Operating Costs (operating + cost)

Distribution by Scientific Domains

Selected Abstracts

Updating free speed models through mechanistic principles for Indian conditions

Errampalli Madhu
The prediction of free speeds of vehicles is an integral part of the economic appraisal of highways. It is to be noted that speeds not only govern the travel time costs, but also have major impacts on Vehicle Operating Costs (VOC). The World Bank has proposed a mechanistic free speed model based on the limiting speed concept for Highway Design and Maintenance (HDM)-III. This model along with some refinements has been included in HDM-4. The underlying assumption in the HDM free speed prediction model is that the free speed at any given point of time is the minimum of possible constraining speeds. This paper mainly addresses the methodology considered to update the free speed models through mechanistic principles (based on HDM-4). This is accomplished by calibration of the model using the current data on free speeds, road and vehicle characteristics. Subsequently, the validation of the developed models has been carried out. [source]

Optimal corrective maintenance contract planning for aging multi-state system

Yi Ding
Abstract This paper considers an aging multi-state system, where the system failure rate varies with time. After any failure, maintenance is performed by an external repair team. Repair rate and cost of each repair are determined by a corresponding corrective maintenance contract with a repair team. The service market can provide different kinds of maintenance contracts to the system owner, which also can be changed after each specified time period. The owner of the system would like to determine a series of repair contracts during the system life cycle in order to minimize the total expected cost while satisfying the system availability. Operating cost, repair cost and penalty cost for system failures should be taken into account. The paper proposes a method for determining such optimal series of maintenance contracts. The method is based on the piecewise constant approximation for an increasing failure rate function in order to assess lower and upper bounds of the total expected cost and system availability by using Markov models. The genetic algorithm is used as the optimization technique. Numerical example is presented to illustrate the approach. Copyright © 2009 John Wiley & Sons, Ltd. [source]

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

M. Khamis Mansour
Abstract 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. [source]

Minimizing shell-and-tube heat exchanger cost with genetic algorithms and considering maintenance

Philippe Wildi-Tremblay
Abstract This paper presents a procedure for minimizing the cost of a shell-and-tube heat exchanger based on genetic algorithms (GA). The global cost includes the operating cost (pumping power) and the initial cost expressed in terms of annuities. Eleven design variables associated with shell-and-tube heat exchanger geometries are considered: tube pitch, tube layout patterns, number of tube passes, baffle spacing at the centre, baffle spacing at the inlet and outlet, baffle cut, tube-to-baffle diametrical clearance, shell-to-baffle diametrical clearance, tube bundle outer diameter, shell diameter, and tube outer diameter. Evaluations of the heat exchangers performances are based on an adapted version of the Bell,Delaware method. Pressure drops constraints are included in the procedure. Reliability and maintenance due to fouling are taken into account by restraining the coefficient of increase of surface into a given interval. Two case studies are presented. Results show that the procedure can properly and rapidly identify the optimal design for a specified heat transfer process. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Optimization of a finned heat sink array based on thermoeconomic analysis

S. Z. Shuja
Abstract The design and specification of heat sinks for electronic systems is not easily accomplished through the use of standard thermal design and analysis tools since geometric and boundary conditions are not typically known in advance. A second-law based thermoeconomic optimization procedure is presented for a finned heat sink array. This involves including costs associated with material, and irreversible losses due to heat transfer and pressure drop. The influence of important physical, geometrical and unit cost parameters on the overall finned array are optimized for some typical operating conditions that are representative of electronic cooling applications. The optimized cost results are presented in terms of ReD, ReL, ,P / ,H, and q for a finned system in a graphical form. In addition the methodology of obtaining optimum parameters for a finned heat sink system which will result in minimum operating cost is demonstrated. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Optimal use of solar collectors for residential buildings

Stig-Inge GustafssonArticle first published online: 5 JUN 200
Abstract Solar radiation is an abundant free resource which may be used in the form of solar heated water. This is achieved in solar collectors which, unfortunately, are expensive devices and, further, the warm water must be stored in accumulators,items which also cost money. This paper shows how we have optimized the situation for a block-of-flats in Sweden. In order to find this point we have used the minimum life-cycle cost (LCC) concept as a criterion. The best solution is therefore found when that cost finds its lowest value. It is also examined under which conditions solar collectors are part of the optimal solution and further it is calculated what happens if this optimal point is abandoned, i.e. how much will the LCC increase if other than optimal solutions are chosen. LCC optimization for multi-family buildings almost always results in a heating system with low operating costs such as district heating or dual-fuel systems where a heat pump takes care of the base load and an oil boiler the peak. The installation cost must, however, be kept to a reasonable level. Expensive solar panel systems are therefore normally avoided if the lowest LCC shall be reached, at least for Swedish conditions. This is so even if the solar system has a very low operating cost. For buildings where the only alternative energy source is electricity, solar collectors seem to be on the rim of profitability, i.e. for an energy price of about 0.6 SEK kWh,1. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Application of genetic algorithm for scheduling and schedule coordination problems

