The decisions made during product development (PD) lock in 70–80 % of total product cost, and the quality of the product is also largely fixed. Therefore, these decisions have a great influence on ...product life cycle cost, quality, and sustainability. To improve such decisions, designers need to make high-level trade-offs among various criteria to see their effects. Therefore, developing a model to support trade-offs for sustainable product development is a significant concern for designers. This research attempts to consider sustainability, quality, and cost simultaneously to make trade-offs between environmental issues and other customer requirements to select the best design specifications on their basis. Sustainability is considered as a customer requirement, which then is translated into design specifications. In this study, sustainable design is treated as an optimization problem to maximize value-added activities while minimizing environmental effects. Multi-attribute utility theory is utilized in order to formulate combination of the customer’s opinions and make a trade-off between different groups of customer requirements in the final model. An optimization model is then defined to model sustainability, quality, and cost in the product development process in order to find the optimum level of their combination thereof. By using this model, designers need not select between different solutions since they can find the optimal solution. A case study is illustrated and the results are discussed.
Purpose: This study was undertaken to investigate the effects of pruning and girdling on yield, fruit size and quality of ‘Kinnow’ mandarin (Citrus reticulate Blanco) trees during two seasons. ... Research method: The treatments included: control (unpruned and ungirdled trees), light pruning (removal 10% of 15-20 cm branches), intense pruning (removal 20% of 15-20 cm branches), girdling (removal 5 mm trunk bark), light pruning + girdling, and intense pruning + girdling. The treatments were applied in on-years (2016 and 2018) and traits were measured in following season. Findings: Light pruning increased yield and fruit number by 170.4% and 191.5%, respectively, while fruit weight and volume slightly decreased by 7.2% and 12.4%%, respectively, compared to control. Fruit dimensions and, TSS and TA of fruit juice were not affected by treatments. However, TSS/TA ratio was significantly declined in both pruning treatments. In addition, vitamin C content of fruits decreased in pruned trees and light pruned + girdled trees compare to control. The yield was positively correlated with fruit number and negatively with fruit weight, fruit volume and vitamin C content. Limitations: Despite these findings, more research is needed to identify mechanisms of pruning and girdling on alternative bearing in citrus. Originality/Value: These results suggested that pruning alone or plus girdling of ‘Kinnow’ mandarin trees reduce competition for nutrients and induce accumulation of carbohydrates in branches, which enhanced yield of the next season.
This study aimed to evaluate the influence of wax, polyethylene film (19 μm thickness) and storage time on the quantitative and qualitative characteristics and shelf life of ‘Kinnow’ mandarin fruit ...(Citrus reticulata Blanco cv. ‘Kinnow’) stored at 5°C for 90 days. The mandarins were analyzed for physicochemical characters such as weight loss, weight of fruit, flesh, pulp, juice and peel, as well as total soluble solids (TSS) content, titratable acidity (TA), and pH. Polyethylene film wrapping reduced fresh weight loss and resulted in the highest fruit weight at the end of the 90-day cold storage period. No significant differences were found among coating treatments in pH, TSS, TA content and TSS/TA. The results revealed an increasing trend in TSS and TSS/TA during storage. It is recommended to use polyethylene coating on ‘Kinnow’ mandarins to prevent weight loss and preserve quality during storage at low temperature (5°C) up to 90 days.
Sintering process at temperature intervals close to the melting point of polymers is greatly important due to its role in synthesizing porous materials. During sintering, particles of polymeric ...materials coalesce throughout a process called interdiffusion. On the contrary, crystallization strongly affects the interdiffusion process at temperature intervals below and close to the melting point. Apparently, the outcome of the contention between these two factors would determine the interfacial width. Therefore, the current study presents a model, which takes both crystallization and interdiffusion into account, to predict sintering kinetic. Consequently, interfacial strength was assessed with respect to the following influencing mechanisms, “reentanglement” relying on mutual interpenetration distance and “cocrystallization” determined by interfacial lamellar thicknesses. Based on the results of the present study, by changing sintering temperature of high molecular weight high density polyethylene nascent powder from 125 to 129 °C, the mutual interpenetration distance changes from 4.8 to 52.9 nm and interfacial lamellae thicknesses also vary from L ≈ 0–35.4 nm. On the other hand, porosity measurements revealed the reverse dependency to the sintering temperature. Interfacial lamellae thicknesses were calculated by means of differential scanning calorimetry (DSC) and also scanning electron microscope (SEM) micrographs. Eventually, the results of the shear punch test clearly demonstrated the role of sintering temperature in interfacial strength. Accordingly, the maximum bearable load in the samples sintered at 125 and 129 °C, increases from 25 to 315 N, respectively, which was attributed to change in interfacial volume of two sintered particles in a simplified model. Resultantly, the present study indicates that even a degree centigrade temperature variation would significantly affect the interfacial strength and porosity of the samples due to its effect on crystallization; which in consequence might transform a porous material into a dense one.
