工程學

Many people in South Africa still use open fires for cooking. There is a\r large amount of wasted heat lost by four methods of heat transfer:-\r radiation, convection, conduction and evaporation.\r I constructed a vessel that would reduce heat loss, and focus the heat\r emitted from a fire onto the bottom of a pot. I used materials that were\r cheap and easy to obtain, so that those using open fires would be able to\r construct similar vessels to save energy and reduce pollution.\r The vessels were made up of a standard wire mesh frame that was\r surround by trial coverings, namely tin foil, asbestos rope, industrial foil,\r papier mache, ceramic, and 2 ceiling insulators.\r 5 mls of methylated spirits was burned in each vessel. The temperature\r gain of 100mls of water in a standard pot was recorded. 5 trials on each\r vessel were performed. 2 groups of vessel were found. Those that\r produced high temperature gains, burned quickly, and produced a large\r amount of soot deposits on the pot, and a second group that did the\r opposite.\r I compared the rate of heating from my best vessel to that of a stove as\r well as a microwave oven. Heating from the vessel was faster than that of\r the stove, and slightly slower than the microwave.\r I measured the heat emitted from a fire in a three-dimensional pattern and\r found that the maximal heat was some distance above the flame.\r From these results I devised 12 guidelines that would minimize the\r energy need, and pollution produced, when cooking on an open fire

本研究主要探討蝌蚪之游泳運動特性，及游泳速度(V)與尾鰭長度(SL)、尾鰭高度(SH)、身體質量(M)、尾鰭擺動頻率(TBF)、擺動幅度(AMP)之關係，並分析蝌蚪游泳之體軸變化及流場變化。祈能了解蝌蚪之游泳運動特性，進而探討其適應環境之機制。研究結果顯示：黑眶蟾蜍蝌蚪體重(M)愈重，則鰭長、鰭高亦隨之生長，並呈現高度相關性(R2=0.9381、R2=0.9809)。另外，尾鰭生長時之長度增加較多。蝌蚪體重(M)與鰭長(SL)、鰭高(SH)之迴歸方程式(M=0.027SL＋0.342SH－0.078，R2＝0.9832)。黑眶蟾蜍蝌蚪之游泳速度，會隨著尾鰭擺動頻率之增加而提高。尾鰭長度愈短之蝌蚪，增加游泳速度時尾鰭擺動頻率增加較多。蝌蚪游泳速度(V)與鰭長(SL)、擺動頻率(TBF)之迴歸方程式(V=0.480TBF＋4.804SL－4.381，R2＝0.9110)。不同尾鰭長度蝌蚪之擺幅對體長之比率並無明顯變化，其擺動幅度(AMP)的範圍介於0.45(BL)至0.56(BL)之間。蝌蚪游泳時各部分體軸之擺動幅度自吻端開始(P=0)至P 為0.24 時逐漸遞減，且在P 為0.24 時呈現最小擺幅，但P 超過0.24 之後直至尾鰭部分卻又大幅遞增，其最大值出現在尾鰭末端(P=1)。蝌蚪游泳是以尾鰭快速向中心軸擺動，產生較大的前進動力，過了軸線則慢速擺動，以減少阻力。This investigation is to explore the swimming habits of tadpoles- the relationship between their swimming velocity, length and height of their tails, mass, the frequency at which their tails movement, and the amplitude of the tail’s movement, as well as analysis their body axes, and the flow distribution of the water, in order to understand how the swimming patterns of the tadpoles are affected by the changes in their environment. The results of this investigation have shown that as the mass of the tadpoles increases, both the length and the height of their tails also increase according to the R values of the tail increases according to the R values of 0.9381 and 0.9809. However, it is observed the length of the tail increases at a faster rate than its height during the tadpoles’s growth. The formula which models the regression relationship between the tadpole’s mass, tail length, and tail height are found to be (M=0.027SL+0.342SH-0.078,R=0.9832). It’s also noted that as the length of the tadpole’s tail decreases, the velocity and the frequency of the tail would increases (the length of the tail is inversely proportional to the tadpole’s velocity and tail frequency). The formula which models the regression relationship between the tadpole’s velocity, tail length and tail frequency is (V=0.480TBF+4.804SL-4.381,R=0.9110) The different frequency model by tails of different lengths do not appear to have an apparent relationship with the tail length, given that the amplitude is between 0.45(BL) and 0.56(BL). As the tadpole swims, the angle between its oscillating body axes decrease as the P values increases from 0 to 0.24, their force the angle is at a minimum whom the P is at 0.24.Yet when P exceeds 0.24 the angle would increase dramatically. The maximum value is observed when P=1.The tadpole’s swimming motion mainly relays on the rapid oscillations of the tail about the centre of mass (body axis)-producing a stronger driving force, and slowing down towards the end of each oscillation to minimise the friction forces acting on the tadpole, which in furn, decrease its velocity.

