A distributed scheduler for air traffic flow management

A system was developed to efficiently schedule aircraft into congested resources over long ranges and present that schedule as a decision support system. The scheduling system consists of a distributed network of independent schedulers, loosely coupled by sharing capacity information. This loose coupling insulates the schedules from uncertainty in long-distance estimations of arrival times, while allowing precise short-term schedules to be constructed. This ??rate profile?? mechanism allows feasible schedules to be produced over long ranges, essentially constructing precise short-range schedules that also ensure that future scheduling problems are solvable while meeting operational constraints. The system was tested operationally and demonstrated reduced airborne delay and improved coordination.     

Adaptive sliding mode control of overhead cranes with varying cable length

An overhead crane transports cargoes of various weights and volumes depending on the operation case. Friction factors characterized by damped coefficients are changeable in terms of the operating environment. In this study, an adaptive version of the sliding mode control of a crane system is developed in the case of no priori knowledge of the payload mass and damped elements. Using two inputs, namely, trolley driving force and cargo lifting force, the proposed adaptive robust controller simultaneously executes four duties, including tracking the trolley, hoisting the cargo, keeping the cargo swing small during transient state, and completely eliminating the payload angle at steady destination. Numerical simulations and experiments are conducted to investigate the quality of the proposed controller. The results show that the proposed controller works well and all system responses are asymptotically stabilized.     

On the chemo-thermo-hydro-mechanical behaviour of geological and engineered barriers

An overview of the recent findings about the chemo-hydro-mechanical behaviour of materials used for both geological and engineered barriers in nuclear waste disposal is presented, through some examples about the natural Boom Clay (BC) and compacted bentonite-based materials. For the natural BC, it was found that compression index identified from both oedometer and isotropic compression tests is similar and the compressibility of BC from the Mol site is higher than that of BC from the Essen site; the shear strength of Mol BC is also higher than that of the Essen BC, suggesting a significant effect of carbonates content; the thermal volume change is strongly overconsolidation ratio (OCR) dependent—low OCR values promote thermal contraction while high OCR values favour thermal dilation; the volume change behaviour is also strongly time dependent and this time dependent behaviour is governed by the stress level and temperature; the effect of pore-water salinity on the volume change behaviour can be significant when the smectite content is relatively high. For the bentonite-based materials, it was found that thermal contraction also occurs at low OCR values, but this is suction dependent—suction promotes thermal dilation. Under constant volume conditions, wetting results in a decrease of hydraulic conductivity, followed by an increase. This is found to be related to changes in macro-pores size—wetting induces a decrease of macro-pores size, followed by an increase due to the aggregates fissuring. The presence of technological voids can increase the hydraulic conductivity but does not influence the swelling pressure.     

Ammonia removal from aqueous solution by membrane distillation

Environmental regulation, increased pressure on water resources and rising cost for wastewater discharges make wastewater treatment for recycling an essential investment for many industries. Ammonia is a major pollutant in many industrial and agricultural wastewaters, and its elimination is essential for wastewater to be reused or meeting local discharge standards. In this study, the removal of ammonia from dilute aqueous solution has been investigated using sweep gas and vacuum membrane distillation (SGMD and VMD). Factors that affect the separation process such as feed and air flow rates, vacuum degree and feed temperature have been investigated. Overall, mass transfer coefficients (K_ov) were calculated, and the results indicated that K_ov for VMD is higher than that for SGMD under similar operation. Overall, ammonia mass transfer coefficient up to 12.06 × 10^?5 and 5.63 × 10^?5 m/s can be achieved for VMD and SGMD, respectively. The ammonia removal efficiency was enhanced by increasing sweep gas flow rate or by decreasing downstream pressure.     

Controlling the electrodeposition,morphology and structure of hydroxyapatite coating on 316L stainless steel

Hydroxyapatite (HAp) coatings were prepared on 316L stainless steel (316LSS) substrates by electrochemical deposition in the solutions containing Ca(NO₃)₂·4H₂O and NH₄H₂PO₄ at different electrolyte concentrations. Along with the effect of precursor concentration, the influence of temperature and H₂O₂ content on the morphology, structure and composition of the coating was thoroughly discussed with the help of X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra. The in vitro tests in simulated body fluids (SBF) were carried out and then the morphological and structural changes were estimated by SEM and electrochemical techniques (open circuit potential, polarization curves, Nyquist and Bode spectra measurements). Being simple and cost-effective, this method is advantageous for producing HAp implant materials with good properties/characteristics, aiming towards in vivo biomedical applications.     

