Structural stabilities, thermodynamics stabilities, elastic properties and electronic structures of Mg₁₇Al₁₂, Al₂Y and Al₄Ba phases were analyzed by first-principles calculations with Castep and Dmol3 program based on the density functional theory. The calculated results of heat of formation indicate that Al₂Y phase has the strongest alloying ability. The calculated thermodynamic properties show that the thermal stability of these compounds gradually increases in the order of Mg₁₇Al₁₂, Al₂Y and Al₄Ba phases. Y or Ba addition to the Mg-Al alloys could improve the heat resistance. The calculated bulk modulus B, shear modulus G, elastic modulus E and Poisson ratio ν show that the adding Y or Ba to Mg-Al alloys could promote the brittleness and stiffness, and reduce tenacity and plasticity by forming Al₄Ba and Al₂Y phases. The calculated cohesive energy and density of state (DOS) show that Al₂Y has the strongest structural stability, then Al₄Ba and finally Mg₁₇Al₁₂. The calculated electronic structures show that Al₂Y has the strongest structure stability because of the strong ionic bonds and covalent bonds combined action.

The radiative properties of a gold surface with one-dimensional Gaussian random roughness distribution were obtained with the finite-difference time-domain (FDTD) method and the recursive convolution treatment of the Drude Model. The bi-directional reflection distribution function (BRDF) for both TM mode and TE mode were obtained and compared with the highly accurate experimental data from the earlier work. The incident wavelength varies from 1.152 μm to 3.392 μm and incident angle is at 30°–70°, respectively. The results show that, the predicted values and experimental results are in good agreement. The highly specular peak in the BRDF is reproduced in the numerical simulations, and the increase of the TM mode BRDF is found to be attributed to the effect of a variation in the optical constant at the incident wavelength period.

In order to propel the development of metal magnetic memory (MMM) technique in fatigue damage detection, the Jiles-Atherton model (J-A model) was modified to describe MMM mechanism in elastic stress stage. A series of rotating bending fatigue experiments were conducted to study the stress-magnetization relationship and verify the correctness of modified J-A model. In MMM detection, the magnetization of material irreversibly approaches to the local equilibrium state M₀ instead of global equilibrium state M_an under cyclic stress, and the M₀−σ curves are loops around the M_an−σ curve. The modified J-A model is constructed by replacing M_an in J-A model with M₀, and it can describe the magnetomechanical effect well at low external magnetic field. In the rotating bending fatigue experiments, the MMM field distribution in normal direction around cylinder specimen is similar to the stress distribution, and the calculation result of model coincides with experiment result after some necessary modifications. The MMM field variation with time at a certain point in fatigue process is divided into three stages with the variation of stable stress-stain hysteresis loop, and the calculation results of model can explain not only the three stages of MMM field changes, but also the different change laws when the applied magnetic field and initial magnetic field are different. The MMM field distribution in normal direction along specimen axis reflects stress concentration effect at artificial defect, and the magnetic signal fluctuates around the defect at late fatigue stage. The calculation results coincide with the initial MMM principle and can explain signal fluctuates around the defect. The modified J-A model can explain experiment results well, and it is fit for MMM field characterization.

ZnO-Bi₂O₃-based varistor ceramics doped with Yb₂O₃ in the range from 0 to 0.4% (molar fraction) were obtained by a solid reaction route. The X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were applied to characterize the phases and microstructure of the varistor ceramics, and a DC parameter instrument for varistor ceramics was applied to investigate their electrical properties and V–I characteristics. The XRD analysis of the samples shows that the ZnO phase, Bi₂O₃ phase, Zn₇Sb₂O₁₂-type spinel phase and Zn₂Bi₃Sb₃O₁₄-type pyrochlore are present, and the Yb₂O₃ phases and Sb₂O₄ phases are found in varistor ceramics with increasing amounts of Yb₂O₃. The average size of ZnO grain firstly increases and then decreases with the increase of Yb₂O₃ content. The result also shows that the threshold voltage is between 656 V/mm and 1 232 V/mm, the nonlinear coefficient is in the range of 14.1–22.3, and the leakage current is between 0.60 μA and 19.6 μA. The 0.20% Yb₂O₃-added ZnO-Bi₂O₃-based varistor ceramics sintered at 900 °C have the best electrical characteristics.

In order to clarify the dispersion of SiC particles in straight-blade mechanical stirring of Al-SiC_p liquid, the dispersion of SiC particles in A356-3.5% SiC_p (volume fraction) liquid in a cylindrical crucible was studied. The relationship between rotating speed of stirrer and radial relative deviation of SiC_p content in A356 liquid between the center and the periphery of crucible was established in the conditions of 35° for the gradient angle α of blade and 10 mm/s for the speed of moving up and down of stirrer. The results show that the radial relative deviation of SiC_p content increases gradually with increasing the rotating speed of stirrer. When the rotating speed of stirrer is 200 r/min, the vertical dispersion of SiC particles in A356 liquid is even, but the radial relative deviation of SiC_p content is 0.24. Consequently, the nonhomogeneous dispersion of SiC particles in A356 liquid is mainly resulted from the nonhomogeneous radial dispersion of SiC particles.

