We present a novel technique for 3D point cloud simplification — the so-called fractal bubble algorithm — to minimize the computational time and overall storage space. The proposed fractal bubble ...algorithm generates 2D elastic bubbles and copies of themselves through 2D data sets representing planar geometric contours. Each of the bubbles, as it grows, is made to select a single point of its first contact, and all the selected points become the simplified set of points. The fractal bubble algorithm is repeatedly applied to the simplification of planar slices of general 3D point clouds corresponding to 3D geometric objects, leading to the global simplification of 3D point clouds. The benefits of the algorithm are: first the algorithm is computationally light and memory efficient, second it is simple to implement and inherently allows the organized selection of the points of contact and finally it enables us to simplify the point cloud data through a multi-scale fashion by varying a set of user-controlled algorithm parameters. Numerical results verify the effectiveness of the proposed algorithm.
A high-efficiency rectenna is designed at 2.4 GHz. In general, a rectenna consists of an antenna, a band-pass filter, a rectifying diode, and a low-pass filter. In this article, to increase ...transmission efficiency, a high-directional antenna is developed using partially reflective surfaces. In addition, the harmonic rejecting band-pass filter is designed to suppress the second and third harmonic signal from the nonlinear diode, resulting in high conversion efficiency. It is experimentally demonstrated that the proposed rectenna achieves an RF to DC conversion efficiency of 72.17% when the received RF power is 63.09 mW at 2.4 GHz.
결정질 실리콘 태양광시스템의 물 발자국 산정에 대한 연구 나원철(Won-Cheol Na); 김영환(Younghwan Kim); 김경남(Kyung Nam Kim) ...
Clean Technology, 20(4),
2014, Letnik:
20, Številka:
4
Journal Article
Recenzirano
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There has been increasing concerns for the problems of water security in countries, caused by the frequent occurrence of localized drought due to the climate change and uncertainty of water balance. ...The importance of fresh water is emphasized as considerable amount of usable fresh water is utilized for power generation sector producing electricity. PV power system, the source of renewable energy, consumes water for the every steps of life cycle: manufacturing, installation, and operation. However, it uses relatively less water than the traditional energy sources such as thermal power and nuclear power sources. In this study, to find out the use of water for the entire process of PV power system from extracting raw materials to operating the system, the footprint of water in the whole process is measured to be analyzed. Measuring the result, the PV water footprint of value chain was $0.989m^3/MWh$ and the water footprint appeared higher specially in poly-Si and solar cell process. The following two reasons explain it: poly-Si process is energy-intensive process and it consumes lots of cooling water. In solar cell process, deionized water is used considerably for washing a high-efficiency crystalline silicon. It is identified that PV system is the source using less water than traditional ones, which has a critical value in saving water. In discussing the future energy policy, it is vital to introduce the concept of water footprint as a supplementary value of renewable energy. 기후변화로 인한 국지적인 이상가뭄 빈발 및 물수지 관련 불확실성 증가 등으로 각국에서는 사용가능한 담수량 확보, 즉 물안보 문제가 크게 대두되고 있다. 사용가능한 담수량 중 상당부분이 전력을 생산하는 발전 분야에도 사용되기 때문에 그 중요성이 점차 증대하고 있다. 신재생에너지원인 태양광발전은 설비제조, 설치 및 운전의 전 과정(life cycle)에서 수자원을 소비하지만 전통적인 에너지원인 화력발전이나 원자력발전에 비하면 상대적으로 수자원을 적게 사용한다는 장점이 있다. 본 연구에서는 태양광시스템의 원료채취부터 운영발전까지 물 사용량을 알아보기 위해 전 과정의 물 발자국을 측정하여 그 결과를 분석했다. 물 발자국 산정결과 태양광시스템의 전체 물 발자국은 $0.989m^3/MWh$이며, 폴리실리콘과 태양전지 공정에서 물 발자국이 높게 나타났다. 폴리실리콘 공정은 에너지 다소비 공정이기 때문에 냉각수 사용량이 많았고 태양전지 공정에서는 고효율 결정질 실리콘 세척을 위한 탈 이온수(deionized water) 사용량이 많았기 때문에 물 발자국이 높은 것으로 보인다. 태양광발전은 기존 에너지원보다 물 사용량이 적은 발전원임을 확인할 수 있었으며, 에너지 분야의 물 사용량을 절감할 수 있는 가치를 가지고 있음을 알 수 있다. 향후 에너지정책 결정에 있어서 신재생에너지의 부가적인 가치로서 물 발자국 개념의 도입이 중요하다.
