Abstract:To obtain the transverse deformation properties of reactive powder concrete (RPC) after high temperature, the uniaxial compression experiments were conducted on 180 prismatic specimens with the size of 70.7 mm×70.7 mm×228 mm for reactive powder concrete (RPC) after exposure to 20～900 ℃. The curves of transverse deformation coefficient with the stress ratio were measured for RPC with various fiber types and contents. Then the relationships between volumetric strain and heating temperature were received. The results indicate that the Poisson's ratio of RPC under room temperature is 0.201～0.212. For the same heat treatment, the Poisson's ratio reduces gradually with the increasing of fiber content. After exposure to 20～400 ℃ the Poisson's ratio decreases gradually with the temperature increases, but it restores when the temperature is higher than 400 ℃. The equation to express the relationship between Poisson's ratio and exposure temperature is proposed, and the fitting curve is in good agreement with the test results.

Abstract:To explore the method of spiral hoops made of steel bar for prestressed concrete and study the mechanism and failure process of concrete column confined by high-strength spiral hoops, the axial compression test of 24 concrete columns confined by steel bar for prestressed concrete spiral hoops and 4 concrete columns confined by steel rebar are carried out. The results show that the ultimate tensile stress of prestressed concrete spiral hoops can be increased with the concrete strength and the ratio of hoop. Based on the results of test, when the columns under axial compression reach the ultimate bearing capacity, the relationship between the tensile strain of spiral hoops and the degree of constraint is suggested, and the calculation formulas are put forward.

Abstract:To ensure the safe design of coal mine refuge chamber, we investigate the strength and deformation of the chamber under explosion. Based on the principle of gas explosion, numerical simulation was performed using ANSYS/LS-DYNA software and ALE fluid-solid coupling algorithm on the flow filed of underground tunnel explosion caused specifically by 9.5％ concentration of 200 m³ gas. Systemically analyses were done on the relationship between the pressure field as well as plastic strain distributions and the dynamic response through the displacement-time curves. The cross-section dimension of the chamber surface where it faces to the explosion directly can significantly influence the anti-explosion performance. The camber with corrugated sidewall structure can imperatively enhance the bending rigidity of the bulkhead. However, there is no much influence on the anti-explosion properties of the carbine by changing its length.

Abstract:Currently, the design of steel structure rarely considers the enclosure wall effect and the quantitative research on the enclosure wall is relatively little. In this paper, the refined finite element model of a steel framework with an enclosure wall was first built by finite element analysis software ANSYS. The numerical simulation results meet the experimental results well considering wallboard contact and friction between the roles. Afterwards, lateral performance was analyzed by taking several key parameters into consideration, including the axial compression ratio, span-depth ratio, siding width, siding thickness and wall open-hole area. The results of this study shows that, when axial compression ratio ranges from 0 to 0.6, the enhancement coefficients of bearing capacity and initial stiffness of the framework with siding boards would range from 1.0 to 2.0; with a constant story height, there is linear positive relation between span-depth ratio and enhancement coefficients; the width of infilled-wallboard is advised as 600mm; different enhancement coefficients should be used when different thicknesses of wall is used; when the hole on wall is strengthened, such influence can be ignored during the design as it has little impact on the whole structure.

Abstract:Impact tests on CFRP laminates with three porosity levels were conducted at impact energy levels of 3,6, 9,2 and 15 J to study the influences of porosity and impact energy on the impact damage tolerance. The impact damage was evaluated by ultrasonic C-scan measurement, metallurgical microscope, thermal deply technique and visual inspections. The experimental results show that the porosity has detrimental effects on the dent depth and the damage area of composite laminates for the same impact energy. The dent depth increases rapidly with the increasing of impact energy, and a progressive increase of the impact area occurs after 9 J. The thermal deply test reveals the failure mechanism of impact damage mutation of CFRP laminates when the impact energy exceeds the threshold 9 J. The impact energy is consumed from the matrix cracks and delaminating to the fiber cracks after 9 J.

Abstract:To enhance the quality of wastewater treatment plant’s (CASS process) effluent in Foshan to satisfy the water reuse standards, the impact of reflux ratios and reflux modes on nitrogen and phosphorus removal performance of a pilot scale of intermittent A/O-MBR fed with municipal wastewater was studied in this paper. The results showed that the reflux ratios and reflux modes had no remarkable influence on removal of CODCr and NH+₄-N, and the concentrations of CODCr and NH+₄-N in the effluent both reached the primary standard A of (GB18918—2002). The reflux ratios and reflux modes had significant influence on removal of TN and TP. The removal efficiencies of TN and TP were poor with a continuous reflux and a larger reflux ratio (350 ％); When the reflux ratio was 130 ％, the continuous mode was propitious to TN removal, and the removal efficiency could reach (48.00±10.05) ％, what’s more, the concentration of TN in the effluent reached the primary standard A, while the intermittent mode was also propitious to TP removal, the removal efficiency could reach (78.27±23.41) ％, and the concentration of TP in the effluent reached the primary standard B.

