Replacement Cost Research Articles

Optimizing Healthcare Expenditure for Spinal Cord Stimulation in Italy: The Value of Battery Longevity Improvement and a Direct-to-Implant Approach

Background: Spinal cord stimulation (SCS) is a treatment for chronic intractable pain powered by an implantable pulse generator that may be rechargeable or not rechargeable (NR). It is performed in 2 stages (a trialing phase followed by permanent device implantation) and necessitates 2 hospitalizations, which may increase infection risk. Objective: This analysis explores the cost impact of improvements in battery longevity and the adoption of 1-step (direct-to-implant [DTI]) SCS implantation. Methods: Since 2019, 3 leading NR-SCS devices have been launched: Device A (2019), Device B (2020), and Device C (2021). The battery longevity of the newest Device C was estimated at comparable stimulation settings for Devices A and B. A Markov model simulated individual patient pathways across 2 scenarios: Device A vs Device C and Device B vs Device C (both with the DTI approach and 2-step approach). Costs considered were the initial device implantation procedure, device replacements, and serious adverse event (SAE) management. Italian diagnosis-related group (DRG) tariffs were applied for costs, and a 15-year time horizon was used. Results: Over 15 years, using a DTI approach, the undiscounted total costs for Device A vs Device C were €26 860 and €22 633, respectively, and €25 111 and €22 399 for Device B vs Device C, respectively. Compared with Devices A and B, Device C offered savings of €4227 and €2712, respectively; similar savings were predicted with a 2-step implant approach. Discussion: The battery longevity of NR-SCS devices directly impacts long-term costs to a payer. The longer the device lasts, the lower mean total cumulative costs the patient will have, especially with regard to device replacement costs. With novel devices and specific programming settings, the lifetime cost per patient to a payer can be decreased without compromising the patient’s safety and positive clinical outcome. Conclusions: Extended SCS battery longevity can translate into tangible cost savings for payers. The DTI approach for SCS supports National Healthcare System cost efficiencies and offers the additional benefits of optimizing operating room time while having only one recovery period for the patient.

Research on the Valuation of Wetland Ecological Products based on Environmental Replacement Cost Method

Research on the Valuation of Wetland Ecological Products based on Environmental Replacement Cost Method

MORPHOLOGY AND HYDROPHOBICITY OF AGAR, BEESWAX, AND AGAR-BEESWAX EMULSION COATED ON POROUS ALUMINA SUPPORT

Membrane degassing technology is based on the principle of hydrophobicity. Up-to-date, the membrane degasifier is industrially produced by extrusion and then stretched to form a hollow fiber shape with long narrow pores along membrane length. Typical degasifiers are engineered with polypropylene (PP) due to its high toughness and flexibility. However, finding environmentally safe materials at a low cost for replacement for PP would be worth investigating. In this work, agar, beeswax, and their emulsion were coated on a tubular alumina membrane for use as a selective layer of the membrane degasifier. The agar solution with different concentrations between 1 and 4 wt% was coated on the alumina membrane support to create a pore network. Beeswax was coated on agar film to enhance the hydrophobicity. SEM images showed that the increase in the concentrations of agar led to a decreased pore size of the selective layer. Moreover, the contact angle increased up to 100° when the concentration of agar solution increased to 4 wt%. The increase in contact angle to 120° was obtained when the beeswax was coated, appropriate for hydrophobic applications.

