Lifespan Cost Research Articles

Enhancing ground source heat pump system design optimization: A stochastic model incorporating transient geological factors and decision variables

In this study, a cost minimization model of a ground source heat pump (GSHP) was performed to obtain its best design configurations based on system reliability. To implement a high-fidelity optimization, the uncertainties of decision parameters and geological parameters' distributions were considered. The GSHP's lifespan costs were functionalized based on an analytical borehole heat transfer model. Multiple constraints were established to serve as reliability goals to ensure a turbulent ground pipe flow without extreme temperature variations. The ground thermal conductivity, groundwater velocity, and unit price of electricity were considered as three random variables. Their dynamic characteristics were incorporated by assigning different increasing rates to the average magnitudes of them. Additionally, their transient fluctuations were accommodated by integrating probabilistic uncertainties into the optimization process, all of which followed normal distributions. The results demonstrated that the time-dependent characteristics of these uncertain variables could significantly affect the system investment of GSHP by reducing the total costs by 20.7% and 21.1% when the increasing rates of groundwater velocity and ground thermal conductivity reach 5% and 4% respectively. The study also provided optimized design variables under an 85% confidence level in various predicted scenarios, considering a wide range of dynamic geological parameters and energy costs.

Hybrid ML-EMT-Based Digital Twin for Device-Level HIL Real-Time Emulation of Ship-Board Microgrid on FPGA

Maritime industries desire high speed and reliability, low lifespan cost, and environmental impact shipping for transportation. Compared to highly congested land shipments and high-cost air freight, all-electric ship (AES) can reduce the lifespan energy consumption and transport a considerable freight volume at a lower rate. Recently, the medium voltage DC (MVDC) topology, recommended by IEEE standard, pushes the AES to the next stage in considering space and weight constraints with the reduction of bulky transformers and simplified parallel connections. However, device-level modeling of this massive parallel MVDC-based ship-board microgrid (SBM) is challenging to both the state-of-the-art general-purpose compute unit and traditional electromagnetic transient (EMT) based emulation. With the rapid development of machine learning (ML) algorithm and its dedicated execution unit, accelerated parallel emulation becomes achievable in different levels of this paralleled connected SBM. Applying the ML-aided technique can help to improve the emulation execution efficiency and reduce the consumption of hardware resource on the field-programmable gate arrays (FPGAs). This work proposes a real-time hybrid ML-EMT based digital twin of the complete SBM at the subsystem-level and equipment-level with validated results from PSCAD/EMTDC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> , and device-level with validated results from SaberRD <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> .

Durability, life cycle cost and life cycle assessment of binary mixtures with fly ash, rice husk ash and concrete demolition waste

Abstract This study analyses, by means of lifespan cost and lifespan assessment, the production of binary concrete admixtures compound by artificial pozzolan and concrete demolition waste. Ten formulations were developed, differentiating them in terms of mixtures, binder and aggregate content, in order to verify their potential use in concrete columns. The replacements were 25% of Portland cement for fly ash and rice husk ash, 15% and 30% of natural coarse aggregates for concrete demolition waste. The results revealed that the mixtures with pozzolan and demolition waste showed higher resistance to chloride penetration. The lowest concrete cost was achieved in the highest compressive strength (35 MPa) and the concrete admixture containing 15% replacement of the natural coarse aggregate by the recycled concrete aggregate and 25% substitution of cement by rice husk ash can be classified as the most environmentally sustainable one, especially in carbon dioxide emissions, among the mixtures studied.

Study of Numerous Resins Used in Polymer Matrix Composite Materials

There are a slew of elements at work in the composites sector, from people and markets to technology and innovation, that are continually reshaping the industry's structure. For now, composite materials' winning combination of high strength-to-weight ratio continues to propel them into new areas, but other attributes are just as crucial. These properties, which may be customized for unique purposes, result in a completed product requiring fewer raw materials and fewer joints and fasteners, as well as reduced assembly times, thanks to composite materials. To lower product lifespan costs, composites also have demonstrated resilience in industrial applications to temperature extremes as well as corrosion and wear. Polymers, ceramics, and metals can all be used as matrices. Thermoplastic (TP) resin is the second most prevalent matrix type, and it is becoming increasingly popular among composite makers. By melting or softening and then chilling the material, thermoplastic linear polymer chains are generated and may be reformed into shaped solids. It is common for thermoplastics to be offered in sheet or panel form, which may be treated using in situ consolidation processes, such as pressing, to manufacture durable, near-net-shape components without the need for an autoclave or vacuum bag cure. Correcting abnormalities or fixing harm done in service is possible with reformability.

