搜尋結果
查詢
the共找到
1526筆。
如查無相關資訊,可至
進階搜尋
進行查詢
科展作品檢索
An Analysis and Optimization of Double Parallelogram Lifting Mechanism
Double Parallelogram Lifting Mechanism (DPLM) is a compact and stable lifting mechanism with a large extension range widely adopted in robot designs. Rubber bands and springs are often installed on the DPLM to lighten the motors' load and maintain its height, yet the installation positions are often obtained through trial and error. This project aims at finding the optimal rubber band installation positions for DPLM using modeling and optimization techniques. A mathematical model which describes the forces and moments acting on all the linkages of DPLM was derived based on the conditions for the static equilibrium and verified with a 3D simulation software. A genetic algorithm (GA) was implemented to optimize rubber band installation positions, which managed to find solutions with the overall root-mean-square- error (RMSE) of the net moment less than 2 for 2 to 6 rubber bands. A further statistical analysis of 50000 random rubber band samples showed that installing rubber bands in triangles is the best solution with the overall lowest RMSE. A test was conducted with a prototype of the DPLM and the results were consistent with our model and optimization. This project derived and verified a mathematical model for the DPLM, and found the optimal way and positions to install rubber bands. The results of this project provides a theoretical basis for controlling DPLM with rubber bands, allowing it to be further adopted in industrial robots that require repetitive lifting and lowering such as inspection robots and aerial work platforms.
> 更多
科展作品檢索
A Person Re-identification based Misidentification-proof Person Following Service Robot
Two years ago, I attended a robot contest, in which one of the missions required the robot to follow the pedestrian to complete the task. At that time, I used their demo program to complete the task. Not long after, I found two main issues: 1. The program follows the closest point read by the depth camera, which if I walk close to a wall next to, the robot may likely ‘follow’ the wall. 2. Not to mention if another pedestrian crosses between the robot and the target. Regarding these two issues, I decided to improve it. We’ve designed a procedure of using YOLO Object Detection and Person re-identification to re-identify the target for continuous following.
> 更多
科展作品檢索
A Person Re-identification based Misidentification-proof Person Following Service Robot
Two years ago, I attended a robot contest, in which one of the missions required the robot to follow the pedestrian to complete the task. At that time, I used their demo program to complete the task. Not long after, I found two main issues: 1. The program follows the closest point read by the depth camera, which if I walk close to a wall next to, the robot may likely ‘follow’ the wall. 2. Not to mention if another pedestrian crosses between the robot and the target. Regarding these two issues, I decided to improve it. We’ve designed a procedure of using YOLO Object Detection and Person re-identification to re-identify the target for continuous following.
> 更多
科展作品檢索
PVA unveiled the actual role of starch in the Briggs-Rauscher reaction
The Briggs Rauscher reaction (BR reaction) is one of the famous oscillating reactions; the aqueous mixture of KIO3, H2SO4, H2O2, C3H4O4, MnSO4, and starch exhibit color change between yellow and blue-purple repeatedly. The blue-purple color formation is due to the iodine test reaction caused by inclusions of polyiodides such as I3- and I5- in the helical structure of starch. Therefore, starch has been regarded as only an indicator in the BR reaction. But our seniors have found that the oscillation did not last without starch. They hypothesized that starch’s linear helical framework is necessary to elongate the lifetime of the oscillating reaction. If this hypothesis is correct, similar BR-type oscillations must be observed when other polymers with helical structures are used instead of starch. We found the literature which reports that polyvinyl alcohol (PVA) forms a helical structure and indicates the iodine test reaction. In our research, we studied the BR reactions using PVA, with different saponification degrees and viscosities. First, we studied the correlation between the structural features of PVA and the iodine color reaction by spectroscopic approach, exhibiting that PVA with low saponification form helical structures and show the iodine color reactions, which gives red color solutions. Second, we found that additions of the helical-structured PVA to the reaction solution instead of starch induces the BR-type oscillating reactions, while PVA without helical structure induces only a few numbers of oscillations. This is the world-first example of the oscillating reaction using PVA. The oscillation that lasted for 6 minutes with 23 oscillations was almost the same as that of the general BR reaction using starch. We concluded that the polymers with helical structures are intrinsic to elongate the lifetime of the BR reaction. Furthermore, we found that the addition of K3[Fe(CN)6], which has a high redox activity, in the reaction solution with PVA drastically elongated the lifetime (50 min) and increased the numbers of the oscillations (nearly 100 times). This result suggests that the oxidation-reduction reactions by the ferricyanide ion promotes the redox process of iodine and iodide ions.