Different types of MnO2 recovered from spent LiMn2O4 batteries and their application in electrochemical capacitors

Three types (λ, γ, and β) of MnO₂ have been successfully prepared from spent LiMn₂O₄ electrode materials and utilized as electrode materials for electrochemical capacitors. Experiments show that the obtained λ-MnO₂ sample has particle sizes ranging from 0.2 to 3 μm and the as-prepared β-MnO₂ and γ-MnO₂ samples both exist in nanorods with diameters of about 100 nm. The length of β-MnO₂ nanorods varies from 0.2 to 3 μm, while γ-MnO₂ nanorods have lengths of 0.2–2 μm. The main results of electrochemical tests indicate that these MnO₂ electrodes exhibit good supercapacitive performances which are dependent on their morphology and microstructure. As electrode material, λ-MnO₂ sample presents a specific capacitance of 200.55 F g^?1, which is higher than those of other two types of MnO₂. However, β-MnO₂ electrode shows superior long-term cyclic stability and rate performance to other two MnO₂ samples. These results indicate that manganese dioxides recycled from spent LiMn₂O₄ batteries show great potential in application as the active materials for electrochemical capacitors. This study could provide a novel and useful approach to the recovery and reuse of spent LiMn₂O₄ batteries.     

Efficient hydrogen production from aqueous methanol in a PEM electrolyzer with porous metal flow field: Influence of change in grain diameter and material of porous metal flow field

Previous research has shown that hydrogen production performance of a PEM methanol electrolyzer was largely improved with a porous flow field made of sintered spherical metal powder compared with a conventional groove type flow field. In this study, we experimentally investigated the effect of the change in grain diameter and material of the porous metal flow field on hydrogen production performance in a PEM methanol electrolyzer cell. The experimental results indicated that the hydrogen production performance of the electrolyzer cell was improved by reducing the grain diameter. This could be mainly attributed to the lower interfacial contact resistance by reducing the grain diameter of the porous metal flow field. For investigating the influence of material, cell performances with a stainless steel and a nickel base alloy were compared.     

粉煤灰作惰性粒子的镍复合镀层

用粉煤灰(FA)作为惰性粒子,电沉积得到复合镀层Ni/FA。粉煤灰的尺寸为3?7μm,主要成分是72%SiO2和25%Al2O3。进行电沉积的工艺条件是瓦兹镀镍液含粉煤灰的浓度为5、20、50 g/L,电流密度为2、4 A/dm2,温度为50°C,磁搅拌速度为250 r/min。采用扫描电子显微镜(SEM+EDX)、电化学测试和硬度测量来研究复合镀层Ni/FA 的形态、成分和性能。镀层中粉煤灰的含量与镀液中粉煤灰的浓度以及相关工艺参数有关。由于镀层中加入了粉煤灰从而使镀层的力学与电化学性能得到改善。复合镀层Ni/FA的硬度达HV430,而纯Ni镀层的硬度只有HV198。电化学测试表明,复合镀层Ni/FA的耐腐蚀比纯镍镀层的高。     

The effect of zeolite treatment by acids on sodium adsorption ratio of coal seam gas water

Many coal seam gas (CSG) waters contain a sodium ion concentration which is too high relative to calcium and magnesium ions for environment acceptance. Natural zeolites can be used as a cheap and effective method to control sodium adsorption ratio (SAR, which is a measure of the relative preponderance of sodium to calcium and magnesium) due to its high cation exchange capacity. In this study, a natural zeolite from Queensland was examined for its potential to treat CSG water to remove sodium ions to lower SAR and reduce the pH value. The results demonstrate that acid activated zeolite at 30%wt solid ratio can reduce the sodium content from 563.0 to 182.7 ppm; the pH from 8.74 to 6.95; and SAR from 70.3 to 18.5. Based on the results of the batch experiments, the sodium adsorption capacity of the acid-treated zeolite is three times greater than that of the untreated zeolite. Both the untreated and acid-treated zeolite samples were characterized using zeta potential, surface characterization, DTA/TG and particle size distribution in order to explain their adsorption behaviours.     

Hydrogel‐Forming Microneedle Arrays for Enhanced Transdermal Drug Delivery

Unique microneedle arrays prepared from crosslinked polymers, which contain no drug themselves, are described. They rapidly take up skin interstitial fluid upon skin insertion to form continuous, unblockable, hydrogel conduits from attached patch‐type drug reservoirs to the dermal microcirculation. Importantly, such microneedles, which can be fabricated in a wide range of patch sizes and microneedle geometries, can be easily sterilized, resist hole closure while in place, and are removed completely intact from the skin. Delivery of macromolecules is no longer limited to what can be loaded into the microneedles themselves and transdermal drug delivery is now controlled by the crosslink density of the hydrogel system rather than the stratum corneum, while electrically modulated delivery is also a unique feature. This technology has the potential to overcome the limitations of conventional microneedle designs and greatly increase the range of the type of drug that is deliverable transdermally, with ensuing benefits for industry, healthcare providers and, ultimately, patients.