搜尋結果
查詢
the共找到
1337筆。
如查無相關資訊,可至
進階搜尋
進行查詢
科展作品檢索
鋅電極低污染性金屬浸鍍處理對銀鋅電池的影響
Because the electrolyte solution used in an alkaline battery is a concentrated KOH solution, the zinc electrode in such a battery undergoes both a charging reaction and a corrosive reaction with the alkaline solution. The corrosive reaction not only reduces the lifetime of the battery but also produces hydrogen, which can cause the battery to explode and burn. Most of the zinc alkaline batteries currently on the market use mercury plating on the zinc electrode to increase its resistance to corrosion. To reduce corrosion of the zinc electrode in an alkaline battery and to avoid the use of toxic mercury, this study aimed to design a device to measure the quantity of hydrogen gas produced during the charging of a zinc-silver battery. We plated the zinc electrode with the immersion electroless plating method, using several different kinds of low-polluting anticorrosive additives(metallic compounds such as lead, tin, and indium)instead of mercury. We also used the vacuum immersion electroless plating method and added zincate ion into electrolyte solution to reduce further the quantity of hydrogen produced. The results of the experiment revealed that either a 10:1 or 100:1 ratio of lead to tin under optimal conditions will yield much better results than mercury.鹼性電池中使用的電解質溶液為濃氫氧化鉀溶液,因此電池中的鋅極除了放電反應之外,也會與濃鹼溶液中發生腐蝕反應。鋅極的腐蝕作用不僅會降低電池放電壽命,而且所產生的氫氣更可能使電池發生爆裂燃燒的危險。目前市面上所售之含鋅鹼性電池,大多是用鋅極鍍「汞」作為鋅極抗腐蝕的方法。為了改善銀鋅鹼性電池中鋅極在放電時的腐蝕效應,以及減少其所產生的氫氣量,本實驗設計了一動態放電裝置,可用於檢測銀鋅電池的放電電壓、放電時間與鋅極腐蝕反應的氫氣生成量。本研究藉由浸鍍其他低污染性金屬溶液 (鉛、錫、銦的化合物)來取代不環保的鍍汞製程,並進一步設計抽真空的浸鍍裝置,以及電解質溶液採用含有ZnO22-的KOH溶液,有效的降低電池中氫氣生成量。最後綜合所有優良條件,以鋅極採用真空浸鍍(Pb:Sn)為(10:1)及(100:1)的條件,此舉非常有效地提高電池中鋅極抗腐蝕性。此項製程所使用的Pb、Sn污染性質遠遠低於目前工業上所使用的汞製程污染,而且製程成本也遠遠低於Hg製程成本。
> 更多
科展作品檢索
The role of miRNAs in plant development and virus defense
微型RNA是最近發現的小RNA,調控生物體內的反應,包括生長、細胞分化、對抗病毒…等。植物利用RNA干擾 (RNAi) 或過敏反應 (HR) 對抗病毒感染。有趣的是,miR168可藉由降解mRNA或抑制轉譯,調控阿拉伯芥AGO1的表達,而AGO1是RNAi的一個重要元件。miR398則調控銅鋅超氧化物歧化? (CSD1, CSD2) 的表達,而CSD1, CSD2負責產生過氧化氫去引發細胞凋亡 (cell apoptosis)。帶有竹嵌紋病毒 (BaMV) 全長基因的轉殖菸草 (Nicotiana benthamiana) 品系27-17是我們的研究材料。27-17的幼葉不具病徵,隨著葉子的生長,病徵會漸漸變嚴重。我發現被病毒感染時,植物會提高AGO1的表達,使RNAi更有效率。然而,病毒藉提高miR168使AGO1的量無法上升。植物亦可提高CSD1, 2 mRNA的量,促進細胞凋亡。病毒卻會引發miR398降解CSD2 mRNA。在病毒力價高的葉子中,雖然CSD2 mRNA降低且miR398升高,植物仍可大量提高CSD2蛋白的量。CSD1 mRNA沒有被miR398負調控,詳細原因仍有待研究。
> 更多
科展作品檢索
探討聲致發光效應中,改變溫度,濃度,液體種類,頻率對氣泡發光的影響?