> 更多
"When the Well is Dry, we will know the Worth of Water." Most of 埃及 and the world suffers from water and petrol shortage. With the current consumption rate, two-thirds of the world's population may face water shortages by 2025. These are water pollution, overpopulation, and agriculture, leading to wastewater from landfills and pipes that seep into the ground and may pollute the water, making it unfit for human consumption and waste more water. Besides, some accidents happen to water distribution and irrigation systems, causing a significant loss in water. According to the ministry of water resources, in 2016, the need for freshwater is 67 billion cubic meters. On the other hand, 埃及 receives only 55 billion cubic meters (2.6 billion cubic meters of them evaporate during runoff). Also, one of the wasting water methods in modern irrigation systems is water leakage from pipes as the water transmission and distribution lose about 31% of the produced water due to pipe leakage. Besides, every day more than 3.3 billion liters of treated water – 20 percent of the nation's supply and 234 million liters a day more than a decade ago – are lost through leaking pipes in England and Wales. Many reasons lead to leakage in pipes like water pressure, clogs, and corrosion. The leakage in pipes does not exist in the lines of water only. Also, the pipes in a petrol can cause dangerous accidents like the accident in the Bahira government that led to the death of 6 people and made 19 in a dangerous state. Our project designed a system that can detect fluid leakage and deal with it fast to prevent the wasting of fluid by using sensors and electronic circuits. Our system provides us with information about the fluid (like the amount of the flowing fluid and its speed). Therefore, if there is a difference in the reads, we understand that there is a leakage in this region, and the system will automatically stop the fluid flowing through the pipes. the system will locate all the leakage sites and send them to the mobile app with the amount wasted and the actions taken.
> 更多
科展作品檢索
Territorial behaviour of the Eurasian Wren (Troglodytes troglodytes) during autumn migration and wintering in the urban environment of Hradec Králové, Czech Republic
In the present paper I studied the winter territories of the Eurasian Wren (Troglodytes troglodytes) in the urban environment of the city of Hradec Králové. The males of this species were detected through the aggressive reactions to the playback of its conspecific call. The Eurasian Wren territories were detected at seven out of the ten observation points in the city. The frequency of the territories decreased during the observation period from October to January and it was also affected by the structure of the biotope. It seemed that the wrens preferred trees and avoided lawns and isolated growths. That illustrates how important it is to maintain wildlife corridors in the cities. Individuals of seven other bird species were seen reacting to the playback of Eurasian Wren songs or warning calls. Eurasian Wren may be applied as an indicator species of the ecological value of the urban environment. Through this species, we can access such quality also for the human inhabitants.