Prabhat Shrivastava
The problems on scheduling and schedule co-ordination usually have conflicting objectives related to user's cost and operator's cost. Users want to spend less time to wait, transfer and travel by public buses. Operators are interested in profit making by lesser vehicle operating cost and having a minimum number of buses. As far as level of service is concerned users are interested in lesser crowing while operators are concerned with maximizing profit and thus to have higher load factors. In schedule co-ordination problems transfer time plays an important role. Users are interested in coordinating services with in acceptable waiting time whereas operators prefer to have lesser services and want to meet higher demands, which invariably increases waiting time. These problems have multiple conflicting objectives and constraints. It is difficult to determine optimum solution for such problems with the help of conventional approaches. It is found that Genetic Algorithm performs well for such multi objective problems. [source]

Fermentation of glucose and starch particles using an inexpensive medium

Nancy Bawa
Abstract BACKGROUND: In North America, compared with sugar, starch is a more economical raw material to produce ethanol. Recently low temperature processing of starch granules directly to ethanol has been commercialized. With a view to minimizing process costs while maintaining a satisfactory ethanol yield, an inexpensive medium that does not require the addition of commercial ,-amylase has been developed for low temperature, direct fermentation of starch particles. RESULTS: Compared with an expensive medium that contained both yeast extract and ,-amylase, the inexpensive medium resulted in identical and 10% higher ethanol yields using glucose and starch granules as the raw substrates, respectively, but required longer processing times. Based on the different ingredient prices for expensive and inexpensive media, the operating cost to produce 10 million litres per year of ethanol utilizing simultaneous raw starch hydrolysis and fermentation is reduced over $ 2 million (Cdn) per year when using inexpensive medium. CONCLUSION: The new inexpensive medium and simultaneous raw starch hydrolysis and fermentation is considered the best strategy to produce ethanol directly from starch particles in North America. Copyright © 2009 Society of Chemical Industry [source]

Simultaneous organic carbon and nitrogen removal in an SBR controlled at low dissolved oxygen concentration

Peng Dangcong
Abstract Simultaneous organic carbon and nitrogen removal was studied in a sequencing batch reactor (SBR) fed with synthetic municipal wastewater and controlled at a low dissolved oxygen (DO) level (0.8,mg,dm,3). Experimental results over a long time (120 days) showed that the reactor achieved high treatment capacities (organic and nitrogen loading rates reached as high as 2.4,kg COD m,3 d,1 and 0.24,kg NH3 -N m3 d,1) and efficiencies (COD, NH3 -N and total nitrogen removal efficiencies were 95%, 99% and 75%). No filamentous bacteria were found in the sludge even though the reactor had been seeded with filamentous bulking sludge. Instead, granular sludge, which possessed high activity and good settleability, was formed. Furthermore, the sludge production rate under low DO was less than that under high DO. Significant benefits, such as low investment and less operating cost, will be obtained from the new process. © 2001 Society of Chemical Industry [source]

Life Cycle Cost Disclosure, Consumer Behavior, and Business Implications

Evidence From an Online Field Experiment
Summary Comprehensive assessments of final consumption have identified "housing" as a major contributor to total environmental impacts. Within this category, electrical-energy-using products are important. Do consumers opt for more energy-efficient household appliances if they are provided with life cycle cost (LCC),that is, the sum of purchase price and operating cost estimated over the life span of the appliance? And what consequences does LCC disclosure have for business? Physical energy figures shown on appliance labels may be cognitively demanding for consumers, whereas monetary information promises to simplify the decision problem. Despite the rising interest in monetary cost disclosure, its effectiveness relative to physical cost disclosure has not been rigorously evaluated. This research approached the question of effectiveness with an online field experiment for washing machines. Customers of a commercially operating online shop were randomly assigned to two groups. The control group was provided with regular product price information; the treatment group received additional LCC information. A total of 2,065 clicks were recorded and analyzed with multiple regression that controlled for several product characteristics. The evidence suggests that LCC disclosure decreases the mean specific energy use of chosen washing machines by 0.8% (p < 0.01) and their mean specific water use by 0.7% (p < 0.05). As to business implications, LCC disclosure had no effect on the indicator of retail volume, which makes it unattractive for retailers to provide LCC on their own initiative. [source]