利用陰極電弧蒸鍍各種薄膜，如：類鑽膜（DLC）、氮化鈦膜（TiN）、氮化鉻膜（CrN）、氮化鋁鈦膜（TiAlN）以及先披覆上一層氮化鋁鈦膜（TiAlN）再加上類鑽膜（DLC）的合成膜等。這些薄膜現在已經被廣泛的應用於各種刀具、模具的表面處理之中。本研究主要在探討高速鋼鍍上氮化鉻膜（CrN）之後，對於硬度、磨耗性質的改變，以及觀察氮化鉻膜（CrN）表面結構之組織。 在研究中我們運用陰極電弧蒸鍍系統蒸鍍氮化鉻薄膜，分析上運用SEM來觀察薄膜表面結構組織，以及運用洛氏微硬度機來觀察試片的硬度，另外還有使用磨耗試驗機來進行磨耗測試。以上這些測試總括來說都是在得知性質有無實際上的改變，而這些實際上的改變對於蒸鍍之後的模具或刀具都能夠大幅的提高使用的壽命。 We evaporated different kinds of thin films by using the anode of the electronic arc, such as DLC (Diamond-Like Carbon), TiN (Titanium Nitride), CrN (Chromium Nitride), TiAlN (Titanium Aluminum Nitride), and synthetic films of covering TiAlN and DLC. These thin films have been used widely in processing the surface of a variety of cutters and moulds. The purposes of this research were to investigate changes of hardness and abrasion and to observe the organization of the surface structure of CrN after High-speed steel evaporates CrN. In this study, we use the system of the anode of electronic arc to evaporate CrN. Besides, SEM is used to observe the organization of the surface structure of the thin films and Rockwell Micro-hardness Test Machine is used to investigate hardness of testing samples. Moreover, we use Abrasion Tester to test abrasion. These tests are taken to lead to a better understanding whether the quality really changed. These changes of evaporated moulds or cutters would extend their frequency of using.

能源危機日益嚴重，開發再生能源成為當務之急。在諸多的再生能源之中，太陽能最易於使用，且可源源不絕的不斷取得利用。但目前太陽能電池的效率始終不高。其中重要的原因是太陽本身的頻譜多為短波長，並不適合絕大部分頻譜響應較佳，多為長波長的太陽能電池。目前改善效率方式，多為改變太陽能電池的頻譜響應以配合太陽之頻譜。本研究提出反向思考的概念，藉由頻譜轉換的方法，改變照射在太陽能電池上的太陽光頻譜，以提升太陽能電池的效率。本研究利用一種珊瑚礁的螢光蛋白質（DsRed）以及人工合成的螢光染料（Cy-5）最為本研究的頻譜轉換的材料，加於低成本，目前市場佔有率較大的單晶矽太陽能電池上，經由理論與實驗的結果顯示，增加的發電效率約為3~5%，證實利用頻譜轉換的概念確實可以提升太陽能電池的效率。Energy crisis has become more and more serious in recent years, which makes recycled-energy development is a must. Among different recycled energies, solar power has two advantages, that is, easy-to-use and endless supply. However, the conventional solar cell makes poor use of the solar spectrum because the solar spectrum is mainly composed of short-wavelength, which can’t fit to most of solar cells which is more sensitive to long-wavelength. Currently, the major method to improve the efficiency is change the function of spectral response, such as concentration lens, tracking devices, and antireflection coating. Up to now, no one notices the possibility of changing solar spectrum yet. This research provides an insight into this issue. Instead of changing the function of spectral response, I changed the solar spectrum, which irradiates solar cells through spectrum conversion to improve solar cells’ efficiency. This research uses one kind of coral fluorescence proteins (DsRed) and one kind of artificial fluorescence dyes (Cy-5) as the materials of spectrum conversion. Then coat them on the low-cost and high-market-share mono-crystal-Si. According to the theories I researched and my experiments, the improvement of the efficiency is about 3~5%, which proves it is actually useful to elevate the efficiency of solar cells through spectrum conversion.

