Teacher Professionalism.

Is teaching a profession? This article compares teachers with other professionals, such as medical doctors or lawyers, in professional knowledge, autonomy, and commitment to the welfare of the clientele. The implications for teacher professionalism include establishment of national/state standards for professional teachers, increased autonomy in teacher education, salary increase, and opportunities for promotion. However, there still remains a question of whether there will be a genuine improvement in the quality of education with “professional” teachers

In-situ and laboratory investigation of modified drilling waste materials applied on base-course construction

Abstract This study focuses on in-situ and laboratory evaluation of modified drilling waste materials (MDWMs) applied on base course construction. Cement treated drilling waste materials have been used on a limited basis for full-depth base repair on Texas Department of Transportation (TxDOT) low volume roads. A road inspection was made of full-scale county roads that were constructed with the MDWMs. Field test results measured by the falling weight deflectomer (FWD) showed reasonable in-situ strengths. The MDWM section had stiffness values similar to those typically observed for newly constructed flexible bases. The old, in-service flexible base adjacent to the MDWM section exhibited values half those of the MDWMs. Cores removed from the field also had significantly higher strength values than the lab-molded samples. Moreover, the other non-TxDOT low volume county roads using MDWMs exhibited good field performance. From this observation, it is concluded that this material clearly has some unique engineering properties which has the ability to gain strength with time though weak initially and there is the potential applicability used in the low volume roadway

Evaluating feasibility of modified drilling waste materials in flexible base course construction

The study focuses on the evaluation of the engineering properties of modified drilling waste materials (MDWMs) as base course materials in roadway construction. This goal was accomplished by two main laboratory test evaluations of the MDWMs which are the basic material characterization and the performance evaluation of base course material

Automated Flight Routing Using Stochastic Dynamic Programming

Airspace capacity reduction due to convective weather impedes air traffic flows and causes traffic congestion. This study presents an algorithm that reroutes flights in the presence of winds, enroute convective weather, and congested airspace based on stochastic dynamic programming. A stochastic disturbance model incorporates into the reroute design process the capacity uncertainty. A trajectory-based airspace demand model is employed for calculating current and future airspace demand. The optimal routes minimize the total expected traveling time, weather incursion, and induced congestion costs. They are compared to weather-avoidance routes calculated using deterministic dynamic programming. The stochastic reroutes have smaller deviation probability than the deterministic counterpart when both reroutes have similar total flight distance. The stochastic rerouting algorithm takes into account all convective weather fields with all severity levels while the deterministic algorithm only accounts for convective weather systems exceeding a specified level of severity. When the stochastic reroutes are compared to the actual flight routes, they have similar total flight time, and both have about 1% of travel time crossing congested enroute sectors on average. The actual flight routes induce slightly less traffic congestion than the stochastic reroutes but intercept more severe convective weather

Effect of pre-treatment on fouling propensity of feed as depicted by the modified fouling index (MFI) and cross-flow sampler-modified fouling index (CFS-MFI)

The effectiveness of different pretreatment on the fouling propensity of the feed was studied using synthetic wastewater. The fouling potential of the feed was characterized by the standard modified fouling index (MFI) and cross-flow sampler modified fouling index (CFS-MFI). In CFS-MFI, a cross-flow sampler was used to simulate the condition of a cross-flow filtration. The results indicated that the pretreatment such as flocculation with an optimum dose of 68 mg/l FeCl3 substantially reduced the fouling propensity of the feed. The standard MFI of flocculated wastewater was reduced by around 99% compared to that of the untreated wastewater. Similarly, the adsorption with powdered activated carbon (PAC) of 1 g/l reduced the standard MFI value to more than 99% compared to that of the untreated wastewater. The CFS-MFI values were lower than the standard MFI values for both treated and untreated wastewater, suggesting that the standard MFI was overestimated. The overestimation of the standard MFI compared to that of the CFS-MFI value was more than 99%. The effect of molecular weight distribution (MWD) of the foulants in the wastewater on the fouling propensity of the feed was investigated. The MWD was correlated with the MFI and CFS-MFI indices. It yielded useful insights in understanding the effect of MW on MFI and CFS-MFI and fouling propensity of the feed. © 2009 Elsevier B.V. All rights reserved

Optimizing Aircraft Trajectories with Multiple Cruise Altitudes in the Presence of Winds

This study develops a trajectory optimization algorithm for approximately minimizing aircraft travel time and fuel burn by combining a method for computing minimum-time routes in winds on multiple horizontal planes, and an aircraft fuel burn model for generating fuel-optimal vertical profiles. It is applied to assess the potential benefits of flying user-preferred routes for commercial cargo flights operating between Anchorage, Alaska and major airports in Asia and the contiguous United States. Flying wind optimal trajectories with a fuel-optimal vertical profile reduces average fuel burn of international flights cruising at a single altitude by 1-3 percent. The potential fuel savings of performing en-route step climbs are not significant for many shorter domestic cargo flights that have only one step climb. Wind-optimal trajectories reduce fuel burn and travel time relative to the flight plan route by up to 3 percent for the domestic cargo flights. However, for trans-oceanic traffic, the fuel burn savings could be as much as 10 percent. The actual savings in operations will vary from the simulation results due to differences in the aircraft models and user defined cost indices. In general, the savings are proportional to trip length, and depend on the en-route wind conditions and aircraft types

Recent advances in osmotic energy generation via pressure-retarded osmosis (PRO): A review