MODELING AND OPTIMIZATION OF A PCM-BASED OCEAN THERMAL ENERGY HARVESTER FOR POWERING UNCREWED UNDERWATER VEHICLES

Abstract As oceans cover over 70% of the planet's surface, they represent a large reservoir of resources that remained vastly untapped. Uncrewed Underwater Vehicles (UUVs) are becoming key technology for ocean exploration. Ocean thermal gradient is a permanent and reliable energy source that can be used to power UUVs using phase change material (PCM)-based thermal engines. When using PCM-based thermal engines to power UUVs, there are different energy conversion stages, thermal, hydraulic, kinetic, and electrical, dependent on a wide variety of parameters. Thus, optimization of the overall energy conversion is still a challenge for powering the increasing energy demanding UUVs for long missions. The goal of this study is to propose a PCM-based ocean thermal energy harvesting system for powering float type UUVs such as the Solo II float. This reduces the cost for battery replacement and expands the float's mission time. For this purpose, we developed a model consisting of hydraulic and electrical systems, designed to provide the electrical power needed by the UUV. The hydraulic and electrical systems are implemented using MATLAB-Simulink. The model developed can provide 13.66 kJ of electrical energy, which is more than 1.5 times the energy requirement per cycle for the SOLO II float.

Обоснование оптимальных наработок основных насосов карьерного гидравлического экскаватора

As the pump operates and wears out, the gap in the friction pairs increases and the volumetric efficiency decreases, the pump flow gets reduced, which leads to increasing duration of working and auxiliary operations, the operating cycle of the excavator, a decrease in its productivity and excessive fuel consumption. Infrequent pump replacement can lead to a significant increase in fuel consumption and reduced excavator performance. If the pump is replaced prematurely, its service life will not be used to the full extent. In order to develop a method for establishing optimal operating hours that allow minimizing fuel consumption and the cost of replacing a pump, taking into account operating conditions, a mathematical model of the pump operation is proposed, which makes it possible to obtain an expression for determining the differentiated optimal value of operating time between replacements. A calculation method and a software algorithm have been developed in the MatLab Simulink software suite to calculate the rate of decrease in the volumetric efficiency, as well as to establish the influence of volumetric efficiency on the fuel consumption and performance of a hydraulic excavator to be utilized in the model using the example of the HPV375 pump of the Komatsu PC2000-8 excavator, Based on the proposed mathematical model of the main pumps operation, a method has been developed for calculating the differentiated operating time between replacements of the main pumps of a mining hydraulic excavator, taking into account the rate of decrease in volumetric efficiency, replacement costs and damage due to changes in productivity and excessive fuel consumption. The dependence of the rate of changes in the volumetric efficiency of the pump is presented for the excavation, viscosity, contamination and temperature of the working fluid parameters. A coefficient of “reserve of partial engine power transferred to the pump” is proposed, determined by the ratio of the difference between the average maximum and initial partial power to the value of the initial partial power, which allows estimation of the operating time of the main pumps without affecting productivity of the excavator.

Barley residue biomass, nutrient content, and relationships with grain yield

AbstractDetermination of barley (Hordeum vulgare L.) nutrient uptake in residue biomass is important for agronomic, economic, and environmental decisions. Improved understanding of grain yield, residue biomass, nutrient uptake, and their relationships are needed. Research determined these factors in 2018 and 2019 from trials of four barley classes (spring animal feed, human food, and malt, as well as winter malt), using three common cultivars of each, at five locations in southern Idaho. Production environment created the largest difference in residue biomass and nutrient uptake. Barley harvest index ranged from 0.46 to 0.52 Mg Mg−1 across feed, food, and malt classes. Compared to previous estimates, nutrient concentrations from the combined dataset were greater than for N, less than for P, and greater than for K. Correlation of grain yields to nutrient uptake (excluding Cu and Fe) had r2 ranging from 0.68 to 0.89. At current prices, economic analysis indicated that fertilizer replacement costs for total residue biomass nutrients were greater than previous estimates and could greatly exceed current sale value. These relationships and value estimates can be used to improve prediction of barley residue biomass production and nutrient uptake to guide best management practices. The decision of how to utilize these metrics (on‐farm, regional, etc.) should be considered based on known variation in measured nutrient and residue data and considered in relation to the proposed task.