To study the mechanics of work-hardening and annealing-softening, a series of experiments were conducted on samples of 304 austenitic stainless steel sheets. In addition, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and tensile testing were carried out to study changes and mechanisms of the stainless steel structures and properties during work-hardening and annealing-softening. The results indicate that annealing at low temperatures (100–500 °C) can only remove partial residual stresses in the sample and the softening via annealing is not obvious. Bright annealing and rapid cooling in a protective atmosphere can completely soften the cold-worked material. In addition, the low-temperature sample without a protective atmosphere only has a little oxidation on the surface, but at higher temperature the oxidized layer is very thick. Thus, high-temperature annealing should include bright annealing.

D,L-lactide was prepared from D,L-lactic acid by means of polymerization and depolymerization at low vacuum level. Morpholine-2,5-dione (MD) was synthesized from the cyclization of chloroacetyl glycine which was made from chloroacetyl chloride and glycine in the basic condition. A novel copolymer (PLAMD) with D,L-lactide (D,L-LA) and morpholine-2,5-dione (MD) was synthesized using stannous octoate as initiator, and characterized with FT-IR and ¹HNMR. The biocompatibility of PLAMD and PLA was investigated by MTT and microscope. The results show that amino acid is introduced into PDLLA main chain. PLAMD has better cell affinity than PLA, so it is a promising biomaterial.

Plenty of dams in China are in danger while there are few effective methods for underwater dam inspections of hidden problems such as conduits, cracks and inanitions. The dam safety inspection remotely operated vehicle (DSIROV) is designed to solve these problems which can be equipped with many advanced sensors such as acoustical, optical and electrical sensors for underwater dam inspection. A least-square parameter estimation method is utilized to estimate the hydrodynamic coefficients of DSIROV, and a four degree-of-freedom (DOF) simulation system is constructed. The architecture of DSIROV’s motion control system is introduced, which includes hardware and software structures. The hardware based on PC104 BUS, uses AMD ELAN520 as the controller’s embedded CPU and all control modules work in VxWorks real-time operating system. Information flow of the motion system of DSIROV, automatic control of dam scanning and dead-reckoning algorithm for navigation are also discussed. The reliability of DSIROV’s control system can be verified and the control system can fulfill the motion control mission because embankment checking can be demonstrated by the lake trials.

A new concept of banana vibrating screen which has the same effect as traditional banana vibrating screen in a new way was put forward. The dynamic model of vibrating screen was established and its working principle was analyzed when the action line of the exciting force did not act through the centroid of screen box. Moreover, the dynamic differential equations of centroid and screen surface were obtained. The motions of centroid and screen surface were simulated with actual parameters of the design example in Matlab/Simulink. The results show that not only the amplitude has a significant decrease from 9.38 to 4.10 mm, but also the throwing index and vibrating direction angle have a significant decrease from 10.49 to 4.59, and from 58.10° to 33.29°, respectively, along the screen surface, which indicates that motion characteristics of vibrating screen are consistent with those of traditional banana vibrating screen only by means of a single angle of screen surface. What’s more, such banana vibrating screen of variable linear trajectory with greater processing capacity could be obtained by adjusting the relative position of force center and the centroid of screen box properly.

A grasping force control strategy is proposed in order to complete various fine manipulations by using anthropomorphic prosthetic hand. The position-based impedance control and force-tracking impedance control are used in free and constraint spaces, respectively. The fuzzy observer is adopted in transition in order to switch control mode. Two control modes use one position-based impedance controller. In order to achieve grasping force track, reference force is added to the impedance controller in the constraint space. Trajectory tracking in free space and torque tracking in constrained space are realized, and reliability of mode switch and stability of system are achieved. An adaptive sliding mode friction compensation method is proposed. This method makes use of terminal sliding mode idea to design sliding mode function, which makes the tracking error converge to zero in finite time and avoids the problem of conventional sliding surface that tracking error cannot converge to zero. Based on the characteristic of the exponential form friction, the sliding mode control law including the estimation of friction parameter is obtained through terminal sliding mode idea, and the online parameter update laws are obtained based on Lyapunov stability theorem. The experiments on the HIT Prosthetic Hand IV are carried out to evaluate the grasping force control strategy, and the experiment results verify the effectiveness of this control strategy.

