Related Operating Costs Research Articles

High Performance Data Centers and Energy Efficiency Potential in Greece

Data centers are amongst the most complex and energy demanding building environments. The trends of increasing data center capacity and power use by information technology equipment, re-emphasize the need to reduce cooling loads, first cost for HVAC equipment, and finally related energy and operational costs. The first part of the paper presents an overview of relevant information and available resources for the efficient design and operation of these critical environments. The second part considers two large data centers located in Athens that serve two major Hellenic banks as case studies in order to investigate and quantify the potential measures for improving their energy performance. The two facilities were audited and actual energy consumption were used for an energy assessment. According to simulation results of various efficiency measures, the Power Usage Effectiveness may be improved from 2.49 to 2.11 for the first case study and from 1.89 to 1.66 for the second one.

STUDY OF WORKING CAPACITY OF THE MARSHALLING YARD

Purpose. The scientific paper has a purpose to choose rational technological parameters of the transportation organization process, which would enable the freight train movement with the most efficient train traffic arrangement, the decrease in idle time due to the increased speed of cargo delivery and the increase in the working capacity of the marshalling yard. Methodology. The work presents the technical and operational characteristics of marshalling yards in Europe and Ukraine. The research methods include the station operation analysis, the car traffic flow analysis, analysis of the train sheet, the DU-1 natural sheets upon arrival and departure of trains. Schemes were developed for calculating working capacity of necks, rehandling capacity of marshalling hump, acceptable levels of system loading. Findings. The research resulted in the calculated working (rehandling) capacity of the main elements of the station. Daily loads of marshalling hump and turnout tracks vary significantly by variations and gradations of movement volume. This affects the idle time of trains and, in general, the value of the criterion according to which the optimal technical equipment, optimum interaction of the subsystems and gridiron of the station will be chosen. This criterion must take into account the costs of technical equipment, construction of tracks, locomotives, as well as related operating costs in all cases. Thus, the selection of the optimal interaction should establish the economically viable level of operational reliability of the sub-systems, their technical and track capacity. Originality. By increasing the productivity of train departure channel, marshalling hump and turnout tracks it is possible the thetrain handling processes and reduce the car idle time. Intensification of production processes in marshalling yards provides a reduction in car turnover and in idle time and high economic efficiency of capital investments. The work covers the issues related to improving the efficiency of functioning of marshalling yards in the railway transport reforming conditions. Practical value. Using the methods of determining the rational working (rehandling) capacity of marshalling yards for distribution of train traffic flows between them makes it possible to improve the quality indicators of marshalling yard operation.

The Psychology of Co‐Branding Alliances: The Business‐to‐Business Relationship Outcomes of Role Stress

ABSTRACTThe study investigates the performance effects of postalliance role stress among retail managers. Co‐branded alliances produce dynamic and complex role structures subject to psychological conflict and ambiguity. These co‐branded outlets enable firms to enter markets efficiently, lower relative operating costs, and raise performance. Despite the seemingly ubiquitous use of this strategy, many co‐branded locations yield less than desirable results. The paper employs role theory to investigate whether ambiguity and conflict become more acute in co‐branded outlets. In addition, it investigates whether competence and communication modality constrain role stress. Data gathered with 416 franchisees indicate that co‐branding alliance influences role stress and interorganizational performance.

Determination of the Technical Energy Flexibility of Production Systems

Besides the energy efficiency approach to reduce energy demands of production systems there are also other possibilities to decrease the energy related operating costs. Amongst others avoiding long-term peak loads represents a common measure. In possible future cases a flexible energy demand of factories can also be refunded by the energy provider within new tariff structures. This paper shows the potentials of production systems to alternate their energy demand within productive state, which is also referred to as technical energy flexibility. The focus is on machines of sensitive main processes, where an influence on the energy demand could induce distinct negative effects on the product quality. It is shown how and to which extent the energy demand of production systems can be controlled without negative effects.