Cost analysis of proton exchange membrane fuel cell systems

AICHE JOURNAL, Issue 7 2008
Ai-Jen Hung
Abstract Tradeoff between capital cost and the operating cost can be seen in the design of proton exchange membrane fuel cell systems. The polarization curve indicates that operating in the region of lower current densities implies less operating cost (hydrogen fuel) and higher capital cost (larger membrane electrode assembly area). The opposite effects are observed when one operates in the region of higher current densities. Therefore, an appropriate design should take both factors into account and the optimality depends on the corresponding costs of hydrogen and membrane area. An analytical cost model is constructed to describe such an economic balance in a proton exchange membrane fuel cell system. The objective function of the optimization is the total annual cost. Six scenarios are used to illustrate the optimal design based on the total annual cost as cost and materials factors fluctuate. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source]

The Effect of a Change in Wages on Welfare in a Two,Class Monocentric City

Youngsun Kwon
This paper performs a comparative static analysis to derive the effect of a change in the wages of the rich living in the suburban area of a city on the welfare of the poor living in the central area of the city. It assumes that commuting cost is a function of distance and wages. A sufficient condition for an increase in the wages of the rich to harm the welfare of the poor is that the time cost of commuting is greater than the operating cost of commuting. [source]

A parallel machine replacement model

Tim McClurg
Abstract This paper considers a finite horizon parallel machine replacement problem where a fixed number of machines is in operation at all times. The operating cost for a machine goes up as the machine gets older. An older machine may have to be replaced by a new one when its operating cost becomes too high. There is a fixed order cost associated with the purchase of new machines. Machine purchase prices and salvage values may depend on the period in which they were purchased. The objective is to find a replacement plan that minimizes the total discounted cost over the problem horizon. We believe that the costs in our model are more commonly observed in practice than those previously used in the literature. The paper develops properties of optimal solutions and an efficient forward-time algorithm to find an optimal replacement plan. A dominance property is developed that further limits the options to be considered, and a simple forecast horizon result is also presented. Future research possibilities are mentioned. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 275,287, 2002; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/nav.10012 [source]

Economic Evaluation of Scale Dependent Technology Investments

Phillip J. Lederer
We study the effect of financial risk on the economic evaluation of a project with capacity decisions. Capacity decisions have an important effect on the project,s value through the up-front investment, the associated operating cost, and constraints on output. However, increased scale also affects the financial risk of the project through its effect on the operating leverage of the investment. Although it has long been recognized in the finance literature that operating leverage affects project risk, this result has not been incorporated in the operations management literature when evaluating projects. We study the decision problem of a firm that must choose project scale. Future cash flow uncertainty is introduced by uncertain future market prices. The firm's capacity decision affects the firm's potential sales, its expected price for output, and its costs. We study the firm's profit maximizing scale decision using the CAPM model for risk adjustment. Our results include that project risk, as measured by the required rate of return, is related to the inverse of the expected profit per unit sold. We also show that project risk is related to the scale choice. In contrast, in traditional discounted cash flow analysis (DCF), a fixed prescribed rate is used to evaluate the project and choose its scale. When a fixed rate is used with DCF, a manager will ignore the effect of scale on risk and choose suboptimal capacity that reduces project value. S/he will also misestimate project value. Use of DCF for choosing scale is studied for two special cases. It is shown that if the manager is directed to use a prescribed discount rate that induces the optimal scale decision, then the manager will greatly undervalue the project. In contrast, if the discount rate is set to the risk of the optimally-scaled project, the manager will undersize the project by a small amount, and slightly undervalue the project with the economic impact of the error being small. These results underline the importance of understanding the source of financial risk in projects where risk is endogenous to the project design. [source]

Hydrodynamic investigation of bubble-column reactors: effect of column configuration

