For example, the number of decreasing morphological filters compo

For example, the number of decreasing morphological filters composed of two structuring elements (mask) with size of 3 �� 3 is 11645 computed below:(��i=19Ci9(29?2i?29?i+1) )/2(1)where i is the number of 1��s in the 3 �� 3 mask.We can understand Equation (1) by a special case when i = 4. For this case, there are C49 possible variations for the first mask. It should be noted that two masks must be not included to each other to avoid redundant computation. To chose the second mask for a special mask A (wor
Standard methods for measurement and low resistance comparison are based on Thompson (Kelvin) bridges, DC current comparators, potentiometers, etc [1]. The new generation high quality multimeters can also be used for this kind of measurement [2,3]. In this paper an original low resistance comparator design is presented.

The circuit diagram of the proposed chopper stabilized comparator is given in Figure 1. The current flow through two serial connected resistors (measured RX and reference RR) provides the adequate voltages in them, UX and UR, respectively. As known, the voltage ratio on the resistor terminals is equal to their resistances ratio. In that case, the value of measured resistance RX could be expressed as:RX=RR UXUR(1)Figure 1.Circuit diagram of chopper stabilized comparator.The maximum relative measurement error is:|��RX|=|��RRRRT|+|��UXUXT|+|��URURT|=|��RR|+|��UX|+|��UR|(2)where ��RR is reference resistance error (could be less than 10?6) and ��UX, ��UR are measurement errors for the appropriate voltages.

In low resistance measurement (four-terminal resistors [4]), the voltage on the potential terminals should theoretically be RI, but in a real measurement environment, except for the RI value, parasitic voltages can occur, such as thermo-electric, noise etc. All these unwanted influences can cause measurement errors and need to be eliminated.Thermo-electric or Peltier voltage is generated at the thermocouple junctions of different metals. Even when all the junctions are at the same temperature, the thermoelectric voltage can reach a value of about 0.1��V/��C. The most significant disturbances are a consequence of offset voltages of the operational amplifiers and can be higher than 50 ��V. These are direct current (DC) parasitic voltages. Alternating current (AC) unwanted voltages can also occur. The AC parasitic voltages are a consequence of AC power supply inductive GSK-3 or capacitive influence, noise, etc. AC parasitic voltages cause dispersion of measured results around the mean value. The mains influence (inductive and capacitive) is periodic and can be efficiently decreased (shielding, filtering, etc). Noise is a random occurrence with a zero mean and its disturbance may be reduced to acceptable levels by filtration.

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