Background: Venous thromboembolism (VTE) is a major public health problem due to its increasing frequency, mortality and management cost. This cost may require major financial efforts from patients, especially in deve...Background: Venous thromboembolism (VTE) is a major public health problem due to its increasing frequency, mortality and management cost. This cost may require major financial efforts from patients, especially in developing countries like ours where less than 7% of the population has health insurance. This study aimed to estimate the direct cost of managing VTE in three reference hospitals in Yaoundé. Methods: This was a cross-sectional retrospective study over a three-year period (from January 1st 2018 to December 31 2020) carried out in the Cardiology departments of the Central and General Hospitals, and the Emergency Centre of the city of Yaoundé. All patients managed during the study period for deep vein thrombosis and pulmonary embolism confirmed by venous ultrasound coupled with Doppler and computed tomography pulmonary angiography respectively were included. For each patient, we collected sociodemographic and clinical data as well as data on the cost of consultation, hospital stay, workups and medications. These data were analysed using SPSS version 23.0. Results: A total of 92 patient’s records were analysed. The median age was 60 years [48 - 68] with a sex ratio of 0.53. The median direct cost of management of venous thromboembolism was 766,375 CFAF [536,455 - 1,029,745] or $1415 USD. Management of pulmonary embolism associated with deep vein thrombosis was more costly than isolated pulmonary embolism or deep vein thrombosis. Factors influencing the direct cost of management of venous thromboembolism were: hospital structure (p = 0.015), health insurance (p 0.001), type of pulmonary embolism (p = 0.021), and length of hospital stay (p = 0.001). Conclusion: Management of VTE is a major financial burden for our patients and this burden is influenced by the hospital structure, health insurance, type of pulmonary embolism and length of hospital stay.展开更多
Accurate software cost estimation in Global Software Development(GSD)remains challenging due to reliance on historical data and expert judgments.Traditional models,such as the Constructive Cost Model(COCOMO II),rely h...Accurate software cost estimation in Global Software Development(GSD)remains challenging due to reliance on historical data and expert judgments.Traditional models,such as the Constructive Cost Model(COCOMO II),rely heavily on historical and accurate data.In addition,expert judgment is required to set many input parameters,which can introduce subjectivity and variability in the estimation process.Consequently,there is a need to improve the current GSD models to mitigate reliance on historical data,subjectivity in expert judgment,inadequate consideration of GSD-based cost drivers and limited integration of modern technologies with cost overruns.This study introduces a novel hybrid model that synergizes the COCOMO II with Artificial Neural Networks(ANN)to address these challenges.The proposed hybrid model integrates additional GSD-based cost drivers identified through a systematic literature review and further vetted by industry experts.This article compares the effectiveness of the proposedmodelwith state-of-the-artmachine learning-basedmodels for software cost estimation.Evaluating the NASA 93 dataset by adopting twenty-six GSD-based cost drivers reveals that our hybrid model achieves superior accuracy,outperforming existing state-of-the-artmodels.The findings indicate the potential of combining COCOMO II,ANN,and additional GSD-based cost drivers to transform cost estimation in GSD.展开更多
Schizophrenia is classified as a priority mental disorder by the World Health Organization (WHO) and accounts for around 35% of diagnoses at the Bingerville Psychiatric Hospital (HPB). The aims of the study were to id...Schizophrenia is classified as a priority mental disorder by the World Health Organization (WHO) and accounts for around 35% of diagnoses at the Bingerville Psychiatric Hospital (HPB). The aims of the study were to identify the cost drivers for hospitalization and to calculate the costs of managing schizophrenia in hospital, with a view to planning household expenditure on care. This pilot cross-sectional study involved 31 patients with schizophrenia who had been hospitalized in the various third-category wards at the HPB between 1st January 2019 and 31st May 2020. Sampling was accidental. The methods used to estimate costs were based on the actual costs of drugs, hospitalization and additional examinations which prices were known, and on patients’ estimations for certain expenses such as food and transport. Results: The sex ratio was 3.42, the mean age was 29.52 years. The mean length of stay was 46.19 days, and the most frequent clinical forms were paranoid schizophrenia (41.9%) and schizoaffective disorder (29%). The combination of haloperidol and chlorpromazine was the most common medications for initial treatment (67.8%) and maintenance treatment (41.9%). The average cost of hospitalization at HPB for schizophrenia was XOF 164,412 (€249.90). The average direct medical cost was XOF 105,412 (€160.226) and the average direct non-medical cost was XOF 59,000 (€89.68). The average daily cost of antipsychotic treatment was XOF 795/day (€1.2084). The high cost of drugs as a proportion of hospitalization costs suggested the need of a reflection on the simplification of prescribing practices, assistance in psychiatric emergencies and the development of other alternatives to psychiatric hospitalization in Côte d’Ivoire.展开更多