Abid Akhtar
Abstract Bubble-column reactors are quite popular in the chemical, biochemical and petrochemical industries due to their relatively simple construction, favourable heat and mass transfer properties and low operating cost. Among the various design parameters, column geometry (configuration) has a significant impact on the overall throughput. In this study, an experimental investigation of the bubble-column configuration on its hydrodynamics has been conducted with three different sizes of the column (ID = 10,45 cm). A comparison in terms of the overall gas holdup as well as localised bubble properties is performed using the four-point optical technique and hydrodynamic similarities/dissimilarities are discussed. The study showed that the overall gas holdup was a function of the gas flow rate. For the range of gas velocity investigated (9.5,22.3 cm3/ min), the smaller column had 50,60% more holdup than the bigger column. Localised bubble properties exhibited similar behaviour (i.e. higher values for the smaller column). A comparative study of L/D illustrated an invariant behaviour at a high value of L/D (>5.5). A low L/D (,1.5), however, showed a prominent influence on hydrodynamics. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Exergoeconomic Analysis of Heat Exchanger Networks for Optimum Minimum Approach Temperature

J. Zun-long
Abstract Heat exchanger networks (HENs) design for optimum minimum approach temperature is presented using exergoeconomic analysis. Cold and hot utilities are integrated with process streams into T-H plots, forming balanced composite curves, based on pinch technology. Exergy consumption of heat transfer in HENs is calculated using subsection integral on balanced composite curves. Exergy consumption expense substitutes utilities cost as operating cost. The objective function based on exergoeconomics is proposed, which determines the optimum minimum approach temperature of HENs. Numerical results in the cases demonstrate the validity of the proposed approach. Some measures of decreasing energy consumption are disclosed in the dealing process as well. [source]

Concepts for computer center power management

A. DiRienzo
Abstract Electrical power usage contributes significantly to the operational costs of large computer systems. At the Hypersonic Missile Technology Research and Operations Center (HMT-ROC) our system usage patterns provide a significant opportunity to reduce operating costs since there are a small number of dedicated users. The relatively predictable nature of our usage patterns allows for the scheduling of computational resource availability. We take advantage of this predictability to shut down systems during periods of low usage to reduce power consumption. With interconnected computer cluster systems, reducing the number of online nodes is more than a simple matter of throwing the power switch on a portion of the cluster. The paper discusses these issues and an approach for power reduction strategies for a computational system with a heterogeneous system mix that includes a large (1560-node) Apple Xserve PowerPC supercluster. In practice, the average load on computer systems may be much less than the peak load although the infrastructure supporting the operation of large computer systems in a computer or data center must still be designed with the peak loads in mind. Given that a significant portion of the time, systems loads can be less than full peak, an opportunity exists for cost savings if idle systems can be dynamically throttled back, slept, or shut off entirely. The paper describes two separate strategies that meet the requirements for both power conservation and system availability at HMT-ROC. The first approach, for legacy systems, is not much more than a brute force approach to power management which we call Time-Driven System Management (TDSM). The second approach, which we call Dynamic-Loading System Management (DLSM), is applicable to more current systems with ,Wake-on-LAN' capability and takes a more granular approach to the management of system resources. The paper details the rule sets that we have developed and implemented in the two approaches to system power management and discusses some results with these approaches. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Is Vancouver Canada's supervised injection facility cost-saving?

ADDICTION, Issue 8 2010
Steven D. Pinkerton
ABSTRACT Objective To determine whether Vancouver's Insite supervised injection facility and syringe exchange programs are cost-saving,that is, are the savings due to averted HIV-related medical care costs sufficient to offset Insite's operating costs? Methods The analyses examined the impact of Insite's programs for a single year. Mathematical models were used to calculate the number of additional HIV infections that would be expected if Insite were closed. The life-time HIV-related medical costs associated with these additional infections were compared to the annual operating costs of the Insite facility. Results If Insite were closed, the annual number of incident HIV infections among Vancouver IDU would be expected to increase from 179.3 to 262.8. These 83.5 preventable infections are associated with $17.6 million (Canadian) in life-time HIV-related medical care costs, greatly exceeding Insite's operating costs, which are approximately $3 million per year. Conclusions Insite's safe injection facility and syringe exchange program substantially reduce the incidence of HIV infection within Vancouver's IDU community. The associated savings in averted HIV-related medical care costs are more than sufficient to offset Insite's operating costs. [source]

