calculated results from the proposed algorithm with those from the pipe impact test, the validity of the method was verified. The results show that the calculated results of the acceleration and stress was precise. The finite element models of the elbows and tees were established, and the transient response of the ship pipes under impact load was analyzed. The results calculated by the new proposed method were compared with those obtained by the finite element method. The results show that discrete-time precise transfer matrix method holds a substantial reduction in computation time with high accuracy. The new method gives a reference to calculate the shock response and evaluate the shock resistance ability.

Abstract:In order to improve the fault diagnosis ability of the system and its accuracy, with previous experience in this article is based on data Rolling health management, this paper presents a novel based on multiple hidden Markov models and Kazuo artificial neural network algorithms and methods of combining ant colony to be used to diagnose and detect bearing faults, which uses HMM and pattern recognition method by combining the bearing vibration signal feature extraction, in the frequency domain analysis of the aging phenomenon, namely the historical data and the new data fault diagnosis and testing, while HMM and ANFIS fault prediction is to estimate the remaining useful life and the life. The experimental results show that the method of HMM and pattern recognition can be used to diagnose and predict the faults. The method can reduce the computational complexity and improve the accuracy of diagnosis, through the different fault diagnosis example elaborates on HMM-based fault diagnosis method effectiveness and feasibility.