Quantifying soil erosion and soil organic carbon conservation services in indian forests: A RUSLE-SDR and GIS-based assessment

Indian forests, having sixteen types of vegetation, provide various ecosystem services. Forests reduce water erosion of soil, reduce floods and conserve low river flow during dry seasons. Present study estimated annual sedimentation, texture, soil organic carbon control service of forests of India using the Revised Universal Soil Loss Equation (RUSLE) and Sediment Delivery Ratio (SDR) approach through GIS technique along with identifying important drivers responsible for erosion in forests. The soil erosion control service was based on five factors viz., rainfall erosivity, soil erodibility, slope, crop management, conservation practice factor and SDR across the various forest dominated river basins. Geo-detector modelling was performed to evaluate environmental drivers responsible for soil erosion. Valuation of soil control service of the India’s forests was estimated based on damage and replacement cost method. Annual soil loss rate was maximum in Tropical Thorn Forest and in Ganga River basin. Maximum sediment control and SOC conservation against the soil erosion control service by India’ forests were due to Tropical Dry Deciduous Forest with a total annual sedimentation control and SOC conservation of 33,056,560 tonnes and 3,31,115.06 tonnes, respectively. The conservative estimate of the economic value of soil conservation service by the forests of India was US$ 535.6 M with an average of 4.40 US$ ha−1 and a maximum share of value for Tropical Dry Deciduous Forest i.e. 294.18 million US$ and average maximum value for Littoral and Swamp Forest (28.91 US$ ha−1). The soil erosion in Tropical and Sub-tropical Forest was influenced by the interactive effects between NDVI and Bulk Density. In contrast, soil erosion in the temperate and alpine area was influenced by anthropogenic activity in combination with climatic factors. Present study accounts the role of India’s forests for the soil conservation service and may provide inputs to implement forest and reservoir management strategies besides providing information for Integrated Watershed management and Catchment Treatment Plans.

Operation and performance analysis of direct hollow fiber nanofiltration: A pilot study at IJsselmeer

This study investigated the performance of direct hollow fiber nanofiltration (dNF40) membranes from NX Filtration BV on a pilot scale for the treatment of pre-treated IJsselmeer water from Waterwinstation Prinses Juliana (WPJ) in Andijk, as well as the direct treatment of raw IJsselmeer water. The objective was to evaluate the long-term fouling potential and the retention of ions and natural organic matter (NOM) using both WPJ pre-treated IJsselmeer water and raw IJsselmeer water. Additionally, the rejection of organic micropollutants (OMPs) under artificially elevated conditions, referred to as ‘spiked solution’, using WPJ pre-treated IJsselmeer water was investigated.Limited to no fouling was observed on the dNF40 membrane during stable operation when treating both WPJ pre-treated IJsselmeer water and raw IJsselmeer water, even under changing process conditions. NOM removal consistently exceeded 90% regardless of process conditions or water type. The retention of per- and polyfluoroalkyl substances (PFAS) was above 80%, with even higher retention observed for higher molecular weight values. Low molecular weight pharmaceuticals, all below the molecular weight cut-off (MWCO) of the dNF40 membrane (400 Da), exhibited approximately 30% retention. The dNF40 membrane showed better retention of negatively charged pharmaceuticals in the spiked solution compared to positively charged and neutral pharmaceuticals.A total cost of ownership (TCO) analysis unveiled that operational expenditures (OPEX) were three times higher than capital expenditures (CAPEX) for a 5-stage full-scale dNF40 system. Among the components, membrane replacement costs constituted the majority of OPEX (68%), followed by energy costs (31%) and chemical costs (<1%). Overall, the study showcased the suitability of the dNF40 membranes for treating IJsselmeer water, achieving effective removal of NOM and PFAS.

