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Fundamentals of Quality in Manufacturing
Published in Jong S. Lim, Quality Management in Engineering, 2019
A power supply unit (or PSU) converts input AC power to low-voltage regulated DC power for the operation of a computer. To assure the perfect function of the digital circuit board in the computer, the built-in PSU is supposed to provide 5 Volt standby (5VSB) voltage output so that the standby functions on the computer and certain peripherals are adequately powered. The typical PSU unit has 5% tolerance of the output, i.e., 5.0 ± 0.25V. The function of the computer should be excellent within the voltage from 4.75V to 5.25V. However, there could be a long-term durability effect between the computers receiving the accurate 5V and the other computers receiving the swing voltage, i.e., 5 ± 0.25V. As a result, some computers equipped with the PSU of high voltage variance (5 ± 0.25V) will fail earlier than the computers with PSU of accurate voltage (5V), resulting in customer dissatisfaction. In other words, the quality output of the two different PSUs is not the same even though the output voltage is still within the functional tolerance limit, 5 ± 0.25V.
Real-time implication of hybrid carbonaceous fibre and powder integrated self-sensing cement composite in health monitoring of beams and columns
Published in European Journal of Environmental and Civil Engineering, 2023
A. Dinesh, D. Suji, Moorthi Pichumani
The compressive strength of the SSC is measured following IS 4031 (Part-6) utilising a 200 T capacity compressive testing machine (AIMIL—AIM 317E-AN). The compressive strength of the SSC is measured at a loading rate of 4 kN/s. The resistivity of the SSC is determined using a four-probe technique. A power supply unit supplies direct current (DC) to the two external current electrodes. Simultaneously, voltage between the two inner current electrodes is measured by a multimeter (fluke 15 b). The resistance (R) value is determined using the formula R = V/I, where V indicates the voltage between two internal electrodes and I signifies the current flowing through the external electrodes of SSC. Resistivity (ρ) based on the geometry of the composite is determined using the formula ρ=RA/L, where A signifies the cross-sectional area of the composite and L determines the distance between the two voltage electrodes. The fractional change in resistivity (FCR) with increasing stress must be evaluated to determine the piezoresistivity. The formula used for calculating the fractional change in resistivity is FCR=(ρ−ρ0)/ρ0, where ρ defines the resistivity at each load increment, and ρ0 denotes the initial resistivity. The FCR per unit stress is called as stress sensitivity (SS). The SS of the composite is computed using the equation SS = FCR/σ, where σ is the longitudinal stress in the SSC.
Effect of anode condition on electro-osmotic consolidation combined with vacuum preloading
Published in Drying Technology, 2022
The kaolinite soil was filled into the testing cell after mixing with a pre-designed amount of solution. Then the soil models were stored at room temperature for 24 hours. The EKGs were installed with the spacing between the anode and cathode of 200 mm. The electrodes were connected to a DC power supply unit. After that, a sealing membrane was placed on the top of the testing cell to facilitate the vacuum preloading. The vacuum pipes were connected to the electrodes through a valve, which could switch the vacuum pressure. A vacuum gauge was installed for real-time monitoring of vacuum pressure. In Test 4 and Test 5, the vacuum pipe connected to the anode was removed after Stage 1, and the CaCl2 solution was injected into the anode slowly by a syringe, which lasted for 1 hour.
Improved Integral Sliding Mode Control Scheme for Inverter-Based Four-Wire Autonomous Power Supply Units
Published in IETE Journal of Research, 2022
Mohammad Pichan, Hasan Rastegar
However, since it is beneficial to utilize these units at operating condition with maximum power point tracking, the energy storage devices should be used to transfer smooth power to the load. In addition, due to intermittent nature of renewable energy resources, they should come together to supply uninterruptible and high reliable electrical power for the loads. Several renewable energy-based DG units with energy storage devices which are operated in parallel with each other through a DC-Link connection can form a power supply unit. This unit can operate at both off-grid and on-grid conditions with different target and filter connections. As depicted in Figure 1, the renewable energy-based power supply unit which operates at off-grid condition forms an autonomous power supply unit (APSU). Accordingly, different renewable energy resources like photovoltaic or fuel cell are depicted in the left side. Sometimes, there are local DC loads which all of them are connected at the DC-Link and after that, the central inverter is used following with a low pass filter to supply different single/three phase linear/non-linear loads.