Temperature control of nutrient solution in floating system cultivation

Water temperature plays a relevant role in the growth and development of plants in floating system cultivation, thus affecting both productivity and quality. A model of a greenhouse which hosts ponds is described, in order to highlight the components of the energy balance and estimate the refrigerating power required to maintain the nutrient solution within acceptable limits. A water cooling plant powered by an electrical water chiller is considered. Results from this model include the prediction of the air temperature and nutrient solution temperature in transient conditions during the growth periods, together with the electrical energy absorption and related operating costs. After a validation by comparison with measured data, simulations are performed at six climate conditions, from typical warm Mediterranean to cold continental conditions.Important energy savings can be achieved by maintaining the water covered by boards during harvesting at the end of the growing cycle. Furthermore, the water cooling system can be designed to be reversible and perform air heating in winter time, with the aim of extending the growing period. The amount of heating power required by the heating system in winter time is thus estimated.

Electrochemical advanced oxidation and biological processes for wastewater treatment: a review of the combined approaches.

As pollution becomes one of the biggest environmental challenges of the twenty-first century, pollution of water threatens the very existence of humanity, making immediate action a priority. The most persistent and hazardous pollutants come from industrial and agricultural activities; therefore, effective treatment of this wastewater prior to discharge into the natural environment is the solution. Advanced oxidation processes (AOPs) have caused increased interest due to their ability to degrade hazardous substances in contrast to other methods, which mainly only transfer pollution from wastewater to sludge, a membrane filter, or an adsorbent. Among a great variety of different AOPs, a group of electrochemical advanced oxidation processes (EAOPs), including electro-Fenton, is emerging as an environmental-friendly and effective treatment process for the destruction of persistent hazardous contaminants. The only concern that slows down a large-scale implementation is energy consumption and related investment and operational costs. A combination of EAOPs with biological treatment is an interesting solution. In such a synergetic way, removal efficiency is maximized, while minimizing operational costs. The goal of this review is to present cutting-edge research for treatment of three common and problematic pollutants and effluents: dyes and textile wastewater, olive processing wastewater, and pharmaceuticals and hospital wastewater. Each of these types is regarded in terms of recent scientific research on individual electrochemical, individual biological and a combined synergetic treatment.

Evaluating the productivity and financial feasibility of a vertical-axis micro-hydro energy generation project using operation simulations

This study proposes a financial feasibility evaluation method for canal-based micro-hydroelectric energy projects. In numerous countries, the use of river water for irrigation or livelihoods typically necessitates the implementation of diversion projects and the construction of canals. Therefore, this study endeavors to explore the productivity of a canal-based micro-hydropower station and perform a financial feasibility analysis. Financial feasibility evaluations are required to support investment decisions when selecting a suitable power station site and conducting the technological development of a vertical-axis micro-hydro energy converter (MHEC). Because of a lack of long-term operational experience, the method proposed in this study referenced detailed operation simulations and related general market conditions for analysis. The factors referenced included the related operational costs, the estimated power generation ability for the station equipment, location criteria for power station establishment, and maintenance strategy selection. For this research, a case study of the Shimen Canal in Taoyuan, Taiwan, was conducted, where 100 MHECs in vertical-axis units were used to perform short-term operational tests. The test results were employed as estimated data in this study. In addition, the micro-hydropower station was adopted for financial feasibility analysis. Finally, sensitivity analyses of the case study were conducted to investigate the effects that crucial parameters have on the financial feasibility of the proposed project.