Introduction: Medical treatment for POAG is continuous and lifelong treatment. The aim of this study was to evaluate the relationship between the cost of this treatment and patients’ income and the impact of this rel...Introduction: Medical treatment for POAG is continuous and lifelong treatment. The aim of this study was to evaluate the relationship between the cost of this treatment and patients’ income and the impact of this relationship on treatment compliance. Materials and Methods: Prospective cross-sectional study with a descriptive aim covering sociodemographic data, average incomes, and direct and indirect costs of treatment of 57 patients followed for POAG during the period from January 1, 2012, to December 31, 2016 (5 years). Results: The patients were aged 25 to 77 years (mean = 54.4 years) with a male predominance (sex ratio = 1.5). Retirees were the most represented (26.32%), followed by workers in the informal sector (14.04%) and housewives (12.28%). Patients who had an annual income less than or equal to 900,000 CFA francs (€1370.83) per year represented 56.14% and those who did not have health coverage represented 57.89%. The treatment was monotherapy (64.91%), dual therapy (31.58%) or triple therapy (3.05%) and the average ratio of “annual cost of treatment to annual income” was 0.56 with for maximum 2.23 and 0.02 as minimum. Patients who considered the cost of treatment unbearable for their income represented 78.95%. Conclusion: Prevention of blindness due to glaucoma requires early detection but also the establishment of health coverage mechanisms to improve compliance with medical treatment. In addition, consideration should be given to the development of glaucoma surgery in our country, the indication of which could be the first intention in certain patients, considering for those patients, the geographical and financial accessibility of medical treatment. .展开更多
This paper presents a peer-to-peer community cost optimization approach based on a single-prosumer energy management system.Its objective is to optimize energy costs for prosumers in the community by enhancing the con...This paper presents a peer-to-peer community cost optimization approach based on a single-prosumer energy management system.Its objective is to optimize energy costs for prosumers in the community by enhancing the consumption efficiency.This study was conducted along two main axes.The first axis focuses on designing a digital twin for a residential community microgrid platform.This phase involves data collection,cleaning,exploration,and interpretation.Moreover,it includes replicating the functionality of the real platform and validating the results.The second axis involves the development of a novel approach that incorporates two distinct prosumer behaviors within the same community microgrid,while maintaining the concept of peer-to-peer energy trading.Prosumers without storage utilize their individual PV systems to fulfill their energy requirements and inject excess energy into a local microgrid.Meanwhile,a single prosumer with a storage system actively engages in energy exchange to maximize the community’s profit.This is achieved by optimizing battery usage using a cost optimization solution.The proposed solution is validated using the developed digital twin.展开更多
Creditors,such as banks,often use disclosed environmental information to assess a company’s environmental risk and ensure the safety of debt funds.Consequently,carbon disclosures have become an important consideratio...Creditors,such as banks,often use disclosed environmental information to assess a company’s environmental risk and ensure the safety of debt funds.Consequently,carbon disclosures have become an important consideration for creditors when making investments.This study explores the relationship between carbon disclosure and debt financing costs using data on listed companies from 2008 to 2019.The results show that carbon disclosure can reduce the debt financing costs of enterprises,and that this influence is more significant for private companies than for state-owned enterprises.Instrumental variables and Propensity Score Matching(PSM)were used to evaluate the robustness of negative relationships.Furthermore,carbon disclosure has a more significant impact on debt costs with less environmental supervision pressure,weak residents’environmental awareness,and weak product market competition.These findings provide guidance for companies’carbon information disclosure and support the establishment of official carbon disclosure standards.展开更多
Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonun...Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonuniform corrosion using different materials.In this study,a reliability-based design optimization(RBDO)procedure is improved for the design of coastal bridge piers using six groups of commonly used materials,i.e.,normal performance concrete(NPC)with black steel(BS)rebar,high strength steel(HSS)rebar,epoxy coated(EC)rebar,and stainless steel(SS)rebar(named NPC-BS,NPC-HSS,NPC-EC,and NPC-SS,respectively),NPC with BS with silane soakage on the pier surface(named NPC-Silane),and high-performance concrete(HPC)with BS rebar(named HPC-BS).First,the RBDO procedure is improved for the design optimization of coastal bridge piers,and a bridge is selected to illustrate the procedure.Then,reliability analysis of the pier designed with each group of materials is carried out to obtain the time-dependent reliability in terms of the ultimate and serviceability performances.Next,the repair time of the pier is predicted based on the time-dependent reliability indices.Finally,the time-dependent LCCs for the pier are obtained for the selection of the optimal design.展开更多
Chemical looping combustion has the potential to be an efficient and low-cost technology capable of contributing to the reduction of the atmospheric concentration of CO_(2) in order to reach the 1.5/2°C goal and ...Chemical looping combustion has the potential to be an efficient and low-cost technology capable of contributing to the reduction of the atmospheric concentration of CO_(2) in order to reach the 1.5/2°C goal and mitigate climate change.In this process,a metal oxide is used as oxygen carrier in a dual fluidized bed to generate clean CO_(2) via combustion of biomass.Most commonly,natural ores or synthetic materials are used as oxygen carrier whereas both must meet special requirements for the conversion of solid fuels.Synthetic oxygen carriers are characterized by higher reactivity at the expense of higher costs versus the lower-cost natural ores.To determine the viability of both possibilities,a techno-economic comparison of a synthetic material based on manganese,iron,and copper to the natural ore ilmenite was conducted.The synthetic oxygen carrier was characterized and tested in a pilot plant,where high combustion efficiencies up to 98.4%and carbon capture rates up to 98.5%were reached.The techno-economic assessment resulted in CO_(2) capture costs of 75 and 40€/tCO_(2) for the synthetic and natural ore route respectively,whereas a sensitivity analysis showed the high impact of production costs and attrition rates of the synthetic material.The synthetic oxygen carrier could break even with the natural ore in case of lower production costs and attrition rates,which could be reached by adapting the production process and recycling material.By comparison to state-of-the-art technologies,it is demonstrated that both routes are viable and the capture cost of CO_(2) could be reduced by implementing the chemical looping combustion technology.展开更多
The recently observed gravitational wave background is explained in terms of the quantum modification of the general relativity (Qmoger). Some UFO, FRB and supernova flares also can be explained in terms of Qmoger.
Thucydides asserts that the occupation of Decelea by the Spartans in 413 BC made the grain supply for Athens costly by forcing the transport from land onto the sea.This calls into question the well-established consens...Thucydides asserts that the occupation of Decelea by the Spartans in 413 BC made the grain supply for Athens costly by forcing the transport from land onto the sea.This calls into question the well-established consensus that sea transport was far cheaper than land transport.This paper contends that the cost of protecting supply lines-specifically the expenses associated with the warships which escorted the supply ships-rendered the grain transported on the new route exceptionally costly.In this paper,the benefits and drawbacks of a maritime economy,including transaction costs,trade dependencies,and the capabilities of warships and supply ships are discussed.展开更多
Construction project cost control involves many complex contents,forming a large amount of data information.If the processing method is unreasonable,it will likely affect the cost control efficiency.Therefore,in the c...Construction project cost control involves many complex contents,forming a large amount of data information.If the processing method is unreasonable,it will likely affect the cost control efficiency.Therefore,in the current construction project management,the review of project cost budget settlement is the focus to solve the cost management problems of construction projects and promote the development of the construction industry.This article mainly analyzes the influencing factors and current situation of construction project cost budget settlement review,and based on this,it explores the project cost budget settlement review strategy to promote the healthy development of construction project cost work.展开更多
