This paper investigates the strategies for adopting blockchain technology in the fresh product supply chain (FPSC) consisting of a supplier, a third-party logistics service provider (3PL) and an ...e-tailer. We analyse the optimal strategies of FPSC members under the benchmark scenario where the FPSC does not adopt blockchain technology and those under the three scenarios where the supplier, 3PL and e-tailer lead the construction of the blockchain-based traceability system (BTS), respectively. We find that adopting blockchain technology is not always the optimal decision for the FPSC, which is related to the consumers' acceptance degree for the product without blockchain technology, the deterioration rate of the fresh product and the allocation proportion of traceability cost of FPSC members when adopting blockchain technology. Regardless of the power and status of each member in the FPSC, it can lead the construction of the BTS. From the perspective of whole FPSC's profit maximisation, the leader of the FPSC should lead the construction of the BTS under the coordination of a two-part tariff contract. This study provides valuable insights for FPSCs to adopt blockchain technology.
Blockchain technology is an emerging technology developed in recent years. It has powerful information traceability function. The blockchain technology plays an important role in monitoring product ...quality and responding to product safety problems. Under considering the traceability awareness of consumers and the cost of using the blockchain technology, should the supply chain adopt the blockchain technology? The research on this issue deserves great attentions. In this paper, for a three-stage supply chain consisting of a supplier, a manufacturer and a retailer, we study the optimal pricing strategies of the supply chain considering the traceability awareness of consumers in two scenarios. These two scenarios are: scenario N (i.e., the supply chain does not adopt the blockchain technology) and scenario B (i.e., the supply chain adopts the blockchain technology). On this basis, we discuss the conditions that the supply chain adopts the blockchain technology by comparing the optimal profits of the supply chain and its members in two scenarios. Further, we discuss the problem of supply chain coordination when adopting the blockchain technology. The results show that it is conditional for the supply chain to adopt the blockchain technology, and the condition is related to the traceability awareness of consumers, the production costs of the supplier and manufacturer, and the cost of using the blockchain technology. We also find that under a certain condition, the revenue sharing contract can realize a Pareto improvement for the supply chain that adopts the blockchain technology.
•Heat dissipation issues at near-junction region of GaN HEMT are reviewed comprehensively.•Phonon transport properties in GaN and GaN nanostructures are discussed based on both computations and ...experiments.•Phonon transport tuning mechanisms in perspectives of particle, wave, and topological nature of phonons for GaN and GaN nanostructures are introduced.
The heat dissipation issue has now become one of the most important bottlenecks for power electronics due to the rapid increase in power density and working frequency. Towards the wide bandgap semiconductor GaN high electron mobility transistors (HEMTs), near-junction thermal management is the breakthrough that mainly includes the accurate thermal modeling and effective thermal design for GaN and GaN HEMTs. In this review, we first offer a comprehensive understanding of phonon thermal transport in GaN and GaN HEMTs, including non-equilibrium transport of electrons and phonons in the heat generation process, phonon thermal conductivity, heat spreading, and interfacial thermal transport. Then, we review the current tuning mechanisms and methods for thermal transport in GaN and GaN HEMTs which are classified into three categories according to the particle nature, wave nature, and topological nature of phonons. At last, we conclude by providing our perspectives on challenges and opportunities in the research of phonon thermal transport and its tuning mechanisms in GaN HEMTs.
•A novel optimization approach is proposed to optimize the performance of a hybrid heat sink.•The Pareto-optimal set is obtained and verified by CFD results.•The optimized heat sink can reduce ...thermal resistance by 18.83% compared with manifold heat sink.•TOPSIS with entropy weight method is applied to select the best compromise solution from Pareto-optimal set.
A novel optimization approach, which combines optimal Latin hypercube design (Opt LHD), Pareto chart analysis, response surface methodology (RSM), the non-dominated sorting genetic algorithm II (NSGA-II) and technique for order preference by similarity ideal solution (TOPSIS), has been proposed and applied to optimize the performance of a hybrid microchannel heat sink combining manifold concept with secondary oblique channels. Four geometric parameters are selected as design variables and the optimization objective is to minimize the total thermal resistance Rt and pumping power Pp simultaneously. First, 160 sample points is generated by Opt LHD and the Pareto chart analysis is performed to identify the dominant design parameters influencing the objectives. Then, RSM is used to generate approximate models relating to the objectives and design parameters, and NSGA-II is selected to minimize Rt and Pp. 374 Pareto-optimal solutions are obtained and verified by CFD results, which indicates that the hybrid design can reduce Rt by 18.83% compared with manifold microchannel heat sink under the same Pp. Finally, the best compromise solution is obtained by TOPSIS combined with entropy weight method. The proposed optimization approach can also be applied to optimize the performance of other types of heat sinks.
•A hybrid design using manifold arrangement and secondary channels for microchannel heat sink is proposed.•A Design Optimization Area (DOA) for the MMC-SOC is defined.•The pressure drop and thermal ...resistance can be both reduced in DOA.•The best hybrid design with geometrical parameters of (λ = 1, β = 1) is obtained.
