Substantial Operational Costs Research Articles

A two-stage hybrid flow-shop formulation for sterilization processes in hospitals

Sterile processing is a critical secondary process and a major cost factor in the processing, acquisition, and storage of costly medical devices. This article aims to improve the performance of sterile processing by developing, implementing, and evaluating a dispatching rule-based algorithm to reduce the time medical devices spend in the central sterile supply department using a two-stage hybrid flow-shop formulation. The algorithm combines dispatching rules with stage decomposition and compatibility conditions. A genetic algorithm is designed to benchmark the performance in addition to an analytic bound. Real-world data from a large German hospital were used to test the effectiveness of the heuristics. The case study demonstrated the practical implications of the approach, leading to a reduction in the time medical devices spend in the system and improved utilization of washer-disinfector machines and sterilizers. It also highlighted the importance of aligning machine capacity with demand and the potential trade-offs associated with batch processing decisions. Our approach can contribute to substantial operational cost savings and efficiency gains, offering significant benefits to decision makers at both the operational and tactical levels.

Green Certification and Its Impact on Hotel Marketability and Profitability

Purpose: The general objective of this study was to analyze the benefits and challenges of obtaining green certifications for hotels. Methodology: The study adopted a desktop research methodology. Desk research refers to secondary data or that which can be collected without fieldwork. Desk research is basically involved in collecting data from existing resources hence it is often considered a low cost technique as compared to field research, as the main cost is involved in executive’s time, telephone charges and directories. Thus, the study relied on already published studies, reports and statistics. This secondary data was easily accessed through the online journals and library. Findings: The findings reveal that there exists a contextual and methodological gap relating to green certification and its impact on hotel marketability and profitability. Preliminary empirical review revealed that green certification significantly enhanced hotel marketability and profitability. Green-certified hotels attracted more environmentally conscious consumers, resulting in higher occupancy rates and increased customer loyalty. Additionally, these certifications led to substantial operational cost savings in areas such as energy and water use, and allowed hotels to command premium pricing. Overall, the findings demonstrated that adopting sustainable practices through green certification provided both environmental and economic benefits, positioning hotels for better success in the competitive market. Unique Contribution to Theory, Practice and Policy: The Institutional Theory, Resource-Based View (RBV) and Signaling Theory may be used to anchor future studies on green certification and its impact on hotel marketability and profitability. The study recommended that hotels pursue green certifications to enhance marketability and profitability, emphasizing their importance as strategic investments. It highlighted the theoretical relevance of Institutional Theory and the Resource-Based View (RBV), suggesting further research into normative pressures and specific resources. Practically, it advised hotels to adopt and communicate sustainable practices, engage guests in sustainability initiatives, and provide staff training. For policymakers, it recommended supportive policies, incentives, and public awareness campaigns. The study also encouraged future research into the long-term financial impacts of green certification and the role of technology in sustainability efforts. Keywords: Green Certification, Hotel Marketability, Hotel Profitability, Sustainability Practices, Operational Cost Savings, Eco-Friendly Accommodations, Energy Efficiency

Critical risk management strategies for the operation of public–private partnerships: a vulnerability perspective of infrastructure projects

PurposeThe success of public–private partnership (PPP) projects is highly correlated to the successful management of risks encountered during the operation phase. PPP projects are especially exposed to risk due to the long operation period over which revenues need to be generated to recoup substantial initial investment and operational running costs. Despite the critical impact of risk exposure, limited research has been specifically undertaken on the matter of operational risk management. This study seeks to address this oversight by identifying and evaluating operational risk management strategies for PPPs.Design/methodology/approachVulnerability theory is the theoretical lens used, with context drawn from Chinese PPP projects. Based on the data collected from expert interviews and questionnaires, 28 operational risk management strategies are identified. A fuzzy synthetic method is employed to analyze the effectiveness of the 28 strategies.FindingsThe findings reveal that providing an exit mechanism clause into the contract, establishing a comprehensive performance evaluation mechanism and developing a clear compensation mechanism are the top three effective strategies. This study also reveals that risk mitigation approaches that reduce vulnerability prove more effective than attempts to reduce external threats. Specifically, strategies aimed at managing contract, political, technical and financial risk are the most effective.Originality/valueThe findings of this study extend current knowledge regarding the risk management of PPP projects. They also offer a reference by which practitioners may select effective operational risk management pathways and thereby, galvanize the sustainable development of PPPs.

