Oxygen Transfer and Hydrodynamics in a Flexible Fibre Biofilm Reactor for Wastewater Treatment

A flexible fibre biofilm reactor was developed for treatment of organic wastewaters.The hydrodynamic characteristics and mass transfer coefficients of oxygen were studied and compared with those of the conventional activated sludge processes.Tracer experiments were performed to obtain the residence time distributions of the reactors.The results indicated that both reactors could be treated as mixed flow reactors.The effects of flow rates of water and air on the overall mass transfer coefficient of oxygen were investigated,and the correlations between the mass transfer coefficient and the ratio of flow rates were obtained.Compared to the conventional activated sludge reactor,the mass transfer coefficients in the flexible fibre reactor were similar to but slightly lower,and less sensitive to the variation in the ratio of flow rates.It indicated that the fibre packing in the reactor hindered the oxygen transfer to some extent.

Evaluation of Ability of Two Different Pneumatic Boxing Gloves to Reduce Delivered Impact Forces and Improve Safety

Two prototype pneumatic boxing gloves of different design were compared against conventional 10?oz (Std 10?oz) and 16?oz (Std 16?oz) gloves in terms of ability to reduce impact forces delivered to a target. One of the pneumatic gloves (SBLI) contained a sealed air bladder inflated to a pressure of 2?kPa. The other (ARLI) incorporated a bladder that allowed release of air to the external environment upon contact with a target, followed by rapid air reuptake. Each glove was placed on to a mechanical fist and dropped 10 times on to an in-floor force plate from each of nine heights ranging from 1.0 to 5.0 metres, with the 5-metre drop generating a peak pre-impact glove velocity close to the reported maximum for elite boxers. Compared to the conventional gloves, the ARLI glove substantially reduced peak impact forces at all drop heights, with the reduction exceeding 30% even at the 5-metre level. The SBLI glove was as effective as the ARLI glove in reducing peak impact forces at drop heights of up to 2.5 metres, but its performance then progressively diminished, and at drop heights of 4.0, 4.5 and 5.0 metres it produced peak force readings similar to those recorded for the Std 10?oz and Std 16?oz gloves. The superiority of the ARLI glove was even more evident in relation to peak rate of force development, with reductions relative to the Std 10?oz glove being ~60% at drop heights up to 3.5 metres and still ~47% at 5 metres. Peak rate of force development for the SBLI glove exceeded that for the ARLI glove for all drop heights of 2.0 metres and above, and at 4.0, 4.5 and 5.0 metres it was higher than the readings for the Std 10 oz and 16?oz gloves. The protective effect of the ARLI glove was?associated with an increase in impact compliance and prolongation of contact time between glove and target. It is concluded that a pneumatic boxing glove that provides for air exchange with the external environment can greatly reduce impact magnitudes across the whole range of pre-impact glove velocities likely to be encountered in boxing, thereby mitigating risks associated with the sport. While acceptance of the gloves by the boxing community is uncertain, opportunity may exist for almost immediate uptake in modified boxing programs.

Numerical modeling of solute transport in deformable unsaturated layered soil

The effect of soil stratification was studied through numerical investigation based on the coupled model of solute transport in deformable unsaturated soil. The theoretical model implied two-way coupled excess pore pressure and soil deformation based on Biot's consolidation theory as well as a one-way coupled volatile pollutant concentration field developed from the advection-diffusion theory. Embedded in the model, the degree of saturation, fluid compressibility, self-weight of the soil matrix, porosity variance, longitudinal dispersion, and linear sorption were computed. Based on simulation results of a proposed three-layer landfill model using the finite element method, the multi-layer effects are discussed with regard to the hydraulic conductivity, shear modulus, degree of saturation, molecular diffusion coefficient, and thickness of each layer. Generally speaking, contaminants spread faster in a stratified field with a soft and highly permeable top layer; soil parameters of the top layer are more critical than the lower layers but controlling soil thicknesses will alter the results. This numerical investigation showed noticeable impacts of stratified soil properties on solute migration results, demonstrating the importance of correctly modeling layered soil instead of simply assuming the averaged properties across the soil profile.