The flow and heat transfer characteristics of a novel hybrid microchannel heat sink with manifold arrangement and secondary oblique channels (MMC-SOC) are numerically studied. Through the relationship between the total thermal resistance ratio (Rt/Rt0) and pressure drop ratio (ΔP/ΔP0), we define a region named Design Optimization Area (DOA), where the pressure drop ΔP and the total thermal resistance Rt can be both reduced due to the secondary channels. The numerical results show that the best heat sink can reduce ΔP by 1.91%, and simultaneously decrease Rt by 19.15% compared to the original MMC heat sink at Re = 295. In addition, the effects of secondary channel on ΔP are dependent on both the geometrical parameters and Reynolds numbers. On the one hand, it can reduce the pressure loss at small Reynolds numbers for most heat sinks. However, it can also increase the pressure loss at high Reynolds numbers for most heat sinks. As Re increases, the ratio (Rt/Rt0) becomes smaller and (ΔP/ΔP0) becomes larger, indicating a better thermal performance and a worse hydraulic performance. The secondary flow field analyses visually show the hydraulic and thermal performance enhancements due to thermal boundary layer re-development and flow mixing.
•Graphene oxide and polyethylenimine layer-by-layer assembly membranes.•The deposition of PEI increases the membrane surface charge.•Membranes with high salt rejection and flux were obtained.
Highly ...positively charged nanofiltration (NF) membranes have been prepared via a layer-by-layer (LbL) self-assembly technique using graphene oxide (GO) and polyethyleneimine (PEI). The high aspect ratio and unique 2D structure of GO nanosheets enabled them to be easily assembled on the membrane surface, and the intrinsic low resistant channels within the GO nanosheets resulted in a high water flux of the membrane. By assembled a PEI layer on the membrane outer surface, the composite membrane exhibited high positive charge and resulted in the high rejections to multivalent ions. The effects of deposition time, PEI and GO concentrations on separation performance of the NF membranes were detailed studied. The best performance among all the membranes was achieved with salt rejections of 93.9% and 38.1% for Mg2+ and Na+, and a water flux of 4.2L/m2hbar at 30°C and 0.5MPa. The attractive performance of these NF membranes showed a great potential in the industrial application of water softening.
•Full-band phonon Monte Carlo simulation is conducted to study thermal spreading resistance in GaN HEMTs.•Different simulation approaches for simulation phonon transport in GaN HEMTs are thoroughly ...compared.•Incorporating first-principle-calculated phonon properties in device thermal simulations is essential.
Accurate thermal simulation is essential for the near-junction thermal management and electro-thermal co-design of GaN HEMTs. While various methods have been employed to simulate phonon thermal transport in GaN, a comprehensive evaluation of their performance and reliability has yet to be conducted. In this work, first-principle-based steady-state full-band phonon tracing Monte Carlo (MC) simulations are conducted to study the thermal spreading resistance in GaN HEMTs. The results of full-band MC serve as a standard against which the applicability, accuracy, and computational efficiency of three widely-used approaches to simulate the near-junction phonon transport in GaN are thoroughly examined. The simulation techniques compared in this study include MC simulations with empirical isotropic phonon dispersion (isotropic MC), MC simulations with gray-medium approximation (gray MC), and finite-element methods (FEM) with effective thermal conductivities (FEM with keff). It is found that isotropic MC largely overestimates the thermal resistance due to the empirical model’s overestimation of phonon mean free path (MFP) distributions. By selecting an appropriate average MFP, gray MC can approximate the full-band results well, but due to its inability to reflect the contributions of different phonon modes, discrepancies are inevitable for some geometric parameters. For FEM-based analysis, although the diffusive nature of Fourier’s law precludes the reproduction of channel temperature distributions, the influence of phonon ballistic effects on the junction temperature can be accurately reflected in the well-chosen effective thermal conductivities. The comparison highlights the importance of directly incorporating first-principles-calculated phonon properties into device thermal simulations, and the paper can provide a clearer understanding of near-junction thermal transport in GaN and can be useful for thermal simulations of GaN-based devices.
The increased threat of antibiotic resistance has created an urgent need for new strategies. Herein, polyprodrug antimicrobials are proposed to mimic antimicrobial peptides appended with a concurrent ...drug release property, exhibiting broad‐spectrum antibacterial activity and especially high potency to inhibit methicillin‐resistant Staphylococcus aureus (MRSA) without inducing resistance. Two series of polyprodrug antimicrobials are fabricated by facile polymerization of triclosan prodrug monomer (TMA) and subsequent quaternization of hydrophilic poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA), affording PDMAEMA‐b‐PTMA and PQDMA‐b‐PTMA, respectively. Optimized samples with proper hydrophobic ratio are screened out, which exhibit remarkable bacterial inhibition and low hemolysis toward red blood cells. Furthermore, synergistic antibacterial mechanisms contribute to the bacteria killing, including serious membrane damage, increased out‐diffusion of cytosolic milieu across the membrane, and intracellular reductive milieu‐mediated triclosan release. No detectable resistance is observed for polyprodrug antimicrobials against MRSA, which is demonstrated to be better than commercial triclosan and vancomycin against in vivo MRSA‐infected burn models and a promising approach to the hurdle of antibiotic resistance in biomedicine.
Polyprodrug antimicrobials with remarkable membrane damage and concurrent drug release are proposed to treat the infection and antibiotic resistance of methicillin‐resistant Staphylococcus aureus (MRSA), exhibiting low hemolysis toward red blood cells and good antibacterial selectivity. Remarkable membrane damage and further intracellular triclosan release synergistically kill MRSA, possessing undetectable resistance compared with commercial antibiotics. Polyprodrug antimicrobials are promising to treat drug‐resistant bacteria in biomedicine.
PDF