> 更多
科展作品檢索
Development of an Audio Modulated Tesla Coil
Originally, the Tesla transformer was developed to transmit energy and messages wirelessly. But it did not prove itself for either of these applications, so today it is only used for research purposes. Over time, the Tesla transformer has evolved and improved. Today it is possible with Tesla transformers to generate powerful and highly precise controlled discharges. During operation, impressive high-voltage discharges occur at the transformer. A tesla transformer is basically a high voltage generator that achieves a voltage boost by using two magnetically coupled LC series resonant circuits of the same resonant frequency. The Dual Resonant Solid State Tesla Coil (DRSSTC) built in this work has a high power IGBT half bridge module to excite the primary resonant circuit at the resonant frequency. The IGBTs are driven in such a way that audible pressure waves, and therefore music, are generated by the electrical discharges at the high voltage electrode. Within the scope of this work were the following two questions: - How is a DRSSTC designed and built? The DRSSTC system realized in this work is about 80 cm high and reaches about one-meter-long discharges. The design, development, and construction of the transformer are documented in detail and extensively in this thesis. - How does one measure an electrical voltage of 200,000 V, which changes sign more than 100,000 times per second? Two approaches have been taken to measure the voltages. Derived from the energy balance of an ideal capacitor and an ideal coil, a secondary voltage of about 200 kV was calculated via secondary current measurement. The second approach uses a voltage measurement via an in-house developed measuring electrode and a calculated divider ratio between the measured voltage and the secondary voltage. A relatively unrealistic secondary voltage of about 750 kV was measured since the divider ratio depends on approximate values. Nevertheless, the measuring electrode can be used for investigations of the voltage curve, or the divider ratio can be calibrated via the secondary current measurement. The development of such a transformer laid the foundation for much further research and scientific analysis.
> 更多
科展作品檢索
THE DESIGN OF MICROFLUIDIC PUMP (MFP) FOR MEDICAL FIELD
The ability of microfluidic (MF) device technologies to provide a lot of information with a small amount of sample, the opportunities it offers increases their use in the medical field in the bedside monitoring in drug delivery systems. Three-dimensional (3D) printer technologies provide advantages such as cost-effectiveness in the production of MF devices and quick and easy production in intricate designs. In our project, it is aimed to design microfluidic pumps (MFP) to be used in the medical field and conduct its production with 3D printer technologies. The developed MFP is intended to be at low cost, bio-compatible, adaptable, and portable to the drug, suitable flow properties as a pharmaceutical pump. First of all, MFP air channel, flow channel, etc. parts were designed and printed with the help of a 3D printer and on AutoCAD, one of the professional drawing programs. The poly(dimethylsiloxane) (PDMS) membrane that will enable MFP activation is produced in different thicknesses and glued to the air channel of MFP. The resistance to the applied pressure is observed, and the appropriate membrane thickness is determined as ~ 235µm. Liquid PDMS was applied to the inner surfaces of MFP's air and flow channel, PDMS membrane was placed between them, and the parts were assembled in the oven at 60ºC. MFP has been connected to the pneumatic valve system, where operation codes have been prepared with Arduino Uno, and flow properties have been examined. The flow rate of MFP is ~ 50 µL/min at a maximum of 15 Hz, and the backpressure is ~ 0.085 Pa under a maximum pressure of 3 bar. Also, values such as size, membrane thickness, and applied pressure for the possible models of MFP were supported by theoretical calculations. As a result, MFP, which is biocompatible, drug adaptable, portable, wearable technology application potential, and has suitable flow characteristics as a pharmaceutical pump, has been developed. MFP introduced a microfluidic pump system that can make life easier for the patient and contribute to the national economy through domestic production and can be used as a drug pump in the treatment of diseases such as diabetes and cancer.
> 更多
科展作品檢索
Ecological inks for markers
Markers have become essential in school and work life due to their great usefulness for teaching and homework. Despite the benefits they have brought, markers are the cause of great contamination from the ink manufacturing process to the excessive production of plastic. Ecological inks in markers and the innovative design of a refillable marker, allow to generate less pollution without having to stop using this product. From dyes created with coffee, fruits and vegetables that pass through different processes, natural inks arise that replace the use of polluting dyes. Likewise, implementing recycling plans in different institutions, markers that were no longer used were collected to be filled with ecological inks and used again. In addition, the excessive production of plastic is reduced by selling and refilling markers and ink kits.