Predicting retailer orders with POS and order data: The inventory balance effect

Despite advances in retail point-of-sale (POS) data sharing, retailers’ suppliers struggle to effectively use POS data to improve their fulfillment planning processes. The challenge lies in predicting retailer orders. We present evidence that retail echelon inventory processes translate into a long-run balance or equilibrium between orders and POS, which we refer to as the inventory balance effect, allowing for more accurate order forecasting. Based on the inventory balance effect, this research prescribes a forecasting approach which simultaneously uses both sources of information (retailer order history and POS data) to predict retailer orders to suppliers. Using data from a consumable product category, this approach is shown to outperform approaches based singularly on order or POS data, by up to 125%. The strength of this novel approach – significantly improved forecast accuracy with minimal additional analysis – make it a candidate for widespread adoption in retail supply chain collaborative planning and forecasting initiatives with corresponding impact on fulfillment performance and related operating costs.

The economy of distribution centers: The case of large retail networks in Brazil

Large retail chains have revolutionized their logistics systems by positioning distribution centers (DC) close to urban centers. The primary objective was to be a prompt supplier for the nearby stores; another was to comply with the increasing traffic problems, which restrict the access of large trucks to urban retailers, while the last objective would be associated with a broader spectrum of reasons, called optimization of logistics processes. Rather than proposing the optimal location of warehouses based on the spatial distribution of flows and associated volumes, this study examines the economical meaning of creating a distribution center. In addition to the obvious reduction in transportation costs, the gains that are evaluated are referred to four factors, namely: (i) reduction of overall inventories and related operating costs, (ii) liberation of space in retail stores for parking and exposure of goods, (iii) reduction of clerical labor due to the centralization of controls on the products received and distributed, and (iv) reduction of back-orders. This study qualifies these factors and quantifies them. Key words: Logistics, distribution center, retail network.

Solving an aggregate production planning problem by using multi-objective genetic algorithm (MOGA) approach

: Received 5 September 2012 Received in revised format 25 September 2012 Accepted September 27 2012 Available online 27 September 2012 In hierarchical production planning system, Aggregate Production Planning (APP) falls between the broad decisions of long-range planning and the highly specific and detailed short-range planning decisions. This study develops an interactive Multi-Objective Genetic Algorithm (MOGA) approach for solving the multi-product, multi-period aggregate production planning (APP) with forecasted demand, related operating costs, and capacity. The proposed approach attempts to minimize total costs with reference to inventory levels, labor levels, overtime, subcontracting and backordering levels, and labor, machine and warehouse capacity. Here several genetic algorithm parameters are considered for solving NP-hard problem (APP problem) and their relative comparisons are focused to choose the most auspicious combination for solving multiple objective problems. An industrial case demonstrates the feasibility of applying the proposed approach to real APP decision problems. Consequently, the proposed MOGA approach yields an efficient APP compromise solution for large-scale problems.

Comparative analysis of low temperature industrial refrigeration systems

This paper compares the energy performance and economics of a direct two-stage ammonia system to an ammonia–carbon dioxide cascade system for low temperature (below −40 °C) applications. Component and system models are developed for both the direct ammonia and the ammonia–carbon dioxide cascade options. These models provide the basis for quantifying the relative operating costs for both systems on annual and life-cycle bases.The analysis shows that the ammonia–carbon dioxide cascade system option using a shell-and-tube cascade condenser offers the potential for increased energy efficiency when compared to a direct two-stage ammonia system when operating with evaporating temperatures that are below −46.2 °C. For the cascade system option, the analysis shows that a shell-and-tube cascade heat exchanger with design approach temperature of 5.6 °C provides the optimal balance of system performance with capital cost.

Vibration signal analysis for condition monitoring of puffer‐type high‐voltage circuit breakers using wavelet transform

AbstractNowadays, the goals of electrical supply utilities are to reduce equipment failures, extend service life, increase equipment reliability, and reduce their related operating and maintenance costs. The high‐voltage circuit breaker is an important element in the electrical network. In order to determine or to detect abnormal conditions inside a circuit breaker, powerful vibration analytical techniques have been proposed. In this paper, a vibrational analysis is carried out by analyzing the signal in the time–frequency domain under no‐load switching operations with a commercially available high‐voltage puffer‐type circuit breaker without opening its major parts. Vibration of the circuit breaker poles, operating mechanism, and various monitored parameters were recorded under normal and variable operating conditions. Moreover, a synthetic mechanical damage introduced deliberately is also investigated. The experimental result indicates that mechanical defects can be detected by analyzing the vibration signal. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Techno-economical evaluation of fluoride removal by electrocoagulation process: Optimization through response surface methodology