Energy-aware coordinated operation strategy of geographically distributed data centers

As digital technology continues to advance rapidly, the substantial operational electricity costs associated with the extensive deployment of globally distributed internet data centers have become a significant concern. Addressing this challenging issue is crucial for the future expansion of internet data centers. In this paper, a coordinated strategy is proposed that leverages the spatial–temporal flexibility of internet data centers and their interaction with the power system. Firstly, an energy-aware internet data center loading model is introduced that incorporates multiple coupled scheduling methods to maximize the utilization of internet data centers' flexibility potential. Secondly, the proposed internet data centers loading model is integrated into a coordinated optimization model aimed at achieving higher profits through cost reduction in response to varying electricity prices across multiple regions. To facilitate the coordinated operation of geo-graphically internet data centers, an incentive profit-sharing mechanism based on Nash Bargaining theory is designed to fairly distribute coordination profits based on the contribution ratio of each data center in coordination. Through comprehensive case studies utilizing real-world datasets, the results demonstrate that the internet data center loading model, considering multiple coupled scheduling methods, can enhance internet data centers’ flexibility potential, resulting in a significant 11.73% reduction in total cost, with the coupling relationship accounting for 5.05% of this reduction. Furthermore, the proposed profit-sharing mechanism effectively fosters coordination and enthusiasm among geographically distributed internet data centers.

Hybrid uncertainty approach for management of energy storage-embedded soft open points in distribution grids

Energy storage-embedded soft open point (ESOP) is an innovative electronic device that incorporates energy storage capabilities and is designed to interconnect two or three neighboring distribution feeders. Its primary functions include active power control, reactive power compensation, and grid voltage regulation. On the other hand, distribution grids have been equipped with other distributed energy resources (DERs) such as smart PV inverters, renewable energy sources (solar and wind), and so on. Therefore, this article proposes a novel management scheme for the mentioned devices in distribution grids based on a convex formulation to take powerful solvers like CPLEX into account. Since there are a set of uncertainties associated with the model, including renewable resources, loads, and market price, a hybrid framework is developed based on the unscented transformation (UT) method and information gap decision theory (IGDT). In other words, the uncertainties of renewable resources and loads are captured by the UT method which could provide a correlation among uncertain parameters, while the IGDT method is employed to model the uncertainty associated with the market price. The hybridization of these methods assists in reducing the discrepancy between the actual and predicted values of uncertain parameters. The model is applied to a 33-bus grid, considering various case studies. The proposed method results in a substantial operational cost reduction of approximately 26.82 %. Additionally, it ensures a flatter voltage profile across the network, with the minimum voltage reaching 0.985 p.u.

Engineering characteristics and classification based on JSCE in portal zones of Tunnel A, Yogyakarta - Bawen toll road, Magelang District, Central Java Province

The Yogyakarta - Bawen Twin Tunnels emerge as an environmentally conscious solution for Toll Road Phase 5 (STA 6+300 to STA 27+640), addressing the ecological impact of open-cut excavation, which demands a staggering 1,209,056 m3. Open-cut excavation not only incurs substantial operational costs, encompassing disposal and treatment, but also poses threats like groundwater loss and erosion-induced landslides. The twin tunnels mitigate these concerns by limiting excavation volume to a mere 1/8, averting substantial costs and ecological damage. Challenges persist, particularly in the portal zones of Tunnel A, characterized by a shallow overburden and exposure to weathering. The Japan Society of Civil Engineers (JSCE) Method proves instrumental in assessing ground quality in these zones, considering factors such as competence, unit weight, unconfined compressive strength, depth of cover, elastic wave velocity, boring core condition, and geological characteristics. The analysis reveals a ground quality classification of E for the portal zone in Tunnel A, emphasizing the necessity for a meticulous design approach that incorporates analytical methodologies alongside empirical considerations. Notably, the unconfined compressive strength ranges from 32.89 to 472.88 kPa, and the elastic wave velocity spans 402 to 2000 meters/sec, reinforcing the imperative for a comprehensive and analytically informed design for excavation and support systems.