A Net Present Value Analysis of Opportunity-Based Age Replacement Models in Discrete Time

Two important opportunistic age replacement models, under replacement first and last disciplines, are generalized in discrete time. The net present value (NPV) is applied to formulate the expected total costs. The priority of multiple replacement options is considered to classify the cost model with discounting into six cases. Since the NPV method accurately calculates the expected replacement costs over an infinite horizon in an unstable economic environment, we discuss some optimal opportunistic age replacement policies which minimize the expected total discounted costs over an infinite time horizon. Furthermore, we formulate a unified model under each discipline, merging six discrete time replacement models with probabilistic priority. Finally, a case study on optimal replacement first and last policies for pole air switches in a Japanese power company is presented.

Effect of Pre-Heating on Residual Stresses and Deformation in Laser-Based Directed Energy Deposition Repair: A Comparative Analysis.

Laser-directed energy deposition (DED), a metal additive manufacturing method, is renowned for its role in repairing parts, particularly when replacement costs are prohibitive. Ensuring that repaired parts avoid residual stresses and deformation is crucial for maintaining functional integrity. This study conducts experimental and numerical analyses on trapezoidal shape repairs, validating both the thermal and mechanical models with experimental results. Additionally, the study presents a methodology for creating a toolpath applicable to both the DED process and Abaqus CAE software. The findings indicate that employing a pre-heating strategy can reduce residual stresses by over 70% compared to no pre-heating. However, pre-heating may not substantially reduce final distortion. Notably, final distortion can be significantly mitigated by pre-heating and subsequently cooling to higher temperatures, thereby reducing the cooling rate. These insights contribute to optimizing DED repair processes for enhanced part functionality and longevity.

Enhancing sulfur resistance of oxides in carbon monoxide oxidation by a high‐entropy‐stabilized strategy

AbstractIndustrial chemical processes require sulfur‐resistant catalysts, which reduce catalyst replacement costs and simplify process operations. Herein, a high‐entropy‐stabilized strategy was put forward for sulfur‐resistant catalysis. A spinel high entropy (Zn0.2Mg0.2Cu0.2Mn0.2Co0.2Al2O4) was introduced by ball milling process with aluminum isopropoxide as the main precursor. Zn0.2Mg0.2Cu0.2Mn0.2Co0.2Al2O4 possessed a high surface area of 171.2 m2 g−1, higher than typical high‐entropy oxides (HEOs). The high‐entropy spinel catalyst exhibited better SO2‐resistance performance in the oxidation of carbon monoxide, better than the simple oxides. The SO2‐resistance of Zn0.2Mg0.2Cu0.2Mn0.2Co0.2Al2O4 was primarily improved by reinforcing the stability of the oxide using a high‐entropy structure to decrease the absorption of SO2 on its surface. Any adsorbed SO2 on the surface of the HEO was then selectively trapped by sacrificial metal ions with stronger electron‐withdrawing ability, protecting the active center (Cu2+, Co2+) from poisoning. This work reveals the significance of high‐entropy structures in sulfur resistance.

An optimal standalone wind-photovoltaic power plant system for green hydrogen generation: Case study for hydrogen refueling station

Sustainability goals include the utilization of renewable energy resources to supply the energy needs in addition to wastewater treatment to satisfy the water demand. Moreover, hydrogen has become a promising energy carrier and green fuel to decarbonize the industrial and transportation sectors. In this context, this research investigates a wind-photovoltaic power plant to produce green hydrogen for hydrogen refueling station and to operate an electrocoagulation water treatment unit in Ostrava, Czech Republic's northeast region. The study conducts a techno-economic analysis through HOMER Pro® software for optimal sizing of the power station components and to investigate the economic indices of the plant. The power station employs photovoltaic panels and wind turbines to supply the required electricity for electrolyzers and electrocoagulation reactors. As an off-grid system, lead acid batteries are utilized to store the surplus electricity. Wind speed and solar irradiation are the key role site dependent parameters that determine the cost of hydrogen, electricity, and wastewater treatment. The simulated model considers the capital, operating, and replacement costs for system components. In the proposed system, 240 kg of hydrogen as well as 720 kWh electrical energy are daily required for the hydrogen refueling station and the electrocoagulation unit, respectively. Accordingly, the power station annually generates 6,997,990 kWh of electrical energy in addition to 85595 kg of green hydrogen. Based on the economic analysis, the project's NPC is determined to be €5.49 M and the levelized cost of Hydrogen (LCH) is 2.89 €/kg excluding compressor unit costs. This value proves the effectiveness of this power system, which encourages the utilization of green hydrogen for fuel-cell electric vehicles (FCVs). Furthermore, emerging electrocoagulation studies produce hydrogen through wastewater treatment, increasing hydrogen production and lowering LCH. Therefore, this study is able to provide practicable methodology support for optimal sizing of the power station components, which is beneficial for industrialization and economic development as well as transition toward sustainability and autonomous energy systems.