The fabrication and characterization of 4H-SiC power UMOSFETs

The fabrication of 4H-SiC vertical trench-gate metal-oxide-semiconductor field-effect transistors（UMOSFETs） is reported in this paper.The device has a 15-μm thick drift layer with 3×10^15 cm^-3 N-type doping concentration and a 3.1μm channel length.The measured on-state source-drain current density is 65.4 A/cm^2 at Vg = 40 V and VDS = 15 V.The measured threshold voltage（Vth） is 5.5 V by linear extrapolation from the transfer characteristics.A specific on-resistance（Rsp-on） is 181 mΩ·cm^2 at Vg = 40 V and a blocking voltage（BV） is 880 V（IDS = 100 μA@880V） at Vg = 0 V.

Comparative Analysis of Internal and External-Hex Crown Connection Systems - A Finite Element Study

The abutment connection with the crown is fundamental to the structural stability of the implant system and to the prevention of mechanical exertion that can compromise the success of the implant treatment. The aim of this study is to clarify the difference in the stress distribution patterns between implants with internal and external-hex connections with the crown using the Finite Element Method (FEM). Material and Methods: The internal and external-hex connections of the Neoss and 3i implant systems respectively, are considered. The geometrical properties of the implant systems are modeled using three-dimensional (3D) brick elements. Loading conditions include a masticatory force of 200, 500 and 1000N applied to the occlusal surface of the crown along with an abutment screw torque of 110, 320 and 550Nmm. The von Mises stress distributions in the crown are examined for all loading conditions. Assumptions made in the modeling include: 1. half of the implant system is modeled and symmetrical boundary conditions applied;2. temperature sensitive elements are used to replicate the torque within the abutment screw. Results: The connection type strongly influences the resulting stress characteristics within the crown. The magnitude of stress produced by the internal-hex implant system is generally lower than that of the external-hex system. The internal-hex system held an advantage by including the use of an abutment between the abutment screw and the crown. Conclusions: The geometrical design of the external-hex system tends to induce stress concentrations in the crown at a distance of 2.89mm from the apex. At this location the torque applied to the abutment screw also affects the stresses, so that the compressive stresses on the right hand side of the crown are increased. The internal-hex system has reduced stress concentrations in the crown. However, because the torque is transferred through the abutment screw to the abutment contact, changing the torque has greater effect on this hex system than the masticatory force. Overall the masticatory force is more influential on the stress within the crown for the external-hex system and the torque is more influential on the internal-hex system.

Reflections on Long-Term Development and Use of Automated Scoring Technology in a Sport (Modified Boxing) Context

Technology is being increasingly used to aid judging in sport, but its employment as the primary means of scoring is rare. We have developed and implemented a fully automated scoring system in the context of a modified, low-risk form of boxing. The system, which requires contestants to wear vests and gloves incorporating sensor fabrics, has been used in multiple settings over the past five years. During that period, it has undergone progressive iteration guided by action research methodology. Here, we summarise that iteration, reflect on present status and identify possible future directions. We have found that concept of automated scoring has wide appeal, and the wearable technology is almost universally considered comfortable. Nevertheless, some issues remain to be addressed. Use of the technology requires considerable prior and subsequent commitment of time. Apparently valid contacts occasionally fail to score. Causative factors include the configuration of electrical circuitry in the vests and deterioration of that circuitry with repeated vest use and washing. Also, false positive scores are sometimes generated by vest self-shorting and effects of sweat. Many contestants adopt unorthodox styles aimed at exploiting the characteristics of the automated scoring methodology, affecting the aesthetics of the modified sport. There is an expectation that technologically-based scoring should have much greater accuracy than human judging, and should be essentially fail-proof. Disillusionment can occur in?situations where this expectation is not met. We have identified potential?solutions to all the existing issues, with some now being actively explored. Continuation of the quest seems justified by popular dissatisfaction with subjective human judging of boxing and other sports, but we have come to realise that purely technological judging can introduce unforeseen complexities. Our observations could be relevant to various sports interested in the notion of technological judging.

