A systematic technique for cost-effective CO<Subscript>2</Subscript> emission reduction in process plants

There has been growing interests to reduce the environmental impact caused by greenhouse gas emissions from process plants through various energy conservation strategies. CO₂ emissions are closely linked to energy generation, conversion, transmission and utilisation. Various studies on the design of energy-efficient processes, optimal mix of renewable energy and hybrid power system are driven to reduce reliance on fossil fuel as well as CO₂ emissions reduction. This paper presents a systematic technique in the form of graphical visualisation tool for cost-effective CO₂ emission reduction strategies in industry. The methodology is performed in four steps. The first step involves calculating the energy consumption of a process plant. This is followed by identification of potential strategies to reduce CO₂ emissions using the CO₂ management hierarchy as a guide. In the third step, the development of “Investment” versus “CO₂ Reduction” (ICO₂) plot is constructed to measure the optimal CO₂ emission reductions achieved from the implementation of possible CO₂ reduction strategies. The Systematic Hierarchical Approach for Resilient Process Screening (Wan Alwi and Manan in AIChE J 11:3981–3988, 2006) method is used in the fourth step via substitution or partial implementation of the various CO₂ reduction options in order to meet the cost-effective emission reduction within the desired investment limit or payback period (PP). An illustrative case study on a palm oil refinery plant has been used to demonstrate the implementation of the method in reduction of CO₂ emissions. The developed graphical tool provides an insight-based approach for systematic CO₂ emission reduction in the palm oil refinery considering both heat and power energy sources. Result shows that 31.2 % reduction in CO₂ emissions can be achieved with an investment of USD 38,212 and PP of 10 months based on the present energy prices in Malaysia.     

Thermoeconomic optimization for a finned‐tube evaporator configuration of a roof‐top bus air‐conditioning system

This paper presents a methodology of a design optimization technique that can be useful in assessing the best configuration of a finned‐tube evaporator, using a thermoeconomic approach. The assessment has been carried out on a direct expansion finned‐tube evaporator of a vapor compression cycle for a roof‐top bus air‐conditioning (AC) system at a specified cooling capacity. The methodology has been conducted by studying the effect of some operational and geometrical design parameters for the evaporator on the entire cycle exergy destruction or irreversibility, AC system coefficient of performance (COP), and total annual cost. The heat exchangers for the bus AC system are featured by a very compact frontal area due to the stringent space limitations and structure standard for the system installation. Therefore, the current study also takes in its account the effect of the variation of the design parameters on the evaporator frontal area. The irreversibility due to heat transfer across the stream‐to‐stream temperature difference and due to frictional pressure drops is calculated as a function of the design parameters. A cost function is introduced, defined as the sum of two contributions, the investment expense of the evaporator material and the system compressor, and the operational expense of AC system that is usually driven by an auxiliary engine or coupled with the main bus engine. The optimal trade‐off between investment and operating cost is, therefore, investigated. A numerical example is discussed, in which a comparison between the commercial evaporator design and optimal design configuration has been presented in terms of the system COP and evaporator material cost. The results show that a significant improvement can be obtained for the optimal evaporator design compared with that of the commercial finned‐tube evaporator that is designed based on the conventional values of the design parameters. Copyright © 2007 John Wiley & Sons, Ltd.     

An Optimized Neural Network with Bat Algorithm for DNA Sequence Classification

Recently, many researchers have used nature inspired metaheuristic algorithms due to their ability to perform optimally on complex problems. To solve problems in a simple way, in the recent era bat algorithm has become famous due to its high tendency towards convergence to the global optimum most of the time. But, still the standard bat with random walk has a problem of getting stuck in local minima. In order to solve this problem, this research proposed bat algorithm with levy flight random walk. Then, the proposed Bat with Levy flight algorithm is further hybridized with three different variants of ANN. The proposed BatLFBP is applied to the problem of insulin DNA sequence classification of healthy homosapien. For classification performance, the proposed models such as Bat levy flight Artificial Neural Network (BatLFANN) and Bat levy Flight Back Propagation (BatLFBP) are compared with the other state-of-the-art algorithms like Bat Artificial Neural Network (BatANN), Bat back propagation (BatBP), Bat Gaussian distribution Artificial Neural Network (BatGDANN). And Bat Gaussian distribution back propagation (BatGDBP), in-terms of means squared error (MSE) and accuracy. From the perspective of simulations results, it is show that the proposed BatLFANN achieved 99.88153% accuracy with MSE of 0.001185, and BatLFBP achieved 99.834185 accuracy with MSE of 0.001658 on WL5. While on WL10 the proposed BatLFANN achieved 99.89899% accuracy with MSE of 0.00101, and BatLFBP achieved 99.84473% accuracy with MSE of 0.004553. Similarly, on WL15 the proposed BatLFANN achieved 99.82853% accuracy with MSE of 0.001715, and BatLFBP achieved 99.3262% accuracy with MSE of 0.006738 which achieve better accuracy as compared to the other hybrid models.