ASSESSMENT OF THE IMPLEMENTATION OF CROSS-INDUSTRY PERFORMANCE INDICATORS OF ENERGY SAVING PROGRAMS IN THE LIFE CYCLE OF BUILDINGS

This article is devoted to the study of the possibility of energy saving of buildings. The relevance of the article lies in the fact that the role of efficiency of energy saving programs is currently growing. The novelty of the research lies in the development of methodology and new approaches for the analysis of energy saving. The author suggests cross-industry indicators of strategic management of energy saving programs. They can provide analysis of a wide range of useful information to confirm the costs of investment, operation and efficiency of a project. Information modeling of buildings is used as the basis of the research in the article. Based on the analysis of scientific literature, the author has developed cross-sectoral indicators of strategic management of energy saving programs. The author proposes a calculation of energy saving taking into account such new indicators as indicators in terms of replacement cost, indicators of power losses, environmental impact, reliability indicators. A methodology for assessing the impact of energy management solutions and the use of key performance indicators is proposed. The methodology consists of a preparatory stage and a two-stage assessment. It can be used to quantify specific aspects or objectives of a project, such as economic feasibility, environmental impact, reliability and quality of electricity. In the study, the author used general scientific methods of systematization and classification of data, methods of statistical processing and generalization, logical, comparative and system analysis, as well as mathematical methods.

Trends and predictors of inflation-adjusted costs in transcatheter and surgical aortic valve replacement in a nationally representative sample

BackgroundTranscatheter aortic valve replacement has become an accepted alternative to surgical aortic valve replacement. We examined the trends and predictors in inflation-adjusted costs of transcatheter aortic valve replacement and surgical aortic valve replacement. MethodsNational Inpatient Sample identified patients who underwent aortic valve replacement for severe aortic stenosis by International Classification of Diseases, Ninth and Tenth Revisions, codes. Hospitalization costs were inflation-adjusted using the Federal Reserve’s consumer price index to reflect current valuation. Outcomes of interest were unadjusted trend in annual cost for each procedure and predictors of in-patient cost. Generalized linear models with a log link function identified predictors of adjusted costs. Interaction terms determined where cost predictors were different by operation type. ResultsBetween 2011 and 2019, the mean annual inflation-adjusted cost of surgical aortic valve replacement increased from $62,853 to $63,743, in contrast to decreasing cost of transcatheter aortic valve replacement from $64,913 to $56,042 ($1,854 per year; P = .004). Significant independent predictors of patient-level cost included operation type (transcatheter aortic valve replacement associated with $9,625 increase; P < .001), incidence of in-hospital mortality ($28,836 increase; P < .001), elective status ($2,410 decrease; P < .001), Elixhauser Index ($995 increase; P < .001), and postoperative length of stay ($2,014 per day increase; P < .001). Compared to discharges with Medicare, discharges with private insurance and Medicaid paid $736 less (P = .004) and $1,863 less (P = .01), respectively. Increasing hospital volume was a significant predictor of decreasing patient level cost (P < .001). ConclusionAnnual cost of transcatheter aortic valve replacement has decreased significantly and has been a more cost-effective modality compared to surgical aortic valve replacement since 2017. Predictors of patient-level costs allow for mindful preparation of healthcare systems for aortic valve replacement.