深埋储层水对吡咯类含氮化合物的蚀变作用

深埋地质体中广泛分布着储层水,在一定的温度和压力下,水可能会与吡咯类含氮化合物发生一定程度的有机氮—无机氧化学交换。对吡咯与水反应体系的热力学问题进行了探讨,发现当温度高于373.15K时,热力学上吡咯与水就可能发生反应。随着温度升高,反应过程正向进行程度增大,即从热力学的角度看,升高温度对反应有利。利用高温高压模拟装置对吡咯与水反应体系进行了初步的模拟实验研究,通过气相色谱和傅立叶变换红外光谱等分析手段对实验结果进行了进一步验证。结果表明,吡咯和水能够发生化学反应,主要生成呋喃和氨气。研究结果为探讨影响深埋储层中吡咯类含氮化合物保存与分布的有机—无机相互作用机制,提供了热模拟实验依据。

OPTIMIZATION OF AGGREGATE TESTING USING POLYNOMIAL REGRESSION

Recycled Aggregate(RA)has only been used as sub-grade applications,roadwork and unbound materials because it is believed that RA has lower strength and poorer quality than normal aggregate.This paper assesses RA quality by propos-ing a new testing procedure.The new procedure is developed by using correlation information among the standard twenty three tests commonly employed in the construction industry.Samples of RA from ten demolition sites were ob-tained with service life ranging from ten to forty years.One additional set of samples was specifically collected from the Tuen Mun Area 38 Recycling Plant,Hong Kong for testing.The characteristics of these eleven sets of samples were then compared with normal aggregate samples.A Vandermonde matrix for interpolation polynomials coefficient estimation is employed to yield detailed mathematical relationships between results of two particular tests,from that redundant tests can be identified.Different orders of interpolation polynomials are used for comparison,hence the best-fit equations with lowestfitting errors from different orders of polynomials can be found.This paper shows that four out of twenty three tests are required in the new testing procedure.

A FEASIBILITY STUDY OF IMPLEMENTING MATERIAL MANAGEMENT IN CONSTRUCTION: UNITED KINGDOM AND HONG KONG EMPIRICAL STUDIES

Construction organizations have a common practice to purchase and to deliver required materials to construction sitesabout one month before activities start. This leads to uneconomical inventory on site and contractors’ warehouses. Thispaper investigates the feasibility in implementing material management in construction. United Kingdom and HongKong are selected for the investigation as one has a long implementation period and another one is just implementingmaterial management as noted by interviewed contractors. Questionnaires and structured interviews are conducted.It is found that United Kingdom construction industry benefi ts are more signifi cant than that in Hong Kong. Thiscan stimulate interests in implementing material management in Hong Kong. Respondents from Hong Kong claimedthat their companies will be willing to implement material management where practicable. This study can also helpcountries currently implementing material management. From that, waste generation can be reduced and a greenconstruction environment can be achieved. Recommendations to improve the implementation are also discussed.

PREDICTING ENVIRONMENTAL PERFORMANCE OF CONSTRUCTION PROJECTS BY USING LEAST-SQUARES FITTING METHOD AND ROBUST METHOD

Recently,an Environmental Management System(EMS)has been used to promote effective environmental protection.Environmental Performance Assessment(EPA)is a critical tool of the EMS in checking,reviewing,monitoring and evaluating environmental performance of organizations.To implement EPA,the relations between Environmental Operational Indicators(EOIs)used in EPA and Environmental Performance Indicators(EPIs)are required,which,however,are lacking in the construction industry.This paper attempts to develop a series of EOIs and EPIs of individual construction projects for EPA and to measure their relations by using least-squares fitting and robust fitting methods.The results show that the defined EOIs correlate strongly with EPIs.Therefore,EPA can be used to identify areas for continuous improvement,and also can provide an early indication of the environmental performance for an organization.

Case Study: Finding Better Solutions for Municipal Solid Waste Management in a Semi Local Authority in Sri Lanka

This case study investigates better and sustainable waste management for a given area in Sri Lanka. A questionnaire and field surveys were performed in a small local authority adjacent to Colombo, the capital city. Composting for organic waste and incineration for non-compostable waste were found to be important treatment methods for solid-waste management. The reduction of solid waste is a critical process for sustainable management. Currently, people in the area do not have much interest in waste recycling to decrease the cost of solid-waste management. It was therefore concluded that raising people’s awareness would play an important role in the reduction of solid waste. A suitable waste-management plan needs to be made for each community and area. The situation and conditions of every area is different, therefore each community needs to make an effort to find its own better and sustainable solid-waste management process.

