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Conventional Pressure Sensors
Published in J G Webster, Prevention of Pressure Sores, 2019
Pax et al (1989) used Interlink sensors to measure palmar pressures. They coated 32-gage stranded wires with silicone rubber to provide strength and flexibility, then attached them with silver paint. They encapsulated the sensor in RTV silicone rubber to provide strain relief for the connections and a more uniform pressure distribution. The RTV layer was then sandwiched between two thin sheets of silicone elastomer. The package had an overall thickness of 2 mm. They explored several methods, but found that a plain sensor responded more repeatably and over a larger area than sensors with a single backing plate or both a top plate and a backing plate. However, in their application the sensor was always applied against a smooth, hard surface, so it was not subject to flexing during measurements.
Mounting Large, Variable-Orientation Mirrors
Published in Paul Yoder, Daniel Vukobratovich, Opto-Mechanical Systems Design, 2017
Single-arch mirrors of the type shown in Figure 2.30e are also hub mounted through a central perforation. One design of this type, due to Carter (1972), is illustrated in Figure 5.46. Here, we see a 152 cm (59.8 in.) diameter mirror made of Cer-Vit. Its edge thickness was chosen to be 2.5 cm (1.0 in.), and the sectional thickness was computed at each 0.25 mm increment of radius so as to maintain a uniform stress on the mirror surface when oriented with axis vertical. For convenience, an available 16.5 cm (6.5 in.) thick blank was used, so the curve on the back surface ended at a radius of ∼39 cm (15.4 in.). The flat portion of the back surface was ground and polished and contacted a 79 cm (31.1 in.) diameter stainless steel mounting plate. The mounting plate was 5 cm (1.96 in.) thick over the central 38.1 cm (15.0 in.) diameter and tapered to an edge thickness of 0.64 cm (0.25 in.). A 30 cm (11.8 in.) diameter stainless steel tube with 0.50 cm (0.21 in.) wall thickness was shrunk fit into a central hole in the mounting plate. The ID of the mirror was bonded to the OD of this tube with RTV silicone rubber (Dow Corning type 93-046, catalyst cured). The elastomer was 0.05 cm (0.02 in.) thick and was injected between the support tube and the glass through a series of grease fittings. Tapped holes in the back of the mounting plate allowed the mirror assembly to be bolted directly to a back plate that formed part of the telescope structure.
Fabrication and Processing of Polyurethanes
Published in Nina M. K. Lamba, Kimberly A. Woodhouse, Stuart L. Cooper, Polyurethanes in Biomedical Applications, 2017
Nina M. K. Lamba, Kimberly A. Woodhouse, Stuart L. Cooper
The process of solvent casting of devices is similar to that for the fabrication of tubing by solventcasting techniques. Solvent-cast methods have been used for the processing of polyurethane intraaortic balloons, which consist of one or more chambers supported on a perforated catheter tube with a suitable tip.35 A mandrel was molded onto a catheter with tip in place and followed by dip coating with Estane 5710-F1 and 5707-F1 polyetherurethanes to form an integral film of uniform coating on the tip and along the entire length of the catheter. Rigidax®, a eutectic water dispersible inorganic salt, was used as the mandrel material, primarily due to its compatibility with the Estanes. This process was not useful for other elastomers because these polyurethanes were only soluble in DMSO or DMF, solvents which attack Rigidax. Fabrication difficulties were overcome by adopting a two stage process in which the balloon envelope was made separately from the catheter and tip. In this process paraffin wax mandrels were fabricated in a RTV silicone rubber mold. The balloon film was then formed on the mandrel by repeated dipping in a polyurethane solution (Figure 5).
Enhancement of Novolac aerogel nanostructure and cellulose cork on thermal performance and ablation properties of lightweight heat shields: with regard to omission of thermal convection
Published in Experimental Heat Transfer, 2020
Golnoosh Abdeali, Faranak Samani, Hamidreza Hadizadeh- Raiesi, Ahmad Reza Bahramian
Commercial Novolac resin as monomer (IP 502 from Resitan Co., Tehran, Iran) contained 9 wt.% of hexamethylenediamine (HMTA) crosslinker and 2-propanol (Dr. Mojallali Co., Tehran, Iran) were used as an organic precursor and polymerization solvent, respectively. Cellulose cork granules (ρ = 200 kg/m3) were afforded from (Amorim Mozelos, Portugal) and were used to produce cellulose cork/aerogel nanocomposites. Selected polymeric adhesive in cellulose cork-based nanocomposites preparation was room temperature vulcanizing (RTV) silicone rubber (ρ = 1150 kg/m3). Commercial Resole-type phenolic resin (IL800.2) was purchased from Resitan Co. Iran to produce resole/graphene oxide nanocomposite coating. Graphite (Roth, Bavaria, Germany), potassium permanganate (KMnO4, Ghatran Shimi Co., Tehran, Iran, 95%), sodium nitrate (NaNO3, Ghatran Shimi, 99%), sulfuric acid (H2SO4, Dr. Mojallali Co., Iran, 98%), hydrochloric acid (HCl, Dr. Mojallali Co., Iran, 99%), and hydrogen peroxide (H2O2, Dr. Mojallali Co., Iran, 30%) were used as received without any further purification.
Capillary Performance of Micropillar Arrays in Different Arrangements
Published in Nanoscale and Microscale Thermophysical Engineering, 2018
Sangbeom Cho, Rao Tummala, Yogendra Joshi
The permeability of the samples is determined using the forced liquid flow method. Figure 4 (a) shows the schematic of the permeability test setup. The reservoir is filled with DI water, and the flow rate of water is controlled by a gear pump (Micropump (GJ-N21), Max flow rate: 1740 mL/min). Pumped water passes through a 7 µm filter to prevent small particles from going into the wick sample under test. As shown in Figure 4 (b), the test section consists of a transparent polycarbonate cover plate, wick sample, and a flow housing with two pressure ports. A rectangular channel of 1 cm x 5 cm is cut in the flow housing to place the wick sample. Room-Temperature-Vulcanization (RTV) silicone rubber is placed between wick sample and the housing to prevent any bypass flow. The cover plate and housing are fastened with bolts, and o-ring placed between the two provides a tight sealing. Two pressure transducers (Omega, 0–6.9 bar) are connected to the two pressure ports at housing to measure pressure difference between the inlet and outlet. All tests are performed at three different inlet pressure conditions, 4, 5, and 6 bar by controlling the flow rate. After the test section, water is collected in a container, and placed on an electronic scale with a resolution of 0.001 g. The scale transfers real-time mass change of the container to a computer through RS232 interface. Measured mass change data is collected for at least 60 s, and it is used to calculate mass flow rate for each test case. Water temperature at inlet and outlet of the test section is measured using T-type thermocouples probes with 813 µm diameter to determine the viscosity and density of water. Prior to each test, the sample is blown with pure nitrogen to remove any particulates.
Support conditions assessment of concrete pavement slab using distributed optical fiber sensor
Published in Transportmetrica A: Transport Science, 2019
Hongduo Zhao, Difei Wu, Mengyuan Zeng, Jianming Ling
Since BOTDA technique can only measure the axial strain of the sensing fiber, the compression sensing unit was designed to stretch the fiber when a vertical compression is applied. It was fabricated by burying the sensing fiber into a unique package tightly. The package was made of room temperature vulcanization (RTV) silicone rubber. The hardness of the RTV silicone rubber is lower than 50°, and the silicone maintains a high elasticity in a temperature range of –50 to 200 °C. The designed package can stretch the sensing fiber with the compression of silicone package and ensures the embedded fiber is well protected.