> 更多
科展作品檢索
AGRIBOT – ROBOTIC SOLUTION TO FOOD SUSTAINABILITY
Food sustainability is key to human survival. Robotic solutions have started playing large roles in automating farming tasks in order to assist with crop yield and the efficiency of production. Due to the unreliability of and lack of manual labour in many parts of the world, Agribots are playing bigger roles. One of the biggest advantages of Agribots is that they can operate 24/7, 365 days a year without payment. Agribots are being used more often in dairy farms to milk cows while others are used to shear sheep. Agribots are fast becoming very important to farmers by gathering valuable data; milking cows; automating animal feed; measuring the right amount of pest control, detecting weeds and pests, harvesting and ploughing with unmanned tractors. In many parts of the world farm labour is scarce and difficult to come by. In 南非 for example farm labourers endure gruesome attacks. These attacks on farmers result in the closure of the farm for an extended period of time resulting in the loss of large quantities of crops. Food sustainability is dire in Africa and many parts of the world. “Each day, 25,000 people, including more than 10,000 children, die from hunger and related causes. Some 854 million people worldwide are estimated to be undernourished, and high food prices may drive another 100 million into poverty and hunger. . 90 percent of the world’s farms produce over 80 percent of the world’s food. They also manage about 75 percent of farmland worldwide. Yet, paradoxically, these farmers are often poor and food insecure themselves. Due to the increase in the world’s population annually, there is a growing demand for food. This has led to increasing pressure on farmers to produce crops. In order to meet this demand, farming innovations are vital for the future of food and agriculture. Constant innovations in agriculture is thus needed to constantly feed a growing and increasing population. Innovation in agriculture is also critical to help farmers use resources in better and more efficient ways. “Innovation is one of our best tools for creating a #ZeroHunger world.
> 更多
科展作品檢索
Limited Query Black-box Adversarial Attacks in the Real World
We study the creation of physical adversarial examples, which are robust to real-world transformations, using a limited number of queries to the target black-box neural networks. We observe that robust models tend to be especially susceptible to foreground manipulations, which motivates our novel Foreground attack. We demonstrate that gradient priors are a useful signal for black-box attacks and therefore introduce an improved version of the popular SimBA. We also propose an algorithm for transferable attacks that selects the most similar surrogates to the target model. Our black-box attacks outperform state-of-the-art approaches they are based on and support our belief that the concept of model similarity could be leveraged to build strong attacks in a limited-information setting.
> 更多
科展作品檢索
HoneySurfer: Intelligent Web-Surfing Honeypots
In Singapore’s evolving cyber landscape, 96% of organisations have suffered at least one cyber attack and 95% of organisations have been reporting more sophisticated attacks in the frame of one year according to a 2019 report[1] by Carbon Black. As such, more tools must be utilised to counter increasingly refined attacks performed by malicious actors. Honeypots are effective tools for studying and mitigating these attacks. They work as decoy systems, typically deployed alongside real systems to capture and log the activities of the attacker. These systems are useful as they can actively detect potential attacks, help cybersecurity specialists study an attacker’s tactics and even misdirect attackers from their intended targets. Honeypots can be classified into two main categories: 1. Low-interaction honeypots merely emulate network services and internet protocols, allowing for limited interaction with the attacker. 2. High-interaction honeypots emulate operating systems, allowing for much more interaction with the attacker. Although honeypots are powerful tools, its value diminishes when its true identity is uncovered by attackers. This is especially so with attackers becoming more skilled through system fingerprinting or analysing network traffic from targets and hence, hindering honeypots from capturing more experienced attackers. While substantial research has been done to defend against system fingerprinting scans (see 1.1 Related Work), not much has been done to defend against network traffic analysis. As pointed out by Symantec[2][3], when attackers attempt to sniff network traffic of the system in question, the lack of network traffic raises a red flag, increasing the likelihood of the honeypot’s true identity being discovered. In addition, the main concern with regards to honeypot deployment being their ability to attract and engage attackers for a substantial period of time, an increased ability to interest malicious actors is invaluable. Producing human-like network activity on a honeypot would appeal to more malicious actors. Hence, this research aims to build an intelligent web-surfer which can learn and thus simulate human web-surfing behaviour, creating evidence of human network activities to disguise the identity of honeypots as production systems and luring in more attackers interested in packet sniffing for malicious purposes.
> 更多