Effective cost control in the investment and design phases of highway construction is crucial for managing project expenses.However,current management practices often overlook pre-construction cost management,leading ...Effective cost control in the investment and design phases of highway construction is crucial for managing project expenses.However,current management practices often overlook pre-construction cost management,leading to budget overruns and project delays during later stages.To ensure the smooth execution and cost control of highway construction projects,this paper examines the significance of cost control,evaluates the current state and challenges of highway construction,and proposes strategies for cost management.These strategies aim to establish a robust foundation for cost management in highway projects.展开更多
In this in-depth exploration, I delve into the complex implications and costs of cybersecurity breaches. Venturing beyond just the immediate repercussions, the research unearths both the overt and concealed long-term ...In this in-depth exploration, I delve into the complex implications and costs of cybersecurity breaches. Venturing beyond just the immediate repercussions, the research unearths both the overt and concealed long-term consequences that businesses encounter. This study integrates findings from various research, including quantitative reports, drawing upon real-world incidents faced by both small and large enterprises. This investigation emphasizes the profound intangible costs, such as trade name devaluation and potential damage to brand reputation, which can persist long after the breach. By collating insights from industry experts and a myriad of research, the study provides a comprehensive perspective on the profound, multi-dimensional impacts of cybersecurity incidents. The overarching aim is to underscore the often-underestimated scope and depth of these breaches, emphasizing the entire timeline post-incident and the urgent need for fortified preventative and reactive measures in the digital domain.展开更多
Drilling costs of ultra-deepwell is the significant part of development investment,and accurate prediction of drilling costs plays an important role in reasonable budgeting and overall control of development cost.In o...Drilling costs of ultra-deepwell is the significant part of development investment,and accurate prediction of drilling costs plays an important role in reasonable budgeting and overall control of development cost.In order to improve the prediction accuracy of ultra-deep well drilling costs,the item and the dominant factors of drilling costs in Tarim oilfield are analyzed.Then,those factors of drilling costs are separated into categorical variables and numerous variables.Finally,a BP neural networkmodel with drilling costs as the output is established,and hyper-parameters(initial weights and bias)of the BP neural network is optimized by genetic algorithm(GA).Through training and validation of themodel,a reliable prediction model of ultra-deep well drilling costs is achieved.The average relative error between prediction and actual values is 3.26%.Compared with other models,the root mean square error is reduced by 25.38%.The prediction results of the proposed model are reliable,and the model is efficient,which can provide supporting for the drilling costs control and budget planning of ultra-deep wells.展开更多
AIM: To analyze and calculate the relative cost of various childhood glaucoma surgical interventions per mm Hg intraocular pressure(IOP) reduction($/mm Hg).METHODS: Representative index studies were reviewed to quanti...AIM: To analyze and calculate the relative cost of various childhood glaucoma surgical interventions per mm Hg intraocular pressure(IOP) reduction($/mm Hg).METHODS: Representative index studies were reviewed to quantitate the reduction of mean IOP and glaucoma medications for each surgical intervention in childhood glaucoma. A US perspective was adopted, using Medicare allowable costs to calculate cost/mm Hg IOP reduction($/mm Hg) at 1y postoperatively.RESULTS: At 1y postoperatively, the cost/mm Hg IOP reduction was $226/mm Hg for microcatheter-assisted circumferential trabeculotomy, $284/mm Hg for cyclophotocoagulation, $288/mm Hg for conventional ab-externo trabeculotomy, $338/mm Hg for Ahmed glaucoma valve, $350/mm Hg for Baerveldt glaucoma implant, $351/mm Hg for goniotomy, and $400/mm Hg for trabeculectomy.CONCLUSION: Microcatheter-assisted circumferential trabeculotomy is the most cost-efficient surgical method to lower IOP in childhood glaucoma, while trabeculectomy is the least cost-efficient surgical method.展开更多
