Analysis of earth-moving systems using discrete-event simulation

AbstractDiscrete-event simulation has been widely used technique in analyzing construction operations for the past three decades due to its great effect on optimizing cost and productivity. In this paper we will present Arena as a tool for simulating earthwork operations, the advantage of Arena is its easiness and flexibility in simulating most kinds of models in different areas of construction. A case study will be presented, a model will be built and results obtained to reveal the mentioned objectives

Modification of bacterial cell membrane to accelerate decolorization of textile wastewater effluent using microbial fuel cells: role of gamma radiation

The aim of the present work was to increase bacterial adhesion on anode via inducing membrane modifications to enhance textile wastewater treatment in Microbial Fuel Cell (MFC). Real textile wastewater was used in mediator-less MFCs for bacterial enrichment. The enriched bacteria were pre-treated by exposure to 1 KGy gamma radiation and were tested in MFC setup. Bacterial cell membrane permeability and cell membrane charges were measured using noninvasive dielectric spectroscopy measurements. The results show that pre-treatment using gamma radiation resulted in biofilm formation and increased cell permeability and exopolysaccharide production; this was reflected in both MFC performance (average voltage 554.67 mV) and decolorization (96.42%) as compared to 392.77 mV and 60.76% decolorization for non-treated cells. At the end of MFC operation, cytotoxicity test was performed for treated wastewater using a dermal cell line, the results obtained show a decrease in toxicity from 24.8 to 0 (v/v%) when cells were exposed to gamma radiation. Fourier-transform infrared (FTIR) spectroscopy showed an increase in exopolysaccharides in bacterial consortium exposed to increasing doses of gamma radiation suggesting that gamma radiation increased exopolysaccharide production, providing transient media for electron transfer and contributing to accelerating MFC performance. Modification of bacterial membrane prior to MFC operation can be considered highly effective as a pre-treatment tool that accelerates MFC performance

Isothermal Modelling Based Experimental Study of Dissolved Hydrogen Sulfide Adsorption from Waste Water using Eggshell Based Activated Carbon

This paper reports on the experimental work using batch process conducted to determine the adsorption capacity of dissolved hydrogen sulfide in the synthetic wastewater onto the activated carbon which is derived from the eggshell. Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray Spectroscopy (EDX), Scanning Electron Microscopy (SEM), and particle size distribution have been used to characterize the prepared material. The raw materials of chicken eggshell are adopted to retrieve the carbon content which is then activated using KOH as the activation agent. The examined concentration of dissolved hydrogen sulfide is ranging from 100 to 500 ppm. The maximum adsorption capacity of the dissolved H2S onto the activated carbon is 289.3 mg/g and the equilibrium time is 6 hours. The examined pH value in this study is ranging from 4.5 to 5.5. The two well-known equilibrium adsorption isotherm models, i.e. the Langmuir and the Freundlich models, are employed. It is found that the adsorption isotherm capacity agrees very well to the Freundlich isotherm model. This paper attempts to show the difficulties of converting CaCO 3 to carbon due to the fact that the raw material contains higher calcium (Ca) content instead of carbon. It is concluded that the carbon derived from the chickens’ eggshells is very beneficial for treatment of dissolved H2S in waste water

CaO impregnated highly porous honeycomb activated carbon from agriculture waste: symmetrical supercapacitor study

This study presents the electrochemical studies of activated carbon prepared from palm kernel shell (ACPKS), with CaO impregnation. The CaO is obtained from chicken eggshell waste to produce CaO/ACPKS, which shows highly porous honeycomb structure with homogeneous distribution of CaO nanoparticles (30–50 nm in size). The prepared materials are evaluated as supercapacitor electrodes by testing their electrochemical characteristics. A high specific capacitance value of 222 F g−1 at 0.025 A g−1 is obtained for CaO/ACPKS, which is around three times higher than that for ACPKS (76 F g−1). In addition, electrochemical impedance data show lower impedance for CaO/ACPKS. Lastly, a practical symmetrical supercapacitor is fabricated by CaO/ACPKS and its performance is discussed

Probabilistic Model Checking for Energy Analysis in Software Product Lines

In a software product line (SPL), a collection of software products is defined by their commonalities in terms of features rather than explicitly specifying all products one-by-one. Several verification techniques were adapted to establish temporal properties of SPLs. Symbolic and family-based model checking have been proven to be successful for tackling the combinatorial blow-up arising when reasoning about several feature combinations. However, most formal verification approaches for SPLs presented in the literature focus on the static SPLs, where the features of a product are fixed and cannot be changed during runtime. This is in contrast to dynamic SPLs, allowing to adapt feature combinations of a product dynamically after deployment. The main contribution of the paper is a compositional modeling framework for dynamic SPLs, which supports probabilistic and nondeterministic choices and allows for quantitative analysis. We specify the feature changes during runtime within an automata-based coordination component, enabling to reason over strategies how to trigger dynamic feature changes for optimizing various quantitative objectives, e.g., energy or monetary costs and reliability. For our framework there is a natural and conceptually simple translation into the input language of the prominent probabilistic model checker PRISM. This facilitates the application of PRISM's powerful symbolic engine to the operational behavior of dynamic SPLs and their family-based analysis against various quantitative queries. We demonstrate feasibility of our approach by a case study issuing an energy-aware bonding network device.Comment: 14 pages, 11 figure

