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Modeling any Obstacle Shapes for Motion Planning of Circular Robots
Md Nasir Uddin Laskar,Seung Y. Choi,Ishtiaq Ahmed,TaeChoong Chung 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
This paper presents an algorithm to model the workspace obstacles of a circular robot. An obstacle of any shape can be represented by line and circular arc segments. Based on robot radius, geometric representation is applied for both line and circular arcs and the operation is known as offsetting. Result of our algorithm creates an efficient configuration space and helps planning high-quality motion paths. Our method works differently for line and circular arc segments. Two major steps are: (i) finding the raw offset curve for both lines and circular arcs and (ii) removing the global invalid loops. The process takes O(n) times to find the raw offset curve and O((n + k) logm) times to remove global invalid loops, where n is the number of vertices in the original polygon, k is the number of self-intersections, and m is the number of segments in the raw offset curve and always m≤n. Local invalid loops are removed before generating the raw offset curve by invoking a pair-wise intersection detection test (PIDT). Our algorithm is very fast and computational complexity is approximately linear.
Hossain, Shahdat,Rahaman, Asiqur,Nahar, Taslima,Basunia, Mafroz Ahmed,Mowsumi, Ferdousi Rahman,Uddin, Borhan,Shahriar, Masum,Mahmud, Ishtiaq 경희한의학연구센터 2012 Oriental Pharmacy and Experimental Medicine Vol.12 No.1
We investigated the effect of Syzygium cumini (L.) Skeels seed extract on the oxidative stress of brain cortical tissues of alcohol-treated rats. The in vitro antioxidative effect of methnolic S. cumini seed extract was initially compared with those of the buytylated hydroxyl toluene (BHT) and Vitamin C, by determining their DPPH-free radical scavenging activity. The S. cumini seed extract exhibited stronger free radical scavenging activity than those of the BHT and Vitamin C. Cortex homogenates were then directly incubated with 15% ethanol and/or Fenton's reagent ($H_2O_2+Fe_2SO_4$) to induce in vitro oxidative stress in the absence or presence of S. cumini seed extract. The S. cumini seed extract significantly reduced the levels of lipid peroxide (LPO) in the cortical homogenates. Twenty four rats were then divided into four groups: Control, S. cumini seed extract (SE)-administered, 15% ethanol-fed (EtOH) and EtOH+SE rats. The oral administration of the extract (400 mg/kg BW.day) for 8 weeks significantly (P<0.05) decreased the levels of LPO in the cortex of the EtOH+SE rats, suggesting that S. cumini seed not only scavenged the DPPH-free radicals and obstructed the ethanol/Fenton's reagents-induced in vitro oxidative stress of the cortical tissues but also reduced their in vivo formation. These results suggest that S. cumini seed could be used as a potential antioxidant therapy for alcoholics.
고 흡수율과 고방사율 다중 코팅 설계를 위한 전산모사 연구
마사우드 하시미(Masaood Hashimi),무하마드 파뤀(Muhamad Farooq),이시크 아메드 오지(Ishtiaq Ahmed Qazi),강은철(Kang Eun-Chul),김기세(Kim Ki-Se),이의준(Lee Euy-Joon) 한국태양에너지학회 2003 한국태양에너지학회 논문집 Vol.23 No.3
본 연구에서는 복층으로 구성된 WSio₂Al 금속절연체의 상세를 보여주고 있는데, 금속과 절연체의 합성물질은 태양 흡수율의 설계와 열적인 현상을 보여주기 위해 종종 사용된다. 금속의 접착기면 위에 얇은 복층 코팅으로 구성되는 디자인은 태양 스펙트럼의 파장권역에서 선택적 흡수를 위함이다. 본 연구는 태양 복사의 열성능 평가를 위해 금속과 절연체 필름의 방사율, 태양흡수율, 코팅순서, 미 반사층(AR)의 두께, 코팅 두께와 코팅 면수, 전체 코팅 두께 등에 대해 시뮬레이션 하였다. 그 결과 네 겹의 코팅설계에서 Sio₂AR 75 nm 두께와 각각의 층에서 0.5∼0.7의 가변 금속부분 구성이 가장 우수한 성능을 갖는 것으로 나타났다. 또한 시뮬레이션으로 금속과 절연체 합성물의 최적의 구성과 각각의 코팅 두께에 대한 예측이 가능했으며, 최대 태양흡수율은 0.94, 방사율은 0.115의 금속과 절연체의 합성물을 구성할 수 있었다.
Offsetting obstacles of any shape for robot motion planning
Laskar, Md Nasir Uddin,Viet, Hoang Huu,Choi, Seung Yoon,Ahmed, Ishtiaq,Lee, Sungyoung,Chung, Tae Choong Cambridge University Press 2015 Robotica Vol.33 No.4
<B>SUMMARY</B><P>We present an algorithm for offsetting the workspace obstacles of a circular robot. Our method has two major steps: It finds the raw offset curve for both lines and circular arcs, and then removes the global invalid loops to find the final offset. To generate the raw offset curve and remove global invalid loops, <I>O(n)</I> and <I>O((n+k)</I>log <I>m</I>) computational times are needed respectively, where <I>n</I> is the number of vertices in the original polygon, <I>k</I> is the number of self-intersections and <I>m</I> is the number of segments in the raw offset curve, where <I>m</I> ≤ <I>n</I>. Any local invalid loops are removed before generating the raw offset curve by invoking a pair-wise intersection detection test (PIDT). In the PIDT, two intersecting entities are checked immediately after they are computed, and if the test is positive, portions of the intersecting segments are removed. Our method works for conventional polygons as well as the polygons that contain circular arcs. Our algorithm is simple and very fast, as each sub-process of the algorithm can be completed in linear time except the last one, which is nearly linear. Therefore, the overall complexity of the algorithm is nearly linear. By applying our simple and efficient approach, offsetting obstacles of any shape make it possible to construct a configuration space that ensures optimized motion planning.</P>