RESUMO
Silicon single crystal (SSC) quality monitoring and control has been a hot research topic in the field of the Czochralski crystal growth process. Considering that the traditional SSC control method ignores the crystal quality factor, this paper proposes a hierarchical predictive control strategy based on a soft sensor model for online control of SSC diameter and crystal quality. First, the proposed control strategy considers the V/G variable (V is the crystal pulling rate, and G is the axial temperature gradient at the solid-liquid interface), a factor related to crystal quality. Aiming at the problem that the V/G variable is difficult to measure directly, a soft sensor model based on SAE-RF is established to realize the online monitoring of the V/G variable and then complete hierarchical prediction control of SSC quality. Second, in the hierarchical control process, PID control of the inner layer is used to quickly stabilize the system. Model predictive control (MPC) of the outer layer is used to handle system constraints and enhance the control performance of the inner layer. In addition, the SAE-RF-based soft sensor model is used to monitor the crystal quality V/G variable online, thereby ensuring that the output of the controlled system meets the desired crystal diameter and V/G requirements. Finally, based on the industrial data of the actual Czochralski SSC growth process, the effectiveness of the proposed crystal quality hierarchical predictive control method is verified.
RESUMO
BACKGROUND: There are many disputes about the definition, diagnosis, therapy, and prognosis of collision tumors. CASE SUMMARY: We describe a rare patient with a collision tumor consisting of neuroendocrine carcinoma (NEC) and squamous cell carcinoma (SCC) in the nasal cavity and paranasal sinus. She received operation, concurrent chemoradiotherapy, and then two cycles of palliative chemotherapy. Follow-up at 12 mo after diagnosis showed that this patient experienced a complete response with no signs of recurrence or metastasis. A literature review of previous 26 cases diagnosed with collision tumor of NEC and SCC in the head and neck was also undertaken. CONCLUSION: It is challenging to manage collision tumors because there are two morphologically and etiologically distinct tumors. Well-designed multimodality therapy including surgery and chemoradiotherapy might lead to a long survival in these patients.