Coal has been dominating the electricity supply in Indonesia,especially in long-term power generation from fossil energy.This dominance is due to lower production costs in coal-fired power plant generation.However,thi...Coal has been dominating the electricity supply in Indonesia,especially in long-term power generation from fossil energy.This dominance is due to lower production costs in coal-fired power plant generation.However,this low price is only based on monetary costs and ignores the social costs.Therefore,this study aims to quantify the social costs of coal-fired generation.Using QUERI-AirPacts modeling,the present study quantifies the social costs resulting from the Tenayan Raya coal-fired generation in Riau,Indonesia.It includes the levelized cost of electricity and health costs into the generation costs.After that,this study calculates the net present value,internal rate return,and project payback period.The study found that as much as$50.22/MWh was the levelized cost of electricity.While$15.978/MWh or$0.015978/kWh was the social cost that was not included in the generating cost.At the electricity production level of 1,380,171.69 MWh per year,there is an expected extra cost of$22,052,383.30 uncounted when externalities are included.For instance,the net present value(NPV)is lower and even negative when external costs are included(-$24,062,274.19)compared to$176,108,091.52 when externalities are not considered.The internal rate of return(IRR)is much higher when the social costs are not considered.The payback period is also shorter when the social costs are excluded than when the externalities are included.This global number indicates that the inclusion of external costs would impact NPV,IRR,and the payback period.This result implies that the government should internalize the external cost to stimulate the electricity producers to conduct cost-benefit analyses.The cost-benefit analysis mechanism would lead the producers to be more efficient.展开更多
文摘Background: Venous thromboembolism (VTE) is a major public health problem due to its increasing frequency, mortality and management cost. This cost may require major financial efforts from patients, especially in developing countries like ours where less than 7% of the population has health insurance. This study aimed to estimate the direct cost of managing VTE in three reference hospitals in Yaoundé. Methods: This was a cross-sectional retrospective study over a three-year period (from January 1st 2018 to December 31 2020) carried out in the Cardiology departments of the Central and General Hospitals, and the Emergency Centre of the city of Yaoundé. All patients managed during the study period for deep vein thrombosis and pulmonary embolism confirmed by venous ultrasound coupled with Doppler and computed tomography pulmonary angiography respectively were included. For each patient, we collected sociodemographic and clinical data as well as data on the cost of consultation, hospital stay, workups and medications. These data were analysed using SPSS version 23.0. Results: A total of 92 patient’s records were analysed. The median age was 60 years [48 - 68] with a sex ratio of 0.53. The median direct cost of management of venous thromboembolism was 766,375 CFAF [536,455 - 1,029,745] or $1415 USD. Management of pulmonary embolism associated with deep vein thrombosis was more costly than isolated pulmonary embolism or deep vein thrombosis. Factors influencing the direct cost of management of venous thromboembolism were: hospital structure (p = 0.015), health insurance (p 0.001), type of pulmonary embolism (p = 0.021), and length of hospital stay (p = 0.001). Conclusion: Management of VTE is a major financial burden for our patients and this burden is influenced by the hospital structure, health insurance, type of pulmonary embolism and length of hospital stay.
文摘Accurate software cost estimation in Global Software Development(GSD)remains challenging due to reliance on historical data and expert judgments.Traditional models,such as the Constructive Cost Model(COCOMO II),rely heavily on historical and accurate data.In addition,expert judgment is required to set many input parameters,which can introduce subjectivity and variability in the estimation process.Consequently,there is a need to improve the current GSD models to mitigate reliance on historical data,subjectivity in expert judgment,inadequate consideration of GSD-based cost drivers and limited integration of modern technologies with cost overruns.This study introduces a novel hybrid model that synergizes the COCOMO II with Artificial Neural Networks(ANN)to address these challenges.The proposed hybrid model integrates additional GSD-based cost drivers identified through a systematic literature review and further vetted by industry experts.This article compares the effectiveness of the proposedmodelwith state-of-the-artmachine learning-basedmodels for software cost estimation.Evaluating the NASA 93 dataset by adopting twenty-six GSD-based cost drivers reveals that our hybrid model achieves superior accuracy,outperforming existing state-of-the-artmodels.The findings indicate the potential of combining COCOMO II,ANN,and additional GSD-based cost drivers to transform cost estimation in GSD.