A nonlinear lateral-torsional coupled vibration model of a planetary gear system was established by taking transmission errors, time varying meshing stiffness and multiple gear backlashes into account. The bifurcation diagram of the system’s motion state with rotational speed of sun gear was conducted through four steps. As a bifurcation parameter, the effect of rotational speed on the bifurcation properties of the system was assessed. The study results reveal that periodic motion is the main motion state of planetary gear train in low speed region when n_s<2 350 r/min, but chaos motion state is dominant in high speed region when n_s>2 350 r/min, The way of periodic motion to chaos is doubling bifurcation. There are two kinds of unstable modes and nine unstable regions in the speed region when 1 000 r/minn_s<3 000 r/min.

For ballistic mid-course targets, in addition to constant orbital motion, the target or any structure on the target undergoes micro-motion dynamics, such as spin, precession and tumbling. The micro-motion characteristics of the ballistic mid-course targets were discussed. The target motion model and inverse synthetic aperture radar (ISAR) imaging model for this kind of targets were built. Then, the influence of micro-motion on ISAR imaging based on the established imaging model was presented. The computer simulation to get mid-course target echoes from static darkroom electromagnetic scattering data based on the established target motion model was realized. The imaging results of computer simulation show the validity of ISAR imaging analysis for micro-motion targets.

Because the signals of global positioning system (GPS) satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. In this case, the receiver autonomous integrity monitoring (RAIM) method cannot exclude faulty satellite. In order to improve the performance of RAIM method and obtain the reliable positioning results with five satellites, the series of receiver clock bias (RCB) is regarded as one useful satellite and used to aid RAIM method. From the point of nonlinear series, a grey-Markov model for predicting the RCB series based on grey theory and Markov chain is presented. And then the model is used for aiding RAIM method in order to exclude faulty satellite. Experimental results demonstrate that the prediction model is fit for predicting the RCB series, and with the clock-based RAIM method the faulty satellite can be correctly excluded and the positioning precision of GPS receiver can be improved for the case where there are only five useful satellites.

Theoretical analysis of consensus for networked multi-agent systems with switching topologies was conducted. Supposing that information-exchange topologies of networked system are dynamic, a modified linear protocol is proffered which is more practical than existing ones. The definition of trajectory consensus is given and a new consensus protocol is exhibited such that multi-agent system achieves trajectory consensus. In addition, a formation control strategy is designed. A common Lyapunov function is proposed to analyze the consensus convergence of networked multi-agent systems with switching topologies. Simulations are provided to demonstrate the effectiveness of the theoretical results.

The presented iterative multiuser detection technique was based on joint deregularized and box-constrained solution to quadratic optimization with iterations similar to that used in the nonstationary Tikhonov iterated algorithm. The deregularization maximized the energy of the solution, which was opposite to the Tikhonov regularization where the energy was minimized. However, combined with box-constraints, the deregularization forced the solution to be close to the binary set. It further exploited the box-constrained dichotomous coordinate descent algorithm and adapted it to the nonstationary iterative Tikhonov regularization to present an efficient detector. As a result, the worst-case and average complexity are reduced down as K^2.8 and K^2.5 floating point operation per second, respectively. The development improves the “efficient frontier” in multiuser detection, which is illustrated by simulation results. In addition, most operations in the detector are additions and bit-shifts. This makes the proposed technique attractive for fixed-point hardware implementation.

Adaptive clustering hierarchy routing (ACHR) establishes a clusters-based hierarchical hybrid routing algorithm with two-hop local visibility for delay tolerant network (DTN). The major contribution of ACHR is the combination of single copy scheme and multi-copy scheme and the combination of hop-by-hop and multi-hop mechanism ACHR, which has the advantages in simplicity, availability and well-expansibility. The result shows that it can take advantage of the random communication opportunities and local network connectivity, and achieves 1.6 times delivery ratio and 60% overhead compared with its counterpart.

Producer gas through gasification of biomass can be used as an alternate fuel in rural areas due to high potential of biomass resources in India. Experiments were conducted to study the performance of a diesel engine (four stroke, single cylinder, 5.25 kW) with respect to its thermal efficiency, specific fuel consumption and diesel substitution by use of diesel alone and producer gas-cum-diesel (dual fuel mode). Three types of biomass, i.e. wood chips, pigeon pea stalks and corn cobs were used for generation of producer gas. A producer gas system consisting of a downdraft gasifier, a cooling cum cleaning unit, a filtering unit and a gas air mixing device was designed, fabricated and used to power a 5.25 kW diesel engine on dual fuel mode. Performance of the engine was reported by keeping biomass moisture contents as 8%, 12%, 16%, and 21%, engine speed as 1 600 r/min and with variable engine loads. The average value of thermal efficiency on dual fuel mode was found slightly lower than that of diesel mode. The specific diesel consumption was found to be 60%-64% less in dual fuel mode than that in diesel mode for the same amount of energy output. The average diesel substitution of 74% was observed with wood chips followed by corn cobs (78%) and pigeon pea stalks (82%). Based on the performance studied, the producer gas may be used as a substitute or as supplementary fuel for diesel conservation, particularly for stationary engines in agricultural operations in the farm.