a. Purpose of the Research Evidence has shown that people are becoming more aware of environmental protection than in the past. Not only has the government made every effort to implement the policies of environmental protection, but Hong Kong citizens are also more willing to cooperate and help out. However, when it comes to conservation of energy and reduction of wastage, many people still regard it as a burden and they just take it lightly. In fact, environmental protection can be achieved in a convenient and simple way. We can easily put in practice in our daily lives. Because of this, we would like to introduce our invention - “shock Induced battery” by using our knowledge of Physics. b. Procedures The “Shock Induced battery” makes use of locomotion of human bodies to generate electricity. The electrical current generated from the specially designed generator will pass through the diode bridges, which adjust the current to one direction. This enables the electrical energy to be stored in the capacitor. This energy will be released when the battery is correctly connected to a circuit with a switch and a resistor. One of the features of the battery is that it is portable. It is mainly used to charge up electrical devices. But it is hoped that it will replace non-chargeable cells one day, and can directly be used in any electrical devices. In fact, our ultimate goal is to reduce the wastage of materials for making the cells, and to solve the problem of disposal of these cells. c. Data The induced a.c. voltage is full-wave rectified by the diode bridge. d. Conclusions In a word, we are trying to provide a chance for people to put environmental protection in practice, so as to raise the awareness of people about environmental protection. After all, high-tech products only solve the power-saving problem to a certain extent, but it is the awareness and the initiatives of the public which matter. We are convinced that environmental protection brings fun to your daily lives, as you will find practices on environmental protection both convenient and simple.

Annually several baby’s and toddlers drown. There are safety devices available on the\r market for ex: Safety nets in which toddlers can get strangled. Pool covers that have to be\r taken off when people swim and replaced after they have swam. If they are not replaced\r afterwards, babies could fall in the water and drown. Fences around the pool:- The gate\r could accidentally be left open and the toddler could fall in and drown.

To-be static objects, such as bridges, volcanoes, seldom move ordinarily but have mini displacement only under special conditions, like flood or earthquakes. Therefore, how to measure their mini displacement has never become fully popular with scientists’ research. Then, beginning with “ Optical Lever Theorem”, through a series of speculation and discussion, I decide to use laser ray as light source to perform an experiment ------- trying to find objects with mini displacement in our daily lives, such as revolving electric fans, engine-opening motorcycles, shaken trees, testing their magnifying effect first. Next, I try to use the control-experiment method to find out the magnifying relation and formula of the rotation angle of the plane mirror and the displacement quantity of light focus. As to the measure of mini displacement on objects, I utilize the pillar mirror as a reflection plane to research the magnifying relation of reflection light focus and original displacement quantity. The image made from the light focus of pillar mirror’s reflection, however, isn’t so perfect that I have to use a special plastic-made light-concentrating mirror, which is also called “ Fresnel Lens ”, to focalize the light for easy observation. Besides, I find out the “ function graph ” of the mini displacement quantity on to-be static objects and the displacement quantity of reflection light focus. At last, I try to build up a “ Bridge Alarm System ” of Optical Lever Theorem. 準靜物如橋樑、火山，由於平常不輕易移動，只有在特殊情況下（如洪水、地震）時，才會發生位移的現象。因此，其微小變位如何測量，一向是科學界較少探討的題目。於是，先由光學槓桿原理著手，經過一番思考、探討，決定採用雷射光作為光源，並作了第一個實驗－－找生活中具極微小變位的東西，如轉動中的電扇、引擎發動的摩托車、被搖動的樹木等，先測試其放大效果。接著就試圖用控制變因的方法，找出平面鏡旋轉角度和光點平移量的放大關係和公式。至於物體微小的平移量之測量，則是利用柱面鏡作為反射面，來探討反射光點的位移與本來的平移量之放大關係。然而，柱面鏡的反射光點成像並不理想，於是用一種特製的塑膠集光鏡，又稱Fresnel Lens，將光點集中以利觀測，並且找出準靜物之微小平移量及反射光點的位移量的函數圖形。最後，嘗試建立一套光學槓桿式的「橋樑預警系統」。