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•Sintering porous polymers requires partial welding through interdiffusion.•Crystallization blocks interdiffusion at temperatures close to the melting point.•Contention between crystallization and interdiffusion determines the interfacial width.•Particles are connected together through reentanglement and cocrystallization.•Sintering at higher temperatures leads to larger interfacial volumes.
Polymer composites can offer a striking combination of properties when a gradient in electrical and thermal properties is generated. Functionally graded composites have shown great promise in ...electromagnetic interference (EMI) shielding, energy storage materials and sensors. This work presents a simple manufacturing route to develop graded microcellular structures, and thereby graded functionality, within polymer composite foams containing graphene nanoplatelets. The polymer/graphene composite foams were fabricated via supercritical fluid treatment in an injection molding machine followed by foaming through rapid depressurization in the mold cavity. The microstructural gradient developed within the composite foams, ranged from shear-induced elongated cells to more isotropic cellular structures over the length of the molded composites. This distinct microstructure offered graded electrical and thermal properties in the composites. The electrical conductivity, permittivity and thermal conductivity of the nanocomposite foams increased, respectively, up to 7 orders of magnitude, 1340% and 143% over the length of the composites. The specific EMI shielding raised up to 45% over the length of the nanocomposite foams. This study shows that foaming can pave the way for manufacture of functionally graded polymer composites for existing and emerging applications such as electromagnetic shielding, energy storage materials and sensors.
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Systematic consideration of environmental aspects within the early stages of product development (PD) can be considered highly significant in order for the overall environmental performance of the ...product to be improved. Many methods and tools have been developed aiming to enable this consideration and provide the properties that need to be considered and improved. This article provides an overview of some well-known and more applicable tools and methods that have been developed and are available today. The identified tools are generally classified in two groups: Guidelines and Analytical tools. The limitations and barriers of current tools are assessed and categorized and two areas for work are proposed in order to address current limitations in the existing literature. One of the areas is followed and a scoring model is proposed as a new tool for sustainable PD.
The present study focuses on simultaneous influence of graphene nanoplatelets (GNP) and hydroxyapatite (HAp) nanopowder on microstructural, wear, tensile and biofunctional behavior of UHMWPE based ...nanocomposites used in biomedical applications, with the aim to utilize GNP's mechanical strength and wear resistance, while benefitting from HAp's biocompatibility at the same time. 0.1, 0.5 and 1 wt% GNP with 10 wt% optimized concentration of HAp were added to the UHMWPE matrix through an easy two-step approach consisting of solvent mixing and ultrasonication in ethanol as a liquid media. The dried nanocomposite samples of powder were then hot pressed at an optimized temperature and pressure to ensure complete melting and flowing of the polymeric material. Tensile testing results indicated a 114% & 24% increase in elastic modulus and yield strength in the sample containing 1 wt% GNP and 10 wt% HAp, respectively, as compared to UHMWPE. However, the sample containing 0.5 wt% GNP showed greatest tensile performance with an increase of 101% and 31% improvement in elastic modulus and yield strength, which proves that the strengthening mechanism is influenced by the content of the reinforcement, especially in case of 2D reinforcing phases such as GNP. Microstructural analysis revealed the nucleating effect of GNPs on the crystalline structure of UHMWPE, to which the escalated mechanical properties could be attributed. Furthermore, the assessments disclosed the dependency of nucleating, and in consequence strengthening effect of GNPs to their concentration and apparent clustering threshold. Moreover, pin-on-disk tribological testing results showed a somewhat similar result for the coefficient of friction, which decreased by 50% with 1 wt% GNP, while the similar parameter for the sample containing 0.5 wt% GNP underwent 54% reduction. Whereas a steady decreasing pattern was observed in the case of wear rate with an 82% decrease in the sample containing 1 wt% GNP, coming to a conclusion that GNP is much more effective in improving wear properties rather than in mechanical strengthening. Biological examinations also demonstrated that HAp promises biocompatibility, osteoconductivity and the elimination of adverse cellular response, while cell adhesion was still dependent on the concentration and was affected adversely with increasing GNP. This destructive biological effect of GNPs was seemingly attributed to the functional groups of the material, or to the inherent edge-shaped structure by means of FTIR, wettability and compaction analyses.