Electric vehicle-based distant energy sharing between zero-emission coastal office and hotel buildings

With the rapid growth of distributed renewable energy systems, energy sharing brings a practical solution to mitigate mismatching between intermittent electricity generation and building demand. In past research, energy sharing was designed mostly for onshore energy integrated systems and is commonly realised with the assistance of microgrids, distributed battery storage, or peer-to-peer energy trading. This research innovatively proposed a distant energy sharing between the ocean energy-supported coastal office building and hotel building by ten electric vehicles, enabling the circulation of ocean renewable energy between two buildings. This project aims to accomplish maximum technical, environmental and economic benefits for the stakeholder. Using bidirectional vehicle-building interaction, advanced control algorithms, including shifting vehicle batches, sizing renewable capacity, and involving stationary batteries, are implemented successively in the TRNSYS simulation as analysis groups to enhance the current system's performance. According to the results, the vehicle-based bidirectional energy sharing between these two buildings can attain a relative net present value of 49.18 million HKD and a weighted matching index of 0.63. After implementing advanced controls with stationary batteries, the system achieved a relative net present value of 62.15 million HKD with an improved matching index of 0.70. Both batteries contributed to increase the matching performance of the system, but the increase in battery capacity reduces the benefit due to their replacement cost. This research developed an energy management system for effectively utilising electric vehicles and coastal renewable energy for distant energy sharing. It elucidated the technological, environmental, and economic benefits to the stakeholders for effective decision-making.

Mechanism of lightning damage to glass fiber composite wind turbine blades

Wind turbine blades (WTBs) are susceptible to lightning damage, resulting in significant costs for repair and replacement, which poses a considerable economic burden on wind farms. Therefore, this study investigates the mechanism of lightning damage of glass fiber composite (GFC)-WTBs to reduce the risk of such damage. The damage of GFC-WTBs caused by lightning strikes was analyzed using a numerical simulation method. The lightning pilot was simulated using high-voltage rod electrodes, and subsequently, the electric field strength and damage area on the blade surface under different conditions were measured. Additionally, a simulation model based on finite element analysis was developed to further predict and validate the experimental findings. The results reveal that the maximum electric field intensity was observed in the blade tip. Notably, the electric field intensity was found to be over 798,000 V/m when the rod electrode was positioned at a 0-degree angle with the blade tip. Further investigation revealed a non-linear and positive correlation between the damage area of GFC and lightning current amplitude, charge, and specific energy. In conclusion, the study provides a comprehensive examination of the relationship between lightning current and the damage to GFC-WTBs, as well as elucidates the mechanism of lightning damage to GFC-WTBs.

Economic Valuation of Women's Unpaid Household Service Work in Bangladesh

This short note estimates the economic value of women’s unpaid household service work in Bangladesh using data from the Time Use Survey 2021 of BBS. This survey collected detailed information 17,772 respondents (10,024 female and 7,748 male) from 8,000 households on how individuals aged 15 years and older spent their time over a 24-hour period in a day on various activities. Productive time of all household members is divided into three categories: i) household chores (e.g. cooking, cleaning, etc.); ii) caregiving services for household members; and iii) paid and self-employed work. The first two categories comprise unpaid household service work. Data show that women and men spent 7 hours and 6.9 hours on productive work, respectively. In order to estimate the total economic value of women’s unpaid work, we follow an input-based replacement cost approach with generalist wage rates. Our estimate shows that the valuation of women’s unpaid care work is BDT 5,307 billion, which is equivalent to 14.8 per cent of the GDP in 2021. This figure is a meagre 2.8 per cent of GDP for men.

