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International Journal of Bioprinting                                      Bioprinting with machine learning







































              Figure 4. Structure of the long short-term memory algorithm. Reprinted from ref. [52] under the terms of the Creative Commons CC-BY license.

            number that is almost zero, this information needs to be   and maps it via a function to a value between zero and
            abandoned in the new cell state. Then, the value is added   one, which is then multiplied by the cell state to determine
            point by point with the output result of the input gate to   what  information  to  discard.  When  its  value  is  one,  the
            update the latest information determined by the neural   information is completely kept, and when the value is zero,
            network to the cell state. Thus, the updated cell state is   the information is completely discarded .
                                                                                               [57]
            obtained .
                   [54]
                                                                  Input gate. Input gate is utilized to revise cell state.
            3.4.2. Gate mechanism                              First, the information about the earlier hidden status and
            The reason that long short-term memory can deal with   the existing input is converted to the  sigmoid function.
            the long-term dependence issue of the recurrent neural   The value will be adjusted into the range of zero to one
            network is that long short-term memory integrates a gate   to determine what information to modify. Zero means not
            mechanism to control the flow and loss of attributes . The   essential, and one means crucial. Second, the information
                                                    [55]
            addition and removal of information are controlled by a   of the preceding hidden state and the current input
            gate mechanism that learns what information should be   information is transmitted to the tanh function to obtain a
            saved or forgotten during the training procedure .  new candidate value vector. Finally, the output value of the
                                                  [56]
                                                               sigmoid function is multiplied by the output value of the
               Forgetting gate. After new information is input, if the
            architecture will forget the old information, the forgetting   tanh function. The output result of the sigmoid function
                                                               will identify which information in the output result of the
            gate is used to accomplish it. The forgetting gate is a vital   tanh function is significant and needs to be retained [58,59] .
            element of the long short-term memory network section,
            which can control what information to retain and what   Output gate. Output gate is employed to predict the
            information to forget, and in some way avoid the issue of   output of the subsequent hidden state, which includes
            gradient vanishing and gradient explosion caused by the   the information that has been input earlier. First, we pass
            reverse propagation of gradient over time. The forgetting   the  previous  hidden  state  and  the  current  input  to  the
            gate  identifies  what  information  the  long short-term   sigmoid function, and then deliver the updated cell state to
            memory networks discard from the cellular state of the   the tanh function. Finally, the result of the tanh function
            previous moment. The gate reads the relevant information   is multiplied by the production of the  sigmoid function


            Volume 9 Issue 4 (2023)                        340                         https://doi.org/10.18063/ijb.739
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