Dynamic weighted idle time heuristic for flowshop scheduling

The constructive heuristic of Nawaz, Enscore and Ham (NEH) has been introduced in 1983 to solve flowshop scheduling. Many researchers have continued to improve the NEH by adding new steps and procedures to the existing algorithm. Thus, this study has developed a new heuristic known as Dynamic Weighted Idle Time (DWIT) method by adding dynamic weight factors for solving the partial solution with purpose to obtain optimal makespan and improve the NEH heuristic. The objective of this study are to develop a DWIT heuristic to solve flowshop scheduling problem and to assess the performance of the new DWIT heuristic against the current best scheduling heuristic, ie the NEH. This research developed a computer programming in Microsoft Excel to measure the flowshop scheduling performance for every change of weight factors. The performance measure is done by using n jobs (n=6,10 and 20) and 4 machines. The weight factors were applied with numerical method within the range of zero to one. Different weight factors and machines idle time were used at different problem sizes. For 6 jobs and 4 machines, only idle time before and in between two jobs were used while for 10 jobs and 20 jobs the consideration of idle time was idle time before, in between two jobs and after completion of the last job. In 6 jobs problem, the result was compared between DWIT against Optimum and NEH against Optimum. While in 10 jobs and 20 jobs problem the result was compared between DWIT against the NEH. Overall result shows that the result on 6 and 10 jobs problem the DWIT heuristic obtained better results than NEH heuristic. However, in 20 jobs problem, the result shows that the NEH was better than DWIT. The result of this study can be used for further research in modifying the weight factors and idle time selections in order to improve the NEH heuristic

The dynamics of divorce, income, and female labor force participation in Singapore.

Singapore has experienced rising income and female labor force participation over the years. This growth, however, is also accompanied by increasing divorce rate. This paper utilizes Granger causality tests within a multivariate error correction framework to examine the short-run and long-run causal interactions among divorce, income and female labor force participation in Singapore. The long–run results suggest the presence of tradeoffs between income, female labor participation and the family unit, with the twin objectives of economic expansion and the move to draw more women into the labor market having a negative impact on the institution of marriage.causality, divorce, female labor force participation, income, Singapore

Hydrogen at the rooftop: Compact CPV-hydrogen system to convert sunlight to hydrogen

Despite being highest potential energy source, solar intermittency and low power density make it difficult for solar energy to compete with the conventional power plants. Highly efficient concentrated photovoltaic (CPV) system provides best technology to be paired with the electrolytic hydrogen production, as a sustainable energy source with long term energy storage. However, the conventional gigantic design of CPV system limits its market and application to the open desert fields without any rooftop installation scope, unlike conventional PV. This makes CPV less popular among solar energy customers. This paper discusses the development of compact CPV-Hydrogen system for the rooftop application in the urban region. The in-house built compact CPV system works with hybrid solar tracking of 0.1° accuracy, ensured through proposed double lens collimator based solar tracking sensor. With PEM based electrolyser, the compact CPV-hydrogen system showed 28% CPV efficiency and 18% sunlight to hydrogen (STH) efficiency, for rooftop operation in tropical region of Singapore. For plant designers, the solar to hydrogen production rating of 217 kWhe/kgH2 has been presented with 15% STH daily average efficiency, recorded from the long term field operation of the syste

Energy distribution function based universal adsorption isotherm model for all types of isotherm

Based upon the adsorbate-adsorbent interactions due to pore size distribution and surface heterogeneity, as characterized by the adsorption isotherms, the adsorption phenomenon has many industrial and environmental applications. These adsorption isotherms are very important to define the information related to the equilibrium uptake of adsorbate-adsorbent pair. Due to the presence of different energy distribution of adsorption sites, pore size distribution, surface area availability and surface heterogeneity, of each of the adsorbent-adsorbate pair, these isotherms are categorized into six types by the International Union of Pure and Applied Chemistry and so far, in the literature, there is no generalized adsorption isotherm model available that can define and predict the behavior of all adsorption isotherm types. In this study, a universal adsorption isotherm model is developed based upon the energy distribution function of the available adsorption sites and the pore size. The proposed model is able to define all adsorption isotherm characteristics, irrespective of their multi- or monolayer formations and micro- or meso-pore distribution

Desalination Processes’ Efficiency and Future Roadmap

For future sustainable seawater desalination, the importance of achieving better energy efficiency of the existing 19,500 commercial-scale desalination plants cannot be over emphasized. The major concern of the desalination industry is the inadequate approach to energy efficiency evaluation of diverse seawater desalination processes by omitting the grade of energy supplied. These conventional approaches would suffice if the efficacy comparison were to be conducted for the same energy input processes. The misconception of considering all derived energies as equivalent in the desalination industry has severe economic and environmental consequences. In the realms of the energy and desalination system planners, serious judgmental errors in the process selection of green installations are made unconsciously as the efficacy data are either flawed or inaccurate. Inferior efficacy technologies' implementation decisions were observed in many water-stressed countries that can burden a country's economy immediately with higher unit energy cost as well as cause more undesirable environmental effects on the surroundings. In this article, a standard primary energy-based thermodynamic framework is presented that addresses energy efficacy fairly and accurately. It shows clearly that a thermally driven process consumes 2.5-3% of standard primary energy (SPE) when combined with power plants. A standard universal performance ratio-based evaluation method has been proposed that showed all desalination processes performance varies from 10-14% of the thermodynamic limit. To achieve 2030 sustainability goals, innovative processes are required to meet 25-30% of the thermodynamic limit