     

A literatu rereview on the improvement strategies of passive design for the roofing system of the modern house in a hot and humid climate region

Increase of indoor temperature compared with outdoor temperature is amajor concern in modern house design. Occupants suffer from this uncomfortable condition because of over-heating indoor temperature. Poor passive design causes heat to be trapped, which influences the rise in indoor temperature. The upper part, which covers the area of the roof, is the most critical part of the house that is exposed to heat caused by high solar radiation and high emissivity levels. During daytime, the roof accumulates heat, which increases the indoor temperature and affects the comfort level of the occupants. To maintain the indoor temperature within the comfort level, most house designs usually depend on mechanical means by using fans or air conditioning systems. The dependence on amechanical ventilation system could lead to additional costs for itsinstallation, operation, and maintenance. Thus, this study concentrates on reviews on passive design and suggests recommendations for future developments. New proposals or strategies are proposed to improve the current passive design through ventilated and cool roof systems. It is possible to achieve the comfort level inside a house throughout the day by reducing the transmitted heat into the indoor environment and eliminating the internal hot air. These recommendations could become attractive strategies in providing a comfortable indoor temperature to the occupants as well as inminimizing energy consumption.     

Immobilized titanium dioxide/powdered activated carbon system for the photocatalytic adsorptive removal of phenol

Titanium dioxide (TiO₂) and powdered activated carbon (PAC) were fabricated via a layer by layer arrangement on a glass plate using a dip-coating technique for the photocatalytic-adsorptive removal of phenol. Thinner TiO₂ layer coated on PAC sub-layer has larger surface area and better phenol removal than the thicker TiO₂ layer. The system obeyed the Langmuir isotherm model, which exhibited a homogeneous and monolayer adsorption with a maximum capacity of 27.8 mg g^-1. The intra-particle diffusion was the rate-limiting step as the linear plot crossed the origin, while the adsorption was unfavorable at elevated temperature. Under light irradiation, the TiO₂/PAC system removed phenol two-times more effectively than the TiO₂ monolayer due to the synergistic effect of photocatalysis by TiO₂ top layer and adsorption by PAC sub-layer. The COD removal of phenol was rapid for 10mg L^-1 of concentration and under solar light irradiation. It was shown that the PAC sub-layer plays a significant role in the total removal of phenol by providing the adsorption sites and slowing down the recombination rate of charge carriers to improve the TiO₂ photocatalytic oxidation performance.     

Review of MEMS flow sensors based on artificial hair cell sensor

An artificial hair cell sensor is the current technology based on a biological inspiration and is widely used in underwater applications including the glider, robotic and autonomous surface vehicle. These papers discuss a few strategies in relation to the principles of sensing, fabrication, performance, and preliminary measurement data. The MEMS flow sensor is generally needed to replace existing commercial sensors that are inadequate for some applications. Material also provides some advantages to the hair cell sensor. Some materials such as Polydimethylsilaxone and Polyurethane have been investigated. The sensing element is reviewed including the doped piezoresistors, strain gauge and force sensitive resistors. Performance and result of each design will be presented briefly. Finally, the importance and the need for modeling, simulation and experiments will be reviewed based on the latest achievements on that particular research area.     

Determination of synthetic phenolic antioxidants in food items using reversed-phase HPLC

A HPLC with gradient elution method for the determination of the synthetic phenolic antioxidants (SPAs) propyl gallate (PG), tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) in food items is described. A C18 column served as the stationary phase; the gradient elution was formed by acetonitrile and water:acetic acid (1%). The UV detector was set at 280 nm. Under the recommended conditions, separation of the four SPAs was achieved in less than 8 min. Analytical characteristics of the HPLC method such as limit of detection, linear range, and reproducibility were evaluated. Extraction parameters were optimized for the recoveries of the SPAs in different types of food items (cooking oil, margarine and butter, and cheese). Before the HPLC separation, the SPAs were extracted with methanol/acetonitrile (1:1, v/v) and were subjected to vortex/ultrasonic treatment. The extracts were next kept in a freezer (∼2 h) to precipitate co-extracted components. Recoveries of the SPAs when spiked to cooking oil, margarine, butter and cheese at 50 and 200 mg l⁻¹ were in the ranges 93.3–108.3% for PG, 85.3–108.3% for TBHQ, 96.7–101.2% for BHA and 73.9–94.6% for BHT. The method was applied to the determination of SPAs in 38 food items (16 cooking oils, ten margarine, six butter and six cheese samples). The levels of SPAs in positive samples are all below the legal limits of Malaysia.     