The operating costs of taxation: a review of the research

Chris Evans
This paper considers key aspects of the literature on the operating costs of taxation, identifying the factors that have led to its development and evaluating its impact on policy responses to compliance and administrative costs issues. It starts by identifying the key components of the operating costs of the taxation system. The paper then identifies the main research trends over the past 60 years or so around the world, placing current concerns about taxation compliance and administrative costs within a broader - deregulatory - context and analyzing governmental responses to concerns about compliance costs highlighted by the literature. Finally, it offers some tentative views on the likely directions that research in the area may take in the coming decades. [source]

Design of dual-purpose membrane desalination systems

Rajindar Singh
Abstract Reverse osmosis (RO) and nanofiltration (NF) membrane plants are used extensively for brackish water desalination and industrial water purification. The operating range of RO plants is 60,80% product water recovery depending on the quality of raw water and feed water pretreatment. Typically, these plants operate at 75% recovery. The disposal of RO reject streams (20,40% of plant feed water) containing high concentration of salts is becoming an environmental problem. To reduce brine disposal costs and to increase product water recovery, several high-recovery energy-efficient membrane processes were analyzed. Generally speaking, a balance is required between brine volume reduction, capital and operating costs, energy consumption, and process simplicity. The analyses showed that up to 90% product water recovery can be achieved for low to medium brackish feed waters using RO/NF membrane systems with minimal feed water chemical pretreatment. The benefits of hybrid membrane systems integrated with fuel cell alternate energy systems are discussed. © 2009 American Institute of Chemical Engineers Environ Prog, 2010 [source]

The restructuring and privatisation of British Rail: was it really that bad?

FISCAL STUDIES, Issue 4 2002
Michael G. Pollitt
Abstract This paper uses a social cost-benefit analysis (SCBA) framework to assess whether rail privatisation in Britain has produced savings in operating costs. The paper shows that major efficiencies have been achieved and consumers have benefited through lower prices, whilst the increased government subsidy has been largely recouped through privatisation proceeds. We also find that output quality is no lower (and is probably better) than under the counterfactual scenario of public ownership (pre-Hatfield). The achievement of further savings is key to delivering improved rail services in the future. This paper finds that a privatised structure, where shareholders demand a return on their investment, has led to significant improvements in operating efficiency. It remains to be seen whether the new regime, with a not-for-profit infrastructure owner, will deliver the same efficiency improvements. [source]

Coding Response to a Case-Mix Measurement System Based on Multiple Diagnoses

Colin Preyra
Objective. To examine the hospital coding response to a payment model using a case-mix measurement system based on multiple diagnoses and the resulting impact on a hospital cost model. Data Sources. Financial, clinical, and supplementary data for all Ontario short stay hospitals from years 1997 to 2002. Study Design. Disaggregated trends in hospital case-mix growth are examined for five years following the adoption of an inpatient classification system making extensive use of combinations of secondary diagnoses. Hospital case mix is decomposed into base and complexity components. The longitudinal effects of coding variation on a standard hospital payment model are examined in terms of payment accuracy and impact on adjustment factors. Principal Findings. Introduction of the refined case-mix system provided incentives for hospitals to increase reporting of secondary diagnoses and resulted in growth in highest complexity cases that were not matched by increased resource use over time. Despite a pronounced coding response on the part of hospitals, the increase in measured complexity and case mix did not reduce the unexplained variation in hospital unit cost nor did it reduce the reliance on the teaching adjustment factor, a potential proxy for case mix. The main implication was changes in the size and distribution of predicted hospital operating costs. Conclusions. Jurisdictions introducing extensive refinements to standard diagnostic related group (DRG)-type payment systems should consider the effects of induced changes to hospital coding practices. Assessing model performance should include analysis of the robustness of classification systems to hospital-level variation in coding practices. Unanticipated coding effects imply that case-mix models hypothesized to perform well ex ante may not meet expectations ex post. [source]

Optimal use of solar collectors for residential buildings

Stig-Inge GustafssonArticle first published online: 5 JUN 200
Abstract Solar radiation is an abundant free resource which may be used in the form of solar heated water. This is achieved in solar collectors which, unfortunately, are expensive devices and, further, the warm water must be stored in accumulators,items which also cost money. This paper shows how we have optimized the situation for a block-of-flats in Sweden. In order to find this point we have used the minimum life-cycle cost (LCC) concept as a criterion. The best solution is therefore found when that cost finds its lowest value. It is also examined under which conditions solar collectors are part of the optimal solution and further it is calculated what happens if this optimal point is abandoned, i.e. how much will the LCC increase if other than optimal solutions are chosen. LCC optimization for multi-family buildings almost always results in a heating system with low operating costs such as district heating or dual-fuel systems where a heat pump takes care of the base load and an oil boiler the peak. The installation cost must, however, be kept to a reasonable level. Expensive solar panel systems are therefore normally avoided if the lowest LCC shall be reached, at least for Swedish conditions. This is so even if the solar system has a very low operating cost. For buildings where the only alternative energy source is electricity, solar collectors seem to be on the rim of profitability, i.e. for an energy price of about 0.6 SEK kWh,1. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Automation of paratransit reservation, routing, and scheduling