Coupling model for waves propagating over a porous seabed

The wave-seabed interaction issue is of great importance for the design of foundation around marine infrastructures. Most previous investigations for such a problem have been limited to uncoupled or one- way coupled methods connecting two separated wave and seabed sub models with the continuity of pressures at the seabed surface. In this study, a strongly coupled model was proposed to realize both wave and seabed processes in a same program and to calculate the wave fields and seabed response simultaneously. The information between wave fields and seabed fields were strongly shared and thus results in a more profound investigation of the mechanism of the wave-seabed interaction. In this letter, the wave and seabed models were validated with previous experimental tests. Then, a set of application of present model were discussed in prediction of the wave-induced seabed response. Numerical results show the wave-induced liquefaction area of coupled model is smaller than that of uncoupled model.

澳大利亚低交通量道路就地稳定技术的成本效益分析

长期以来,澳大利亚和世界很多地方的工程师都利用就地稳定技术进行路面施工和修复。因其成本低,很多路面管理者也都会优先考虑这一技术。本文提出了一种评估工程和路面修复直接成本的方法,可以帮助决策者在路面养护时选择不同的施工技术。文章还对水泥就地稳定技术和其他路面修复方法进行了成本效益分析,并比较了再生技术对路面结构的影响。稳定后的路面厚度应符合澳大利亚稳定行业协会颁布的《路面设计暂行规定》(AustStab,2006)。文章最后还提到了澳大利亚(2004)新颁布的《水泥路面力学设计细则》。

Design and Experimentation of a Novel Separable Vibration-Assisted Stage

In this paper,a novel,separable two-degrees-of-freedom stage with high-precision motion and resolution is proposed for the application of vibration-assisted micromilling.A separable design was realized on the basis of the detachable structure of the platform.Flexible stages with different dimensions and types can be utilized in the devices.A circular-fillet hinge is selected as the flexible unit with a parallel structure to realize output decoupling and reduce the coupling error between the two vibration directions.Analytical modeling is conducted to explore the static and dynamic characteristics of the stage.Results reveal a good agreement with the finite element simulation result.A series of experiments were conducted to assess the static and dynamic performances of the flexible stage,encompassing tests such as amplitude response,motion trajectory,and coupling trajectory.The results of these tests revealed that the designed vibration-assisted system exhibits precise movement capabilities.

A novel mathematical template for developing fDOM probe fluorescence signal correction models for freshwaters

The reliable application of field deployable fluorescent dissolved organic matter(fDOM)probes is hindered by several influencing factors which need to be compensated.This manuscript describes the corrections of temperature,pH,turbidity and inner filter effect on fluorescence signal of a commercial fDOM probe(fDOMs).For this,Australian waters with wide ranging qualities were selected,e.g.dissolved organic carbon(DOC)ranging from∼1 to∼30 mg/L,specific UV absorbance at 254 nm from∼1 to∼6 L/m/mg and turbidity from∼1 to∼350 FNU.Laboratory-based model calibration experiments(MCEs)were performed.A model template was developed and used for the development of the correction models.For each factor,data generated through MCEs were used to determine model coefficient(α)values by fitting the generated model to the experimental data.Four discrete factor models were generated by determination of a factor-specificαvalue.Theαvalues derived for each water of the MCEs subset were consistent for each factor model.This indicated generic nature of the fourαvalues across wide-ranging water qualities.High correlation between fDOMs and DOC were achieved after applying the four-factor compensation models to new data(r,0.96,p<0.05).Also,average biases(and%)between DOC predicted through fDOMs and actual DOC were decreased by applying the four-factor compensationmodel(from3.54(60.9%)to 1.28(16.7%)mg/L DOC).These correction models were incorporated into a Mi-crosoft EXCEL-based software termed EXOf-Correct for ready-to-use applications.