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Abstract Electromagnetic pollution presents growing challenges due to the rapid expansion of portable electronic and communication systems, necessitating lightweight materials with superior shielding ...capabilities. While prior studies focused on enhancing electromagnetic interference (EMI) shielding effectiveness (SE), less attention is given to absorption‐dominant shielding mechanisms, which mitigate secondary pollution. By leveraging material science and engineering design, a layered structure is developed comprising rGOnR/MXene‐PDMS nanocomposite and a MXene film, demonstrating exceptional EMI shielding and ultra‐high electromagnetic wave absorption. The 3D interconnected network of the nanocomposite, with lower conductivity (10 −3 –10 −2 S/cm), facilitates a tuned impedance matching layer with effective dielectric permittivity, and high attenuation capability through conduction loss, polarization loss at heterogeneous interfaces, and multiple scattering and reflections. Additionally, the higher conductivity MXene layer exhibits superior SE, reflecting passed electromagnetic waves back to the nanocomposite for further attenuation due to a π/2 phase shift between incident and back‐surface reflected electromagnetic waves. The synergistic effect of the layered structures markedly enhances total SE to 54.1 dB over the K u ‐band at a 2.5 mm thickness. Furthermore, the study investigates the impact of hybridized layered structure on reducing the minimum required thickness to achieve a peak absorption (A) power of 0.88 at a 2.5 mm thickness.
Electrospun strain sensors allow facile integration with wearable devices, however, achieving high sensitivity and extended working range are often hindered by their non-homogenous, 2-dimensionally ...(2-D) responsive network and its instability under large stimuli. In this study, a novel strategy consisting of (i) nano-scale surface functionalization, materials formulations and (ii) micro-scale in-situ coating technique were employed to address these challenges. A nanohybrid sensor composed of 2-D tannic acid (TA) functionalized Ti3C2Tx MXene and 1-dimensional (1-D) graphene nanoribbons (GnRs) were developed taking advantage of the short response time from Ti3C2Tx and GnR's bridging effect and flexibility. TA functionalization helped increasing the electronegative surface terminations of Ti3C2Tx, enhancing the interfacial interaction between GnR and Ti3C2Tx and the integrity of the conductive network. The robustness and the interfacial stability of the responsive network was also promoted via a technique combining coaxial electrospinning with simultaneous electrospraying. The styrene-butadiene-styrene (SBS) nanofibers functionalized with electropositive cetryl ammonium bromide (CTAB) to provide electrostatic attraction for conformal coating of the electronegative nanohybrid onto the SBS platform. This, along with the synergism between 2-D Ti3C2Tx and 1-D GnR, led to in-situ formation of a 3-D responsive network. Also, a comprehensive assessment was conducted to study the effect of the additives' geometry on the electromechanical performance. The reported structure provided exceptionally high sensitivity (Gauge Factor (GF) of 2090 at 550%), excellent dynamic stability (enduring 5000 cyclic test under 100% strain), an extended working range (0.1%–550% strain) and fast response and recovery times (50, and 46 ms, respectively) at a low detection limit (0.1%).
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•Increased mechanical and environmental stability of Ti3C2Txvia tannic acid (TA) surface treatment.•Electromechanical synergism between 2-D Ti3C2Tx-TA and 1-D graphene nanoribbon (GnRs).•Ti3C2Tx-TA@GnR 3-D networks were assembled in situ via simultaneous electrospinning/spraying.•Electrical field assisted orienting of GnRs in the formation of 3D active networks.
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