A multi-objective optimization model for sizing decisions of a grid-connected photovoltaic system

Greenhouse gasses are by-products of using fossil fuels to generate energy. It is known that climate change is caused by an increase in greenhouse gasses in the Earth's atmosphere. Solar energy is a renewable energy source that is an environmentally friendly resource for generating power. The photovoltaic (PV) system is a well-established technology for transforming solar energy into electric power. Sizing-decisions of a PV system is a strategic decision-making process that has a long-term impact on the project. This work proposes a multi-objective optimization (MOO) model for sizing-decisions of a grid-connected PV system. The objectives consider the economic aspect in terms of minimizing the project lifespan costs and non-economic aspects, including maximizing system reliability and reducing CO2 emissions. The sizing decisions are the number of PV panels, the amount of energy purchased from the main grid, and the amount of energy supplied to the main grid. In addition to a binary variable for an either-or decision, either purchase or supply from the grid. The model generates Pareto-optima to assist the decision-maker in assessing trade-offs between alternatives. A case study based on monthly demand for the residential area at King Fahd University of Petroleum & Minerals (KFUPM) is provided to clarify the practicality of the model. It is found that 1713 PV modules are required to meet annual demand at an annual cost of M$1.61 over 25 years.

Preliminary Realization of an Electric-Powered Hydraulic Pump System for a Waste Compactor Truck and a Techno-Economic Analysis

Most industrial trucks are equipped with hydraulic systems designed for specific operations, for which the required power is supplied by the internal combustion engine (ICE). The largest share of the power consumption is required by the hydraulic system during idling operations, and, consequently, the current literature focuses on energy saving strategies for the hydraulic system rather than making the vehicle traction more efficient. This study presents the preliminary realization of an electric-powered hydraulic pump system (e-HPS) that drives the lifting of the dumpster and the garbage compaction in a waste compactor truck, rather than traditional ICE-driven hydraulic pump systems (ICE-HPSs). The different components of the e-HPS are described and the battery pack was modelled using the kinetic battery model. The end-of-life of the battery pack was determined to assess the economic feasibility of the proposed e-HPS for the truck lifespan, using numerical simulations. The aim was twofold: to provide an implementation method to retrofit the e-HPS to a conventional waste compactor truck and to assess its economic feasibility, investigating fuel savings during the use phase and the consequent reduction of CO2 emissions. Results show that the total lifespan cost saving achieved a value of 65,000 €. Furthermore, total CO2 emissions for the e-HPS were about 80% lower than those of the ICE-HPS, highlighting that the e-HPS can provide significant environmental benefits in an urban context.

Access to females and early life castration individually extend maximal but not median lifespan in male mice.

Investment in reproduction is predicted to accelerate ageing, but the link between reproductive investment and lifespan can be sex- and context-specific. In mammals, female reproductive costs are linked to pregnancy and lactation, but in males substantial reproductive allocation is required for a range of pre- and post-copulatory reproductive traits. Such traits include male-specific increased body size, olfactory signalling and territory defence-traits often expressed under androgen-dependent control. In this experimental study, we explored how reproduction influences lifespan in male mice, contrasting this to the established lifespan costs of reproduction in females. In a 2 × 2 factorial design, we gave either castrated or intact males (factor 1) access to a female or a male cage-mate across their entire life (factor 2). Neither castration nor access to females influenced median lifespan in male mice, but maximal lifespan was increased by either castration or reproduction when compared to intact males housed in male groups (standard male housing conditions). In females, mating significantly reduced lifespan, and while both sexes had similar lifespans in non-reproductive environments, males had a much longer lifespan when allowed mating. This data highlights the sex-specific nature of social environments and reproduction on lifespan, and the role of these conditions in promoting sexual dimorphism in ageing.