© 2015 by the authors. Global energy consumption has been highly dependent on fossil fuels which cause severe climate change and, therefore, the exploration of new technologies to produce effective renewable energy plays an important role in the world. Pressure-retarded osmosis (PRO) is one of the promising candidates to reduce the reliance on fossil fuels by harnessing energy from the salinity gradient between seawater and fresh water. In PRO, water is transported though a semi-permeable membrane from a low-concentrated feed solution to a high-concentrated draw solution. The increased volumetric water flow then runs a hydro-turbine to generate power. PRO technology has rapidly improved in recent years; however, the commercial-scale PRO plant is yet to be developed. In this context, recent developments on the PRO process are reviewed in terms of mathematical models, membrane modules, process designs, numerical works, and fouling and cleaning. In addition, the research requirements to accelerate PRO commercialization are discussed. It is expected that this article can help comprehensively understand the PRO process and thereby provide essential information to activate further research and development

Assessment of pretreatment to microfiltration for desalination in terms of fouling index and molecular weight distribution

In this study, different processes such as flocculation with ferric chloride (FeCl3) and deep bed filtration (sand filtration and dual media filtration) as a pre-treatment to microfiltration (MF) were used for seawater desalination. The performance of these pre-treatments was determined in terms of silt density index (SDI) and modified fouling index (MFI) and flux decline in MF. Flux decline of MF with seawater was 45% without any pre-treatment, 42% after pre-treatment of FeCl3 flocculation, 24% after pre-treatment of sand filtration with in-line coagulation and 22% after pre-treatment of dual media filtration (sand and anthracite), respectively. MFI and SDI also indicated that deep bed filtration with in-line flocculation was better pre-treatment than flocculation alone. Detailed molecular weight distribution (MWD) of seawater organic matter was examined after different pretreatments. MWD of the initial seawater mainly ranged from 1510 Da to 130 Da. Deep bed filtration with in-line flocculation removed relatively large molecular weight of organic matter (1510-1180 Da), while the small molecular weights (less than 530 Da) were not removed. © 2009 Elsevier B.V. All rights reserved

Role of various physical and chemical techniques for hollow fibre forward osmosis membrane cleaning

© 2015 Balaban Desalination Publications. All rights reserved. Fouling is an inevitable phenomenon with most of the water treatment systems. Similar to RO, NF and other membrane-based systems, fouling also seriously affects the performance of low-cost forward-osmosis (FO) systems and disturbs the overall efficiency of these systems, and various cleaning practices have been evaluated to restore their designed performances. This study evaluates the performance of various physical and chemical cleaning techniques for hollow fibre forward-osmosis (HFFO) membrane. HFFO membrane was subjected to various fouling conditions using different brackish groundwater qualities and model organic foulants such as alginate, humic acid and bovine serum albumin. Results indicated that physical cleaning affects differently the flux restoration according to the type of foulants (i.e. inorganic or organic) and the crossflow rates play an important role in membrane cleaning in both membrane orientation. The higher cross flow Re values at any particular area seem important for the cleaning. With hydraulic flushing, the flux performances of HFFO were recovered fully when operated in AL-FS orientation, as high shear force helps to detach all scaling layers from the surface; however, the lower shear force did not fully restore the flux for the FS membrane in AL-DS orientation. Chemical cleaning was planned for the fouled HFFO membrane, and HCl and NaOH were used in various combination sequences. It was found that HCl did not clean the membrane used for AL-DS orientation for combined fouling. HCl cleaning (at pH 2) was found to be more effective for removing inorganic scale, whereas NaOH cleaning (at pH 11) for a similar period successfully restored the flux for all the membranes used for FS with inorganic and/or organic foulants. ethylenediamine tetra acetic acid (EDTA) was also evaluated for its cleaning performances and it was found that compared to NaOH, EDTA cleaning (1 mM concentration at pH 11) showed superior results in terms of membrane cleaning, as it helped to successfully restore the membrane flux in a very short time

Performances of PA hollow fiber membrane with the CTA flat sheet membrane for forward osmosis process

© 2013, © 2013 Balaban Desalination Publications. All rights reserved. Abstract: Fertilizer drawn forward osmosis desalination has been earlier explored using flat sheet forward osmosis (FSFO) membrane, which highlighted flux and reverse solute flux (RSF) performance. This study evaluated and compared the performances of a newly developed polyamide (PA)-based hollow fiber forward osmosis (HFFO) membrane and cellulose triacetate FSFO membrane. Both membranes were evaluated for pure water permeability, salt rejection rate (1,000 mg/L NaCl) in RO mode. Physical structure and morphology were further examined using scanning electron micrograph (SEM). SEM images revealed that the overall thickness of the HFFO and FSFO membranes was 152 and 91 μm, respectively. Flux and RSF performances of these two membranes were evaluated using nine fertilizer DS as NH4Cl, KNO3, KCl, (NH4)2SO4, Ca(NO3)2, NH4H2PO4, (NH4)2HPO4, NaNO3, and CO(NH2)2 in active layer–feed solution membrane orientation. HFFO membrane clearly showed better performance for water flux with five DS ((NH4)2SO4, NH4H2PO4, KNO3, CO(NH2)2, and NaNO3) as they showed up to 66% increase in flux. Beside thick PA active layer of HFFO membrane, higher water flux outcome for forward osmosis (FO) process further highlighted the significance of the nature of support layer structure, the thickness and surface chemistry of the active layer of the membrane in the FO process. On the other hand, most DS showed lower RSF with HFFO membrane with the exception of Ca(NO3)2. Most of DS having monovalent cation and anions showed significantly lower RSF with HFFO membrane