Physician assessment of patient smoking in Indonesia: a public health priority

Objective

To explore Indonesian physician''s smoking behaviours, their attitudes and clinical practices towards smoking cessation.

Design

Cross‐sectional survey.

Setting

Physicians working in Jogjakarta Province, Indonesia, between October and December 2003.

Subjects

447 of 690 (65%) physicians with clinical responsibilities responded to the survey (236 men, 211 women), of which 15% were medical faculty, 35% residents and 50% community physicians.

Results

22% of male (n = 50) and 1% of female (n = 2) physicians were current smokers. Approximately 72% of physicians did not routinely ask about their patient''s smoking status. A majority of physicians (80%) believed that smoking up to 10 cigarettes a day was not harmful for health. The predictors for asking patients about smoking were being male, a non‐smoker and a medical resident. The odds of advising patients to quit were significantly greater among physicians who perceived themselves as sufficiently trained in smoking cessation.

Conclusions

Lack of training in smoking cessation seems to be a major obstacle to physicians actively engaging in smoking cessation activities. Indonesian physicians need to be educated on the importance of routinely asking their patients about their tobacco use and offering practical advice on how to quit smoking.Tobacco use is one of the greatest causes of preventable deaths and disease in human history. According to the World Bank, four‐fifths of the world''s 1.1 billion smokers live in low‐income or middle‐income countries.¹ East Asian and Pacific countries currently account for about 38% of the world''s smokers and men, especially those aged 30–49 years, account for about 80% of these smokers.² In Indonesia, 59% of male, but only <5% of women, smoke.³ Notably, the rates of tobacco use, especially among adolescents and young adults in East Asia, continue to rise.¹ Although reliable national data are unavailable for Indonesia, estimates in 2004 showed a high incidence rate of tobacco‐attributable mortality and morbidity.⁴ For example, in 2002, the International Agency of Research on Cancer Globocan estimated that the age‐standardised mortality of respiratory tract cancer in Indonesia among men was 68.5 per 100 000 population, but that among women was only 21.5 per 100 000 population.⁵Nations such as Indonesia continue to bear significant health and socioeconomic burdens associated with tobacco use, primarily due to aggressive tobacco industries marketing and the slow progress in tobacco control activities resulting from a strong dependency of the national economy on the tobacco trade.⁶ To reduce the economic and health burden from cigarette smoking, effective measures for smoking cessation and tobacco control are clearly needed. Public health education, and governmental policies such as taxation on sales and restrictions on advertisement may serve as useful tools to limit the use of tobacco products.^7,8 Currently, such measures are lacking in Indonesia.Smoking behaviour and attitudes towards smoking cessation by healthcare providers in Western countries have been studied extensively.^9,10,11 Research findings suggest that asking about smoking and offering advice about cessation help smokers quit.^{12,13,14,15,16} Of equal importance is the observation that the smoking status of healthcare providers may influence their willingness to offer smoking cessation advice to smokers.^16,17 Unfortunately, limited research is available on non‐Western countries in regard to behaviours, perceptions and attitudes towards smoking among physicians and other healthcare providers.^16,18,19,20Understanding the attitudes of health professionals towards cessation of tobacco use is an important early step in the development of a country''s comprehensive anti‐tobacco initiative. This step is especially important in countries like Indonesia, where there are few anti‐tobacco initiatives and physicians play a particularly important role as opinion leaders and role models. To understand physician''s attitudes towards tobacco, we conducted a survey of physicians to explore a range of issues including smoking behaviours, and their attitudes and clinical practices regarding smoking.     

Potential electricity savings by variable speed control of compressor for air conditioning systems

The potential of a variable-speed compressor running on a controller to provide enhanced load-matching capability, energy saving and thermal comfort for application in air-conditioning system is demonstrated. An air-conditioning system, originally operated on a constant speed mode, is retrofitted with an inverter and a PID controller. The system was installed to a thermal environmental room together with a data acquisition system to monitor energy consumption and temperature of the room. Measurements were taken 2 h daily at a time interval of 5 min for an on/off and an inverter variable-speed conditions. The results indicate that thermal comfort of the room together with energy saving can be obtained through a proper selection of K for the controller. At a temperature setting of 22°C, the energy saving for the system is estimated to reach 25.3% for PID controllers.