聲致發光效應(sonoluminesence)為最近二十年來相當新穎的研究領域,其基本原理是利用超聲波將水中的氣泡集中,並使之隨著超聲波快速且連續的膨脹壓縮,當氣泡被壓縮至最小時溫度急遽上升,並放出藍白色的光芒。正因為這是一個嶄新的領域,所以許多實驗是以嘗試錯誤的方法去進行,但也因此發現了一些特殊的現象:1. 氣泡在正常的頻率(30kHz)以外,經過一段不可發光的頻率後,還可在更高頻率(接近40kHz)的地方發光2. 氣泡發光效率曲線在不同性質溶液中的差異3. 針對高頻率發光及雙泡發光的部分,做了兩個相關的假設並進一步驗證,得到了相當特別的結論。至今已有許多關於此研究的成果發表,但對於同時兩顆氣泡存在並發光的雙泡發光現象(double-bubble sonoluminesence)卻還很少人研究。因此我們嘗試較系統化地分析雙泡發光,期望能夠對這個現象有進一步的認識,並對日後的多泡發光(muti-bubble sonoluninesence)研究奠定基礎。Sonoluminescence has been a very popular topic for the past twenty years. Single-bubble sonoluminescence occurs when an acoustically trapped and periodically driven gas bubble collapses so strongly that the energy focusing on collapse leads to light emission. Because it is a new topic, few related experiments on this issue have been carried out before. However, while doing the research and making adjustments at the same time we discovered some special phenomenon: 1. Besides the normal amplitude frequency (30kHz) added on the bubble, we found that after a period of frequency which can not emit, the bubble is able to remain and emit in higher amplitude frequency (about 40 kHz). 2. We also compared the emission efficiency when bubbles are in different liquids. 3. To explain part of the results in high frequency and double-bubble sonoluminescence, we made two assumptions and attempted to demonstrated them in the end of the report. Some research studies in this field have been released already; nevertheless, few people concentrate on “double-bubble sonoluminescence.” Therefore, we attempt to systematically analyze the emission of double-bubble, expecting to have more comprehension of this marvelous effect and also establish the fundamental background to “muti-bubble sonoluninescence.”
> 更多
科展作品檢索
The Main Features Of Climate Change On The South-West Of Yakutia In The Last 100 Years
1. Purpose of the research to detect the dynamics of the change of moisture regime on the territories of Olekminsk area for the past 100 years.\r 2. Procedures for analysis we used as materials of observations on the testing areas of school of ecological control of our Center, so and of the meteorological station Jikimda situated on the territories of Olekminsk reserve, as literary sources. Time-series analysis was conducted as to following scheme: for period 1901 -1914, 1949-1958 and for period 1996 -2009.\r 3. Data The changes of the temperature of air and sediments for the period of instrumental observations from 1901 to 2009 were analyzed\r 4. Conclusions Climate is characterized with many parameters coming in radiation, the heat and aqueous balances of territory. The most simple and widely measured parameters are the temperature of air and the quantity of atmospheric condensation. Carried out researches and the analysis of received results let us make tentative conclusions:\r 1. Average amount of precipitation increased on 41% (with 229 mm during the period 1901-1914 till 390 mm for period 1998 - 2006)\r 2. The decrease of firm precipitation in cold period and increasing of fluid precipitation in warm period are noticed for 100 years.\r 3. The gross amount of days with precipitation grows from 135 days (period 1901 - 1914) till 160 days (for period 1996 - 2006). For period 1901 -1914 a month with the greatest quantity of days with precipitation is January. The middle quantity of days with precipitation in it composes 16 days. A month with the least quantity of days with precipitation is July. The middle quantity of days with precipitation in it composes 8 days for period 1996 -2006. We should note that though increasing of the quantity of days with precipitation is on the cold period of year, increasing of the value of precipitation arises at expense of warm months. This reflects well the annual motion of the force of precipitation as to studied periods, the force of precipitation grows, in the first case achieving maximum in August, into second - in July. The maximal significances of the force of the precipitation of second period exceed of such the first period almost in two times.