T. Chira-Chavala
Santa Clara County, California experienced a sharp growth in demand-responsive paratransit ridership for individuals with disabilities, as a result of the passage of the 1990 Americans With Disabilities Act (ADA). This paper describes an automated paratransit system for the ADA-type paratransit operation implemented in Santa Clara County. It automated paratransit reservation, scheduling, and routing functions. The key components of this system were a digital geographic database (DGD) and an automated trip scheduling system (ATSS). Empirical evidence after one year of operation indicates numerous benefits of this automation. There were significant reductions in the paratransit operating costs and an increase in the percent shared rides. The savings in operating costs far exceeded the annualized capital cost of automation. A user survey indicates that these improvements were achieved without degradation to service quality such as vehicle on-time performance, invehicle travel times, vehicle response to open return, and ride comfort. [source]

Biodesulfurization of dibenzothiophene using recombinant Pseudomonas strain

Lavanya Meesala
Abstract BACKGROUND: The sulfur content in crude oil available from various sources ranges from 0.03 to values as high as 8.0 wt%. These high quantities of sulfur must be removed before the crude oil is processed because combustion of this oil would result in severe environmental pollution, such as acid rain. Due to high utility and operating costs, the conventional hydrodesulfurization process (HDS) is considered to be uneconomic. The biotechnological option, biodesulfurization (BDS) seems an attractive low cost, environmentally benign technology. RESULTS: This paper reports the development of a recombinant strain of bacteria designed by introducing desulfurizing, dsz genes containing plasmid pSAD 225-32, which was isolated from Rhodococcus erythropolis IGTS8 into a gram negative solvent-tolerant bacterium, Pseudomonas putida (MTCC 1194). This recombinant bacterium can desulfurize the dibenzothiophene (DBT) in the sulfur selective 4S-pathway. It has been observed that for the same concentration of DBT, the recombinant strain's growth rate is greater than that of the parent strain. Increasing the concentration of DBT resulted in an increase of lag phase as well as decreased growth rate, which shows that the bacteria is following substrate inhibition type kinetics. This genetically modified bacterium can desulfurize 73.1% of 1.2 mmol L,1 DBT (dissolved in ethanol) in 67 h of cultivation time using growing cells. CONCLUSIONS: It is concluded that further research in this area of biodesulfurization using genetically modified organisms may remove the bottlenecks presently in the way of commercialization of the BDS process. Copyright © 2007 Society of Chemical Industry [source]

Evaluation of a simple batch distillation process for treating wastes from metalworking industries

P Cañizares
Abstract A simple batch distillation process for the treatment of two types of industrial waste generated in a metalworking factory has been evaluated. Both types of waste are oil-in-water emulsions composed of numerous compounds and each type has a high content of water-soluble species. The water-soluble nature of the wastes precludes the use of conventional treatment technologies, such as ultrafiltration or chemical emulsion breaking, since they need to be complemented with additional treatment processes that would probably increase the cost considerably. A simple characterization of the liquid,vapour equilibrium and a scale-up study has demonstrated the applicability of this technology. The process allows 90% of the waste to be recovered as water, thus achieving the required quality limits for discharge into a municipal wastewater treatment plant. An approximate estimation of capital investment and operating costs for an existing case has shown the economic viability of this process. Copyright © 2004 Society of Chemical Industry [source]

The Effect of Life Cycle Cost Information on Consumer Investment Decisions Regarding Eco-Innovation