The research goal is to develop a new solar water heater system (SWHS) that uses a solar bubble pump instead of an electric pump. The pump is powered by the steam produced from an evacuated tube collector. Therefore, heat could be transferred downward from the collector to a hot water storage tank. The designed system consists of two sets of heat-pipe evacuated tube collectors, a solar bubble pump installed at an upper level and a water storage tank with a heat exchanger at a lower level. Discharge heads of 1 and 5 m were tested. The bubble pump could operate at the collector temperature of about 90–100 °C and vapor gage pressure of 80–90 kPa. It is found that water circulation within the SWHS depends on the incident solar intensity and system discharge head. Experimental investigations are conducted to obtain the system thermal efficiencies from the hourly, daily and long-term performance tests. The thermal performance of the proposed system is compared with conventional solar water heaters. The results show that the proposed system achieves system characteristic efficiency of 10% higher than that of the conventional systems using electric pump if taking the consumption of electric power into account. And the former is a zero carbon system.

A new methodology was proposed for contamination source identification using information provided by consumer complaints from a probabilistic view. Due to the high uncertainties of information derived from users, the objective of the proposed methodology doesn’t aim to capture a unique solution, but to minimize the number of possible contamination sources. In the proposed methodology, all the possible pollution nodes are identified through the CSA methodology firstly. And then based on the principle of total probability formula, the probability of each possible contamination node is obtained through a series of calculation. According to magnitude of the probability, the number of possible pollution nodes is minimized. The effectiveness and feasibility of the methodology is demonstrated through an application to a real case of ZJ City. Four scenarios were designed to investigate the influence of different uncertainties on the results in this case. The results show that pollutant concentration, injection duration, the number of consumer complaints nodes used for calculation and the prior probability with which consumers would complaint have no particular effect on the identification of contamination source. Three nodes were selected as the most possible pollution sources in water pipe network of ZJ City which includes more than 3 000 nodes. The results show the potential of the proposed method to identify contamination source through consumer complaints.

From the viewpoints of environmental conservation and energy efficiency, seawater-source heat pump system (SWHP) to provide district cooling and heating is applied in coastal areas. Based on the system, a heat transfer model was established for cast heat exchanger (CHE) adopted by SWHP systems. The CHE consists of pipes immersed in the seawater and used for transferring heat between the seawater and the heat exchanger pipes of SWHP system. An experimental study was carried out to test the validity of the model. A program was developed in VB language and the effects of inlet temperature, flow rate of the secondary refrigerant and length of CHE on the results were investigated. The results of the numerical simulation are in consistence with the experiments in both winter and summer conditions. As a result, application of SWHP systems with CHE in coastal areas in China is feasible due to the favorable geographical conditions and environment.

A model for liquid-gas flow (MLGF), considering the free movement of liquid surface, was built to simulate the wastewater velocity field and gas distribution in a full-scale Caroussel oxidation ditch with surface aeration. It was calibrated and validated by field measurement data, and the calibrated parameters and sections were selected based on both model analysis and numerical computation. The simulated velocities of MLGF were compared to that of a model for wastewater-sludge flow (MWSF). The results show that the free liquid surface considered in MLGF improves the simulated velocity results of upper layer and surface. Moreover, distribution of gas volume fraction (GVF) simulated by MLGF was compared to dissolved oxygen (DO) measured in the oxidation ditch. It is shown that DO distribution is affected by many factors besides GVF distribution.

In order to investigate the mechanism of nanoparticles enhancing the heat and mass transfer of the ammonia-water absorption process, several types of binary nanofluids were prepared by mixing Al₂O₃ nanoparticles with polyacrylic acid (PAA), TiO₂ with polyethylene glycol (PEG 1000), and TiN, SiC, hydroxyapatite (noodle-like) with PEG 10000 to ammonia-water solution, respectively. The thermal conductivities were measured by using a KD2 Pro thermal properties analyzer. The influences of surfactant and ammonia on the dispersion stabilities of the binary nanofluids were investigated by the light absorbency ratio index methods. The results show that the type, content and size of nanoparticles, the temperature as well as the dispersion stability are the key parameters that affect the thermal conductivity of nanofluids. For the given nanoparticle material and the base fluid, the thermal conductivity ratio of the nanofluid to the ammonia-water liquid increases as the nanoparticle content and the temperature are increased, and the diameter of nanoparticle is decreased. Furthermore, the thermal conductivity ratio increases significantly by improving the stabilities of nanofluids, which is achieved by adding surfactants or performing the proper ammonia content in the fluid.

