Step 2. Establishing candidate models for carbon emission forecasting. GM(1,1) is employed to forecast the carbon emission for the three provinces, the residual is the difference between actual data and the forecasting of GM(1,1). The residuals are respectively predicted by SVR, GWOSVR, PSOSVR and PSOGSASVR, where inputs are the different lags of influencing factors. Taking Qinghai as an example, the number of influencing factors is 3 and lag order is 3, so there are 3^3\ast4=108 individual models.

这段话也没有发现任何语法错误。该段介绍了GM-GRA-DPC-PSOSVR模型的构建过程中的第二步，即建立碳排放预测的候选模型。使用GM(1,1)对三个省份的碳排放进行预测，残差是实际数据与GM(1,1)预测值之间的差异。残差分别由SVR、GWOSVR、PSOSVR和PSOGSASVR进行预测，其中输入是影响因素的不同滞后期。以青海省为例，影响因素的数量为3，滞后期为3，因此有108个个体模型。

相关问题

Step 4. GM-GRA-DPC-PSOSVR combined forecasting. The forecasting results of individual models are as the inputs to PSOSVR for establishing nonlinear combination, and the whole procedure based on Step 1 to Step 4 is called GM-GRA-DPC-PSOSVR model. Step 5. Forecasting comparisons. In order to test the effectiveness of the forecasting models, this research introduces MAPE(Mean Absolute Percentage Error), MAE(Mean Absolute Error), MSE, and improvement rates to compares the forecasting ability of GM-GRA-DPC-PSOSVR with individual forecasting models.

这段话也没有发现任何语法错误。该段介绍了GM-GRA-DPC-PSOSVR模型的构建过程中的第四步和第五步，即使用PSOSVR建立个体模型的非线性组合，整个过程基于步骤1到步骤4被称为GM-GRA-DPC-PSOSVR模型。为了测试预测模型的有效性，该研究引入MAPE（平均绝对百分比误差）、MAE（平均绝对误差）、MSE和改进率来比较GM-GRA-DPC-PSOSVR与个体预测模型的预测能力。

警告: Having failed to acquire a resource, com.mchange.v2.resourcepool.BasicResourcePool@2e85fbb is interrupting all Threads waiting on a resource to check out. Will try again in response to new client requests. Thu Jun 01 19:10:58 CST 2023 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification. Thu Jun 01 19:10:58 CST 2023 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification. java.sql.SQLException: Connections could not be acquired from the underlying database!

这个警告信息表明，在使用c3p0连接池向MySQL数据库请求连接时，连接池无法获取连接资源，导致所有等待连接的线程都被中断。同时，还出现了一个关于SSL连接的警告。

对于连接池无法获取连接资源的问题，可能有以下几个原因：

1. 数据库连接池资源不足，请检查连接池的配置，确保连接池的最大连接数足够应对高并发的请求。

2. 数据库连接泄漏，请检查应用程序代码，确保连接在使用后及时释放并归还到连接池。

3. 数据库连接超时，请检查连接池的配置，确保连接的最大空闲时间和最大生存时间符合应用程序的需要。

对于SSL连接的警告，建议您配置SSL连接，以提高连接的安全性。具体方法请参考MySQL的文档，或者在JDBC连接字符串中设置useSSL=true并提供服务器证书验证的信任库。

希望这些信息能够帮助您解决问题。