With people's increasing concern about food safety, cold-chain logistics distribution centre is playing an important role in preventing food from going bad. Now cold-chain logistics distribution centres have the problems of too much transportation, low degree of automation, unreasonable layout planning, complex distribution process etc. It is important to solve these problems in order to achieve efficient distribution. Firstly the modeling and simulation for the operation process of a fruits and vegetables cold-chain logistics distribution centre by using Flexsim software is realized. Then the paper analyses the preliminary output data and finds out the bottleneck and idle resources. Finally this paper makes adjustments for the system to get a better result which hopes to give a reference for the modeling and simulation for the operation process of other cold-chain logistics distribution centres.

A photonic approach to generate triangular waveform signals is proposed and analyzed. With active bias control, two sub-MZMs (MZ-a and MZ-b) of a dual-parallel Mach-Zehnder modulator (DP-MZM) operate at minimum transmission point, leaving the main MZM (MZ-c) at quadrature transmission point. Triangular waveform can be observed by a parameter setting of modulation index. The proposal is first analyzed and then validated by simulation. The key significance of the scheme is that it is capable of generating triangular waveform signals via a sinusoid local oscillator.

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