Cyclic strength of sand under a nonstandard elliptical rotation stress path induced by wave loading

The principal stress rotation is one of the most important features of the stress state in a seabed subjected to wave loading. Most prior investigations focused their attention on the cyclic behaviour of soil deposits under the circular rotation stress path based on the analytical solutions for a seabed of infinite thickness. In this paper, the nonstandard elliptical, i.e., non-circular, rotation stress path is shown to be a more common state in the soil sediments of a finite seabed with an alternating changeover in stress due to a travelling regular wave. Then an experimental investigation in a hollow cylinder triaxial-torsional apparatus is conducted into the effect of the nonstandard elliptical stress path on the cyclic strength. A special attention is placed on the difference between the circular rotation stress path and the elliptical rotation stress path. The results and observations show that the shear characteristics for the circular rotation stress path in the literature are not applicable for analyzing the cyclic strength of sand in a finite seabed, and also indicate that due to the influence of three parameters about the size and the shape of a nonstandard ellipse, the cyclic strength under a nonstandard elliptical rotation stress path is evidently more complex and diversified as compared with that under a circular rotation stress path. Especially the influence of the initial phase difference on the cyclic strength is significant.

Spatial–temporal distribution and potential ecological risk assessment of nonylphenol and octylphenol in riverine outlets of Pearl River Delta, China

The aquatic environments of the Pearl River Delta in Southern China are subjected to contamination with various industrial chemicals from local industries. In this paper, the occurrence, seasonal variation and spatial distribution of alkylphenol octylphenol （OP） and nonylphenol （NP） in fiver surface water and sediments in the runoff outlets of the Pearl River Delta were investigated. NP and OP were detected in all water and sediment samples and their mean concentrations in surface water during the dry season ranged from 810 to 3366 ng/L and 85.5 to 581 ng/L, respectively, and those in sediments ranged from 14.2 to 95.2 ng/g dw and 0.4 to 3.0 ng/g dw, respectively. In surface water, much higher concentrations were detected in the dry season than those in the wet season. In sediments, the concentrations in the dry season were also mostly higher. High concentrations of NP and OP were found in Humen outlet, likely due to high levels of domestic and industrial wastewater discharges. An ecological risk assessment with the use of hazard quotient （HQ） was also carried out and the HQvalues ranged from 3.6 × 10^-5 to 35 and 64% of samples gave a HQ 〉 1, indicating that the current levels of NP and OP pose a significant risk to the relevant aquatic organisms in the region.

Combined zero valent iron and hydrogen peroxide conditioning significantly enhances the dewaterability of anaerobic digestate

The importance of enhancing sludge dewaterability is increasing due to the considerable impact of excess sludge volume on disposal costs and on overall sludge management. This study presents an innovative approach to enhance dewaterability of anaerobic digestate（AD） harvested from a wastewater treatment plant. The combination of zero valent iron（ZVI, 0–4.0 g/g total solids（TS）） and hydrogen peroxide（HP, 0–90 mg/g TS） under pH 3.0 significantly enhanced the AD dewaterability. The largest enhancement of AD dewaterability was achieved at 18 mg HP/g TS and 2.0 g ZVI/g TS, with the capillary suction time reduced by up to 90%. Economic analysis suggested that the proposed HP and ZVI treatment has more economic benefits in comparison with the classical Fenton reaction process. The destruction of extracellular polymeric substances and cells as well as the decrease of particle size were supposed to contribute to the enhanced AD dewaterability by HP ＋ ZVI conditioning.

Simulation Analyses of Two On-Ramp Lane Arrangements

Ramps are vital pieces of infrastructure connecting city traffic networks to freeways.The performance of a ramp is to some extent determined by the on-ramp lane arrangement.In this paper,our primary aim is to evaluate the performance in terms of travel time and vehicle emissions for two on-ramp lane arrangements:added lane and zip merging.We estimate the travel time and CO_(2) emissions on the basis of the speed,and acceleration of vehicles in accordance with the improved comprehensive modal emission model(CMEM),and then analyse the impacts of traffic volume and heavy goods vehicles(HGVs)on travel time and emissions.The impacts of main road traffic flow on travel time and emissions for the two on-ramp lane arrangements are analysed under scenarios with traffic volumes of 800,1000,1200,1400,1600 and 1800 vehs/h/lane.Meanwhile,the relationships between travel time,emissions and various proportions of HGVs(2%,4%,6%,8%and 10%)for both on-ramp lane arrangements are evaluated as well.We eventually present emission contour charts for the two onramp lane arrangements based on the possible combinations of traffic volumes and HGV percentages.