文摘Schizophrenia is classified as a priority mental disorder by the World Health Organization (WHO) and accounts for around 35% of diagnoses at the Bingerville Psychiatric Hospital (HPB). The aims of the study were to identify the cost drivers for hospitalization and to calculate the costs of managing schizophrenia in hospital, with a view to planning household expenditure on care. This pilot cross-sectional study involved 31 patients with schizophrenia who had been hospitalized in the various third-category wards at the HPB between 1st January 2019 and 31st May 2020. Sampling was accidental. The methods used to estimate costs were based on the actual costs of drugs, hospitalization and additional examinations which prices were known, and on patients’ estimations for certain expenses such as food and transport. Results: The sex ratio was 3.42, the mean age was 29.52 years. The mean length of stay was 46.19 days, and the most frequent clinical forms were paranoid schizophrenia (41.9%) and schizoaffective disorder (29%). The combination of haloperidol and chlorpromazine was the most common medications for initial treatment (67.8%) and maintenance treatment (41.9%). The average cost of hospitalization at HPB for schizophrenia was XOF 164,412 (€249.90). The average direct medical cost was XOF 105,412 (€160.226) and the average direct non-medical cost was XOF 59,000 (€89.68). The average daily cost of antipsychotic treatment was XOF 795/day (€1.2084). The high cost of drugs as a proportion of hospitalization costs suggested the need of a reflection on the simplification of prescribing practices, assistance in psychiatric emergencies and the development of other alternatives to psychiatric hospitalization in Côte d’Ivoire.
文摘Introduction: Medical treatment for POAG is continuous and lifelong treatment. The aim of this study was to evaluate the relationship between the cost of this treatment and patients’ income and the impact of this relationship on treatment compliance. Materials and Methods: Prospective cross-sectional study with a descriptive aim covering sociodemographic data, average incomes, and direct and indirect costs of treatment of 57 patients followed for POAG during the period from January 1, 2012, to December 31, 2016 (5 years). Results: The patients were aged 25 to 77 years (mean = 54.4 years) with a male predominance (sex ratio = 1.5). Retirees were the most represented (26.32%), followed by workers in the informal sector (14.04%) and housewives (12.28%). Patients who had an annual income less than or equal to 900,000 CFA francs (€1370.83) per year represented 56.14% and those who did not have health coverage represented 57.89%. The treatment was monotherapy (64.91%), dual therapy (31.58%) or triple therapy (3.05%) and the average ratio of “annual cost of treatment to annual income” was 0.56 with for maximum 2.23 and 0.02 as minimum. Patients who considered the cost of treatment unbearable for their income represented 78.95%. Conclusion: Prevention of blindness due to glaucoma requires early detection but also the establishment of health coverage mechanisms to improve compliance with medical treatment. In addition, consideration should be given to the development of glaucoma surgery in our country, the indication of which could be the first intention in certain patients, considering for those patients, the geographical and financial accessibility of medical treatment. .
基金supported by the Tunisian Ministry of Higher Education and Scientific Research under Grant LSE-ENIT-LR 11ES15funded in part by the PAQ-Collabora(PAR&I-Tk)program。
文摘This paper presents a peer-to-peer community cost optimization approach based on a single-prosumer energy management system.Its objective is to optimize energy costs for prosumers in the community by enhancing the consumption efficiency.This study was conducted along two main axes.The first axis focuses on designing a digital twin for a residential community microgrid platform.This phase involves data collection,cleaning,exploration,and interpretation.Moreover,it includes replicating the functionality of the real platform and validating the results.The second axis involves the development of a novel approach that incorporates two distinct prosumer behaviors within the same community microgrid,while maintaining the concept of peer-to-peer energy trading.Prosumers without storage utilize their individual PV systems to fulfill their energy requirements and inject excess energy into a local microgrid.Meanwhile,a single prosumer with a storage system actively engages in energy exchange to maximize the community’s profit.This is achieved by optimizing battery usage using a cost optimization solution.The proposed solution is validated using the developed digital twin.
文摘Creditors,such as banks,often use disclosed environmental information to assess a company’s environmental risk and ensure the safety of debt funds.Consequently,carbon disclosures have become an important consideration for creditors when making investments.This study explores the relationship between carbon disclosure and debt financing costs using data on listed companies from 2008 to 2019.The results show that carbon disclosure can reduce the debt financing costs of enterprises,and that this influence is more significant for private companies than for state-owned enterprises.Instrumental variables and Propensity Score Matching(PSM)were used to evaluate the robustness of negative relationships.Furthermore,carbon disclosure has a more significant impact on debt costs with less environmental supervision pressure,weak residents’environmental awareness,and weak product market competition.These findings provide guidance for companies’carbon information disclosure and support the establishment of official carbon disclosure standards.
