Yellow rosewood, the scientific name of the fragrant rosewood, also known as Hainan rosewood, Hainan huanghuali wood. It grows in the low-altitude plains and hilly areas of Jianfengling, Hanglu Mountain, Hainan Island, China. Huanghua pear is the main material for hardwood furniture in the Ming and Qing Dynasties. It is better to have a yellow-brown heartwood. The texture is either hidden or present, and the color is not static. It is regarded as a superior product. It is favored by the Ming and Qing dynasties, especially the literati and scholar-officials of the Ming and Qing Dynasties, and the aesthetic taste of the furniture, which makes the Huanghuali furniture of this period It is a treasure in the world of furniture art.
The wood quality of Huanghua Pear is extremely stable. It does not deform, does not crack, does not bend, and has certain toughness. It is suitable for all kinds of special-shaped furniture, such as three-bend legs, and its curvature is very large, but Huanghuali can be made. The yellow pear wood is golden and warm, and the heartwood is dark reddish or dark brown with a rhinoceros horn. The proportion of yellow pear wood is lighter and it is half-sinked in the water. The texture of the yellow pear wood is very clear, such as flowing water, very beautiful. The most special thing is that there are many hibiscus in wood grain. These hibiscus is also very flat and does not crack. It shows the texture of fox head, old man's head and old man's hair. It is beautiful and human, that is, people often say "ghost face".
Most of the high-end furniture produced in the Ming Dynasty and the early Qing Dynasty were made of huanghuali wood. The Tang dynasty Chen sang "Herbal Supplement" has "The Palm Tree is out of Annan and the South China Sea. It is used as a bed, like red sandalwood and red, strong." Good" record. Due to excessive harvesting in the previous period, the huanghuali wood was drastically reduced and was threatened with extinction before the middle of the Qing Dynasty, and later replaced with rosewood. Judging from the published furniture materials of the Ming and Qing Dynasties, the yellow rosewood has large materials, and the single-panel flat case with a width of half a meter and a length of two meters can be seen.
Experts have found that the furniture made of Hainan's huanghuali has many heavy oils, and the benefits are obvious: first, it is natural and smooth, and it is made into furniture without painting; secondly, it is naturally patina, and the color is getting better and better; It does not rot and is durable. These benefits are unmatched by other woods. Since the experts highly valued Hainan Huanghua Pear, Huanghuali has suddenly become the target of collectors. Some people transported huanghuali to Beijing at a very low price.
At present, in addition to the production of huanghuali in Hainan, this kind of wood is also found in northern Vietnam. However, the Vietnamese huanghuali material is slightly loose, the brown eyes are thick, and the material is slightly more, the price is ten times cheaper than the Hainan huanghuali. In the past, it was thought that Vietnamese huanghuali was not sandalwood, and it could not be compared with Hainan huanghuali. Recently, after the identification of the Ministry of Forestry, the two kinds of wood are actually the same kind of wood, but the place of growth is different. They are called: fragrant wood.
In fact, China has used huanghuali wood to make utensils since the Tang Dynasty. At that time, Huanghuali was produced in the Guangdong and Guangxi regions. According to the "History of the Museum", "Pear Blossoms (ie, Jiaozhi) is widely distributed (ie, Guangdong, Guangxi), a flower palm tree, leaves like pears and no real, wood color red and purple and delicate texture, can be used as utensils, Tables, chairs, and textbooks." Ming "Ge Gu Yao Lun" mentioned: "The rosewood is a male, Guangdong, purple, similar to the true fragrance, but also has a fragrance. Its flowers have a cute face, thick flowers The color is low, and the people are mostly used as tea wine." This shows that the huanghuali wood was actually produced in Guangdong and Guangxi, but in recent years, people have discovered the advantages of Hainan huanghuali, but instead I recognize Vietnamese yellow pears.
At present, Hainan huanghuali wood is already expensive like gold. Up to 9,000 yuan per kilogram. Beijing Redwood Enterprise Yuan Henry puts a whole box of gold bars in the mahogany Daguanlou, collecting the old Hainan huanghuali Mujia, as long as the expert identification is Hainan huanghuali wood, even the rolling pin, the old pot lid, the squat stool can be exchanged for gold. 1 kilogram of yellow rosewood can be exchanged for 40 grams of gold, worth about 6,800 yuan. The San Francisco Museum of the United States has a collection of beautiful ancient Hainan huanghuali wooden chairs, estimated at $7 million, and is considered their treasure. 2007 China (Wenzhou) International Luxury Exhibition, a set of Hainan Huanghuali furniture, the price of 68 million yuan alone, and on the first day of development, was bought by several Wenzhou people.
With the high price of Hainan huanghuali, Vietnamese huanghuali is also depleted. In the past few years, Vietnam has not allowed the export of huanghuali. At present, the only deposits in China are very precious, and the price has reached more than 1,000 yuan per kilogram. I believe that in the near future, Vietnam's Huanghua Pear will continue to increase prices to narrow the gap with Hainan Huanghua Pear. Because, after all, they are the same kind of wood.
Proportional valve is a valve that relies on the statics to supply a reduced pressure to an output line.
A simple example is where spring load applies a reducing force so that the output pressure is reduced. Proportioning valves are frequently used in cars to reduce the brake fluid pressure to the rear brakes.
There are different types of proportional valves as below:
1. Electro-hydraulic proportional valve
2. Proportional pressure Reducing Valve
3. Proportional servo valve
Proportional Valve
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