In recent times, flexible piezoresistive polymer nanocomposite-based strain sensors are in high demand in wearable devices and various new age applications. In the polymer nanocomposite-based strain sensor, the dispersion of conductive nanofiller remains challenging due to the competing requirements of homogenized dispersion of nanofillers in the polymer matrix and retaining of the inherent characteristics of nanofillers. In the present work, waterproof and flexible poly(vinylidene difluoride) (PVDF) with a polymer-functionalized hydrogenexfoliated graphene (HEG)-based piezoresistive strain sensor is developed and demonstrated. The novelty of the work is the incorporation of polystyrene sulfonate sodium salt (PSS) polymer-functionalized HEG in a PVDF-based flexible piezoresistive strain sensor. The PSS-HEG provides stable dispersion in the hydrophobic PVDF polymer matrix without sacrificing its inherent characteristics. The electrical conductivity of the PVDF/PSS-HEG-based strain sensor is 0.3 S cm −1 , which is two orders of magnitude higher than the PVDF/HEG-based strain sensor. Besides, near the percolation region, the PVDF/PSS-HEG shows a maximum gauge factor of 10, which is about two times higher than the PVDF/HEG-based flexible strain sensor and 5-fold higher than the commercially available metallic strain gauge. The enhancement in the gauge factor is due to the stable dispersion of PSS-HEG in the PVDF matrix and electron conjugation caused by the adherence of negatively charged sulfonate functional groups on the HEG. The developed waterproof flexible strain sensor is demonstrated using portable wireless interfacing device for various applications. This work shows that the waterproof flexible PVDF/ PSS-HEG-based strain sensor can be a potential alternative to the commercially available metallic strain gauge.
The burden material in a blast furnace is essentially a collection of particles having wide range of size and shape. It is discharged from the hopper and distributed on the stock level. The mass distribution of the falling stream determines the shape of the stock profile. The stock profile dictates the radial variation of ore/coke ratio, size segregation, gas distribution and burden descent, which in turn influence the formation and shape of the cohesive zone. Knowledge of the stock profile is therefore essential for understanding these phenomena. The complex nature of the flow has made a first-principle prediction of the mass distribution in the falling stream extremely difficult. Kondoh et al. 1) have reported mass fraction distribution in the falling stream at different elevation but the complete description as a function of chute angle is not reported. The present work attempts to predict the mass fraction distribution in the falling stream for three burden materials, viz. iron ore, coke and sinter. ExperimentationThe experiments were conducted using actual bell less top charging equipment of the furnace in a trial rig. Figure 1 shows a schematic diagram of the experimental setup. The rig was comprised of the complete material charging system including receiving hopper, common hopper, upper seal valve, lower seal valve, flow control gate and rotation chute. A brick-walled cylindrical tank of 5 m diameter and 1.5 m height was built for simulating the furnace throat. A small section of the cylindrical wall was kept open for removal of the charged materials. Proper electrical and mechanical arrangements were made for the rotational motion of the distributing chute. Tilting angle of the chute was changed manually and the chute was set to rotate at a constant speed. To feed the material in the receiving hopper, a special charging hopper of volume 1.43 m 3 was fabricated with a discharge gate at the bottom.For the purpose of collecting the materials from the falling particle stream, a semi-cylindrical pipe was inserted along the throat diameter at 1.6 m below the chute tip (design stock level). The pipe was divided into 25 compartments of 20 cm width each. In the experiment, rotating chute distributed the material along the peripheral direction and completed full rings. When the falling stream crossed the inserted pipe, material was collected in the different compartments, as shown in Fig. 2. For each full ring rotation of the chute, material was collected in two different locations, one on either side of the throat centre-line. Materials from individual compartments were weighed and mass fraction distribution was calculated. Results and DiscussionThe striking position of the falling stream of sinter for different chute inclination angle is shown in Fig. 3. The stream moves toward furnace wall with the increase in chute angle. In the figure, the filled points are the striking positions of the outer stream and the void points are the striking points of the inner stream. The stream width, defined as the distance...
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