“珠中皇后”落凡尘：育珠新术填补国内珍贵珠宝生产空白

传说,一滴露珠落进海里时,如果正好被一只张开口的海贝接住,就会形成一颗晶莹的珍珠。如果天气不好,映染灰色天空的露珠形成的就是一颗黑珍珠。生产黑珍珠的珍珠贝母是一种会分泌黑色珍珠质的黑蝶贝。     

掉牙记

正这几天,我的牙齿有点不耐烦,一连掉了两颗。我打开收藏了几年的牙盒,数了数,一、二、三、四,一共四颗。回想这四颗牙宝宝掉下来的过程让我惊叹。第一颗是我和妈妈最盼望掉的牙,为什么呢?因为这颗牙称霸一方,一下堵住了两颗牙,让我的新牙长歪了。妈妈带我去医院把它们拔了下来。掉的第二颗牙奇丑无比,上面还有一个大洞。都怪我有贪吃糖的坏习惯,才招来了见糖就吃的"大     

打破关住自己的门

一个木匠做得一手好门。他给自己家做了一扇门，他认为这门用料实在，做工精良，一定会经久耐用。过了一段时间，门的钉子锈了，掉下一块木板，木匠找出一颗钉子补上，门又完好如初。不久又掉了一颗钉子，木匠就换上一颗钉子。再后来，门闩坏了，木匠又换了一个新门闩。     

Tone-3 Accent Realization in Short Chinese Sentences

To investigate how a low tone （tone-3, T3） syllable in Chinese can be perceived to be focal accented or not, a total of 156 sentences containing tone-3 words were synthesized and used as stimuli in a perceptual study. The sentences differed in the falling value between the two high pitches, and in the duration and phonation types of the T3 syllables. Thirty-nine subjects were asked to judge where the focus or accent was for each sentence. The results show that at least three degrees of pitch drop are involved in the focus recognition： a big sized drop of about 10 semitones; a middle sized drop of about 6 semitones; a small sized drop of about 2 semitones. The results suggest that the three sizes of pitch drop have different indications in Chinese intonation, depending on both the tone and the tone combination. In perception, there are various ways to realize tone-3 focus in the Tx-T3-Ty sentences series, but in production or for text-to-speech synthesis, the rule simply is making a middle sized pitch drop with a long and creaky T3 syllable. Similarly, to focus on the low tone syllable in the T3-Tx-Ty sentences, a creaky T3 syllable is essential. However, a long T3 syllable is a strong determinant for a low tone focus in the Tx-Ty-T3 sentences.     

补门

有一个木匠，造一手好门，他费了好多时日给自家造了一扇门．他想这门用料实在，做工精良，一定会经久耐用。后来．门上的钉子锈了，掉下一块板，木匠找出一颗钉子朴上，门又完好如初。后来又掉下一颗钉子．木匠就又换上一颗钉子；后来有一块板朽了，木匠就又找出一块板换上；后来门闩坏了，木匠就又换了一个门闩；再后来门轴坏了，木匠就又换了一个门轴。     

Failure analysis of corrosion cracking and simulated testing for a fluid catalytic cracking unit

The failure of a fluid catalysis and cracking unit (FCCU) in a Chinese refinery was investigated by using nondestructive detection methods, fracture surface examination, hardness measurement, chemical composition and corrosion products analysis. The results showed that the failure was caused by the dew point nitrate stress corrosion cracking. For a long operation period, the wall temperature of the regenerator in the FCCU was below the fume dew point. As a result, an acid fume NO_x-SO_x-H₂O medium presented on the surface, resulting in stress corrosion cracking of the component with high residual stress. In order to confirm the relative conclusion, simulated testing was conducted in laboratory, and the results showed similar cracking characteristics. Finally, some suggestions have been made to prevent the stress corrosion cracking of an FCCU from re-occurring in the future.     