A coupled fluid-thermo-mechanical evaluation of various freeze recovery strategies for molten salt parabolic trough collectors

This research advances the field of Concentrating Solar Power (CSP) by offering a comprehensive assessment of freeze-recovery strategies for molten salt parabolic trough collectors, essential for the next generation of CSP plants. Employing a cutting-edge transient 3D Conjugate Heat Transfer (CHT) model, the research elucidates the significant yet previously underestimated role of natural convection in the phase transition of solidified salts. The study demonstrates that the strategic inclusion of impedance heating not only accelerates the defrosting process but also minimizes thermal stresses within the absorber tubes, ensuring mechanical integrity. Moreover, the dual-method approach, which combines solar and impedance heating, reveals a potential to improve the Levelized Cost of Electricity (LCOE) by 4% annually following a complete freeze event. The research conclusively suggests that this synergistic strategy could yield substantial operational cost savings while maintaining the structural robustness of CSP systems. The presented findings provide a detailed blueprint for enhancing plant resilience and economic viability, opening new avenues for operational excellence in CSP technology.

Optimization of wastewater treatment systems for growing industrial parks

Wastewater treatment is one of the crucial functions of industrial parks as wastewater from industrial facilities usually contains toxic compounds that can cause damage to the environment. To control their environmental loads, industrial parks make investment decisions for wastewater treatment plants. For this, they need to consider technical and economic factors as well as future growth projections as substantial construction and operational costs of wastewater treatment plants have to be shared by all companies in an industrial park. In this paper, we consider the long-term capacity planning problem for wastewater treatment facilities of a stochastically growing industrial park. By explicitly modeling randomness in the arrival of new tenants and their random wastewater discharges, our model calculates the future mean and variance of wastewater flow in the industrial park. Mean and variance are used in a Mixed Integer Programming Model to optimize wastewater treatment plant selection over a long planning horizon (30 years). By fitting our first model to empirical data from an industrial park in Turkey, we find that considering the variance of wastewater load is critical for long-term planning. Also, we quantify the economic significance of lowering wastewater discharges which can be achieved by water recycling or interplant water exchange.

Analysis and optimization of thermo-hydraulic characteristics of phase change slurry in wavy MCHS with porous fins based on RSM and desirability methods

In this study, the hydromechanical and diathermanous characteristics of microencapsulated phase change material (MPCM) slurry in wavy microchannel heat sink (MCHS) with porous fins are investigated by using two–phase mixture and Dacry–Brinkman–Forchheimer models. Based on the finite volume method (FVM) and response surface methodology (RSM), 54 cases considering 6 structural parameters are carried out. The correlations of Nusselt number (Nu) and friction factor (f) in straight and wavy microchannels with phase change slurry and porous fin designs are creatively proposed and unified. The maximum deviations between the actual and predicted values of Nu and f are 13.24% and 14.21%, respectively. In addition, the effects of radiator's parameters on Nu and f are emphatically discussed and analyzed by using three-dimensional surface diagram. It reveals that within the range of parameters tested, wavy amplitude (A) has the most obvious effect on responses, while channel aspect ratio (α) has the least impact on them. Moreover, the interactive effects between the five structural parameters are significant and complex, as one factor influences the impact of another on responses. Finally, the optimal parameters are obtained by desirability method with the goal of maximum Nu and minimum f. The results indicate that the overall performance of optimized configuration improved by 48.6% over the initial design. Our results may provide helpful guidance for the optimization design of MCHS, as significant improvement in heat transfer coefficient is expected to save substantial operating costs.

Microgrid Optimal Scheduling

This paper presents the optimal scheduling of renewable resources using interior point optimization for grid-connected and islanded microgrids (MG) that operate with no energy storage systems. The German Jordanian University (GJU) microgrid system is used for illustration. We present analyses for islanded and grid-connected MG with no storage. The results show a feasible islanded MG with a substantial operational cost reduction. We obtain an average of $1 k daily cost savings when operating an islanded compared to a grid-connected MG with capped grid energy prices. This cost saving is 10 times higher when considering varying grid energy prices during the day. Although the PV power is intermittent during the day, the MG continues to operate with a voltage variation that does not 10%. The results imply that MGs of GJU similar topology can optimally and safely operate with no energy storage requirements but considerable renewable generation capacity.