\r 4. The disposition of meteorological phenomena shows the change of climate to moistness. There are more days with fog, snow-storm, the quantity of days with precipitation increases from more 1mm, so more and 5 mm and it’s noticed that the quantity of days at a speed of wind more 10 and 15m/sec increases.\r 5. The change of the precipitation amount, especially in warm period affects the level and the expense of water in the Lena River. Analyzing as to decades the statistics on stratum of flow as to stratum flow since 1930 till 2006 can be noted tendency increasing of stratum flow from 132.8 mm in 1930 till 289 mm in 2006. The significance of the annualized expense of water with 6370 in 1999 till 8710 m/sec in 2006 enlarge, the annualized level of water changes from 282 till 376 cm. It is according. The area of the movement of the significances of the indicators changes to their increasing in the course of the year for the last 10 years. Averaging their significance exceed the norm of 18%.\r In conclusion we want to note that global change of climate actually touches all of us and already has significant influence on natural environment and the life of people. In simple words warming - the increase of temperature - for the many areas of our north country might become a favorable change of the conditions of life. But the trouble is that the change of climate is much more complex process, and one of its main manifestations is the augmentation of the instability of climatic conditions, changes of flora and fauna, increasing of infectious diseases. This influences badly on natural ecosystems and complicates the life of people. Besides, too quick warming does not let natural ecosystems adapt themselves, and they can be destroyed. And at least now we shouldn’t wait doing nothing, it is necessary to take all efforts to try to reduce climate change effect.
> 更多
科展作品檢索
The Solution to Global Water Pollution?
The waters of the Benguela, the Atlantic Ocean off South Western African shorelines, are amongst the most productive in the world, supporting prolific marine life. However despite the abundance of animals, survival in this marine ecosystem is not always easy. Oxygen-deficient bottom water, often containing toxic hydrogen sulphide, is a feature of the northern Benguela coastal upwelling system. Here, superfluous cells from excess phytoplankton production, decay and sink to the bottom to form the oozy diatomaceous mud belt sediment off the Namibian coastline. Within this diatomaceous mud further intensified decay takes place to form toxic hydrogen sulphide in the sediment. Sporadically large amounts of the hydrogen sulphide are released into the water column, causing the deadly annual "sulphur" events, as they are locally known in Namibia, to take place. Sulphur eruptions result in the deaths of thousands of marine animals. This marine system off the Namibian coast, with its harsh natural conditions of hydrogen sulphide and low oxygen, is similar to an ecosystem suffering intensive marine pollution. These natural conditions of the Benguelan waters are closely related to the conditions of many coastal areas suffering from the global marine pollution problem, created by man all over the world, through the discharge and disposal of wastes, such as nitrate fertilisers, sewage and biological decay material. A specialsed group of bacteria known as sulphur bacteria occur within the sulphidic conditions of the sediments. Sulphur bacteria actually use some of the produced toxic hydrogen sulphide in the sediments, converting it to harmless elemental sulphur micro granules in their cytoplasm. Where no other life occurs, due to the harsh conditions unfriendly to most marine lifr, sulphur bacteria thrive. Sulphur bacteria control and decrease the amount of hydrogen sulphide, which goes from the sediment into the water, through their complex metabolic systems. The biggest and most effective sulphur bacteria, only found off the Namibian coast, were dubbed Thiomargarita namibiensis. Thio means sulphur and namibiensis refers to its occurrence in