用爱呵护幼小的心灵

办公室里新来了一位朋友——一盆美丽诱人的文竹。文竹从茎到叶都是绿色的，绿得直逼你的眼，显得十分清新雅致。文竹的叶子上有几颗小小的露珠，晶莹透明，好似珍珠，每当太阳向着文竹微笑的时候，那些小珍珠就会变成水蒸气到空中旅行去了。一阵微风吹过．文竹便会悠悠地荡漾．如一个翩翩起舞的绿衣少—女。     

Analysis of condenser shell side pressure drop based on the mechanical energy loss

The condenser performance is strongly affected by the tube arrangement.The steam pressure drop in the tube bundle influences the condenser back pressure,which is an important indicator of the condenser performance used to compare different condenser tube arrangements.The condenser shell side pressure drop is studied here using the mechanical energy loss of the steam flow in the condensers.The mechanical energy loss is due to the flow resistance of the tube bundle and the steam condensation.Three typical tube arrangements are analyzed numerically.The results show that a higher condenser shell side pressure drop for different tube arrangements always corresponds to a larger mechanical energy loss.The mechanical energy loss is mainly in the periphery of the tube bundle,indicating that the flow pattern and the mechanical energy losses are markedly determined by the tube bundle profile.The condenser shell side pressure drop can be reduced by reducing the total mechanical energy loss when the steam enters the tube bundle more uniformly.Thus,a well designed tube arrangement will reduce the mechanical energy loss,and also the shell side pressure drop.     

暑假拔牙记

暑假里，我的一颗乳牙松动了却一直没掉，成了吃饭时的“小障碍”。那天，我无意舔了下那颗牙。突然感觉到在它的上方有个又小又硬的东西，不像是米粒。我一下子慌了，跑到镜子前张开嘴一看：呀，“老牙”还没掉，新牙竞长出来了!怎么办？总不能学电视里演的那样拿块砖拍掉它吧!我急得像热锅上的蚂蚁团团转。对，粗暴的方式行不通，可以用温柔的办法，我灵机一动，想出一个好点子——晃掉它。于是，我忍着疼，用力地前后晃那颗牙。可是，它像安了家似的，在我嘴里“荡秋千”，怎么晃也不掉。     

一种新的考虑启动压力梯度产能方程的建立

The flowing mechanism of a low permeability gas reservoir is different from a conventional gas reservoir,especially for that with higher irreducible water saturation the threshold pressure gradient exists. At present,in all the deliverability equation,the additional pressure drop caused by the threshold pressure gradient is viewed as constant,but this method has big error in the practical application. Based on the non-Darcy steady flow equation,the limited integral of the additional pressure drop is solved in this paper and it is realized that the additional pressure drop is not a constant but has something to do with production data,and a new deliverability equation is derived,with the relevant processing method for modified isochronal test data. The new deliverability equation turns out to be practical through onsite application.     

首饰变凉了

<正>深秋的清晨,很凉很凉,植物上有一颗颗露珠。两片小叶子正在说自己的露珠首饰。"你的首饰凉吗?大地妈妈和空气阿姨之前给我戴首饰,我觉得挺舒服,怎么今天首饰变得凉凉的?""你忘记现在是什么时候啦?每年一到寒露节气,她们不就开始给我们戴凉凉的首饰吗?""每年?去年,我还没有出生呢!""哦,对!我告诉你,现在我们虽然被首饰冰得不舒服,但这种首饰也戴不了多少次。"     

Effect of alloying elements and processing parameters on the Portevin-Le Chatelier effect of Al-Mg alloys

The effects of alloying elements and processing parameters on the mechanical properties and Portevin-Le Chatelier effect of Al-Mg alloys developed for inner auto body sheets were investigated in detail. Tensile testing was performed in various Zn and Mg contents under different annealing and cold-rolling conditions. In the results, the stress drop and reloading time of serrations increase with increasing plastic strain and exhibit a common linear relationship. The increase rates of stress drop and reloading time increase with increasing Mg or Zn content. The alloys with a greater intensity of serrated yielding generally exhibit a greater elongation. The stress drop and reloading time of serrations decrease with increasing grain size in the case of the annealed samples. The cold-rolled sample exhibits the most severe serration because it initially contains a large number of grain boundaries and dislocations.     