Hydrogen sulfide emission sources, regulations, and removal techniques: a review

This review highlights the recent technologies of H2S removal from wastewater in the petroleum refinery. H2S is a harmful, putrid, and hazardous gaseous compound. The main processes such as physicochemical, chemical, biological, and electrochemical methods were compared and discussed in detail. The effects of various parameters and adsorbent characteristics were highlighted and correlated with the adsorption capacities. Surface functional groups and porosity surface area play a crucial role in the process of single-phase and composite adsorbents. Composite materials impregnated with some metals showed high removal efficiencies. It was found that the adsorption process is the most relevant way for H2S removal due to its high removal efficiency, low cost, eco-friendly, and operational simplicity. This study serves as a useful guideline for those who are interested in H2S removal

Kinetic, Isotherm And Equilibrium Study Of Adsorption Of Hydrogen Sulfide From Wastewater Using Modified Eggshells

The studies of adsorption equilibrium isotherm and kinetics of hydrogen sulfide-water systems on calcite-based adsorbents prepared from eggshell are undertaken. The effects of operating variables such as contact time and initial concentration on the adsorption capacity of hydrogen sulfide are investigated. The modified eggshells are characterized by using different analytical approaches such as Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR). The batch mode adsorption process is performed at optimum removal conditions: dosage of 1 g/L, pH level of pH 6, agitation speed of 150 rpm and contact time of 14h for adsorbing hydrogen sulfide with an initial concentration of 100-500 mg/L. In the current study, the Langmuir, Freundlich, Temkin, and Dubinin models are used to predict the adsorption isotherms. Our equilibrium data for hydrogen sulfide adsorption agrees well with those of the Langmuir equation. The maximum monolayer adsorption capacity is 150.07 mg/g. Moreover, the kinetics of H2S adsorption by using the modified calcite of eggshell follows a pseudo-second-order model. From the current work, we have found that the calcite eggshell is a suitable adsorbent for H2S embeded inside the waste water. Most importantly, chicken eggshell is a waste and vastly available; hence, it could serve as a practical mean for H2S adsorption

The effect of EGR rates on NOX and smoke emissions of an IDI diesel engine fuelled with Jatropha biodiesel blends

The depletion of fossil fuels and the worst impact on environmental pollution caused of their burning have led to the search for renewable clean energies. Nowadays, there are many sources of renewable energy. Biodiesel is just one source, but a very important one. Biodiesel has been known as an attractive alternative fuel although biodiesel produced from edible oil is very expensive than conventional diesel. Therefore, the uses of biodiesel produced from non-edible oils are much better option. Currently Jatropha biodiesel (JBD) is receiving attention as an alternative fuel for diesel engine. However, previous studies have reported that combustion of JBD emitted higher nitrogen oxides (NOX), while hydrocarbon (HC) and smoke emissions were lower than conventional diesel fuel. Exhaust gas recirculation (EGR) is one of the techniques being used to reduce NOX emission from diesel engines; because it decreases both flame temperature and oxygen concentration in the combustion chamber. Some studies succeeded to reduce NOX emission from biodiesel fuelled engines using EGR; but they observed increase in smoke emission with increasing engine load and EGR rate. The aim of the present work is to investigate the effect of EGR on an indirect injection (IDI) diesel engine fuelled with JBD blends in order to reduce NOX and smoke emissions. A 4-cylinder, water-cooled, turbocharged, IDI diesel engine was used for investigation. Smoke, NOX, carbon monoxide (CO) and carbon dioxide (CO2) emissions were recorded and various engine performance parameters were also evaluated. The results showed that, at 5% EGR with JB5, both NOX and smoke opacity were reduced by 27% and 17% respectively. Furthermore, JB20 along with 10% EGR was also able to reduce both NOX and smoke emission by 36% and 31%, respectively compared to diesel fuel without EGR

Magnetic Electrodeposition of the Hierarchical Cobalt Oxide Nanostructure from Spent Lithium-Ion Batteries: Its Application as a Supercapacitor Electrode

In this study, electrodeposition of cobalt oxide (Co3O4) from spent lithium-ion batteries is successfully enhanced by the magnetic field effect. In the presence of magnetic field, well-defined hierarchical Co3O4 nanostructures with higher electroactive surface area are formed during the electrodeposition process. Electrochemical analysis shows that the enhanced Co3O4 nanostructures exhibit excellent charge storage capabilities of 1273 F g–1 at 1 A g–1, approximately 4 times higher than the electrodeposited Co3O4 that is formed without magnetic field effect. It also reveals the high cycling stability of enhanced Co3O4 nanostructures, with 96% capacitance retention at 5000 charge discharge cycles. The results manifest the enhancement of Co3O4 recovery from spent lithium-ion batteries, which can be the potential electrode material for supercapacitor application