Desalination Processes’ Efficiency and Future Roadmap

For future sustainable seawater desalination, the importance of achieving better energy efficiency of the existing 19,500 commercial-scale desalination plants cannot be over emphasized. The major concern of the desalination industry is the inadequate approach to energy efficiency evaluation of diverse seawater desalination processes by omitting the grade of energy supplied. These conventional approaches would suffice if the efficacy comparison were to be conducted for the same energy input processes. The misconception of considering all derived energies as equivalent in the desalination industry has severe economic and environmental consequences. In the realms of the energy and desalination system planners, serious judgmental errors in the process selection of green installations are made unconsciously as the efficacy data are either flawed or inaccurate. Inferior efficacy technologies' implementation decisions were observed in many water-stressed countries that can burden a country's economy immediately with higher unit energy cost as well as cause more undesirable environmental effects on the surroundings. In this article, a standard primary energy-based thermodynamic framework is presented that addresses energy efficacy fairly and accurately. It shows clearly that a thermally driven process consumes 2.5-3% of standard primary energy (SPE) when combined with power plants. A standard universal performance ratio-based evaluation method has been proposed that showed all desalination processes performance varies from 10-14% of the thermodynamic limit. To achieve 2030 sustainability goals, innovative processes are required to meet 25-30% of the thermodynamic limit

A multi evaporator desalination system operated with thermocline energy for future sustainability

All existing commercial seawater desalination processes, i.e. thermally-driven and membrane-based reverse osmosis (RO), are operated with universal performance ratios (UPR) varying up to 105, whilst the UPR for an ideal or thermodynamic limit (TL) of desalination is at 828. Despite slightly better UPRs for the RO plants, all practical desalination plants available, hitherto, operate at only less than 12% of the TL, rendering them highly energy intensive and unsustainable for future sustainability. More innovative desalination methods must be sought to meet the needs of future sustainable desalination and these methods should attain an upper UPR bound of about 25 to 30% of the TL. In this paper, we examined the efficacy of a multi-effect distillation (MED) system operated with thermocline energy from the sea; a proven desalination technology that can exploit the narrow temperature gradient of 20 °C all year round created between the warm surface seawater and the cold-seawater at depths of about 300–600 m. Such a seawater thermocline (ST)-driven MED system, simply called the ST-MED process, has the potential to achieve up to 2 folds improvement in desalination efficiency over the existing methods, attaining about 18.8% of the ideal limit. With the major energy input emanated from the renewable solar, the ST-MED is truly a “green desalination” method of low global warming potential, best suited for tropical coastal shores having bathymetry depths of 300 m or more

Energy-water-environment nexus underpinning future desalination sustainability

Energy-water-environment nexus is very important to attain COP21 goal, maintaining environment temperature increase below 2 °C, but unfortunately two third share of CO2 emission has already been used and the remaining will be exhausted by 2050. A number of technological developments in power and desalination sectors improved their efficiencies to save energy and carbon emission but still they are operating at 35% and 10% of their thermodynamic limits. Research in desalination processes contributing to fuel World population for their improved living standard and to reduce specific energy consumption and to protect environment. Recently developed highly efficient nature-inspired membranes (aquaporin & graphene) and trend in thermally driven cycle's hybridization could potentially lower then energy requirement for water purification. This paper presents a state of art review on energy, water and environment interconnection and future energy efficient desalination possibilities to save energy and protect environment

Bioactive compounds from Ploiarium alternifolium (Theaceae) and Calophyllum mucigerum (Guttiferae)

Chemical and cytotoxic studies were carried out on two plant species, Caiophyllum mucigerum (Guttiferae) and Ploiarium alternifolium (Theaceae). The chemical investigations covered anthraquinones, triterpenes, xanthone and coumarins. These compounds were isolated using common chromatographic techniques and HPLC and identified using spectroscopic methods including 2-D NMR, GCMS, MS, IR andUV. Ploiarium alternifolium provided emodin, ploiariquinone A, 1,8-dihydroxy-3- methyl-6-methoxy-anthraquinone, 3 β-benzoyloxyolean-ll-en-13β,28-olide and euxanmodin C. Emodin and 1, 8-dihydroxy-3-metbyl-6-methoxy-antbraquinone have not been reported from Ploairium aiternifolium. Calophyllum mucigerum gave the common steroidal triterpenes friedelin and stigmasterol, a prenylated xanthone cudraxanthone C and two new coumarins mucigerin I and mucigerin II. The crude n-hexane, ethyl acetate and ethanol stem bark extracts of both plants were screened for their larvicidal activity against the larvae of Aedes aegypti. The crude n-hexane, ethyl acetate and ethanol extracts for both of the plants were susceptible to the larvae of Aedes aegypti with LC₅₀ values of 95.0 µg/ml, 129.4 µg/ml and 131.6 µg/ml, respectively for Ploiarium alternifolium whereas 87.9 µg/ml, 138.5 µg/ml and 147.4 µg/ml, respectively for Calophyllum mucigerum. Larvicidal activity on the pure compound, emodin gave an LCso value of 2.79 µg/ml. The cytotoxicity, antibacterial and antifungal activities test were also carried out on the three crude extracts of both plants and also on the pure compounds. Cytotoxicities were determined by performing the microtitration assay. All the crude extracts were weakly cytotoxic towards the CEM-SS cell line except hexane extracts from C. mucigerum and P. alternifolium which gave moderate activity with IC₅₀ = 16.2 µg/ml and lC₅₀ = 19.2 µg/ml, respectively. The pure compound euxanmodin C was the most sensitive against the cell line with IC₅₀ = 5.9 µg/ml. The antimicrobial activity was tested using the modified disc diffusion method. The crude extracts from both plants also showed different antimicrobial activity against the growth of four bacteria; Bacillus subtiUs mutant, Bacillus subtilis wild type, Staphyloccus aures and Pseudomonas aeruginosa. However, these crude extracts were weakly active against the bacteria with less than 10 mm diameter inhibition zone