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Aim of study: To explore the different patterns of fine-root traits by elucidating changes in their chemistries and morphologies in Chinese fir plantations along an altitudinal gradient. Area of study: National Mazongling Nature Reserve (Anhui Province). Material and methods: Soil and fine roots (≤ 2 mm) samples were extracted from three soil layers (0-10 cm, 10-20 cm, and 20-30 cm) at four altitudes (750 m, 850 m, 1000 m, and 1150 m), after which their nutrient concentrations and morphological traits, respectively, were quantified. We employed mixed model ANOVA to test the effects of altitude, soil layer, and their interactions on the characteristics of soil and fine roots. The relationships between the functional traits of fine roots and climate, soil and stand structures were evaluated by the standard major axis regression and the structural equation model. Main results: The chemical traits of fine roots were higher at medium altitudes (which decreased significantly with the soil layer). In contrast the morphological traits of fine roots did not change significantly. In chemical traits, both altitude, organic matter components, and soil total phosphorus (TP) exerted dominant effects on fine-root N, and both altitude and soil TP exerted dominant effects on fine-root P. However, in morphological traits, we found that altitude and soil C:N were crucial impact factors. Research highlights: Fine roots might preferentially adjust their chemical traits rather than morphological traits to facilitate higher root efficiencies in response to variable environmental conditions.

As aspect-level sentiment labels are expensive and labor-intensive to acquire, zero-shot aspect-level sentiment classification is proposed to learn classifiers applicable to new domains without using any annotated aspect-level data. In contrast, document-level sentiment data with ratings are more easily accessible. In this work, we achieve zero-shot aspect-level sentiment classification by only using document-level reviews. Our key intuition is that the sentiment representation of a document is composed of the sentiment representations of all the aspects of that document. Based on this, we propose the AF-DSC method to explicitly model such sentiment composition in reviews. AF-DSC first learns sentiment representations for all potential aspects and then aggregates aspect-level sentiments into a document-level one to perform document-level sentiment classification. In this way, we obtain the aspect-level sentiment classifier as the by-product of the document-level sentiment classifier. Experimental results on aspect-level sentiment classification benchmarks demonstrate the effectiveness of explicit utilization of sentiment composition in document-level sentiment classification. Our model with only 30k training data outperforms previous work utilizing millions of data.

Regenerative chatter can reduce machining quality, tool life, and productivity during milling process. In order to control the milling chatter, the stability analysis of milling system is very important. It has been found that variable spindle speed milling and the use of variable-angle tools are effective to control milling chatter. This paper mainly studies the control effect when these two methods are used simultaneously. Firstly, the improved full-discretization method is used to predict the stability of variable spindle speed milling process with variable pitch cutters. And on the basis of stability prediction, the influence of spindle speed modulation parameters on stability is analyzed. Meanwhile, the stability prediction results of down-milling and up-milling operations, different radial immersion ratio and different tooth pitch variation form are compared. The results show that the stability of variable spindle speed milling process with variable pitch cutters is better than that of variable pitch cutters in constant spindle speed milling process. And the improvement of the stability is related to the spindle speed modulation parameters. When the modulation parameters are bigger, the stable cutting area of the stability lobes diagram will be larger. Secondly, in the up-milling operation and the low immersion operation, the variable spindle milling with variable pitch cutters has better stability than the down milling operation and the high immersion operation. Under the condition that the pitch angles vary linearly, the stability is better. Finally, the time domain simulation is performed and the simulation results verify the accuracy of the stability prediction results.