Lifespan cost analysis of alternatives to global sulphur emission limit with uncertainties

Following the updated global sulphur emission cap from 1 January 2020, shipowners are facing an increasing cost burden to comply with the new regulation in a tough shipping market. This research compares the lifespan costs of three main alternatives, all of which can satisfy the 2020 global sulphur emission regulation. A lifespan cost analysis model is built considering several cost items across the three alternatives, including the initial cost of investment, maintenance cost and fuel consumption cost. Two vessels with a capacity of 5000 and 10,000 TEUs are selected as case study vessels. The @risk software is utilized to conduct an uncertainty analysis with respect to the fuel price and the discount rate to test the three alternatives in different circumstances. The results indicate that the larger the vessel, the lower the discount rate, and the greater the price of Mixed Fuel Oil (a mixture of Very Low Sulphur Oil and Marine Gas Oil), the more attractive the scrubber option. Quantitatively, if the refining technology of low-sulphur fuel improves in the future and the price differential between Mixed Fuel Oil and Heavy Sulphur Fuel Oil decreases to $29 per ton for the 5000 TEU vessel or $27 per ton for the 10,000 TEU vessel, the fuel-switch alternative will be as competitive as the use of a scrubber in terms of the lifespan cost. Additionally, as the discount rate increases, the cost gap between the use of a scrubber and the other two alternatives gradually decreases.

New hybrid meta-heuristic algorithm for reliable and cost-effective designing of photovoltaic/wind/fuel cell energy system considering load interruption probability

In this paper optimal and cost-effective design of a photovoltaic/wind turbine/fuel cell (PV/WT/FC), the renewable energy system is proposed with the objective of lifespan cost of hybrid system (LSCS) minimisation and considering reliability constraint as a maximum of load interruption probability (LIP) as LIPmax to supply the demand of residential-commercial centres (RCC) located in Iran based on real data of irradiance and wind speed of this region. A new hybrid meta-heuristic algorithm named hybrid grey wolf optimiser-sine cosine algorithm (HGWOSCA) based on the exponential decreasing function (EDF) with high accuracy and speed of optimisation in achieving to the global solution is applied to determine the optimal size of system components. The superiority of the proposed HGWOSCA is compared with SCA, GWO and particle swarm optimisation (PSO) methods in designing of different combinations of the hybrid system and under varying reliability constraint. The results showed that the PV/WT/FC combination is the best combination in view of LSCS and LIPmax for supplying the RCC as a cost-effective and reliable combination. The superiority of the HGWOSCA in designing different combinations of the hybrid system is proved with fewer LSCS and LIP than the other methods with more convergence speed and accuracy. The results clearly showed that the use of hydrogen storage as a reserve power has well compensated the fluctuations in renewable sources production for meeting the RCC load to achieve optimal reliability. The results cleared that the cost of per kW of RCC supply for LIPmax = 1% and LIPmax = 5% is 0.853 and 0.764 $. The results indicated that increasing the failure rate of the components increases the system cost and weakens the reliability. In addition, the results showed that increased FC efficiency has reduced the level of reserve hydrogen, reduced the LSCS, and improved reliability.

Scrubber: A potentially overestimated compliance method for the Emission Control Areas: The importance of involving a ship’s sailing pattern in the evaluation

Different methods for sulphur emission reductions, available to satisfy the latest Emission Control Areas (ECA) regulations, may lead to different sailing patterns (route and speed choices of a vessel) and thus have significant impact on a shipping company’s operating costs. However, the current literature does not include sailing pattern optimization caused by ECA, and its corresponding cost effects, in the evaluation and selection process for sulphur abatement technology. This leads to an inaccurate estimation of the value of certain technologies and hence an incorrect investment decision. In this paper, we integrate the optimization of a ship’s sailing pattern into the lifespan cost assessment of the emission control technology, so that such expensive and irreversible decisions can be made more accurately. The results shows that a considerable overestimation of the value of scrubbers, and thus a substantial loss, can occur if the sailing pattern of a ship is not considered in the decision-making process. Furthermore, we also illustrate that it is more important to involve a ship’s sailing pattern when the port call density inside ECA is low.