Abstract:To study the effect of alkalinity on partial nitrification(PN) and the feasibility to control the ratio of nitrite to ammonia in effluent, the PN was rapidly started-up in a sequencing batch reactor. The ammonia conversion rate, ammonia oxidation rate and the microbial activity were investigated in different ratio of the inflow alkalinity to ammonia. Results showed that the PN could be achieved quickly by pre-cultivating the sludge with high ammonia nitrogen, and over 96％ nitrite accumulation rate was sustained. The rate can be controlled flexibly with the liner relationship between ammonia conversion and the ratio of alkalinity to ammonia while alkalinity is insufficient. Cycling experiments show a good indication of alkalinity on nitrite, the alkalinity less than 50 mg/L will stop the ammonia oxidation, and the inorganic carbon less than 3.0 mmol·g-1 will lead to the reduction of microbial population and activity. In actual operation, the ratio of nitrite to ammonia in effluent can be effectively controlled by the alkalinity.

Abstract:To expose the kinetic law of enrofloxacin oxidation by potassium permanganate in aquatic environment, the article studied the rate constant of reaction, and simultaneously investigated the reaction influencing factors such as potassium permanganate dosage, pH value and temperature. The results showed that the oxidation reaction of enrofloxacin by potassium permanganate in aqueous solution followed second-order kinetics. The reaction rate constant was observably influenced by the three effect factors. The reaction rate increased with the increasing of temperature and potassium permanganate dosage. Under neutral condition, the reaction is easily conducted at the acidic and basic condition. The reaction activation energy Ea is 53.27 kJ·mol-1,slightly lower than that of the common chemical reaction, which reveals that the oxidation reaction between enrofloxacin and potassium permanganate is feasible under usual water treatment condition.

Abstract:Two bacterial fermentation products containing amylase were added singly or combinationally to waste activated sludge (WAS). Biochemical methane potential (BMP) experiment of enzyme treated sludge was carried out to investigate the effects of amylase, which could be released by WAS, on the digestibility of sludge. The results show that enzymatic pretreatment can facilitate the hydrolyzation of macromolecule organic matters into small molecular organics, with a 56％ increase in volatile fat acids. For treated sludge, the volume occupied by particle between 200～2 000 μm decreased obviously. Although the hydrolyzability of sludge is low, the digestibility of pretreated sludge was remarkably improved. The reduction of volatile was enhanced from 36.02％ to 42.19％. The specific methane yield was 434 mL CH₄ per gram volatile solid removed, which was higher than that of untreated sludge (381 mL/g).

Abstract:Due to the low efficiency of traditional azo dye treatment process, in this study a novel up-flow biocatalyzed electrolysis reactor was used for azo dye alizarin yellow R (AYR) decolorization. The reactor operated in an up-flow, continuous flow mode, and the results showed that the decolorization efficiency was 82.1％ and the decolorization rate was 1.74 mol·m-3·d-1 at HRT of 4 h. The chrominance of the effluent was as low as 80. AYR was mainly discolored via electrochemical reaction in the cathode zone of UBER. The bio-anode also made some contribution to the decolorization. Two stable products p-phenylenediamine and 5-aminosalicylic acid were produced finally without accumulation of nitro intermediates.

Abstract:To explore the degradation effects of AMF on the residual of tricyclazole in the soil and plant of rice, we assay the residual quantity of tricyclazole in soil and plant of rice which were set by different AMF and different concentration. The results showed that the infection rate was significantly increased after applying agent. The infection rate of GI+GM was 56.06％, which was better than that of GM with 53.86％ and GI with 34.57％. The digestion rate of tricyclazole of those treatments with AMF was bigger than that without AMF. The half-life period of tricyclazole of those treatments with AMF were shorter than that without AMF. The digestion effect of three AMF on tricyclazole in soil was GM+GI> GM> GI. AMF got the best effect at 150％ which was the one of four different concentrations. The digestion effect of three AMF on tricyclazole in plant was GM> GM+GI> GI, GM and GM+GI got the best effect at 150％.

Abstract:Transfer and fate of naphthalene (PAHs) in multi-medium of Songhua River was studied. A level III fugacity model was applied to calculate the multi-interface transfer flux and concentration distribution of naphthalene in Songhua River under steady-state assumptions. The results indicated that soil was the largest storage of naphthalene, accounting for 40％ of the total amount of residual. In air, water, soil and sediment, the concentrations of naphthalene were 3.58×10-6 μg·g-1, 0.142 μg·L-1, 5.28×10-4 μg·g-1 and 3.62×10-3 μg·g-1 respectively. The reliability of the model was verified by the coincidence of the calculated and the measured concentration in the same period.

