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Abstract: Convolution integral and convolution summation play an important role in the analysis of the linear time invariant systems. At present, many text books have published in my home country or foreign country , especially the ??sSignals and Systems??t all discuss the methods by use of the graph to determine the up limit, low limit and the interval of exist of the convolution integral or convolution...
Invoices are the voucher to reimburse for official expenses. However, fake paper invoices spread in our lives. The appearance of electronic invoices can solve the problem of fake invoices. Before the business purchases invoices from Inland Revenue, The Inland Revenue and the business identify the authenticities of each other and generate a temporary session key between them through Key Distribution...
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