Scrubber: A Potentially Overestimated Compliance Method for the Emission Control Areas - The Importance of Involving a Ship's Sailing Pattern in the Evaluation

Different methods for sulphur emission reductions, available to satisfy the latest Emission Control Areas (ECA) regulations, may lead to different sailing patterns (route and speed choices of a vessel) and thus have significant impact on a shipping company's operating costs. However, the current literature does not include sailing pattern optimization caused by ECA, and its corresponding cost effects, in the evaluation and selection process for sulphur abatement technology. This leads to an inaccurate estimation of the value of certain technologies and hence an incorrect investment decision. In this paper, we integrate the optimization of a ship's sailing pattern into the lifespan cost assessment of the emission control technology, so that such expensive and irreversible decisions can be made more accurately. The results shows that a considerable overestimation of the value of scrubbers, and thus a substantial loss, can occur if the sailing pattern of a ship is not considered in the decision-making process. Furthermore, we also illustrate that it is more important to involve a ship's sailing pattern when the port call density inside ECA is low.

Does early-life diet affect longevity? A meta-analysis across experimental studies

Life-history theory predicts that nutrition influences lifespan owing to trade-offs between allocating resources to reproduction, growth and repair. Despite occasional reports that early diet has strong effects on lifespan, it is unclear whether this prediction is generally supported by empirical studies. We conducted a meta-analysis across experimental studies manipulating pre- or post-natal diet and measuring longevity. We found no overall effect of early diet on lifespan. We used meta-regression, considering moderator variables based on experimental and life-history traits, to test predictions regarding the strength and direction of effects that could lead to positive or negative effects. Pre-natal diet manipulations reduced lifespan, but there were no effects of later diet, manipulation type, development mode, or sex. The results are consistent with the prediction that early diet restriction disrupts growth and results in increased somatic damage, which incurs lifespan costs. Our findings raise a cautionary note, however, for placing too strong an emphasis on early diet effects on lifespan and highlight limitations of measuring these effects under laboratory conditions.

Optimization of Drilling Process Parameters for Material Removal Rate and Surface Roughness on Titanium Alloy using Response Surface Methodology and Fire Fly Algorithm

Material removal rate and surface roughness are the important aspects in manufacturing of components. In recent daysvarious newer materials is introduced in power generation, chemical processing, petroleum, automotive industries and armor applications due to their inherent properties. The application of titanium alloy is increased more rapidly than before this decade, since it can decrease lifespan costs through a broad range of equipment and processes. In addition, titanium is one of the newer materials and its machining parameters on drilling operation are to be investigated owing to its poor machinability. In the present work, the influences of spindle speed and feed rate on metal removal rate and surface roughness are studied. To support this objective, Response Surface Methodology (RSM) was used to make a relationship between drilling parameter and responses. Subsequently a new meta-heuristic Fire Fly Algorithm (FFA) was used to optimize the drilling parameters. The developed empirical model is solved by FFA for maximizing the volume of material removed and minimizing the surface roughness of titanium alloy.

Mating damages the cuticle of C. elegans hermaphrodites.

Lifespan costs to reproduction are common across multiple species, and such costs could potentially arise through a number of mechanisms. In the nematode Caenorhabditis elegans, it has been suggested that part of the lifespan cost to hermaphrodites from mating results from physical damage owing to the act of copulation itself. Here, we examine whether mating damages the surface of the hermaphrodite cuticle via scanning electron microscopy. It is found that mated hermaphrodites suffered delamination of cuticle layers surrounding the vulva, and that the incidence of such damage depends on genetic background. Unmated hermaphrodites demonstrated almost no such damage, even when cultured in soil with potentially abrasive particles. Thus, a consequence of mating for C. elegans hermaphrodites is physical cuticle damage. These experiments did not assess the consequences of cuticle damage for lifespan, and the biological significance of this damage remains unclear. We further discuss our results within the context of recent studies linking the lifespan cost to mating in C. elegans hermaphrodites to male secretions.

Reproductive Capability Is Associated with Lifespan and Cause of Death in Companion Dogs

Reproduction is a risky affair; a lifespan cost of maintaining reproductive capability, and of reproduction itself, has been demonstrated in a wide range of animal species. However, little is understood about the mechanisms underlying this relationship. Most cost-of-reproduction studies simply ask how reproduction influences age at death, but are blind to the subjects' actual causes of death. Lifespan is a composite variable of myriad causes of death and it has not been clear whether the consequences of reproduction or of reproductive capability influence all causes of death equally. To address this gap in understanding, we compared causes of death among over 40,000 sterilized and reproductively intact domestic dogs, Canis lupus familiaris. We found that sterilization was strongly associated with an increase in lifespan, and while it decreased risk of death from some causes, such as infectious disease, it actually increased risk of death from others, such as cancer. These findings suggest that to understand how reproduction affects lifespan, a shift in research focus is needed. Beyond the impact of reproduction on when individuals die, we must investigate its impact on why individuals die, and subsequently must identify the mechanisms by which these causes of death are influenced by the physiology associated with reproductive capability. Such an approach may also clarify the effects of reproduction on lifespan in people.