Ambient vibration, the movement of the ground caused by transient objects such as the relative to values obtained using the commercial recorder. The natural ambient vibration of a control site was simultaneously obtained using the mechanical prototype and the commercial recorder, which were situated next to each other during the actual recording. Moreover, both sensors were used to record a control stimulus for a constant amount of time. The data obtained from these subparts were processed using WinWaveShot which quantified and presented ambient vibration as waves. The deviations of the maximum and minimum amplitudes, mode and median values of these waves, as graphed by DADiSP2002, was performed to verify the accuracy or reliability of the prototype. These graphs were converted to their DFT graphs and histograms, with accompanying converted wave properties which characterized the predominant frequency. Based from the results, the recordings obtained from the mAVR are proportional from the ones obtained from the eAVR. Therefore, the mechanical prototype is capable of recording the predominant frequency of a site. The prototype, when improved, is a potential alternative to commercial sensors since it is able to record actual movements and its scale is proportional to the scale of the eAVR. Since the prototype was constructed and can be reproduced from readily available and inexpensive materials, ambient vibration analysis can be used more commonly by architects and engineers for construction purposes. To verify the reliability of the values obtained using the prototype, the ambient vibration of other sites must be recorded and compared to those using the eAVR. wind, sounds and human activities, is one major site effect evaluation method presently used. The respective predominant frequencies of a site and the structures above it obtained using this method serve as reference to the renovation and/or construction of structures. Predominant frequencies of the landmass and the structures above it should be non-identical to avoid prolonged shaking with the occurrence of an extensive movement of the ground as dictated by resonance effect. Since electronic ambient vibration or microtremor recorders, specifically their sensors, are expensive and inaccessible, a mechanical prototype of such device was designed and constructed. The proposed design of the mechanical ambient vibration recorder (mAVR) was mainly based on the IRIS Seismograph which makes use of the principle of electromagnetic induction. The relationship between ground motion and the movement of the prototype lever, which is a direct proportion, was the concept highlighted by the prototype’s mechanism. After the design of the mAVR prototype was finalized, its assembly, which consisted of the calibration of the solenoid and the inertial mass, was performed. The calibration of the solenoid was based on the voltage output of its solenoid based on the number of turns while the inertial mass was determined based on the equilibrium level of the prototype lever. Having proven the mAVR’s capacity to function by simulating stimulus, the testing of its accuracy was done with two setups: recording of (1) natural and (2) induced ambient vibration. This tested the prototype’s accuracy

Water is very vital in our lives as we cannot live without it. However our world is now facing a serious problem. Owing to the increasing population, water resources are scarce. In recent years, we can see that droughts have been affecting millions of people around the globe. In the meantime, people in developed countries have been wasting huge amount of water for flushing the toilet. According to the US Environmental Protection Agency, 30% of household water goes toward flushing the toilet. Countries like China, US, Canada and UK are still using fresh water in flushing, consuming 190 million L of fresh water every day, not to mention the energy needed in pumping the water. In fact, it is not necessary to use so much water to flush away substances like tissue, hair, urine etc. The water we used is far more than we need. However, as we cannot control how much water is used when we flush, all water in the cistern is flushed away. Realizing the seriousness of water shortage and wastage in flushing, we tried to invent a device to conserve water by controlling the amount of flushing water used. Firstly, we study the principle of normal flushing system so as to understand why flushing cannot be controlled. Then, we tried to think of ways to control flushing. We have tried various methods and materials. After the 6-month testing and modification, we successfully invented Fast Fabulous Flush. It is a device which can be fit into existing cistern to conserve water. With our invention, users can control the amount of water flushed according to needs, so as not to waste unnecessary water. Our invention costs a low price which is no more than 2 US dollar. Also, it can be fit into existing cistern within 3 minutes with simple installation process. Most importantly, flushing water can be conserved effectively. It is estimated that around 200L of water can be saved per household every day.

My project ‘Avert’ (To avert and vertebrae combined) involves research into posture related back problems and a solution to help prevent back pain by maintaining correct posture. My solution is a chain-like structure fitted with 24 sensors that is sewn into a Skins compression top. When worn the chain is aligned with the user’s spine from the lower back to the base of the neck and moulds to the spine as it moves. As everybody’s back is slightly different it is important that the device can recognise the difference between what may be bad posture for one person, yet relatively normal for another. To solve this the device takes an initial reading of the user’s spine in correct posture and saves it as a reference measurement. Bad posture is defined by the device as angles that exceed the natural movement of individual vertebrae and their platelets. While in use the 24 sensors are continually measuring the shape of the user’s spine and comparing it with the original reference measurement taken earlier. If any measurement links to unhealthy posture a light will flash and an alarm will sound either aloud or through headphones until the posture is corrected. This device can be worn during light activity and non contact sports to encourage the user to maintain correct and healthy posture. The device can also record and save poor posture measurements that can be uploaded later to a software program I designed to draw the shape of the spine as a vector diagram. The device can also be plugged directly into a computer so that the user can see the shape of their spine as it moves in real time. I, along with others, tested my solution with many activities and found Avert to be a beneficial and reliable product as it successfully detects slouching and many potentially problematic spine shapes. Throughout my research I gained a thorough understanding about the potential damage bad posture can cause and the endless number of activities it occurs in. With further development I feel there is a huge potential for Avert to become a marketable product used not only for posture correction in everyday activity, but for many other purposes such as physiotherapy, biomechanics and athletic performance. Many people have approached me with praise and requests for the Avert system which is extremely exciting and also rewarding to know that my research has the potential to help people.