Namibia. This giant sulphur-eating microbe is the earth's biggest known bacterium, visible to the naked eye. I conclude with a personal hypothesis to suggest a solution to global water pollution by utilising this magnificent bacterium. Through bacterial cultivation and processing Thiomargarita namibiensis could be employed in tacking extent of global marine pollution. The bacteria use toxic hydrogen sulphide as "fuel" for their metabolism and nitrate as an oxidizing agent, to produce harmless sulphur granules. This explains the bacteria's effectivity in removing nitrate and hydrogen sulphide wastes, the forms most biological wastes eventually occur in, from the water. This spectacular process, as it occurs within these magnificent "sulphur pearl strings", could be the sensational answer to the regeneration of polluted marine waters on a worldwide scale. This absolutely natural treatment of the water would not bear any harmful consequences such as those artificial treatment leaves behind. Sewage treatment or denitrifying treatments applied by man on polluted water leaves chemical discharge and damage to affected ecosystems. Especially Thiomargarita could be used in the regeneration of rural and urban waters (should those survive in fresh water)and sewage schemes as well as most marine waters, due to its high effectivity in removing hydrogen sulphide from affected water. It is not the solution to global water pollution to fight chemicals with chemicals. Nature has provided an excellent and valuable resource that could enable absolute natural recovery within polluted marine ecosystems. We should dedicate ourselves towards such magnificent discoveries and help nature help itself. Research on these Sulphur bacteria(especially Thiomargarita namibiensis)is very recent and ongoing. I recently enjoyed the privilege of a 24 hour marine research ship cruise off the Namibian coast with marine biologists from the Namibian Ministry for Fisheries and Marine Resources, to obtain mud cores holding Thiomargarita namibiensis bacteria. Several chemical tests are done and biological reactions are studied to collect the necessary data concerning Thiomargarita namibiensis. The discovery of Thiomargarita namibiensis awoke worldwide scientific excitement and interest. Its application to solve the problem of global water pollution would be a spectacular scientific breakthrough for the human race.
> 更多
科展作品檢索
磁性流體可調性折射率特性之研究與應用
磁性流體(magnetic fluids)是一種含有磁性奈米粒子的液體,當磁場外加於磁性流體時,流體中各磁性奈米粒子的磁矩會沿外加磁場方向排列,而導致粒子間相互吸引,形成較大的磁性叢集,即所謂的磁鍊。當外加磁場增強,該磁鍊數會變多,並使磁性流體的折射率產生變化。磁性流體的折射率變化會隨外加磁場之變大而增大。本研究除探討磁性流體折射率受外加磁場控制的變化情形及其物理原由外,並進一步運用此特性研發可調性光纖「光調制器」 ,以探討磁性流體可調性折射率應用在光電元件上的可行性。A magnetic fluid is one kind of colloids which contain magnetic nano-particles. Under an external magnetic field, the magnetic moment of nano-particles is aligned along the direction of the external magnetic field. This leads to the agglomeration of magnetic particles and to form magnetic clusters under an external magnetic field. With the formation of the magnetic clusters, the refractive index of magnetic fluid is varied. The refractive index of magnetic fluid was found to increase under a higher magnetic field. In this work, In addition to investigating in detail the behavior of the field-dependent refractive index of the magnetic fluid, we also explore the relevant physical origins. Furthermore, the feasibility of developing fiber-optical modulators by utilizing the tunable refractive index of magnetic fluids is discussed.
> 更多
本研究主題是要探討以電解質作為電介質之電容器的放電情況及電容值。作者在電容器的兩極板中,灌入電解質溶液,作為電介質,發現確實能使電容值大增。作者再以不同電解質和外加磁場為變因,作出以下研究,以深入了解電容和電解質溶液的關係。The main idea of this topic is to explore the amount of capacitance with electrolyte as dielectrics. The authors poured electrolyte solutions into the polar plate of capacitor and found the amount of capacitance increased. Then the authors used the different kinds of electrolyte and added magnetic field as changing factors. Authors performed the following research to deeply find out the correlations between capacitance and electrolyte solutions.