基金National Natural Science Foundation of China under Grant Nos.51921006 and 51725801Fundamental Research Funds for the Central Universities under Grant No.FRFCU5710093320Heilongjiang Touyan Innovation Team Program。
文摘Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonuniform corrosion using different materials.In this study,a reliability-based design optimization(RBDO)procedure is improved for the design of coastal bridge piers using six groups of commonly used materials,i.e.,normal performance concrete(NPC)with black steel(BS)rebar,high strength steel(HSS)rebar,epoxy coated(EC)rebar,and stainless steel(SS)rebar(named NPC-BS,NPC-HSS,NPC-EC,and NPC-SS,respectively),NPC with BS with silane soakage on the pier surface(named NPC-Silane),and high-performance concrete(HPC)with BS rebar(named HPC-BS).First,the RBDO procedure is improved for the design optimization of coastal bridge piers,and a bridge is selected to illustrate the procedure.Then,reliability analysis of the pier designed with each group of materials is carried out to obtain the time-dependent reliability in terms of the ultimate and serviceability performances.Next,the repair time of the pier is predicted based on the time-dependent reliability indices.Finally,the time-dependent LCCs for the pier are obtained for the selection of the optimal design.
文摘Chemical looping combustion has the potential to be an efficient and low-cost technology capable of contributing to the reduction of the atmospheric concentration of CO_(2) in order to reach the 1.5/2°C goal and mitigate climate change.In this process,a metal oxide is used as oxygen carrier in a dual fluidized bed to generate clean CO_(2) via combustion of biomass.Most commonly,natural ores or synthetic materials are used as oxygen carrier whereas both must meet special requirements for the conversion of solid fuels.Synthetic oxygen carriers are characterized by higher reactivity at the expense of higher costs versus the lower-cost natural ores.To determine the viability of both possibilities,a techno-economic comparison of a synthetic material based on manganese,iron,and copper to the natural ore ilmenite was conducted.The synthetic oxygen carrier was characterized and tested in a pilot plant,where high combustion efficiencies up to 98.4%and carbon capture rates up to 98.5%were reached.The techno-economic assessment resulted in CO_(2) capture costs of 75 and 40€/tCO_(2) for the synthetic and natural ore route respectively,whereas a sensitivity analysis showed the high impact of production costs and attrition rates of the synthetic material.The synthetic oxygen carrier could break even with the natural ore in case of lower production costs and attrition rates,which could be reached by adapting the production process and recycling material.By comparison to state-of-the-art technologies,it is demonstrated that both routes are viable and the capture cost of CO_(2) could be reduced by implementing the chemical looping combustion technology.
文摘The recently observed gravitational wave background is explained in terms of the quantum modification of the general relativity (Qmoger). Some UFO, FRB and supernova flares also can be explained in terms of Qmoger.
文摘Thucydides asserts that the occupation of Decelea by the Spartans in 413 BC made the grain supply for Athens costly by forcing the transport from land onto the sea.This calls into question the well-established consensus that sea transport was far cheaper than land transport.This paper contends that the cost of protecting supply lines-specifically the expenses associated with the warships which escorted the supply ships-rendered the grain transported on the new route exceptionally costly.In this paper,the benefits and drawbacks of a maritime economy,including transaction costs,trade dependencies,and the capabilities of warships and supply ships are discussed.
文摘Construction project cost control involves many complex contents,forming a large amount of data information.If the processing method is unreasonable,it will likely affect the cost control efficiency.Therefore,in the current construction project management,the review of project cost budget settlement is the focus to solve the cost management problems of construction projects and promote the development of the construction industry.This article mainly analyzes the influencing factors and current situation of construction project cost budget settlement review,and based on this,it explores the project cost budget settlement review strategy to promote the healthy development of construction project cost work.
文摘Effective cost control in the investment and design phases of highway construction is crucial for managing project expenses.However,current management practices often overlook pre-construction cost management,leading to budget overruns and project delays during later stages.To ensure the smooth execution and cost control of highway construction projects,this paper examines the significance of cost control,evaluates the current state and challenges of highway construction,and proposes strategies for cost management.These strategies aim to establish a robust foundation for cost management in highway projects.
