Impulse signal distortion in transmission line

Today most electronic equipment consists of signal generators and processing units. These units are connected with transmission lines. These lines have big influence in signal distortions. On these lines depends transmition lines stability. Let’s see how transmition lines affect transmitted signals. (G- signal generator; Za– output impedance; I- signal receiver Zb– input impedance; L- transmission line length; Z0– Line impedance. When line is tuned and without losses then input voltage: Ub(t) = ZbE(t-t)/(Za + Zb) E(t)- generators signal amplitude; t– signal delay in line. t =l/v ; l- line lenght; v- signal speed. If line is not tuned up, then there are distortions in line because of reflections in line: If signal E(t) is step function: Then signal in line exit in discrete time moments will be: U(0) = p; U(t) = p*(1+pb) U(2t) = p*(1+pb+pa*pb) U(3t) = p*(1+pb+pa*pb+pa*pb^2); U(4t) = p*(1+pb+pa*pb+pa*pb^2+pa^2*pb^2); U(5t) = p*(1+pb+pa*pb+pa*pb^2+pa^2*pb^2+pa^2*pb^3) … where Depending on reflectance …

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Flash vs. EEPROM

There are many questions about Flash and EEPTOM differences. Well these are two different technologies converging together. Flash technology was created to replace mass storage media. Requirements for Flash were minimum power consumption and high number of write cycles. Information written in flash memory is usually in blocks at a time. EEPROM was originally designed to store configuration information or store programs to be boot loaded by microcontrollers or other devices. EEPROMS usually are smaller capacities and can be programmed in smaller information quantities like bytes or bits (serially). Read time is shorter than from Flash but EEPROM has less write cycles. But recently these differences are disappearing as technologies are catching up. So this should explain why in microcontrollers like Atmega128 is more convenient to write data to EEPROM than to Flash. If you would like to store data in flash you would have to rewrite whole sector of …

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Life-giving to Atmega8

I have got two atmegas from my friend. He stated that they are burned and can be thrown to garbage. He also mentioned that they stopped responding after they were programmed. So I asked him to give those to me to try them. I had in my mind, that this is a result of bad usage of security bits. There is always confusion in these bits, because security bits are programmed by writing ‘0’ values and unprogramed with ‘1’. I didn’t really expected to make them working again as my friend did quite rude experiments with them. What can I say – he was right by saying they are burned. Bu I guess some of you will like to see what I was doing in order to recover them. I decided that he unprogrammed all four security bits ( CKSEL0, CKSEL1, CKSEL2, CKSEL3 )by writing ‘1’ to them. This situation …

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SkinSeg – segmentation of melanoma

SkinSeg is simple tool used for skin lesion segmentation. This little program was developed by Intelligent Systems laboratory students: L. Xu, M. Jackowski, A. Goshtasby, C. Yu, D. Roseman, S. Bines, A. Dhawan, A. Huntley. Their method is working similar as in my earlier experiment with matlab pigmented lesion boundary tracing algorithm. First image is converted to intensity image and then the lesion edges are detected. ant test results: More informative description you can find here Program can be downloaded from here:  This version of the Skin Cancer Segmentation program (skinseg) runs on the Windows 95/NT platforms. Make sure all files reside in the same directory after extraction. No setup program is required to install skinseg on your machine. To run, execute the program skinseg.exe.

Filter output dependency on tolerance of elements

Sometimes we need to project simple filter with particular characteristics. We usually take calculations with ideal parameters and don’t look on tolerances of them. Let us see how simple filter output depends on its elements tolerances. For this let’s choose simple filter circuit: We are going to calculate filter response characteristics. The band pass frequency is taken on 0.707 level of response. We will see how this frequency depends on electronic elements tolerances. I will model elements with tolerances ±10%.

DullRazor – digital skin hair shaver

DullRasor uses image processing techniques to analyze and segments skin areas with dark hair. This program removes dark hairs form images, and makes skin lesion images clean to further processing.    Many skin images contain various numbers of hairs. Other skin segmentation programs may mislead because of hairs – especially dark ones. One solution can be shaving skin before taking pictures of it. But shaving of skin adds more time to processing and this is uncomfortable and in some cases unaesthetic.  Hence, a software approach for dark thick hair removal from skin images is needed.

Skin Cancer causing factors

Substance Where this can be found How to avoid Arsenic Pesticides, wood preservatives, alloy additive non ferrous metals. Use protective clothing when working with arsenic substances Creosote Wood preservative Use protective clothing when working with  creosote substances Ionizing radiation Ionizing radiation are certain industrial sterilization sources Limit exposure if possible. Wear a dosimeter while working with radiation. Sunlight Summer, and when on sun holiday. Avoid strong sunlight, especially at midday. Wear protective clothing to protect your skin. Cover exposed skin with sunscreen of factor 15 or higher. Tar Coal tar Use protective clothing Gluteraldehyde Gluteraldehyde is used as a disinfectant. It is also can be found in X-ray films. Use protective clothing when dealing with gluteraldehyde. Work only in well ventilated areas. Soot Black particles of carbon, produced by incomplete combustion of coal, oil, wood, or other fuels Use protective clothing Pitch It is made by the destructive distillation of …

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