Abstract:Novel polyimide with better thermostability, lower dielectric constant and constant loss were synthesized by fluorinated modification and molecular structural design and predicted as coatings with highly electromagnetic wave permeability. 4-(4-aminophenoxy)-3-fluoroaniline (APFA) was obtained by 2-fluoro-4-nitrophenol and 4-nitrochlorobenzene, then the formed 2-fluoro-4-nitro-1-(4-nitrophenoxy)benzene(FNNB) was transferred by catalytic reduction with hydrazine hydrate and catalyst of Pd/C. The asymmetric fluorinated was synthesized with 6FDA in DMAc solution by imidization of polyamic acid. Asymmetric polyimide exhibited excellent thermal stability with the decomposition temperature and the glass transition temperature of 502.50 and 251.60 ℃. The residual weight (Rw) at 700 ℃ was 49.86％. AFM images of polyimide film showed that the grain sizes were in narrow ranges with evenly surface and mean roughness of 9.024 nm. The UV-Vis absorption edge was at 357 nm and the transparency at 450 nm was higher than 80％. The dielectric constant was 3.65 at 1 MHz and 2.38 at 10 MHz, and the maximum dielectric loss was 0.010 7.

Abstract:To evaluate splitting tensile stress-strain properties of cement stabilized reclaimed asphalt pavement (RAP), four types of mixture containing varying percentages of RAP (0,5％ and 30％) and cement (4.5％ and 5.0％) were designed in this paper. A mix made from only virgin material and cement dosage of 4.5％ was selected as the control mix for the investigation. Five indexes, splitting tensile strength, splitting resilient modulus, peak strain, energy density and brittleness index, were used to assess the influence of RAP content and test temperature (-5,5, 20 ℃ and 35 ℃) on splitting properties via splitting tensile test. The test results have indicated that splitting tensile strength, splitting resilient modulus and brittleness index decrease with the increasing of temperature, and the decreasing amplitude increases with the increasing of RAP content. The splitting tensile strength and peak strain decrease persistently with the increasing of RAP content, while the brittleness index augments at -15 ℃. In positive temperature cases, splitting strength, peak strain and energy density increase first and then diminish with the increasing of RAP content, whereas, modulus and brittleness index tend to decrease. A positive linear correlation between splitting strength and other indexes exists, and the optimal RAP content is from 15％ to 20％.

Abstract:To enhance the robustness of IR fast small target tracking, an improved mean shift tracking algorithm based on membership degree weighted kernel histogram target representing model is proposed. Firstly, the local background interference problem in tracking fast small target with original mean shift algorithm is analyzed and the membership degree weighted kernel histogram target representing model merged into background information is presented. This model is able to enhance the representing capability of target and suppress local background interference. Then, the shift vector of this model is deduced in the framework of mean shift by regarding Bhattacharyya coefficients as the similarity measure. The target shift tracking is achieved effectively according to target gray level of large membership degree with high shift weight, and vice versa with low shift weight. Finally, the local background time-varying is conquered by employing model updating method and the robustness of target tracking is further improved. The experimental result indicates that the algorithm can improve the shift weight of target pixel gray level and suppress background interference, thus the performance of tracking the IR fast small target is robust.

Abstract:To investigate the effect of volume fraction of coarse aggregate(VFCA) on the developments of elastic modulus and prismatic compressive strength of early-age concrete, mixtures with different VFCA were designed for concretes with water to cementitious material ratio (w/b) of 0.2,0.43 and 0.3 respectively. Keeping the mortar composition and w/b unchanged, and merely increasing the VFCA gradually from zero, the elastic modulus of concrete at the age of 28 days increased significantly, whereas the compressive strength of prismatic specimen first slightly decreased when VFCA is small, and subsequently increased gently when VFCA became larger. External drying induced evaporable water loss in concrete decreased the degree of cement hydration, which resulted in a reduction on elastic modulus, and a reduction on compressive strength as well in the dried specimens compared to that of sealed ones with the same curing age. The larger the w/b was, the bigger reduction the elastic modulus exhibited. Degree of cement hydration-based predictions of concrete elastic modulus and compressive strength were proposed, and good agreements were found between the test and the analytical results regardless of w/b, VFCA and curing conditions.

Abstract:The performance of slotted-in steel plates dowelled and glued-in bar post-to-beam connections were tested with monotonic and reversed cyclic loading protocols. The performance of different types of filled-in shear wall hybrid post-and-beam frame constructions was studied using a finite element model that was developed with SAP2000. Results indicate that the initial stiffness of slotted-in steel plates dowelled post-to-beam connections approximately equals to zero and glued-in bar post-to-beam connections have relative high initial stiffness and resistance capacities. The racking displacement capacity of post-and-beam frame is 2～3 times than that of shear wall, the lateral load resistance capacity of post-and-beam frame cannot be fully employed in hybrid constructions. The hybrid constructions behave more similar to shear walls. Based on the analysis of the tests, mathematical models verified by experimental tests for the hybrid constructions were developed and proposed.