文摘In this in-depth exploration, I delve into the complex implications and costs of cybersecurity breaches. Venturing beyond just the immediate repercussions, the research unearths both the overt and concealed long-term consequences that businesses encounter. This study integrates findings from various research, including quantitative reports, drawing upon real-world incidents faced by both small and large enterprises. This investigation emphasizes the profound intangible costs, such as trade name devaluation and potential damage to brand reputation, which can persist long after the breach. By collating insights from industry experts and a myriad of research, the study provides a comprehensive perspective on the profound, multi-dimensional impacts of cybersecurity incidents. The overarching aim is to underscore the often-underestimated scope and depth of these breaches, emphasizing the entire timeline post-incident and the urgent need for fortified preventative and reactive measures in the digital domain.
基金supported by the Science and Technology Innovation Foundation of CNPC“Multiscale Flow Law and Flow Field Coupling Study of Tight Sandstone Gas Reservoir”(2016D-5007-0208)13th Five-Year National Major Project“Multistage Fracturing Effect and Production of Fuling Shale Gas HorizontalWell Law Analysis Research”(2016ZX05060-009).
文摘Drilling costs of ultra-deepwell is the significant part of development investment,and accurate prediction of drilling costs plays an important role in reasonable budgeting and overall control of development cost.In order to improve the prediction accuracy of ultra-deep well drilling costs,the item and the dominant factors of drilling costs in Tarim oilfield are analyzed.Then,those factors of drilling costs are separated into categorical variables and numerous variables.Finally,a BP neural networkmodel with drilling costs as the output is established,and hyper-parameters(initial weights and bias)of the BP neural network is optimized by genetic algorithm(GA).Through training and validation of themodel,a reliable prediction model of ultra-deep well drilling costs is achieved.The average relative error between prediction and actual values is 3.26%.Compared with other models,the root mean square error is reduced by 25.38%.The prediction results of the proposed model are reliable,and the model is efficient,which can provide supporting for the drilling costs control and budget planning of ultra-deep wells.
文摘AIM: To analyze and calculate the relative cost of various childhood glaucoma surgical interventions per mm Hg intraocular pressure(IOP) reduction($/mm Hg).METHODS: Representative index studies were reviewed to quantitate the reduction of mean IOP and glaucoma medications for each surgical intervention in childhood glaucoma. A US perspective was adopted, using Medicare allowable costs to calculate cost/mm Hg IOP reduction($/mm Hg) at 1y postoperatively.RESULTS: At 1y postoperatively, the cost/mm Hg IOP reduction was $226/mm Hg for microcatheter-assisted circumferential trabeculotomy, $284/mm Hg for cyclophotocoagulation, $288/mm Hg for conventional ab-externo trabeculotomy, $338/mm Hg for Ahmed glaucoma valve, $350/mm Hg for Baerveldt glaucoma implant, $351/mm Hg for goniotomy, and $400/mm Hg for trabeculectomy.CONCLUSION: Microcatheter-assisted circumferential trabeculotomy is the most cost-efficient surgical method to lower IOP in childhood glaucoma, while trabeculectomy is the least cost-efficient surgical method.
文摘Coal has been dominating the electricity supply in Indonesia,especially in long-term power generation from fossil energy.This dominance is due to lower production costs in coal-fired power plant generation.However,this low price is only based on monetary costs and ignores the social costs.Therefore,this study aims to quantify the social costs of coal-fired generation.Using QUERI-AirPacts modeling,the present study quantifies the social costs resulting from the Tenayan Raya coal-fired generation in Riau,Indonesia.It includes the levelized cost of electricity and health costs into the generation costs.After that,this study calculates the net present value,internal rate return,and project payback period.The study found that as much as$50.22/MWh was the levelized cost of electricity.While$15.978/MWh or$0.015978/kWh was the social cost that was not included in the generating cost.At the electricity production level of 1,380,171.69 MWh per year,there is an expected extra cost of$22,052,383.30 uncounted when externalities are included.For instance,the net present value(NPV)is lower and even negative when external costs are included(-$24,062,274.19)compared to$176,108,091.52 when externalities are not considered.The internal rate of return(IRR)is much higher when the social costs are not considered.The payback period is also shorter when the social costs are excluded than when the externalities are included.This global number indicates that the inclusion of external costs would impact NPV,IRR,and the payback period.This result implies that the government should internalize the external cost to stimulate the electricity producers to conduct cost-benefit analyses.The cost-benefit analysis mechanism would lead the producers to be more efficient.