Comparative analysis of battery energy storage systems’ operation strategies for peak shaving in industries with or without installed photovoltaic capacity

Battery energy storage systems can address energy security and stability challenges during peak loads. This study examines the integration of such systems for peak shaving in industries, whether or not they have photovoltaic capacity. The battery-sizing problem has been analyzed extensively. However, most analyses assume a specific battery operation strategy and ignore the impact of battery-charging schemes on system behavior. In this paper, the authors compare three different operation strategies for charging batteries in an industrial peak-shaving application based on historical demand data from a large electricity consumer in El Salvador. The three strategies are fast charging, time-based charging, and low-power threshold charging. The study analyzes the possible integration of a photovoltaic system with two different sizes for a range of battery sizes (from 250 to 1,500 kWh capacity), examining optimal peak shaving levels, economic savings, and battery degradation. Results indicate that fast-charging reduces monthly billing but degrades batteries faster. The estimated lithium-ion battery lifespan is 10-10.5 years, with a maximum difference of five months. These differences could affect the life cycle economics due to the high costs of battery replacement. The economic savings achieved by the peak shaving operation of the storage system are not enough to compensate the battery investment in this study. However, other case studies with different load profiles or other locations with more expensive electricity tariffs could make the adoption of these systems economically viable.

FAKE PRODUCT DETECTION USING BLOCKCHAIN TECHNOLOGY

End consumers face threats to their finances, health, and safety when counterfeit or duplicate goods are manufactured and marketed. Through revenue loss, product defamation, downtime, replacement costs, causing brands to spend money battling counterfeits, compromising partner trust, stealing sales, etc., it also has an adverse effect on the economic growth of original manufacturers and businesses. A block chain-based system that uses barcodes and QR codes to authenticate objects is suggested as a solution to this problem, enhancing security with the SHA-256 algorithm. This technology makes use of a camera scanner to confirm the product's unique code that is kept on an impenetrable block chain, guaranteeing the legitimacy of every item thanks to the cryptographic strength of SHA-256. The consumer is notified if a product's code matches the block chain record after it is scanned; if there are any differences, the manufacturer and the customer are notified about the product's counterfeit status. By giving consumers direct verification capabilities and protecting producers' interests with an opaque, safe, and secure verification system against counterfeit goods, this strategy drastically lowers reliance on merchant promises. Keywords: Block chain, smart contracts, QR (Quick Response) code, anti- counterfeit.

Enhancing Accuracy and Consistency in the Valuation of Plant and Equipment through Cubic Regression Models of Physical Deterioration

The valuation of plant and equipment often involves valuers deducting physical, functional and economic depreciation from replacement cost estimates. These calculations have faced accuracy and consistency problems in the aspect of determining how much physical deterioration should be deducted. This study attempted to develop cubic regression models to resolve these accuracy and consistency problems in the basic metal, iron and steel and fabricated metal product sectors in Ogun state, Nigeria (Sango Ota and Agbara). Questionnaire surveys were administered on senior operators of plant and equipment in these sectors to draw information on the degree of physical deterioration of plant and equipment over service life, using expenditure on repairs as a proxy for physical deterioration. The questionnaire sought information on the service lives of plant and equipment, the pattern of physical depreciation over the service lives, and the degree to which the pattern is influenced by various operational factors. Data were analysed using means, standard deviations, multiple linear regressions and cubic regressions, to produce what could be the first potentially accurate and consistent valuation model of physical deterioration in Africa. The service lives of various plant and equipment were found to range at various times between 8 to 60 years. Cubic regression analyses showed that the pattern of the movement of transitions of expenditure on repairs (proxy for physical deterioration) over useful life of plant and equipment were not linear but cubic, and generally followed S-shaped patterns. Multiple regression analyses showed that the S-shaped patterns were in turn influenced by operational factors (such as intensity of use and power outages). The study concluded that valuers’ interests in accuracy and consistency in plant and equipment valuation were not served by any of the accounting methods hitherto used by valuers; accuracy in physical deterioration modelling follows an S-shaped transition over time.