To achieve CO₂ emissions reductions, the UK Building Regulations require developers of new residential buildings to calculate expected CO₂ emissions arising from their energy consumption using a methodology such as Standard Assessment Procedure (SAP 2005) or, more recently SAP 2009. SAP encompasses all domestic heat consumption and a limited proportion of the electricity consumption. However, these calculations are rarely verified with real energy consumption and related CO₂ emissions. This work presents the results of an analysis based on weekly heat demand data for more than 200 individual flats. The data were collected from a recently built residential development connected to a district heating network. A method for separating out the domestic hot water (DHW) use and space heating (SH) demand has been developed and these values are compared to the demand calculated using SAP 2005 and SAP 2009 methodologies. The analysis also shows the variation in DHW and SH consumption with size of flats and with tenure (privately owned or social housing). Evaluation of the space heating consumption also includes an estimate of the heating degree day (HDD) base temperature for each block of flats and compares this to the average base temperature calculated using the SAP 2005 methodology.

The method for calculating wall surface heat storage coefficient was introduced, and the coefficients of several common walls with light-weight external thermal insulation materials and the traditional solid clay brick wall were calculated. In order to study the impact of light-weight external thermal insulation materials, a contrasting experiment was carried out between an external insulated room and an uninsulated room in August, 2010, in Chongqing, China. The result shows that outside surface heat storage coefficient of the insulated wall is much less than that of the traditional wall. However, during sunny time, the surface temperature of external walls of the insulated room is obviously higher than that of the uninsulated room. In different orientations, due to different amounts of solar radiation and being irradiated in different time, the contrasting temperature difference (CTD) appears different regularity. In a word, using light-weight external thermal insulation materials has a negative impact on building surrounding thermal environment and people’s health. Finally, some suggestions on how to eliminate the impact, such as improving the surface condition of the building envelop, and plating vertical greening, are put forward.

This research was conducted to study the performances of the heat and multilayer reflection insulators used for buildings in South Korea to realize eco-friendly, low-energy-consumption, green construction, and to contribute to energy consumption reduction in buildings and to the nation’s greenhouse gas emission reduction policy (targeting 30% reduction compared to BAU(business as usual) by 2020). The heat insulation performance test is about the temperatures on surfaces of test piece. The high air temperature and the low air temperature were measured to determine the overall heat transfer coefficient and thermal conductivity. The conclusions are drawn that the heat transmission coefficients for each type of existing reflection insulator are: A-1 (0.045 W/(m·K)), A-2 (0.031 W/(m·K)), A-3 (0.042 W/(m·K)), A-4 (0.078 W/(m·K)), and the average heat conductivity is 0.049 W/(m·K); The heat conductivity for each type of Styrofoam insulator are 0.030 W/(m·K) for B-1, 0.032 W/(m·K) for B-2, 0.037 W/(m·K) for B-3, 0.037 W/(m·K) for B-4, and the average heat conductivity is 0.035 W/(m·K) regardless of the thickness of the insulator; The heat conductivity values of the multilayer reflection insulators are converted based on the thickness and type C-1 (0.020 W/(m·K)), C-2 (0.018 W/(m·K)), C-3 (0.016 W/(m·K)), and C-4 (0.012 W/(m·K)); The multilayer reflection insulator keeps the indoor-side surface temperature high (during winter) or low (in summer), enhances the comfort of the building occupants, and conducts heating and moisture resistance to prevent dew condensation on the glass-outer-wall surface.

Evaluating how park characteristics affect the formation of a park cool island (PCI) is the premise of guiding green parks planning in mountain cities. The diurnal variation of PCI intensity was achieved, and correlations between PCI intensity and park characteristics such as park area, landscape shape index (LSI), green ratio and altitude were analyzed, using 3 010 temperature and humidity data from measurements in six parks with typical park characteristics in Chongqing, China. The results indicate that: 1) the main factor determining PCI intensity is park area, which leads to obvious cool island effect when it exceeds 14 hm²; 2) there is a negative correlation between PCI intensity and LSI, showing that the rounder the park shape is, the better the cool island effect could be achieved; 3) regression analysis of humidity and PCI intensity proves that photosynthesis midday depression (PMD) is an important factor causing the low PCI intensity at 13:00; 4) the multivariable linear regression model proposed here could effectively well predict the daily PCI intensity in mountain cities.