Towards environmental detection of Chagas disease vectors and pathogen

Chagas disease vector control relies on prompt, accurate identification of houses infested with triatomine bugs for targeted insecticide spraying. However, most current detection methods are laborious, lack standardization, have substantial operational costs and limited sensitivity, especially when triatomine bug densities are low or highly focal. We evaluated the use of FTA cards or cotton-tipped swabs to develop a low-technology, non-invasive method of detecting environmental DNA (eDNA) from both triatomine bugs and Trypanosoma cruzi for use in household surveillance in eastern Colombia, an endemic region for Chagas disease. Study findings demonstrated that Rhodnius prolixus eDNA, collected on FTA cards, can be detected at temperatures between 21 and 32 °C, when deposited by individual, recently blood-fed nymphs. Additionally, cotton-tipped swabs are a feasible tool for field sampling of both T. cruzi and R. prolixus eDNA in infested households and may be preferable due to their lower cost. eDNA detection should not yet replace current surveillance tools, but instead be evaluated in parallel as a more sensitive, higher-throughput, lower cost alternative. eDNA collection requires virtually no skills or resources in situ and therefore has the potential to be implemented in endemic communities as part of citizen science initiatives to control Chagas disease transmission.

Low-field benchtop versus high-field NMR for routine 31P analysis of lignin, a comparative study

Over the past decade, advances in lignin characterization methods have led to a better understanding of lignin structure and reactivity. Novel chromatographic and spectrometric techniques, especially NMR, are now essential and routine for lignin analysis. Among these methods, quantitative 31P NMR spectroscopy proved itself as a powerful technique for the qualitative and quantitative analyses of diverse types of hydroxyl groups in lignin. Nevertheless, 31P NMR spectroscopy is typically accomplished using high-field NMR equipment that necessitates substantial investment and operational cost, limiting its ability to be employed as a routine tool for analysis and quality control in a production environment. In this work 31P NMR experiments were performed on several lignins, including technical, depolymerized, and modified lignins, using both an 80 MHz benchtop NMR and a 400 MHz high-field conventional NMR. Both NMR spectrometers showed similar results for both non-functionalized and modified lignins. This work demonstrates that low-field benchtop NMR is an excellent alternative to the conventional high-field NMR equipment to analyze the hydroxyl content of lignins.

Asynchronous Peer-to-Peer Federated Capability-Based Targeted Ransomware Detection Model for Industrial IoT

Industrial Internet of Thing (IIoT) systems are considered attractive ransomware targets because they operate critical services that affect human lives and have substantial operational costs. The major concern is with brownfield IIoT systems since they have legacy edge systems that are not fully prepared to integrate with IoT technologies. Various existing security solutions can detect and mitigate such attacks but are often ineffective due to the heterogeneous and distributed nature of the IIoT systems and their interoperability demands. Consequently, developing new detection solutions is essential. Therefore, this paper proposes a novel targeted ransomware detection model tailored for IIoT edge systems. It uses Asynchronous Peer-to-Peer Federated Learning (AP2PFL) and Deep Learning (DL) techniques as a targeted ransomware detection algorithm. The proposed model consists of two modules: 1) Data Purifying Module (DPM) aims to refine and reconstruct a valuable and robust representation of data based on Contractive Denoising Auto-Encoder (CDAE), and 2) Diagnostic and Decision Module (DDM) is used to identify targeted ransomware and its stages based on Deep Neural Network (DNN) and Batch Normalization (BN). The main strengths of this proposed model include: 1) each edge gateway’s modules work cooperatively with its neighbors in an asynchronous manner and without a third party, 2) it deals with both homogeneous and heterogeneous data, and 3) it is robust against evasion attacks. An exhaustive set of experiments on three datasets prove the high effectiveness of the proposed model in detecting targeted ransomware (known and unknown attacks) in brownfield IIoT and the superiority over the state-of-the-art models.

JOINT EFFECT OF FORECASTING AND LOT-SIZING METHOD ON COST MINIMIZATION OBJECTIVE OF A MANUFACTURER: A CASE STUDY

Forecasting and lot-sizing problems are key for a variety of products manufactured in a plant of finite capacity. The plant manager needs to put special emphasis on the way of selecting the right forecasting methods with a higher level of accuracy and to conduct procurement planning based on specific lot-sizing methods and associated rolling horizon. The study is conducted using real case data form the Fibertex Personal Care, and has evaluated the joint influence of forecasting procedures such as ARIMA, exponential smoothing methods; and deterministic lot-sizing methods such as the Wagner-Whitin method, modified Silver-Meal heuristic to draw insights on the effect of the appropriate method selection on minimization of operational cost. The objective is to explore their joint effect on the cost minimization goal. It is found that a proficient selection process has a considerable impact on performance. The proposed method can help a manager to save substantial operational costs.