> 更多
因特殊的地理關係而形成奇特之新竹北埔冷泉,其水溫長年偏低且水質特殊。本研究報告主要在探討生長於冷泉中的蝦子其所屬物種、生命力、生態及新竹科學園區所排放的廢水對其生存之影響等議題。為能獲得科學與客觀性的結果,我自己設計了實驗以及適當的實驗步驟來幫助我找到解答,這也讓我對問題有深入的瞭解。我發現這些黑殼沼蝦,螯足各節間有粗糙橙斑,可以耐7℃的低溫,靠嗅覺覓食,小蝦在前4 週呈快速的成長,污水中的蝦子短期內一定死亡,從基部斷肢才能有再生能力等結果。茲條列所探討的問題如下:1.探討北埔冷泉蝦的身體構造與其功能。2.了解北埔冷泉蝦和一般食用蝦身體構造的差異性。3.探討北埔冷泉蝦的生長環境與其行為之關係。4.探討北埔冷泉蝦的食性。5.探討北埔冷泉蝦的覓食行為。6.探討北埔冷泉蝦與養殖蝦存活率的差異性。7.探討北埔冷泉蝦與養殖蝦的耐溫能力。8.瞭解北埔冷泉蝦的雌、雄判定。9.探討北埔冷泉蝦交配與孵卵方式。10.探討北埔冷泉蝦小蝦的成長曲線。11.探討不同水質對北埔冷泉蝦的影響。12.探討北埔冷泉蝦斷肢後的再生現象。經由這次的研究,讓我對北埔冷泉蝦子的身體構造、生長環境、覓食行為、耐溫能力、交配與孵卵、小蝦的成長、斷肢後的再生、甚至水質對蝦子生存之影響等等已能深入瞭解。除此之外之外,更重要的是從疑問的產生,實驗方法與步驟的構思、做實驗的過程,及獲得可信的結果,再再使我深刻體會到科學精神的真諦。Bei-Pu cold spring of Hsinchu was formed due to the unique geographical feature. This paper investigates the species, livability, ecology and affection of water quality of the wildlife shrimps that live in this special environment. I design my own experiments and suitable procedures to help me to get the scientific and objective results. The research topics on Bei-Pu wildlife shrimps are listed below. 1. Body structure. 2. Distinguish bred and this wildlife shrimp. 3. Growth environments and its behavior. 4. Foods. 5. Hunting 6. Livability. 7. Tolerance of low temperate. 8. Male and female. 9. Mating and incubating. 10. Growth characteristics. 11. Affection of water quality. 12. Limbed and re-generation. These crayfishes can survive under 7℃. Hunting behavior is guided by olfaction other than vision. They grow rapidly in the first 4 weeks. Regeneration occurs only from the joint. Water quality is vital to them. From this study, I understood the species, hunting, mating, incubating, growth, temperature tolerance and regeneration of this wildlife shrimps. Moreover, I deeply appreciate what real scientific essence is through defining the questions, designing the experiments, procedures and obtaining the results finally.
> 更多
科展作品檢索
Rubik's Cube Solver
Aim: Over the years I became quite quick at solving the cube. I was keen to see if I could create a mechanical system that would do it in a similar time. Because of financial limitations and equipment I thought it impossible to achieve my usual times of around 1 minute and so settled on a target of 10 minutes. So my aim became; “To create a mechanical system that could solve the cube 100% reliably in less than 10 minutes” What I did: I started from the view that I wanted to get it to find a solution using the process that I usually use. The downside of this approach was that this approach meant that most internet research was irrelevant to my project. Also some methods I found were very sophisticated and expensive eg. the university professor who created a system to solve it in 6 seconds. I wrote software capable of solving the cube, printed out its results then testing the instruction steps by manually manipulating the cube. This was improved until 100% reliable. I then developed the user interface to input the colours on each face. The building of the hardware to manipulate the cube proved my most difficult challenge. To get the cube flipped and rotated accurately using the 5 servos. I modeled this using lego and popsicle sticks until the movements met the accuracy and reliability outcomes I needed. Surprisingly these materials held up to the challenge. Integrating the software and hardware functional models took a lot longer than anticipated to get the software instructions executed and coordinated. A great deal of fine tuning was required. Outcome: The system solves the cube 100% of the time. I was exceptionally pleased with this result in view of the lego and popsicle stick model. On reflection I have achieved a successful working model that university students have aspired to and this gives me great satisfaction. Conclusion: While the outcome is pleasing I envisaged achieving a much faster system with easier data input using camera and colour recognition software. Unfortunately time and my budget restrictions prevented this from being developed. However this is a step I am interested in implementing in the future. The speed could be improved by designing more efficient cube solving algorithms, implementing a camera with colour recognition, and possibly rethinking and redesigning my mechanical design. I would also like to Figure 1 illustrates how the air would flow through a fan, and get pushed underground in several short HDPE pipes. This tempered air would then be fed into a small, insulated air chamber built against the home that contains an air-sourced heat pump. The walls of this chamber would have small vents to balance air pressure, and an exit near the top for cooled exhaust air. When the temperature outdoors is in the coldest stage of winter (daily average of -3.0ºC), the tempered air being brought into the chamber would simulate an outdoor ambient temperature of about 10.0ºC, allowing a heat pump to operate with a COP of ~3.79 (based on data from Goodman Air Conditioning and Heating).² This means that for every unit of energy put into the heat pump, 3.79 units of energy are extracted. 4. Conclusions: In building an enclosed air chamber for around an air-sourced heat pump, it was found that it is possible to simulate a 10.0ºC climate in the coldest parts of winter through air tempering. This will allow the heat pump to run substantially more efficiently throughout the year. This system could be used effectively to heat a home in the winter, as well as cool a home in the summer.