An active pipe-embedded building envelope, which is an external wall or roof with pipes embedded inside, was presented. This structure may utilize the circulating water in the pipe to transfer heat or coolth inside directly. This kind of structure is named “active pipe-embedded building envelope” due to dealing with the thermal energy actively inside the structure mass by circulating water. This structure not only deals with thermal energy before the external disturbance becomes cooling/heating load by using the circulating water, but also may use low-grade energy sources such as evaporative cooling, solar energy, and geothermal energy. In the meantime, this structure can also improve the indoor thermal comfort by tempering the internal wall surface temperature variation due to the thermal removal in the mass. This work further presents the thermal performance of this structure under a typical hot summer weather condition by comparing it with that of the conventional external wall/roof with numerical simulation. The results show that this pipe-embedded structure may reduce the external heat transfer significantly and reduce the internal wall surface temperature for improving thermal comfort. This work also presents the effects of the water temperature and the pipe spacing on the heat transfer of this structure. The internal surface heat transfer may reduce by about 2.6 W/m² when the water temperature reduces by 1 °C as far as a brick wall with pipes embedded inside is concerned. When the pipe spacing reduces by 50 mm, the internal wall surface heat flux can also reduce by about 2.3 W/m².

In order to get prepared for the coming extreme pollution events and minimize their harmful impacts, the first and most important step is to predict their possible intensity in the future. Firstly, the generalized Pareto distribution (GPD) in extreme value theory was used to fit the extreme pollution concentrations of three main pollutants: PM₁₀, NO₂ and SO₂, from 2005 to 2010 in Changsha, China. Secondly, the prediction results were compared with actual data by a scatter plot. Four statistical indicators: E_MA (mean absolute error), E_RMS (root mean square error), I_A (index of agreement) and R² (coefficient of determination) were used to evaluate the goodness-of-fit as well. Thirdly, the return levels corresponding to different return periods were calculated by the fitted distributions. The fitting results show that the distribution of PM₁₀ and SO₂ belongs to exponential distribution with a short tail while that of the NO₂ belongs to beta distribution with a bounded tail. The scatter plot and four statistical indicators suggest that GPD agrees well with the actual data. Therefore, the fitted distribution is reliable to predict the return levels corresponding to different return periods. The predicted return levels suggest that the intensity of coming pollution events for PM₁₀ and SO₂ will be even worse in the future, which means people have to get enough preparation for them.

A full-scale experimental study of treating mustard wastewater by the integrated bioreactor with designed scale of 1 000 m³/d is conducted combined with a demonstration project. The systematical researches on the efficiency of combined operation conditions of anaerobic-aerobic and anaerobic-aerobic-flocculation as well as chemical phosphorus removal of hypersaline mustard wastewater are conducted. The optimal operation condition and parameters in pretreatment of mustard wastewater in winter (the water temperature ranges 8–15 °C) are determined: the anaerobic load is 3.0 kg (COD)/(m³·d), the average COD and phosphate concentration of the inflow are respectively 3 883 mg/L and 35.53 mg/L and the dosage of flocculent (PAC) is 400 mg/L. The anaerobic-aerobic-flocculation combined operation condition and postpositive phosphorous removal with ferrous sulfate are employed. After treatment, the COD of the effluent is 470 mg/L and the average phosphate concentration is 5.09 mg/L. The effluent could achieve the third-level of Integrated Wastewater Discharge Standard (GB 8978-1996).

To degrade the organic compounds in the electroplating wastewater, magnetic field was tentatively introduced into electrocatalytic oxidation on Ti-PbO₂ anode. The magnetic field assisted electrocatalytic oxidation can promote anion movement and the generation of active species, resulting more organic compounds to be oxidized and degraded. Oxidation parameters such as treatment time, current density and initial pH of the wastewater were systematically discussed and optimized. The mineralization of organic compounds is improved by over 15% under a magnetic density of 22 mT while the current density is 50 A/m², pH is 1.8 and the reaction time is 1.5 h. The results indicate that the magnetic field assisted electrocatalytic oxidation has considerable potential in electroplating wastewater treatment.

Combined technology of SDS-CuO/TiO₂ photocatalysis and sequencing batch reactor (SBR) were applied to treating dyestuff wastewater. Photocatalysis was carried out in a spiral up-flow type reactor as pre-treatment. SDS-CuO/TiO₂ photocatalyst was prepared by modification of nano-TiO₂ using CuO and sodium dodecyl sulfate (SDS). Results show that the SDS-CuO/TiO₂ photocatalyst contains two kinds of crystals, including TiO₂ and CuO. The band gap of this photocatalyst is 1.56 eV, indicating that it can be excited by visible light (λ<794.87 nm). And characterization also shows that there are alkyl groups on its surface. It takes 40 min to improve the biodegradability of dyestuff wastewater. Five-day biochemical oxygen demand (BOD₅) and dehydrogenase activity (DHA) of wastewater reach the maximum value when dissolved oxygen is higher than 2.97 mg/L. SBR reactor was used to treat this biodegradability improved wastewater. Chemical oxygen demand (COD) and colority decline to 72 mg/L and 20 times, respectively, when the sludge loading is 0.179 kg(COD)/[kg(MLSS)·d], dissolved oxygen is 4.09 mg/L and aeration time is 10 h.