Measurement of contact angle between stainless steel surface and carbon dioxide by pendant drop method

To measure contact angle between CO2 and solid surface, in this study a visual high-pressure vessel has been developed, with a corresponding well-controlled constant temperature system. Pendant drop method is applied to the investigation of the contact angles of CO2 on a stainless steel surface in its own vapor. The image of the pendant drop is recorded by a camera, and a B-Snake method is used to analyze the contour and the contact angle of the droplet. The experimental results have provided a set of well tested data, which show that C02 has good infiltration into stainless steel surface and the developed method can be used as a standard testing one for measuring the contact angle between high-pressure liquid and solid surface.     

小人物的大政治

远在南美茂密的亚马孙原始森林里，一滴露水突然掉到正在僻静一角栖息的小蝴蝶身上，惊得小蝴蝶掠起，振翅振动了空气，一波波扩散出去竞引发北美大陆狂烈的飓凤。这就是人们所熟知的“蝴蝶效应”。“蝴蝶效应”其实讲的也是“小人物效应”，在此我们可以举三个例子。     

我与他们

<正>他们大都长得四四方方,有的"胖",有的"瘦";他们从不夸夸其谈,却满腹经纶、知识渊博;他们很内向,总是安静地躺在那里,等待你主动与他们"交谈",如果你足够勤奋,他们就会变得热情似火,向你敞开心扉,毫无保留地将自己渊博的知识传授给你;他们被称为人类进步的阶梯、人类思想的宝库,与他们相伴,其乐无穷。他们是我的好朋友。清晨,太阳公公露出了灿烂的笑脸,树上的小鸟在欢快地歌唱,草地上的一颗颗亮晶晶的小露珠像是小草晨练后冒出的汗     

露珠游记

它是一颗露珠,在那个阳光明媚的早晨,它就清楚明白了这个事实。它以自然的姿态卧在狗尾草的一片叶子上,沉重到压得叶子弯了腰。夏日的阳光照在身上,它在叶子上伸了个懒腰,开始像哲学家一样思考自己的价值。从生命的开始,     

Interfacial morphologies between iron and Ag-Cu-Sn alloy

A series of experiments have been designed to investigate the effect of different space positions between liquid Ag-Cu-Sn alloy drop and iron substrates on the liquid/solid inter-facial morphologies by a sessile drop method. The results show that Ag-Cu-Sn alloy diffuses into the solid iron substrate, and the amounts are greater and the distances are longer when it diffuses into the lower substrate than that into the upper one. Moreover, there are many primary α-Fe dendrites in the liquid Ag-Cu-Sn alloy close to the upper substrate of liquid bridge or the surface of metal drop. That is due to the effect of gravity.     

小心“笑掉”大门牙

贝西的大门牙掉了，是笑掉的。她哈哈大笑过了头，不小心撞在门的金属把手上，于是她那两颗布满蛀斑的大门牙就这么“光荣退休”了。一想到自己变成了“大豁牙”，贝西伤心极了。     

Spreading kinetics of a Sn-30Bi-0.5Cu alloy on a Cu substrate

The reactive wetting kinetics of a Sn-30Bi-0.5Cu Pb-free solder alloy on a Cu substrate was investigated by the sessile drop method from 493 to 623 K.The triple line frontier,characterized by the drop base radius R was recorded dynamically with a high resolution CCD using different spreading processes in an Ar-H 2 flow.We found a good agreement with the De Gennes model for the relationship between ln(dR/dt) and lnR for the spreading processes at 493 and 523 K.However,a significant deviation from the De Gennes model was found for the spreading processes at 548 and 623 K.Our experimental results show a complicated temperature effect on the spreading kinetics.Intermetallics at the Sn-30Bi-0.5Cu/Cu interface were identified as Cu 6 Sn 5 adjacent to the solder and Cu 3 Sn adjacent to the Cu substrate.The intermetallic compounds effectively enhanced the triple line mobility because of reaction product formation at the diffusion frontier.     

神农架野人探秘

它,来得突然,去得神速,匆匆打个数秒钟的照面后,一闪身不见了踪影,只留下一串或清晰或模糊的脚印,留下几缕或黑色或棕红色的毛发。紧接着,你对密林进行搜索,想“捕获”它。它却如同一颗得到阳光爱抚的小小露珠,林中蒸发了!