In this research, response surface methodology (RSM) was applied to evaluate the effect of main operational variables including initial pH, initial fluoride concentration, current density and reaction time for the removal of fluoride and its relative operating costs by electrocoagulation. It was found that the effect of initial pH was negligible on fluoride removal efficiency and operating costs. With the decrease of initial fluoride concentration, fluoride removal efficiency improved; however, it had no effect on operating costs. On the other hand, the increase of current density and reaction time severely influenced process performance and increase fluoride removal efficiency and operating costs. According to the ANOVA (analysis of variance) results, the models presented the high R2 values of 96.5% and 97.3% for fluoride removal efficiency and operating costs, respectively. The optimum initial pH, initial fluoride concentration, current density and reaction time were found to be 7, 25 mg/l, 0.0167 A/cm2, 25 min, respectively, for the removal of fluoride. Fluoride removal efficiency of 94.5% was observed in the experiment at optimum conditions which confirmed close to model predicted (90%) result.

Dynamic simulations of waste water treatment plant operation

AbstractActivated Sludge Model No. 1 (ASM1) was used to model the biological stage of an actual waste water treatment plant (WWTP). Some possibilities for the utilisation of simulation programs for WWTP operation are presented. Simulation calculations were performed taking the conditions of WWTP in Nové Zámky, the Slovak Republic, into consideration, where measurements of the diurnal variations in waste water flow and composition at the inlet and outlet were carried out. A calibrated model predicting the influence of changes in the waste water composition and the operational parameters on the effluent waste water quality and related operational costs is available. Values of the operational parameters (solids retention time, internal recirculation flow, dissolved oxygen concentration) for effective operation (effluent concentration values, oxygen consumption, charges, i.e. charges for waste water discharge into the recipient water body) of the WWTP were obtained by simulations. The presented results are for illustration purposes only and are not intended as instructions for the operation of a waste water treatment plant. They correspond to the calibrated mathematical model ASM 1 based on the results of experimental measurements and operational data, as well as on the technical and monitoring level of the WWTP.

IT Product Genetics & Inventoriable Simplicity - The Aggregate Bicameral Core Op System Model

In the last 30 years Product Distribution Enterprises have implemented Information Management Systems (ERP, MRP…) to facilitate and improve operational management. Directly attributable improvements in efficiency or realized profits have been minimal at best. Indeed, real profit (%Net) has often decreased while related operational costs have soared! Why?

Review of micromachining of ceramics by etching

In the last two decades, there has been an enormous surge in interest in ceramic materials and, as a result, there have been significant advances in their development and applications. Their inherent properties, such as capability of operating at temperatures far above metals, high level of hardness and toughness, low coefficient of thermal expansion and high thermal conductivity rendered ceramics to be one of the leading engineering materials. Many research works have been conducted in the past few years on machining of advanced ceramics using different processing methods in order to obtain a better surface roughness, higher material removal rate and improved tool life. Micromachining using chemical etching is one of those methods that do not involve the problem of tool life and direct tool–work piece contact. However, only a few research works have been done on micromachining of ceramics using chemical etching. Hence, study of chemical machining of advanced ceramics is still needed as the process has found wide application in the industry because of its relative low operating costs. In this work, we summarize the recent progresses in machining of different types of advanced ceramics, material processing methods such as wet etching and dry etching, and finally the prospects for control of material removal rate and surface quality in the process of ceramic micromachining.