How Does Dockless Bike-Sharing System Behave by Incentivizing Users to Participate in Rebalancing?

Dockless bike-sharing has provided a flexible and convenient travel mode in recent years, with which shared bikes can be rented and returned easily. However, addressing the imbalance between demand and supply effectively becomes a major challenge to guarantee the sustainability of such systems. Vehicle-based approach results in substantial operating costs and more emissions. This study proposed a user-based model to incentivize users to participate in bike rebalancing. This model contains three important components: 1) determination of a bike surplus region by sorting surplus level in descend order; 2) determination of a bike deficient region from the perspective of users' utility maximization; and 3) updating the states of regions. Several numerical tests were implemented to evaluate the model's performance based on predefined parameters and historical trip data in downtown of Nanjing. As the results indicate, unmet demand can be greatly reduced if providing a certain level of monetary incentive. Different values of the maximum acceptable walking distance make little difference in demand loss and operating cost at a low level of incentive. With regard to the users, it implies that higher proportion of cooperative customers who are willing to participate in rebalancing can lead to a larger reduction of unmet demand. In addition, using surplus level as the index to define bike surplus regions is beneficial to saving the overall operating cost.

KELAYAKAN FINANSIAL USAHA PERIKANAN HUHATE DI KECAMATAN SAPARUA KABUPATEN MALUKU TENGAH

Saparua is a district in Central Maluku Regency which has 8 units of huhate (pole and line) fishing fleet and can be operated throughout the season. This condition shows that this business should be able to provide benefits, both for the owners and fishermen. However, the utilizing of skipjack resources that have exceeded the MSY value and also the substantial operational costs cause income to decline. Therefore this study aims to analyze the financial feasibility of the pole and line fisheries business in Saparua District. A survey for 5 pole and line business units in Saparua was conducted to obtain data, which were then analyzed by using several investment criteria such as NPV (Net Present Value), IRR (Internal Rate of Return), and B / C (Benefit Cost Ratio). The results show that: 1). The implementation of business management is still simple, but the tasks division among fishermen is clear. The decision is generally made by the owner. The frequency of fishing depends on the fishing season. During the west season, the fishing ground is in Banda Sea to the southern part of Seram Sea, while in the eastern season is in the northern part of Seram Sea; 2). Based on the pattern of revenue sharing, the average fishermen's income / month is lower than the minimum wage provincial (UMP) in Maluku; and 3). The highest economic benefit is achieved by the 4th pole and line unit, as well as the B / C Ratio criteria index so that it becomes a development priority because B / C Ratio shows the comparison of sacrifice (output) and results (input).

Enhancing boron rejection on electrically conducting reverse osmosis membranes through local electrochemical pH modification

Reverse-osmosis (RO) has become a prevailing technology for seawater desalination. While RO removes the majority of ions in seawater, the removal of small, uncharged contaminants remains challenging. Boron existing as uncharged boric acid (B (OH)3) in seawater is partially removed during the RO process, requiring further treatment if the desalinated seawater will be used for certain crop irrigation. Boron removal efficiency is significantly improved under a high pH condition where non-charged B(OH)3 turns into negatively charged borate (B(OH)4−). Therefore, RO desalination plants often exploit a double-pass configuration, where the pH of the RO permeate from the first pass is chemically increased above the pKa of B(OH)3, and is treated again using RO membrane (the second pass). Although this process can achieve high boron removal efficiency, it incurs substantial operating and capital costs. In this study, commercial RO membranes are coated with carbon nanotubes forming an electrically conducting, porous layer. We explore the impact of applied cathodic potentials on boron and salt rejection, membrane flux, and fouling. We demonstrate that applying cathodic potentials can elevate the near-membrane pH, which dramatically increases boron rejection. However, the higher pH results in membrane scaling (Mg(OH)2), although the formed scaling does not dramatically reduce membrane flux.

