Search

Lasers are used to cut different materials also textiles. Laser cutting is highly accurate and can easily and precisely create complex shapes, it can also ensure very high productivity. The laser cutting process creates unwanted by--products -- a variety of dust, smoke, and aerosols which are generated melting and evaporating cut textile materials. The by--products have to be extracted, filtered and discharged into the ambient air to ensure safe work process and environmental protection. Several parts of a laser cutting machinery are responsible for extraction gases and solid particulates: cutting gas, a cutting surface, an extraction system and filters. Cutting gas drives out the debris and molten material from a cut material kerf. By help of an extraction system the smoke particles and soiling are drawn away above and below the cut material. The filter system separates and removes coarse and fine dust particles and hazardous substances. [ABSTRACT FROM AUTHOR]

The distributed global velocity-free attitude coordination control problem for multiple formation spacecraft without unwinding phenomenon and with disturbance is investigated in this paper. Initially, a fixed-time observer is constructed to estimate the states of the virtual leader in fixed time. For the formation spacecraft with attitude-only measurements, a filter system is developed. To estimate the disturbance, a fixed-time extended state observer is proposed. With the application of the fixed-time observers and the filter system, a distributed global velocity-free attitude coordination controller is designed to grantee that the leader with time-varying trajectory can be tracked coordinately by the formation spacecraft, where the unwinding problem of the spacecraft can be avoided. In addition, a distributed velocity-free attitude coordination controller on the basis of the fixed-time extended state observer is designed to compensate the effect of the lump disturbance. Finally, the effectiveness of the proposed controller is demonstrated by numerical simulation. [ABSTRACT FROM AUTHOR]

Considering attitude-only measurements, physical limitations of actuator and state-independent observer time, a distributed velocity-free attitude coordination control problem for multiple formation spacecraft with torque saturation is studied in this work. Initially, aiming at speeding up the convergence rate and realizing the maximum value of the convergence time without requiring prior knowledge of the initial system state values, a fixed-time observer is constructed to estimate the desired time-varying states in fixed time. Then, a filter system is developed for the spacecraft with attitude-only measurements. With the application of the fixed-time observers and the filter systems, a distributed velocity-free attitude coordination controller with torque constraint is designed to grantee that the leader with desired state trajectory can be tracked coordinately by the formation spacecraft. Finally, the performance of the proposed controller is demonstrated by simulation results. [ABSTRACT FROM AUTHOR]

The surface structure development of the in situ‐formed oxide layer on carbon‐bonded alumina refractory samples immersed in liquid 42CrMo4 steel at a temperature of 1650 °C is studied. The surface morphology is characterized using areal parameters such as the developed interfacial area ratio Sdr, the texture aspect ration Str, the arithmetic mean peak curvature Spc, the density of peaks Spd, and the maximum height Sz defined in ISO 25178‐2:2012 and on the basis of own defined parameters using laser‐optical measured line profiles of the surface's height. The development of the surface morphology is found to be independent of the oxygen content of the steel melt at immersion time. The formed crystal structures are based on alumina and an (Al, Fe, Mg, Mn)‐containing spinel. The spinel's lattice parameters are found to vary between 8.0367 and 8.1194 Å corresponding to oxygen contents of the steel melt between 30 and 85 ppm. [ABSTRACT FROM AUTHOR]

Organic matter and nutrient in pig manure were treated using an integrated filter system. The influent flowed into an anaerobic filter (AF), and the AF effluent was polished in a biological aerated filter (BAF). The filter system was operated with recirculation ratios of 1-3. The filter system was operated with two recirculation methods. When a filter system was operated under bottom recirculation conditions, the nitrated effluent from the BAF was mingled with the influent in the AF. For upper recirculation conditions, the nitrated effluent from the BAF was injected into a height of 36% from the bottom in the AF. Removal of organic matter and nitrogen under upper recirculation conditions was greater than those under bottom recirculation conditions. The average chemical oxygen demand and solids removals were over 99 and over 97% under upper recirculation conditions. Total nitrogen and total phosphorus removals were over 77 and over 69% at recirculation 3 under upper recirculation conditions. [ABSTRACT FROM AUTHOR]

Urban stormwater runoff is contaminated by nutrients that wash off of roadways, parking lots and lawns during storms. In-ground permeable filter systems that consist of carefully selected filter material have the potential to remove these nutrients from the run-off. In this paper, four filter materials, calcite, zeolite, sand and iron filings, were investigated using laboratory batch tests to evaluate their efficiency in the removal of nitrate and phosphate from the simulated stormwater at different initial concentrations under the same 24-h exposure time period. The range of removal for nitrate was from 39 % to 65 % for calcite, from 42 % to 77 % for zeolite, from 40 % to 70 % for sand, and from 74 % to 100 % for iron filings. The removal of phosphate ranged from 35 % to 41 % for calcite, 59 % to 100 % for zeolite, 49 % to 100 % for sand, and 73 % to 100 % for iron filings. The removal of nitrate is mainly attributed to electrostatic adsorption, except when iron filings were used as a filter material where additional processes such as electrochemical reduction, ligand complexation and precipitation may have contributed to the higher nitrate removal. Phosphate removal is also attributed to electrostatic adsorption in all filter materials; however, at higher phosphate concentrations, the precipitation process may be the dominant process for all of the filter materials except calcite. The Langmuir and Freundlich isotherms fitted the observed nonlinear adsorption results, but the mechanism of removal of phosphate changed from adsorption to precipitation at concentrations higher than 1 mg/l in zeolite, sand, and iron filings; therefore, the adsorption models are valid below this concentration limit. A typical application of these batch adsorption test results is presented in the design of a field in-ground permeable filter system. [ABSTRACT FROM AUTHOR]