> 更多
科展作品檢索
利用浮沈子測量液體表面張力並演示"Cheerios Cheerios effect"
密閉容器置入待測液,放入浮沉子,施加壓力,當浮沉子恰要沒入液中瞬間,因表面張力的總力達極大值且向上,外加壓力(p1)為極大值,浮沉子沒入液中;液面減壓,當浮沉子在液面正下方時,外加壓力 p2,量 p1、(p1- p2),浮沉子的質量 m,外半徑 R,及玻璃管的體積 G V ,可求得液體表面張力。 液面再減壓,浮沉子恰要露出液面時,表面張力的總力達極大值且向下,外加壓力(p3)為極小值,量 p3、(p2- p3),浮沈子的質量 m,外半徑 R及 G V ,應亦可求得表面張力;但實驗時浮沉子漂移到容器邊,並吸附在器壁上,因此發現浮沉子的”Cheerios effect”。 利用浮沉子和容器的相吸及相斥現象,可解釋西式早餐的小榖片放入牛奶中為何會漂移到碗緣,並支持 Vella在 2005 年 9 月份美國物理期刊(AJP)認為 Cheerios effect的成因除了由於接觸角不同外,浮力、重力、表面張力共同作用,使小榖片間有相吸、相斥現象。 The experiment apparatus is equipped with a Cartesian diver by using a glass tube with air trapped inside that floats or submerses in a closed vessel containing liquid. The external pressure may be varied with a syringe and measured with a water manometer. The maximum pressure P1 inside the vessel is measured when the diver is just about to sink, where the surface tension that acts on the diver is upward. Then the pressure P2 of the vessel is measured when the diver is just beneath the liquid surface, where no surface tension acts on the diver. Finally, the surface tension is calculated from P1, P2 and the radius of the diver, R. When the pressure inside the vessel is decreased, the diver will rise. As the diver is about to emerge from the liquid, we get the minimum pressure P3 inside the vessel, and the surface tension that acts on the diver is downward. By measuring P3, P2, and R, the magnitude of surface tension is found to be the same as above. When the diver is just about to sink into the liquid, it floats to the center of the vessel. When the diver is about to emerge from the liquid, it sticks to the wall of the vessel. This phenomenon is named the “Cheerios effect.” Our results again strongly support that the cause of the effect is due to the different contact angles between the diver and water, as well as the balance of gravity and surface tension in the case of the sinking diver, and the balance of buoyancy and surface tension in the case of rising diver as Vella claimed in his paper (AJP 73, 817 (2005)).