Josef Kaenzig
Summary Life cycle cost (LCC) computations are a well-established instrument for the evaluation of intertemporal choices in organizations, but they have not been widely adopted by private consumers yet. Consumer investment decisions for products and services with higher initial costs and lower operating costs are potentially subject to numerous cognitive biases, such as present-biased preferences or framing effects. This article suggests a classification for categorizing different cost profiles for eco-innovation and a conceptual model for the influence of LCC information on consumer decisions regarding eco-innovation. It derives hypotheses on the decision-making process for eco-innovation from a theoretical perspective. To verify the hypotheses, the publication reviews empirical studies evaluating the effects of LCC information on consumer investment decisions. It can be concluded that rather than finding ways to make customers pay more for environmentally sound products, the marketing challenge for eco-innovation should be reconceptualized as one of lowering customers' perceived initial cost and increasing awareness of LCC. Most existing studies report a positive effect of LCC information on the purchase likelihood of eco-innovations. Disclosing LCC information provides an important base for long-term thinking on the individual, corporate, and policy levels. [source]

Synthesis of mechanical driver and power generation configurations, Part 1: Optimization framework

AICHE JOURNAL, Issue 9 2010
Frank L. Del Nogal
Abstract This article presents a novel, systematic, and robust procedure for driver and power plant selection based on mathematical programming. The discrete nature of gas turbines is considered as gas turbine drivers and gas turbine-based power plants are selected from a group of candidates. Plant availability with considering parallel compression has also been included, which allows a more comprehensive exploitation of the trade-offs between capital costs, operating costs, and availability. When neglecting process heating and any steam equipment, the formulation can be applied to heavily power dominated processes, such as LNG. However, a more comprehensive formulation, allowing waste heat recovery and the integration with a multilevel steam system, is also proposed to produce more thermally efficient systems. This approach proved to be flexible and robust and is the first in producing solutions ranging from no-steam to all-steam systems, including all-gas turbine, all-motor and hybrid gas turbine/motor/steam systems. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source]

A ,Catch Up' Plan for radiotherapy in New South Wales to 2012

Graeme Morgan
Summary In New South Wales (NSW) from 1996 to 2006, only 34,37% of newly diagnosed cancer patients were treated with radiotherapy instead of the 50% proposed by NSW Health in Radiotherapy Plans released in 1991, 1995 and 2003. As a consequence, over 50 000 cancer patients were not treated and has resulted in the estimated premature death of over 8000 patients and over 40 000 years of life lost. In 2008, there were 42 linear accelerators in NSW rather than the 62 recommended. Based on cancer incidence projections, NSW will require 69 linear accelerators in 2012 , a shortfall of 27 linear accelerators. Already 15 linear accelerators have been approved. NSW Health has funding for seven extra linear accelerators, and eight extra linear accelerators are to be funded by the private sector. To make up the shortfall, a ,Catch Up' Plan is proposed for an additional 12 linear accelerators by the end of fiscal year 2012. This is estimated to cost $200 million over 4 years for one-off establishment costs for buildings and equipment plus $50 million per year for recurrent operating costs such as staff salaries. The ,Catch Up' Plan will create five new departments of radiation oncology in country hospitals and three new departments in metropolitan hospitals. These will be in addition to those already approved by NSW Health and will markedly improve access for treatment and result in an improvement in cancer survival. This significant increase in departments and equipment can only be achieved by the creation of an NSW Radiotherapy Taskforce similar to that proposed in the Baume report of 2002, ,A vision for radiotherapy'. Even if the ,Catch Up' Plan bridges the gap in service provision, forward planning beyond 2012 should commence immediately as 76 linear accelerators will be required for NSW in 2015 and 81 linear accelerators in 2017. [source]

Energy optimization for the design of corn-based ethanol plants

AICHE JOURNAL, Issue 6 2008
Ramkumar Karuppiah
Abstract In this work, we address the problem of optimizing corn-based bioethanol plants through the use of heat integration and mathematical programming techniques. The goal is to reduce the operating costs of the plant. Capital cost, energy usage, and yields,all contribute to production cost. Yield and energy usage also influence the viability of corn-based ethanol as a sustainable fuel. We first propose a limited superstructure of alternative designs including the various process units and utility streams involved in ethanol production. Our objective is to determine the connections in the network and the flow in each stream in the network such that we minimize the energy requirement of the overall plant. This is accomplished through the formulation of a mixed-integer nonlinear programming problem involving short-cut models for mass and energy balances for all the units in the system, where the model is solved through two nonlinear programming subproblems. We then perform a heat integration study on the resulting flowsheet; the modified flowsheet includes multieffect distillation columns that further reduces energy consumption. The results indicate that it is possible to reduce the current steam consumption required in the transformation of corn into fuel grade ethanol by more than 40% compared to initial basic design. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source]