Periodically kicked feedforward chains of simple excitable FitzHugh-Nagumo neurons

This article communicates results on regular depolarization cascades in periodically-kicked feedforward chains of excitable two-dimensional FitzHugh-Nagumo systems driven by sufficiently strong excitatory forcing at the front node. The study documents a parameter exploration by way of changes to the forcing period, upon which the dynamics undergoes a transition from simple depolarization to more complex behavior, including the emergence of mixed-mode oscillations. Both rigorous studies and careful numerical observations are presented. In particular, we provide rigorous proofs for existence and stability of periodic traveling waves of depolarization, as well as the existence and propagation of a simple mixed-mode oscillation that features depolarization and refraction in alternating fashion. Detailed numerical investigation reveals a mechanism for the emergence of complex mixed-mode oscillations featuring a potentially high number of large amplitude voltage spikes interspersed by an occasional small amplitude reset that fails to cross threshold. Further careful numerical investigation provides insights into the propagation of this complex phenomenology in the downstream, where we see an effective filtration property of the network; the latter amounts to a successive reduction in the complexity of mixed-mode oscillations down the chain.

Experimental Investigation on The Effect of PolyVinyl Alcohol on Cement Fluid Loss in Oil Wells

This study presents the effect of PolyVinyl Alcohol Cement Fluid Loss Additive (PVA FLAC) on the API Filtration property of a cement slurry. In Cementing operations of oil wells, different type of fluid loss agents and chemicals are used based on the condition of the wells. PVA FLAC recently introduced in Kurdistan oil industry as loss agent additive to reduce the API Filtration Rate and fluid loss of the cement slurry. Four cementing formulations with different concentration of PVA FLAC additive prepared and their API filtration rates are measured. The results showed that when adding 1.94 gm, 2.91 gm and 3.88 gm of PVA FLAC additive to the cement slurry, the API Filtration Rate reduced by %17, %29 and %42, respectively. The new concentration significantly reduced the rate of filtration when compared to using only 0.97 gm of PVA FLAC additive.

Filtration Property of Monofilament Core–Shell Mesh Fabric Treated Via Tourmaline Hot Coating

In this study, woven fabrics with numerous electrostatic charges and desirable charge stability were investigated. A kind of core–shell monofilaments with different melting points between outer and inner layers were applied to wove the fabrics. These fabrics were hot coated through tourmaline particles as an charge enhancer at 122°C. Benefiting from the anions released by tourmaline particles and optimized content of the particles, the fabrics were endowed with surface potentials from −10 to −160 V and the voids content decreased from 45.4% to 41.2%, which contribute to the improvement in the filtration performance of the fabrics. A filtration mechanism was proposed while incremental surface charges with increasing tourmaline particles content have been confirmed through the noncontact measurement of electrostatic charges. The resultant fabrics exhibited a high filtration efficiency of 64.8% and superior long-term service performance. This study can provide a new application of the screen window for PM 2.5 governance.

Triboelectric Effect of Polytetrafluoroethylene Fibers to Improve the Filtration Performance of Air-Purified Materials

The effect of triboelectric behavior of polytetrafluoroethylene (PTFE) on the filtration performance of common air-purified filters was studied. Variations of triboelectric charge density on PTFE films were analyzed by four typical parameters (cycle, applied load, contact area and velocity). The results demonstrated that the addition of PTFE fibers could significantly improve the filtration property of air-purified materials, owning to the accumulation of triboelectric static charge on the fibers.