> 更多
醫學上的植皮手術成功率受皮膚厚度影響,皮膚愈薄癒合速度愈快,其中以取皮厚度介於0.05mm 到0.1mm 為佳。在實驗量測時,需要經過一連串繁複的薄皮標本製作,再放到光學顯微鏡下測量,這種厚度測量方式不但耗時,又因嚴重損毀皮膚而不精確。由於使用螺旋測微器做接觸式測量會有形變的問題,因此我們想做間接接觸式的測量,所以採用氣體為媒介,做非破壞性檢測膜厚,這對於在皮膚上的施力遠小於螺旋測微器或是接觸式膜厚計。我們設計一套三頭連管線,使用空氣為媒介,儀器運作原理為在管線一端針頭非常靠近被測物時,所流出的氣體會受到被測物阻礙產生反壓使管線內的壓力上升,導致連通於另一管路的氣泡指示計壓出氣泡,當氣泡為最大氣泡時(半球形)視為達到平衡狀態。實驗時先用已知厚度且不變形的蓋玻片來當作被測物,此時可以算出針尖至蓋玻片的實際距離做為參考值。在量測軟性薄膜時,設計上採用兩側雙針頭靠近軟性被測薄膜兩側以達到氣流氣泡平衡,這時使用螺旋測微器讀取兩針尖距離,減去已知參考值的兩倍距離,即可測出未形變的軟物質厚度。本研究開發一套能測量軟性薄膜的厚度裝置,尤其在皮膚厚度測定上,不但不會直接接觸標本造成損毀,並且能夠快速地測量出厚度值,此為本儀器的最大特色。The thickness of skin graft has deterministic influences on the success of graft surgery. Experimental measurements of skin graft thickness involve complicated specimen preparation processes followed by optical microscopic examination, which are time-consuming and may incur inaccuracy due to possible damage. Here we propose a novel method using air as the media to avoid direct contact of the measured object. The physical operation relies on the following principles: When the tip of a needle connecting to a catheter system is placed close to the object to be measured, the air pumped forward from the catheter system becomes impeded by the object. The resulting backflow pressure opposing the air flow causes an increase in air pressure within the catheter and inflates the bubble connected at the other end. Balance at maximal surface tension is attained when the bubble reaches its maximum volume in hemispherical shape. In practice, a two-needle design was used, each approaching simultaneously from each side of the object. A micrometer was then used to read the distance between the two needle tips, from which the film thickness was derived, subtracting the thickness of the air layer pre-calibrated using cover glass with known thickness. The system implemented was capable of measuring thickness on soft thin films with an accuracy of ± 0.001mm. In addition to rapid measurements with high accuracy, since the pressure exerted on the skin graft is much less than in conventional calipers requiring direct contact, our method has the unique non-distorted and non-destructive advantages.
> 更多
一般人從小就知道如果要判斷西瓜有無成熟,只要用手輕拍瓜皮,利用聲音的特性就可以知道西瓜是否成熟,此技術看起來容易,卻需有多年經驗之西瓜商始可為之。本研究利用拍擊西瓜所造成之聲音進行非破壞性音波檢測,來探討西瓜之成熟度。換言之,本研究希望在依照西瓜商拍擊的習慣下,從客觀的科學角度,探討存在於西瓜商手上「聽音辨瓜」的奧秘。由研究結果得知,西瓜的拍聲在頻譜中可分為三個頻區,即西瓜殼所造成的高頻區,水及含水量高的果肉所形成的中頻區,及由空洞及含水量低的果肉所造成的低頻區,而西瓜商就是藉由這三種音頻所表現出的綜合效果進行判斷。The method, tapping the watermelon rind and listening to the sound, has been often used to judge whether the watermelon is mature or not. Although it is not difficult to tap the rind of a watermelon, it is not so easy to have a correct judgment of the maturity just from the sound you heard, unless you are an experienced watermelon farmer. In order to investigate the secret that the farmers have, this research detects and analyzes the sound of tapping watermelons in an objectively scientific way. According to the experimental results, the sound could be approximately partitioned into three regions in the frequency spectrum, denoted as high-frequency, mid-frequency, and low-frequency regions. The high-frequency region and mid-frequency region are resulted from the hard solid rind and the juicy flesh of a watermelon, respectively. As for the low-frequency region, it comes from the vacant holes or flesh with little amount of water. Based on the experiment, it can be concluded that the maturity of a watermelon can be correctly judged from the combination of these three frequency regions, just like the farmer’s method.
> 更多