In our screening program for insecticidal activity of the essential oils/extracts derived from some Chinese medicinal herbs and spices, garlic (Allium sativum L.) essential oil was found to possess strong insecticidal activity against overwintering adults of Cacopsylla chinensis Yang et Li (Hemiptera: Psyllidae). The commercial essential oil of A. sativum was analyzed by gas chromatography-mass spectrometry. Sixteen compounds, accounting for 97.44% of the total oil, were identified, and the main components of the essential oil of A. sativum were diallyl trisulfide (50.43%), diallyl disulfide (25.30%), diallyl sulfide (6.25%), diallyl tetrasulfide (4.03%), 1,2-dithiolane (3.12%), allyl methyl disulfide (3.07%), 1,3-dithiane (2.12%), and allyl methyl trisulfide (2.08%). The essential oil of A. sativum possessed contact toxicity against overwintering C. chinensis, with an LC50 value of 1.42 microg per adult. The two main constituent compounds, diallyl trisulfide and diallyl disulfide, exhibited strong acute toxicity against the overwintering C. chinensis, with LC50 values of 0.64 and 11.04 /g per adult, respectively.
To investigate the drilling process of titanium alloys, the three dimensional finite element model of two flutes twist drill was established. The drilling process of Ti6Al4V was simulated based on the presented model. In addition, the drilling experiments were carried out under the different spindle speed and feeding speed. The drilling forces of the experiment and simulation were achieved. The result of simulation agrees with the result of experiment well. It proves that the finite element model is correct. Simultaneously, the results show that more high drilling speed can improve the quality of hole in drilling process of Ti6Al4V obviously.
A combination features based technology is proposed to matching point cloud models. Firstly, automatically segment the point cloud to get ruled shape data from which the statistics features are extracted. Calculate the distance and angle between component elements of statistics feature and datum plane. The distance and angle constraints are introduced to automatically search correspondence statistics features of overlap region and the optimal combination of statistics features. The optimal combination is coupled for combination feature. If combination feature can completely identify pose of model, we call this as completely matching question; otherwise, this is called as partly matching question. For the latter, adjust the degrees of freedom which are not constrained and then precisely match the models using ICP algorithm. The examples show the proposed algorithm is simple and efficient, and the matching results are stable, reliable and convergent to a global optimal solution.
As there are the errors during the manufacturing and assembling of horizontal driving machine (HDM). The exceptional knocking noise is generated during some products running. The failure rate of product quality is rising as well. The forward and reverse driving noise of HDM was tested and analyzed. The pictures was collected by universal tool microscope. The results show that hot runner is not smooth enough to reduce transferring pressure and increase the shrinkage of worm pouring gate, which lead to slight conical degree of product and pitch deviation at worm pouring gate. As the pitch makes worm inset slightly worm gear when clockwise rotating, the noise and vibration was produced consequently in this direction. The proposals were given, such as strengthening the maintenance of hot runners, controlling and inspecting product conical degree, and optimizing HDM mould and increasing its accuracy, and so on.
Since the features are not prominent and the algorithm is complex during whole reconstruction of section data, a step-by-step optimization reconstruction method is proposed. The order of reconstruction is optimized: line features are reconstructed firstly; Then arc features are reconstructed (constraints are satisfied between the arc and known lines); finally freeform features are reconstructed (constraints are satisfied between the B-spline and known lines/arcs). In this way, the reconstruction accuracy of the line/arc features is ensured in the first. Since freeform features have more freedom, it is convenient to be adjusted to meet the more constraints. Linear boundary constraints are constructed and the algorithm becomes optimization problem of the quadratic objective function under the linear constraints. The examples show that the reconstruction accuracy is improved greatly under satisfying constraints; the expected goal is achieved in real application.
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