Ion Transport in Temperature Sensitive Polyelectrolytes

Temperature sensors are widely employed and play a key role in many industries, such as automotive vehicles, medical devices, environmental monitoring, and process control. The state-of-the-art thermal sensing elements are made of rigid and costly inorganic materials, such as vanadium oxide and platinum. These materials have limitations for emerging applications such as wearable devices and prosthetic devices. Ideal temperature sensing materials for such applications need to be flexible, reliable under mechanical deformation, and suitable for large-area production. Electrical conductive polymers were found to be a promising solution because of their flexibility and solution processability. However, they often lag in temperature resolution compared to their inorganic counterparts. A recent discovery revealed that the ionic conductivity of crosslinked pectin, a biopolymer extracted from plant cell walls, has a record-high temperature response. It is biocompatible, flexible when hydrated, and solution-processable, making it a strong candidate for wearable temperature sensing and conformal temperature mapping. However, open questions remain about the origin of its temperature sensitivity and the principles governing its ion transport. Furthermore, the heterogeneity of the complex molecular structure of pectin presents challenges to its integration in sensing devices. In this thesis, we study the origin of the high thermal sensitivity in pectin and develop a synthetic polyelectrolyte that mimics its key structure and properties. In Chapter 3, we focus on the ion transport mechanism in crosslinked pectin. We show that the binding between multivalent ions and certain chemical functional groups of pectin plays a critical role in its temperature sensitivity. In Chapter 4, the impact of water content on the ion transport and dielectric processes in crosslinked pectin is also investigated. In the following chapter, we present a novel synthetic polyelectrolyte designed to mimic pectin with a simpler structure. It has superior flexibility, high temperature sensitivity, and is stable under mechanical deformation. To further study this new material, we examine its ion transport dynamics under varying humidity and temperature conditions in Chapter 7. We discover that temperature and humidity have a similar effect on ion transport. Overall, we showed a biomimetic approach to design temperature sensitive polymers where the strong ion-polymer binding is the key to the ultrahigh temperature response.</p

State Estimation for Electrolytic Capacitor with Parameter Fitting

Metro supply system composed of PWM rectifier, i.e. supply system with bi-directional power flow, contributes much to improve supply quality. However, the electrolytic capacitors, working as DC-side supporting capacitor, are relatively weakest in the whole system, so that state estimation for electrolytic capacitor should be taken into consideration. In view of the difficulty in application of conventional capacitor estimation approach with voltage and current ripples into PWM rectifier, this paper proposes a novel approach, which first searches into capacitor’s aging mechanism, presents approximate relation between capacitance and equivalent serial resistance of electrolytic capacitor through mathematical fitting, and then derives the discrete iterative equations of  capacitance and equivalent serial resistance from the analytical model of PWM rectifier. Finally, capacitor state estimation is combined with Miner criterion, which implies digital accumulated damage principle. DOI: http://dx.doi.org/10.11591/telkomnika.v11i8.3049

Diel vertical migration of Peridiniopsis niei, Liu et al., a new species of dinoflagellates in an eutrophic bay of Three-Gorge Reservoir, China

In spring, a typical dinoflagellate (Peridiniopsis niei Liu et al.) constitutes most of the phytoplankton biomass in most of eutrophic bay of Three-Gorge Reservoir (TGR, China). There are few field observations on vertical migration of the members of the genus Peridiniopsis. We studied diel vertical migration of the new species (Peridiniopsis niei) at sampling stations A and B in an eutrophic bay (Xiangxi Bay) of TGR during both day and night in March 2007. The present study suggests that vertical migration by Peridiniopsis niei is similar in nature to the migration patterns observed for other dinoflagellates. Solar irradiance incident was an important factor regulating the ascent and descent of Peridiniopsis niei. The vertical descent of Peridiniopsis niei during nighttime was restricted when the thermocline (Temperature gradient > 1A degrees C m(-1)) was present in the station B

Effect of silicon addition on the growth and photosynthesis of Castanopsis hystrix in manganese stress

Silicon (Si) plays important role in reducing the toxic effects of manganese (Mn) in plants, however, more research is needed to elucidate the photosynthetic response with different Si and Mn treatments. This study aimed to investigate the alleviating effect of Si on the growth and photosynthesis of Castanopsis hystrix (C. hystrix) under Mn stress. Seedlings were grown in pot experiments with five Mn levels (0, 200, 600, 1500, and 3000 mg·kg-1) and four Si levels (0, 115, 230, and 460 mg·kg-1). The results showed that three types of (positive, stagnant, and negative) growth of C. hystrix seedlings were observed among twenty treatments. Low concentrations of Si (Si ≤ 115 mg·kg-1) and Mn treatments (Mn ≤ 600 mg·kg-1) can stimulate a positive growth of seedlings by increasing net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs). The 230 mg·kg-1 Si with low concentration of Mn treatments can cause a stagnant growth of seedlings by increasing Gs, Tr and maximum photochemical efficiency of PSII (Fv/Fm) but decreasing intercellular carbon dioxide concentration (Ci). High concentrations of Si (Si ≥ 460 mg·kg-1) or Mn treatments (Mn ≥ 1500 mg·kg-1) treatments can cause negative growth of seedlings by decreasing photochemical quenching (qP), non-photochemical quenching (qN), Gs, Pn and pigment contents. The application of Si alleviated the stress induced by Mn and promoted the growth-defense regulation mechanism of seedlings to avoid stress. Hence, we concluded that the most suitable concentration of Si was 115 mg·kg-1 Si for C. hystrix’s growth under low Mn stress

Joint Resource Allocation and Trajectory Design for Resilient Multi-UAV Communication Networks

In contrast to terrestrial wireless networks, dynamic Unmanned Aerial Vehicle (UAV) networks are susceptible to unexpected link failures arising from UAV breakdowns or the depletion of its batteries. Drastic user rate fluctuations and sum rate drops can occur due to the unexpected UAV link failures. Previous research has focused primarily on re-establishing these links to maintain service continuity, while neglecting overall system performance, including sum rate and user rate fluctuations. This letter proposes a resilient UAV network design utilizing the modern portfolio theory (MPT), which jointly optimizes the bandwidth allocation, UAV-user association, and UAV trajectories to enhance the overall service stability. Specifically, the design incorporates a novel utility function based on MPT to achieve a better balance between the sum rate and user rate fluctuations. To solve the joint optimization problem, we propose an iterative algorithm based on alternating optimization (AO) and successive convex approximation (SCA). Simulation results show that our scheme outperforms the other two baselines in terms of sum rate and user rate fluctuations. Furthermore, the resilience requirement in terms of sum rate, user rate fluctuations and user fairness can be achieved by flexibly tuning weight factor in our proposed algorithm

Optimal bike allocations in a competitive bike sharing market

This paper studies the bike allocation problem in a competitive bike sharing market. To overcome computational challenges, a continuum approximation (CA) approach is applied, where the allocation points and user demand are assumed to be continuously distributed in a two-dimensional region. Companies offering bike sharing service bear both allocation cost and bike depreciation cost while earning revenue from fare collection. The user's selection of bike service is affected by both walking distance and preference towards bike quality. The elasticity of the demand is considered in relation to the density of allocation points in the market. A leader-follower Stackelberg competition model is developed to derive the optimal allocation strategy for market leader. Two sets of numerical studies - one hypothetical case and one from a real case - are conducted to specify the impact of the parameters on model performance and illustrate how the proposed model can be applied to support the decision making.<br/