The Production of Reduced Graphene Oxide by a Low-Cost Vacuum System for Supercapacitor Applications

Graphene has attracted significant interest because of its excellent electrical properties. However, a practical method for producing graphene on a large scale is yet to be developed. Graphene oxide (GO) can be partially reduced to graphene-like sheets by removing the oxygen-containing groups and recovering the conjugated structure. GO can be produced using inexpensive graphite as the raw material via cost-effective chemical methods. High vacuum and temperature (10−7 mbar and 1100°C, respectively) conditions are well-known to enable the preparation of reduced powder at the laboratory scale. However, a large-scale high vacuum reduction system that can be routinely operated at 10−7 mbar requires considerable initial capital as well as substantial operational and maintenance costs. The current study aims at developing an inexpensive method for the large-scale reduction of graphene oxide. A stainless steel vessel was evacuated to backing-pump pressure (10−2 mbar) and used to process GO at a range of temperatures. The reduction of GO powder at low vacuum pressures was attempted and investigated by X-ray diffraction and Fourier transform infrared spectroscopy. The experimental results of processing GO powder at various temperatures (200–1000°C) at relatively low pressures are reported. The microstructures of the processed materials were investigated using scanning electron microscopy and chemical microanalyses via energy dispersive X-ray analysis.

A Parametric Study of Different Recycling Configurations for the Natural Gas Dehydration Process Via Absorption Using Triethylene Glycol

In this work, the effect of triethylene glycol (TEG) flowrate on the water content in dry product gas, the TEG loss rate, and the BTEX (i.e. benzene, toluene, ethylbenzene, and xylene) emission of a conventional natural gas dehydration process via absorption using TEG were evaluated. Given the conflicting nature of decreasing water content against increasing BTEX emission and TEG loss rate with increasing TEG flowrate, an optimum TEG flowrate was determined that gives the minimum water content in dry product gas with minimum TEG loss rate and BTEX emission. The possibility of improving the dehydration process performance was additionally investigated through recycling the flash vapour or the regenerator overhead or both the flash vapour and the regenerator overhead into the absorber. The aforementioned recycling configurations aim towards sustainable design for a natural gas dehydration process that provides a lower BTEX emission and TEG loss rate (i.e. plant’s wastage). These recycling configurations were also evaluated based on economic analysis. Our simulation results however revealed that the TEG loss rate is only reduced by 0.4% in all three different configurations. The reduction in water content, on the other hand, is always traded-off by the increase in the total BTEX emission and vice versa, by marginal amount, relative to the base case scenario. Therefore, applying such configuration does not contribute towards sustainable design and significant process performance improvement despite requiring substantial additional capital and operational costs.

Combined biological and advance oxidation processes for paper and pulp effluent treatment

During recent years, the socio political pressure to develop suitable technologies capable of treating wastewater from the paper and pulp industry has increased due to strict environmental regulations. System closure could potentially lead to substantial operating and discharge cost savings. This study evaluates the potential of combining an aerobic moving bed biofilm reactor (MBBR) (biological) and a Fenton-like system (advanced oxidation processes) for treating recycle mill effluent (RME). The performance of the moving bed biofilm reactor (MBBR) was evaluated at three different hydraulic residence times (HRT). The HRT used were 24, 16 and 5 h and the corresponding total chemical oxygen demand (COD) removals were 55, 49 and 43% respectively. The volatile organic acids (VOA) removals were 63.5, 58.7 and 53% respectively. The Kincannon-Stover model was used to describe the kinetic behaviour of the MBBR. The calculated KB and Umax parameters for the COD were 26.37 g.L−1.d−1 and 15.06 g.L−1.d−1 respectively. For the VOA, the KB and Umax parameters were 11.81 g.L−1.d−1 and 8.87 g.L−1.d−1. The Fenton-like experiments were carried out in batch runs. The first experiments were carried out to determine the optimal reaction parameters. Maximum COD removals were found to be at a pH of 3.33, Fe3+ dosage of 1,000 mg/L and H2O2 of 14.55 mM. Pseudo-first order reaction kinetics was used to describe the kinetic characteristics of the Fenton-like treatment system. The calculated kinetic parameters ηmax (%) and kCOD (min−1) were 53.8% and 0.112 min−1 respectively at a pH of 3.24, Fe3+ dosage of 250 mg/L and a H2O2 dosage of 77 mM.