Overcoming stairs is an important requirement for mobile robots. Therefore, many studies have been conducted to develop robots with novel stair-climbing mechanisms. A curved-spoke-based ...stair-climbing robot has been developed to overcome stairs, but had some limitations during stair climbing, such as damage caused by friction with the edge of the stair and impact during locomotion. In a previous study, several tail mechanisms were suggested to solve these problems, and the tri-wheel tail mechanism showed remarkable performance improvements. However, the previous study used only one step size of 300
×
160
mm
2
. Therefore, in this study, a robust optimal design of the tri-wheel tail mechanism using the Taguchi method is conducted to achieve outstanding performance improvements even for stairs of various sizes and different climbing speeds as user conditions. The design of simulations of the tri-wheel tail mechanisms are performed via orthogonal arrays using a commercial dynamic simulation software tool. The objective function is to minimize the minimum required friction coefficient for a mobile robot to climb stairs without slip. The performance improvements are verified experimentally using a measurable performance index. Thus, these findings can be used to design stair-climbing mobile robots.
This paper presents a Ku-band monolithic multifunction transmitter and receiver chipset fabricated in 0.25-μm GaAs pseudomorphic high-electron mobility transistor technology. The chipset achieves a ...high level of integration, including a 4-bit 360° digital phase shifter, 5-bit 15.5-dB digital attenuator, amplifier and 9-bit digital serial-to-parallel converter for digital circuit control. Since the multifunction chipset includes a medium power amplifier and a low-noise amplifier, it features high P1dB and low noise figures over the full Ku-band frequencies. The multifunction transmitter shows a peak gain of 16.5 dB with output P1dB of 19.2 dBm at 15 GHz. The multifunction receiver shows a peak gain of 17.3 dB with noise figure of 2.5 dB at 15 GHz. The attenuation range is 15.5 dB with a step of 0.5 dB and the phase shift range is 360° with a step of 22.5°. Each chip area of the transmitter and receiver is 4.2 × 2.8 mm2.
Trauma with prolonged shock can cause systemic capillary leak syndrome regardless of the site of injury and a transfusion can aggravate it. The systemic capillary leak induces both an abdominal ...compartment syndrome and pulmonary edema, and a transfusion can aggra-vate these sequelae within hours. In our case, 21-year-old man with a penetrating injury in his left thorax experienced delay in rescue and definitive surgery. To manage life-threatening shock, massive blood transfusion and crystalloids had been infused. Cardiopulmonary cerebral resuscitations were performed 2 times during the surgery. Massive amount of pulmonary secretions emitted from his airways with severe hypoxia along with development of massive ascites causing abdominal compartment syndrome, while the surgery was underway. After temporary abdominal closure, he was moved to the intensive care unit and underwent venovenous extracorporeal membranous oxygenation. He recovered without any notable complications. It is important to prevent and correct the shock rapidly by appropriate rescue, controlling the source and infusing less amount of crystalloid and transfusion.
Pedestrian bridges with I-shaped girders exhibit frequent construction errors and difficulties in the construction of curved sections because the bridges are composed of straight girders mounted on ...piers. Therefore, a pedestrian bridge utilizing circular steel tubes as the main girder, which is easy to construct and more economical, is proposed to resolve these problems. When steel pedestrian bridges are used for long periods, fractures can occur owing to fatigue in the joints between the main girder and the bottom support. Full-scale circular steel tube joint test units were fabricated and subjected to two million cycles of fatigue performance tests and one million cycles of fatigue fracture tests to quantify the fatigue behavior of a new pedestrian bridge design comprising circular steel tubes. Finite element analysis (FEA) was used to verify the results of the fatigue fracture tests. The proposed pedestrian bridge exhibited excellent stability in terms of fatigue behavior. Moreover, the fatigue fracture of the bridge was successfully predicted using FEA.
Genetic sensor-regulators functional in Clostridia Han, SongI; Kim, Younghwan; Karanjikar, Mukund ...
Journal of industrial microbiology & biotechnology,
08/2020, Letnik:
47, Številka:
8
Journal Article
Recenzirano
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This study addressed the functionality of genetic circuits carrying natural regulatory elements of
Clostridium acetobutylicum
ATCC 824 in the presence of the respective inducer molecules. ...Specifically, promoters and their regulators involved in diverse carbon source utilization were characterized using mCherryOpt or beta-galactosidase as a reporter. Consequently, most of the genetic circuits tested in this study were functional in
Clostridium acetobutylicum
ATCC 824 in the presence of an inducer, leading to the expression of reporter proteins. These genetic sensor-regulators were found to be transferable to another
Clostridium
species, such as
Clostridium beijerinckii
NCIMB 8052. The gradual expression of reporter protein was observed as a function of the carbohydrates of interest. A xylose-inducible promoter allows a titratable and robust expression of a reporter protein with stringency and efficacy. This xylose-inducible circuit was seen to enable induction of the expression of reporter proteins in the presence of actual sugar mixtures incorporated in woody hydrolysate wherein glucose and xylose are present as predominant carbon sources.
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