Prediction and test of stable transmission time of spiral bevel gear during a loss-of-lubrication event in helicopter transmission system

Purpose This paper aims to establish a prediction model of stable transmission time of spiral bevel gear during a loss-of-lubrication event in helicopter transmission system. Design/methodology/approach To observe the temperature change of spiral bevel gear during working condition, a test rig of spiral bevel gear was developed according to the requirements of experiments and carried out verification experiments. Findings The prediction is verified by the test of detecting the temperature of oil pool. The main damage form of helicopter spiral bevel gears under starved lubrication is tooth surface burn. The stable running time under oil-free lubrication is mainly determined by the degree of tooth surface burn control. Originality/value The experimental data of the spiral bevel gear oil-free lubrication process are basically consistent with the simulation prediction results. The results lay a foundation for the working life design of spiral bevel gear in helicopter transmission system under starved lubrication.

Mapping Forest Burn Extent from Hyperspatial Imagery Using Machine Learning

Support vector machines are shown to be highly effective in mapping burn extent from hyperspatial imagery in grasslands. Unfortunately, this pixel-based method is hampered in forested environments that have experienced low-intensity fires because unburned tree crowns obstruct the view of the surface vegetation. This obstruction causes surface fires to be misclassified as unburned. To account for misclassifying areas under tree crowns, trees surrounded by surface burn can be assumed to have been burned underneath. This effort used a mask region-based convolutional neural network (MR-CNN) and support vector machine (SVM) to determine trees and burned pixels in a post-fire forest. The output classifications of the MR-CNN and SVM were used to identify tree crowns in the image surrounded by burned surface vegetation pixels. These classifications were also used to label the pixels under the tree as being within the fire’s extent. This approach results in higher burn extent mapping accuracy by eliminating burn extent false negatives from surface burns obscured by unburned tree crowns, achieving a nine percentage point increase in burn extent mapping accuracy.

‘BOMBILE’ – Newest enemy to our sight? – A case series

As possession of a mobile phone becomes ubiquitous in the general population, its hazards, especially for vision, should be better known and understood. Although blast injuries are common in war, gas cooking and with firecrackers, mobile phone blasts, popularly known as BOMBILE (Blast of Mobile Battery in the Living Eye), are becoming more and more frequent. We present three cases phone battery explosion diagnosed with ocular surface burn. Although none had severe injuries and vision was salvageable and no visual or cosmetic impairment resulted, this may not always be so. Public education, producer liability, and better technological solutions are urgently required to lessen the risks.

PASSAGE OF WHEAT FIRE IMPACT ON SOIL PROPERTIES AND ENVIRONMENT IN KURDISTAN REGION

The study was conducted to examine the effect of surface burn severity (Moderate, Severe and Unburned) of wheat straw on soil properties. The results showed statistical differences in some soil physical, chemical and biological properties. Bulk density and field capacity increased statistically by the severity of fire; however, porosity and infiltration rate were statistically lower in sever burned plot when compared to unburned plot. The chemical properties, soil organic matter (SOM), P, Ca, S, Cl, K, Mo, Fe and As were not affected by the fire. The pH value was increased slightly by increasing the fire severity, while, EC was decreased when compared with the unburned plot. It was found a statistical reduction in the number of bacterial and fungal cells per gram soil in the burned plots. A moderate and severe fire reduced seed germination percentage significantly. This finding suggests that fire severity may destruct the biological, physical and some of the chemical properties of the soil, and this may impact negatively on plant growth in the next growing season.

Laurel (Litsea glaucescens Kunth) Regeneration in the Presence of Disturbance Events: A Case Study

A study was carried out in an Abies religiosa Kunth Schltdl. et Cham forest of the community of San Antonio Tecocomulco Tres Cabezas, Municipality of Singuilucan, Hidalgo, to evaluate the resprouting ability of laurel (Litsea glaucescens Kunth) in response to controlled burning treatments and removal of entire stems. The number of laurel bushes, shoots, and mean plant height were evaluated, and three treatments were applied: controlled surface burn; all sprouts cut from the base; and control treatment. Nine weeks after the treatments were applied, the plants in the stem removal treatment remained alive (100 percent), and the appearance of shoots with a mean height of 4.8 cm increased by 18 percent, whereas in the controlled burning treatment, the number of live plants and shoots decreased by 38.2 and 71.5 percent, respectively, with a mean height of 1.1 cm. In the control, the number of bushes remained at 100 percent, and shoots increased by 9.9 percent with a mean bush height of 7.6 cm. This indicates that although surface forest fires tend to affect laurel, surviving plants tend to emit more vigorous shoots, whereas stem removal in laurel bushes generates more shoots