提出CENDRe方法,实现对时序模型中时空概念的自动提取与定位。
CENDRe: Concept Extraction with Natural Domain Representations

- 通过双阶段聚类与轮廓引导自动确定概念数量
- 生成时空双域定位图,准确识别驱动预测的关键频段和时段
- 适用于工业故障诊断等需解释性的关键领域
卷积神经网络(CNN)广泛用于时序分类,但在关键场景中需理解其预测所依赖的时空模式。概念提取(CE)方法通过分析模型潜空间表示来识别这些模式。现有时序CE方法存在三大局限:仅在时域操作、忽略频域特征;预设概念数量;定位结果与模型实际关注区域不匹配。为此,本文提出CENDRe,一种面向CNN的新型概念提取方法。它首先通过两阶段聚类分析每时刻的潜在表示,利用轮廓系数引导聚合,自动确定概念数量;随后通过存在度梯度对比潜在表示与原型,生成聚焦于关键区域的概念定位掩码。该梯度经可微逆映射(如傅里叶变换)传播,实现频域概念定位。最后,为每个概念分配贡献得分,量化其对各类别的影响。在合成基准上,CENDRe的表示正确性达到当前最优水平,重要性正确性显著更优;在真实轴承故障数据上,成功提取出模型预测所依赖的频率带,位于常见故障诊断区域,为模型可信性评估提供时域方法无法获得的证据。
原文摘要 · Abstract (English)
Convolutional neural networks (CNNs) are widely used for time-series classification, but their deployment in critical domains requires understanding the temporal and spectral patterns that drive their predictions. Concept extraction (CE) methods identify such patterns by analyzing representations within the models' latent space. However, existing time-series CE methods have three limitations: they operate only in the time domain and overlook frequency features, predefine the number of concepts, and produce localizations misaligned with the regions the model uses. We address these limitations by proposing CENDRe, a concept extraction method for CNNs. It first discovers concepts by clustering per-timestep latent representations in two stages, where silhouette-guided aggregation selects the number of concepts automatically. Then, it localizes each concept through gradients of a presence score that contrasts the latent representations with their prototypes, producing masks that concentrate on the regions driving the concept. These gradients, propagated through a differentiable invertible mapping of the input such as a Fourier transform, yield localizations for the same concepts in the frequency domain. Finally, each concept receives a relevance score that quantifies its contribution to each class. On synthetic benchmarks, CENDRe achieves representation correctness comparable to state-of-the-art CE methods and significantly higher importance correctness. On real bearing-fault data, CENDRe extracts the frequency bands driving the model's predictions, located in regions commonly inspected for fault diagnosis, producing evidence to assess the model that time-domain CE methods cannot.
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