Diet, sex, and death in field crickets

Senescence is shaped by age-dependent trade-offs between fitness components. Because males and females invest different resources in reproduction, the trade-offs behind age-dependent reproductive effort should be resolved differently in the sexes. In this study, we assess the effects of diet (high carbohydrate and low protein vs. equal carbohydrate and protein) and mating (once mated vs. virgin) on lifespan and age-dependent mortality in male and female field crickets (Teleogryllus commodus), and on male calling effort. Females always had higher actuarial ageing rates than males, and we found a clear lifespan cost of mating in females. Mated males, however, lived longer than virgin males, possibly because virgins call more than mated males. The fastest age-dependent increases in mortality were among mated males on the high-carbohydrate diet. Males on a high-carbohydrate diet showed a faster increase in calling effort earlier in life, and a more pronounced pattern of senescence once they reached this peak than did males on a diet with equal amounts of protein and carbohydrates. Our results provide evidence that the cost of mating in this cricket species is both diet and sex-dependent, and that the underlying causes of sex differences in life-history traits such as lifespan and senescence can be complex.

Experimental Evolution Reveals Antagonistic Pleiotropy in Reproductive Timing but Not Life Span in Caenorhabditis elegans

Many mutations that dramatically extend life span in model organisms come with substantial fitness costs. Although these genetic manipulations provide valuable insight into molecular modulators of life span, it is currently unclear whether life-span extension is unavoidably linked to fitness costs. To examine this relationship, we evolved a genetically heterogeneous population of Caenorhabditis elegans for 47 generations, selecting for early fecundity. We asked whether an increase in early fecundity would necessitate a decrease in longevity or late fecundity (antagonistic pleiotropy). Caenorhabditis elegans experimentally evolved for increased early reproduction and decreased late reproduction but suffered no total fitness or life-span costs. Given that antagonistic pleiotropy among these traits has been previously demonstrated in some cases, we conclude that the genetic constraint is not absolute, that is, it is possible to uncouple longevity from early fecundity using genetic variation segregating within and among natural populations.

Adult diet affects lifespan and reproduction of the fruit‐feeding butterfly Charaxes fulvescens

Fruit-feeding butterflies are among the longest lived Lepidoptera. While the use of pollen-derived amino acids by Heliconius butterflies has been interpreted as important for the evolution of extended lifespans, very little is known about the life-history consequences of frugivory. This issue is addressed by investigating effects of four adult diets (sugar, sugar with amino acids, banana, and moistened banana) on lifespan and reproduction in the fruit-feeding butterfly Charaxes fulvescens Aurivillius (Lepidoptera: Nymphalidae). Female butterflies were collected from Kibale National Park, Uganda, and kept individually in cages near their natural habitat and data were collected on lifespan, oviposition, and hatching of eggs. Lifespan in captivity was longer for the sugar and the amino acid cohort, than for the banana cohorts. The longitudinal pattern of oviposition was erratic, with many days without oviposition and few periods with high numbers of eggs laid. Butterflies typically did not lay eggs during their 1st week in captivity and the length of the period between capture and first reproduction was significantly shorter for butterflies fed moistened banana. The length of the reproduction period (first reproduction-last reproduction in captivity) and the reproduction rate (total number of eggs/length of the reproduction period) did not differ significantly between the diet treatments. Those fed with amino acid and moistened banana had significantly higher egg hatchability than those fed with sugar and banana. We found no evidence for a lifespan cost of reproduction. Our results show that (1) female C. fulvescens can use amino acids in their diet for laying fertile eggs, (2) more wing-wear does correlate with lower survival in captivity (indicating aging in the wild), but not with intensity of reproduction (providing no evidence for reproductive aging), and (3) fruit-feeding butterflies may be dietary restricted in the field.