Protoplasts from Candida tropicalis and Candida lipolytica were fused under an optimized electrofusion (electrical pulse strength 6 kV/cm, pulse duration time 40 μs and pulse times 5) and then regenerated on YEPD media for achieving new genotypes with higher chromium loading capacity. A target fusant RHJ-004 was screened out by its chromium resistance and chromium-sorbing capacity tests for further research. The comparative study of applicability shows that the fusant has better performance than its parent strains in respect of solution pH, biomass concentration and chromium loading capacity. Especially for treating low concentration Cr(VI) (≤20 mg/L), above 80% chromium is sequestered from the aqueous phase at pH 1–9. Atomic force microscopy (AFM) visualizes the distribution of chromium on the binding sites of the cells, suggesting that the altered surface structure and intracellular constitutes of the fusant associate with its increased biosorption capacity. The rapid biosorption processes of chromium follow the Langmuir model well.

The flotation tests and XPS analyses on galena, sphalerite and pyrite have been carried out in a collecting-depressing-reactivating system (hereafter referred as the CDR system). In this system, sulfide minerals were first collected and activated by the collector, and then depressed strongly by Ca(OH)₂ in the strong alkaline solution, and finally reactivated by H₂SO₄. The flotation tests of pure minerals show that in this system the flotation behaviors of sphalerite and pyrite present irreversible characteristics along with the change of pulp potential. Furthermore, through the CDR system, considerable differences in the flotabilities between galena and sphalerite/pyrite are also observed. The XPS analysis results for galena, sphalerite and pyrite in a CDR system show that in the strong alkaline solution, some of the collectors, that have been already adsorbed on the mineral surface in the collecting process, are desorbed by Ca(OH)₂. The XPS analysis results also show that in H₂SO₄ reactivating process, the surface hydroxides of galena are desorbed again by H₂SO₄ and replaced by diethyl dithiocarbamate, but those of sphalerite and pyrite are not desorbed. This flotation system may be applied to the bulk-differential flotation process of sulfur-bearing low-grade lead-zinc ores.

Two reagents including salicylhydroxamic acid (SHA) and tributyl phosphate (TBP) were tested as collectors either separately or together for electro-flotation of fine cassiterite (<10 μm). Subsequently, the flotation mechanism of the fine cassiterite was investigated by adsorbance determination, electrophoretic mobility measurements and Fourier transform infra-red (FT-IR) spectrum checking. Results of the flotation experiments show that with SHA as a collector, the collecting performance is remarkably impacted by the pulp pH value as the floatability of cassiterite varies sharply when the pH changes, and flotation with SHA gives distinct maximum at about pH 6.5. Additionally, the floatability of cassiterite is determined by using SHA and TBP as collectors. The range of pulp pH for good floatability is broadened in the presence of TBP as auxiliary collector, and the utilization of TBP improves the recovery of cassiterite modestly. Moreover, the optimum pH value for cassiterite flotation is associated with adsorbance. The results of FT-IR spectrum and the electrophoretic mobility measurements indicate that the adsorption interaction between the collectors and the cassiterite is dominantly a kind of chemical bonding in the form of one or two cycle chelate rings due to the coordination of carbonyl group, hydroxamate and P=O group to the metal tin atoms, where the oxygen atoms contained in carbonyl group, hydroxamate and P=O group of the polar groups have the stereo conditions to form five-membered rings. In addition, the adsorption interactions of SHA and TBP on the surfaces of cassiterite are also dominated by means of hydrogen bonds.

Chalcopyrite oxidation rates were examined under various conditions in the presence of Leptospirillum ferriphilum, in which the effects of different pulp content, inoculation amount, external addition of Fe³⁺ and initial pH value were studied. The bioleaching residues were investigated by X-ray diffractograms (XRD), scanning electron microscopy (SEM) and energy dispersion spectrum (EDS) analysis. The results show that low pulp concentration increases the leaching rate of copper, and external addition of Fe³⁺ is also beneficial to leaching chalcopyrite. The changes of inoculation amount and initial pH from 1.6 to 2.5 have a little effect on the final leaching rate. The results also imply that Fe³⁺ ions are important for bioleaching of chalcopyrite. At the end of bioleaching, jarosite and sulfur are observed on the surface of chalcopyrite residues by using XRD, SEM and EDS. With the passivation layer formed by jarosite and sulfur, the continuous copper extraction is effectively blocked.

Rotary kiln process for iron ore oxide pellet production is hard to detect and control. Construction of one-dimensional model of temperature field in rotary kiln was described. And the results lay a solid foundation for online control. Establishment of kiln process control expert system was presented, with maximum temperature of pellet and gas temperature at the feed end as control cores, and interval estimate as control strategy. Software was developed and put into application in a pellet plant. The results show that control guidance of this system is accurate and effective. After production application for nearly one year, the compressive strength and first grade rate of pellet are increased by 86 N and 2.54%, respectively, while FeO content is 0.05% lowered. This system can reveal detailed information of real time kiln process, and provide a powerful tool for online control of pellet production.