Pulsed corona treatment of gases: system scaling and efficiency

A pulsed corona facility for the treatment of gases at relatively high gas flow rates and powers is described. Data are presented, mainly for the example of toluene removal, which illustrate specific energy scaling of the system with power, gas flow rate, charging voltage of the pulsed power supply and inlet concentration. The effect of plasma reactor length and charging capacitance of the pulsed power supply on the system efficiency is also investigated. The implications of the scaling and efficiency in determining the size of systems and the relative operating and capital costs for practical applications are discussed briefly.

Biomass dewaterability, filterability and settleability in a membrane bioreactor operated with different sludge ages

Membrane bioreactors (MBR) are designed to maintain high solid concentrations, thus limiting sludge production and the related operational costs of the process. Sludge physical properties strongly affect the operation of these systems, due to their influence on the filtration process and also on excess sludge handling. This study reports the physical characterization of a bench scale MBR biomass with different sludge ages and with complete sludge retention. The results span over a period of three years when a bench scale MBR was operated under the same conditions except for the sludge retention time (SRT). The main dewatering properties were measured over time and their steady state average values were related to the SRT. The capillary suction time (CST) and the specific resistance to filtration (SRF) showed similar decreasing trends during the transient phase and reached equilibrium values under steady state conditions, except in the case of complete sludge retention. Under all the tested conditions, the average equilibrium values of the CST, the SRF and the compressibility (s) of the MBR sludge were similar to those reported for conventional activated sludge, suggesting the adoption of the same dewatering technologies. In terms of settleability, the relationship between the diluted sludge volume index (DSVI) and the sludge age appeared weak for SRT higher than 20 days. Under the tested conditions, the best performances in terms of physical properties of the MBR excess sludge were obtained for sludge retention times between 40 and 80 days.

Physical characteristics of the sludge in a complete retention membrane bioreactor

Sludge physical characteristics play an important role in the operation of membrane bioreactors (MBR) due to their influence on filtration and their effects on handling of excess sludge. These systems are designed to maintain high solid concentrations, thus limiting sludge production and the related operational costs of the process. In this study, the sludge from a bench scale MBR operated for about 1 year with complete solid retention was investigated to assess its physical and rheological properties. Concentrations of mixed liquor suspended solids (MLSS) up to 24 g TSS L −1 affected the diluted sludge volume index (DSVI), the capillary suction time (CST), the specific resistance to filtration (SRF) and the compressibility (s). The MBR sludge displayed similar dewatering properties of conventional waste activated sludge, suggesting that the upgrade of wastewater treatment plants with the MBR technology would not affect the behaviour of the dewatering equipment. The apparent viscosity was expressed as a function of the MLSS and the experimental data were interpreted by comparing different models. Ostwald model was chosen, and two equations for viscosity were proposed. The thixotropy of MBR sludge was also evaluated by measuring the reduced hysteresis area (rHa) and relating this parameter to the characteristics of the sludge. The evaluation of energy consumption for mixing evidenced that, under the tested conditions, the increase of solid concentration from 3 to 30 g TSS L −1 resulted in a limited increase of energy requirements (25–30%).

Waste management of electric and electronic equipment: comparative analysis of end-of-life strategies

This article analyzes diverse aspects of the waste management of electronic and electric equipment. The scope of the study focuses on end-of-life strategies currently implemented in industrialized economies such as Japan, the United States, and the European Union. The objective is a comparative analysis of such strategies in order to identify logistic issues that may contribute to the further improvement of waste management policies. The results indicate that although all strategies follow the extended producer responsibility principle, in practice several logistic differences arise due to particular interpretations of the concept. In general, it was observed that a direct comparison is rather difficult since the strategies consider different legal frameworks, they cover different types and numbers of products, and the resultant mass flows and related operational costs are highly context-dependent variables. Therefore, it is not possible to indicate which strategy presents the highest overall efficiency. The study concludes that a little contribution is feasible if the advantages and weaknesses of the models depicted and discussed here are considered in further regulatory decisions.