Oil spill incidents are hazardous and have prolonged damage to the marine environment. Management and spill clean-up procedures are practical and rapid, with several shortcomings. Coco peat (CP) and coco fibre (CF) are refined from coconut waste, and their abundance makes them desirable for diesel spillage treatment. Using a filter-based system, the selectivity of coco peat sorbent was tested using CP, CF and peat-fibre mix (CPM). CP exhibited maximal diesel sorption capacity with minimal seawater uptake, thus being selected for further optimisation analysis. The heat treatment considerably improved the sorption capacity and efficiency of diesel absorbed by CP, as supported by FTIR and VPSEM–EDX analysis. Conventional one-factor-at-a-time (OFAT) examined the performance of diesel sorption by CP under varying parameters, namely temperature, time of heating, packing density and diesel concentration. The significant factors were statistically evaluated using response surface methodology (RSM) via Plackett–Burman design (PB) and central composite design (CCD). Three significant (p < 0.05) factors (time, packing density and diesel concentration) were identified by PB and further analysed for interactions among the parameters. CCD predicted efficiency of diesel absorbed at 59.92% (71.90 mL) (initial diesel concentration of 30% v/v) and the experimental model validated the design with 59.17% (71.00 mL) diesel sorbed at the optimised conditions of 14.1 min of heating (200 °C) with packing density of 0.08 g/cm3 and 30% (v/v) of diesel concentration. The performance of CP in RSM (59.17%) was better than that in OFAT (58.33%). The discoveries imply that natural sorbent materials such as CP in oil spill clean-up operations can be advantageous and environmentally feasible. This study also demonstrated the diesel-filter system as a pilot study for the prospective up-scale application of oil spills. [ABSTRACT FROM AUTHOR]

Fluidity of two commercial eutectic alloy liquids, grey cast iron and Al–Si alloy, was investigated. Effects of pouring temperature, modulus of the fluidity channel and incorporation of a filtering system were evaluated. Graphs of fluidity show a linear relationship between fluidity and superheat, as well as fluidity and modulus squared, in both alloys. Comparison of fluidity results indicates that fluidity of Al–12.5%Si alloy is nearly double that of cast iron. The lower fluidity of cast iron liquid may be due to its higher rate of heat loss by radiation. The results of this investigation were compared with those of previous investigators. Although the height of sprue in this work is higher than the common fluidity tests, the results of unfiltered fluidity tests from this work show a similar, but possibly slightly lower, fluidity, probably as a result of additional bulk turbulence in the melt that effectively enhances viscosity. In contrast, when a filter system is employed before the fluidity channel, provided sufficient superheat is available to preheat the filter, the fluidity is increased over that indicated by conventional tests. [ABSTRACT FROM AUTHOR]

Liquid cast iron (carbon equivalent, CE = 4.3%) and Al-12.5Si were poured down a 500 mm tall sprue and cast in a straight fluidity test channel, with and without a filter system. Different arrangements of filter and bubble trap were compared to assess their effectiveness. The filling sequence was recorded on videotape by the use of real time x-ray radiography. Measurements were made of the speed of the metal and the distance to which it flowed in the fluidity casting. A critical finding was that the soundness of samples revealed a relationship with the velocity of the melt; the lower the velocity, the fewer the defects. The final design of a filtering system seems to require a mechanism for the detrainment of bubbles and the reduction in velocity of the melt from over 2 m s-1 to 0.4–0.8 m s-1. In consequence, the fluidity of the melt is reduced, but the internal quality of the casting improved from being unacceptably impaired by entrained bubbles to being substantially free from such defects. [ABSTRACT FROM AUTHOR]

FILTER is an innovative, CSIRO developed system for treating effluent using high rate land application and subsequent effluent recapture via a closely spaced, subsurface drainage network. We report on the summer performance of a FILTER system established in a subtropical environment on a relatively impermeable swelling clay soil underlain by a deep regional water table. Using secondary treated sewage effluent,the FILTER system produced effluent of tertiary nutrient standards (

The treatment of synthetic diary wastewater was carried out using cross flow medium trickling filter of specific surface area 243 m2/m3. The operating variables in this study were hydraulic and organic loading rates. The hydraulic loadings employed in this study were 5, 9, 13 and 17 m3/m2.d for the influent COD concentrations of 427 to 1384 mg/l. It was observed thatthe relationship between organic removal rate and organic loading rate showed two regions of linear behaviour with the point of inflection at an organic loading rate of 26 g COD/m2.d. Kornegay model was used to evaluate the kinetic coefficients for the system. Theresults were found to be satisfactory. [ABSTRACT FROM AUTHOR]