Abstract:Aiming at the problem of large number of the weathered granite existed along the expressway, and to recycle the excavation and meet the social and economic benefits, this paper attempts to improve the properties of weathered granite material which is easy to disintegrate and poorly graded. The lime-fly-ash-cement was used to improve the weathered granite material for the pavement sub-base. Three different mix proportion, the mass ratio of cement∶lime∶fly-ash∶weathered granite is:Ⅰ (2∶4∶16∶78),Ⅱ (2∶6∶14∶78),Ⅲ (2∶8∶12∶78) were tested; And four tests of compaction, strength, dry shrinkage and temperature shrinkage were taken to evaluate the effect of road base course performance of lime-fly-ash-cement stabilized weathered granite material. The tests result shows that the strength decreases first and then keeps stable with the increasing of lime, and keeps stable first and then increases with the increasing of fly-ash. The plan I and Ⅱ have bigger maximum dry density, the compressive strength and spilt strength of plan I are the biggest, those of plan II are the second. The drying shrinkage of plan I and II is similar, and that of plan III is the worst. The rule of temperature shrinkage is the same to the drying shrinkage rule. According to the experimental result, the best mix proportion scheme is mix proportion I (2∶4∶16∶78), which is suitable to the pavement sub-base.

Abstract:To provide base isolation design simplified method of LNG storage tank,combining base isolation engineering design requirement of LNG storage tanks, based on the response spectrum design theory, considering and not considering mass spring damping parameters 2 kinds of LNG storage tank simplified mechanical models were established. Seismic effect coefficient curve for the LNG tank response spectrum design and response spectrum basic steps of LNG storage tank base isolation were presented. Selecting 1.6×10⁵ m³ LNG tank response spectrum and time history analysis method supplementary checking, the results showed that: compared with the traditional structure, it could effectively reduce the base shear and the tank wall overturning moment,the simplified model was feasible based on response spectrum theory, the calculation results desirable time-history method average value and response spectrum method a larger value, tank design can only consider flexible impulse mass and the convective mass contribution to the base shear and tank wall overturning moment, the foundation design should consider all mass contribution to the base shear and base moment.

Abstract:To analyze the mesoscopic strength characters of aggregate contact surface, the quantitative testing technology of adhesion strength between bitumen and aggregates and the cohesion strength of bitumen binder itself under shear load were researched. According to the failure forms and the corresponding relationship of shear adhesion strength between aggregates and bitumen, adhesion failure area, shear cohesion strength of bitumen binder, cohesion failure area and shear failure load, the shear cohesion strength and shear adhesion strength can be determined, and the quantitative test of adhesion and cohesion strength of mineral aggregate contact surface can be realized. The test results show that the experimental temperature and oil film thickness of mineral aggregate contact surface have a big influence on shear adhesion strength, besides, the quality of bitumen also has an effect on it. The shear adhesion strength of bitumen binder has strong correlation with experimental temperature and the quality of bitumen.

Abstract:To analyze failure mechanism and internal essence of macro-mechanical properties difference for crumb rubber asphalt micture, discrete element models are established, contact force vector diagram, force chain network chart and contact force local enlarging graphs belong to gap gradation crumb rubber asphalt mixture, continuous grading crumb rubber asphalt mixture and asphalt mixture are systematically studied firstly, their internal strength chain, weak force chain and deformation characteristics are obtained respectively, their bearing capacity sorting and deformability sorting are proposed. Then, local enlarged drawing in adhesive contact failure position and displacement vector map of crumb rubber asphalt mixture are deeply researched, failure mechanism of crumb rubber asphalt mixture is obtained. The results show that their bearing capacity from big to small in proper order is asphalt mixture, gap gradation crumb rubber asphalt mixture, continuous grading crumb rubber asphalt mixture. Their deformability from big to small in proper order is asphalt mixture, gap gradation crumb rubber asphalt mixture, continuous grading crumb rubber asphalt mixture.

Abstract:Based on traditional control strategy, it is very limited to low voltage ride-through (LVRT) of doubly fed wind power generators. It can not meet technical rule for connecting wind farm to power system of China. It has to add the hardware circuit if the control strategy is not improved. The popular method is to add crowbar circuit to the rotor side. A model of doubly fed wind power generators based on traditional control strategy is built in this paper. The theory of LVRT was analyzed. Simulation of doubly fed wind power generators with crowbar circuit was undertaken and an experiment was undertaken in order to verify its virtue. The results show doubly fed wind power generators with crowbar circuit is more practical, which provides a powerful reference for improving the ability of LVRT of wind farm wind.