Carbon and oxygen isotope and dating analyses of foraminiferan in sediment cores collected from three different areas of the northern slope of the South China Sea were conducted, in order to examine the records of the gas hydrate decomposition events since the late Quaternary under the conditions of methane seepage. The results show that: 1) the δ¹³C values of the benthic foraminiferan Uvigerina spp. (size range of 0.25–0.35 mm) are from −0.212% to −0.021% and the δ¹⁸O values of the planktonic foraminiferan Globigerinoides ruber (size range of 0.25–0.35 mm) are from −0.311% to −0.060%; 2) three cores (ZD2, ZD3 and ZS5) from the bottom of a hole are aged for 11 814, 26 616 and 64 090 a corresponding to the early oxygen isotope stage (MIS) I, III and IV final period, respectively; 3) a negative-skewed layer of carbon isotope corresponds to that of MIS II (cold period), whose degree of negative bias is −0.2‰; and 4) the δ¹³C compositions of foraminiferans are similar to those of the Blake Ridge and the Gulf of Mexico sediments of the late Quaternary. According to the analysis, the reasons for these results are that the studied area is a typical area of methane seep environment in the area during MIS II due to the global sea-level fall and sea pressure decrease. Gas hydrate is decomposed and released, and a large number of light carbon isotopes of methane are released into the ocean, dissolved to inorganic carbon (DIC) pool and recorded in the foraminiferan shells. A pyrite layer developed in the negative bias layers of the foraminiferans confirms that the δ¹³C of foraminiferans is more affected by methane and less by the reduction of marine productivity and early diagenesis. The use of foraminiferan δ¹³C could accurately determine late Quaternary hydrate release events and provide evidence for both reconstructing the geological history of methane release events and exploring natural gas hydrate.

The material sources and control factors of rare earth elements (REEs) for 25 borehole bulk samples from the Late Permian Longtan Formation in Mount Huaying (borehole number: ZK10-6), Sichuan Province, South China, were investigated. All samples were determined by inductively coupled plasma mass spectrometry (ICP-MS). The chondrite-normalized distribution patterns of mudstone samples are uniform. All samples belong to the light rare earth element (LREE)-rich type and are enriched in LREEs relative to heavy rare earth elements (HREEs). The distribution curves of REEs in mudstone are highly similar to Mount Emei basalt and the three periods of REEs enrichment correspond to three Mount Emei basalt eruption cycles in Longtan period. The results indicate that REE patterns are not controlled by materials from the seawater or land plants. The predominant sources of REEs are from terrigenous material as indicated by negative Eu anomaly. So, the sources of REEs are controlled by terrigenous material, and the Mount Emei basalt is the predominant source of terrigenous material. Thus, transgression-regression is another control factor of REEs enrichment.

Finite element method was performed to investigate the influences of beam stiffness, foundation width and cushion thickness on the bearing capacity of beam foundation on underlying weak laminated clay. The comparison between numerical results and results from field test including plate-bearing test and foundation settlement observation shows reasonable agreement. According to the numerical results, the beam width, length, cross section and cushion thickness were optimized. The results show that the stresses in subgrade soil decrease greatly with increasing the cushion thickness and width of foundation. However, the foundation settlement and influencing depth of displacement also increase correspondingly under conditions of relatively thinner cushion thickness. For the foundations on underlying weak layer, increasing foundation width merely might be inadequate for improving the bearing capacity, and the appropriate width and cushion thickness depend on the response of subgrade. A comparison between rigid and flexible beams was also discussed. The influence of a flexible beam foundation on subgrade is relatively smaller under the same loading conditions, and the flexible beam foundation appears more adaptable to various subgrades. The proposed flexible beam foundation was adopted in engineering. According to the calculation results, beam width of 2.4 m and cushion thickness of 0.8 m are proposed, and a flexible beam foundation is applied in the optimized design, which is confirmed reasonable by the actual engineering.

The hybrid genetic algorithm is utilized to facilitate model parameter estimation. The tri-dimensional compression tests of soil are performed to supply experimental data for identifying nonlinear constitutive model of soil. In order to save computing time during parameter inversion, a new procedure to compute the calculated strains is presented by multi-linear simplification approach instead of finite element method (FEM). The real-coded hybrid genetic algorithm is developed by combining normal genetic algorithm with gradient-based optimization algorithm. The numerical and experimental results for conditioned soil are compared. The forecast strains based on identified nonlinear constitutive model of soil agree well with observed ones. The effectiveness and accuracy of proposed parameter estimation approach are validated.