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Published in Wai-Kai Chen, Computer Aided Design and Design Automation, 2018
The input to the placement phase is a set of blocks, the number of terminals for each block, and the netlist. If the layout of the circuit within a block has been completed, then the dimensions of the block are also known. The blocks for which the dimensions are known are called fixed blocks and the blocks for which dimensions are yet to be determined are called flexible blocks. Thus, during the placement phase, we need to determine an appropriate shape for each block (if shape is not known), the location of each block on the layout surface, and determine the locations of pins on the boundary of the blocks. The problem of assigning locations to the fixed blocks on a layout surface is called the placement problem. If some or all of the blocks are flexible, the problem is called the floorplanning problem. Hence, the placement problem is a restricted version of the floorplanning problem. The terminology is slightly confusing as floorplanning problems are placement problems as well, but these terminologies have been widely used and accepted. It is desirable that the pin locations are identified at the same time the block locations are fixed. However, due to the complexity of the placement problem, the problem of identifying the pin locations for the blocks is solved after the locations of all the blocks are known. This process of identifying pin locations is called pin assignment.
Circuit construction
Published in Mike Tooley, Electronic Circuits, 2019
The selection of a soldering bit (see Figs 20.18 and 20.19) depends on the type of work undertaken. Fig. 20.20 shows a number of popular bit profiles, the smaller bits being suitable for sub-miniature components and tightly packed boards. The procedures for making soldered joints to terminal pins and PCB pads are shown in Figs 20.21 and 20.22, respectively. In the case of terminal pins, the component lead or wire should be wrapped tightly around the pin using at least one turn of wire made using a small pair of long-nosed pliers. If necessary, the wire should be trimmed using a small pair of side cutters before soldering. Next, the pin and wire should then be simultaneously heated by suitable application of the soldering iron bit and then sufficient solder should be fed on to the pin and wire (not via the bit) for it to flow evenly around the joint, thus forming an airtight ‘seal’. The solder should then be left to cool (taking care not to disturb the component or wire during the process). The finished joint should be carefully inspected and re-made if it suffers from any of the following faults: (a) Too little solder. The solder has failed to flow around the entire joint and some of the wire turn or pin remains exposed.(b) Too much solder. The solder has formed into a large ‘blob’, the majority of which is not in direct contact with either the wire or the pin.(c) The joint is ‘dry’. This usually occurs if either the temperature of the joint was insufficient to permit the solder to flow adequately or if the joint was disturbed during cooling.
Basic Considerations in Design
Published in Yogesh Jaluria, Design and Optimization of Thermal Systems, 2019
In the manufacture of electronic systems, a classical process that is frequently used is that of soldering a pin to a board. Solid solder is placed around the pin in the form of a doughnut, as shown in Figure 2.4, and heated to a temperature beyond its melting point. The molten solder is driven by surface tension forces to form a joint, which solidifies on cooling to give the desired connection between the pin and the copper plated-through hole in the board. The heating had traditionally been done by radiation or by convection, using air or a liquid for immersion. Excessive and nonuniform heating of the boards was a common problem with radiation. Cleaning of the fluid and low heat transfer rates were the concerns with convection. In response to the need for an improved technique for this problem, a new and innovative method based on condensation of a vapor was proposed to yield a rapid heat transfer rate, while ensuring a clean environment with no overheating of the board. This resulted in the design of a thermal system to generate the vapor of a fluid with the appropriate boiling point. This vapor would then condense on a circuit board immersed in the condensation region, thus heating the material and forming the desired solder joint. Higher and more uniform heat transfer rates are achieved by this method. The quality of the joint and the production rate are improved. Figure 2.4 gives the basic features of the process and of a simple condensation soldering system that can be used for such applications. Figure 2.5 shows a photograph of a condensation soldering facility, based on this concept, for large electronic components, indicating the typical scale of such practical systems. Example 2.3 discusses this process in greater detail. Figure 2.6 shows a different type of facility that uses the same basic concept and is available commercially. This system is more compact, easier to control, and has less fluid loss than the one shown in Figure 2.4(b). Dally (1990) may be consulted for further details on this and other soldering processes used in the manufacture of electronic circuitry. This system may also be used for other applications that require high rates of heating without overheating.
User-centred multimodal authentication: securing handheld mobile devices using gaze and touch input
Published in Behaviour & Information Technology, 2022
Mohamed Khamis, Karola Marky, Andreas Bulling, Florian Alt
The touch-only (Figure 1(a)) method uses the traditional PIN keypad (baseline). This served as a baseline that uses touch input only.The touch+random ( Figure 1(b,c)) method uses touch to select the desired digit from one of two randomly shuffling layouts. This will provide insights about the shuffling idea and help distinguish the impact of the multimodal factor.GazeTouchPIN ( Figure 1(b,c)) uses touch input to select a pair of horizontally aligned PIN digits and then a gaze gesture to the left/right to select the desired PIN.
Hybrid combination of Taguchi-GRA-PCA for optimization of wear behavior in AA6063/SiCp matrix composite
Published in Production & Manufacturing Research, 2018
Narinder Kaushik, Sandeep Singhal
The wear studies on matrix composite samples strengthened with 3.5 wt. %, 7 wt. % and 10.5 wt. % have been directed in unlubricated dry slippery conditions on pin- on-disc tribometer [DUCOM (TR-20LE)]. The test set up was comprise of a rotary plate made of material EN-31 steel with hardness estimation of 62HRC and has 100mm diameter and10mm thickness (in Figure 2 (a,b)). Pin- on- disc tribometer was microprocessor controlled, in which height loss and frictional force has been recorded simultaneously. The rectangular pin test specimens (Figure 3) of size 32 × 6 x 6 mm have been squeezed against the counter face rotating plate. A load lever was swiveled near the load sensor for putting the dead weights. The specimens to be analyzed were fine cleaned to make level flat before start of wear investigation and grasped against the rotary counter face plate. For the wear testing three input process factors at three levels were selected as appeared in Table 1. Composite samples have been exposed to dry slippery wear tests at room temperature in agreement with Taguchi L9 orthogonal array as appeared in Table 2. Provision of LVDT (linear variable differential transformer) with precision of 1µm throughout the wear testing persistently gained the wear statistics in terms of displacement in micrometer of the test specimen. Wear displacement sensor grants for getting immediate readings of the deflection because of load lever, which are analogous to the wear of the test samples. The wear conduct is generally demonstrated as wear volume or weight reduction and the wear rate was computed from height loss estimations by applying the formula:
SEVA: Secure E-Voting Application in Cyber Physical System
Published in Cyber-Physical Systems, 2022
Rahul Johari, Arvinder Kaur, Mohammad Hashim, Prateek Kumar Rai, Kanika Gupta
In Estonia, the majority of people have been equipped with Id Card containing a computer chip. Their Id card and PIN are used for authentication. They can cast their vote in local and parliamentary elections. All they need is a computer with internet, electronic card reader, their card and PIN. They can vote from anywhere in the world.