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排序方式: 共有162条查询结果,搜索用时 15 毫秒
1.
To achieve size preserving tracking, in addition to controlling the camera’s pan and tilt motions to keep the object of interest
in the camera’s field of view (FOV), the camera’s focal length is adjusted automatically to compensate for the changes in
the target’s image size caused by the relative motion between the camera and the target. The estimation accuracy of these
changes determines the effectiveness of the resulting zoom control. The existing method of choice for real-time target scale
estimation applies structure from motion (SFM) based on the weak perspective projection model. In this paper we propose a
target scale estimation algorithm with a linear solution based on the more advanced paraperspective projection model, which
improves the accuracy of scale estimation by considering center offset. Another key issue in SFM based algorithms is the separation
of target and background features, especially when composite camera (pan/tilt/zoom) and target motions are involved. This
paper designs a fast target feature separation/grouping algorithm, the 3D affine shape method. The resulting separation automatically
adapts to the target’s 3D geometry and motion and is able to accommodate a large amount of off-plane rotation, which most
existing separation/grouping algorithms find difficult to achieve. Experimental results illustrate the effectiveness of the
proposed scale estimation and feature separation algorithms in tracking translating and rotating objects with a PTZ camera
while preserving their sizes. In comparison with the leading size preserving tracking algorithm described by Tordoff and Murray,
our algorithm is able to reduce the cumulative tracking error significantly from 17.4% to 3.3%. 相似文献
2.
Point fingerprint: a new 3-D object representation scheme 总被引:1,自引:0,他引:1
Yiyong Sun Joonki Paik Koschan A. Page D.L. Abidi M.A. 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2003,33(4):712-717
This paper proposes a new, efficient surface representation method for surface matching. A feature carrier for a surface point, which is a set of two-dimensional (2-D) contours that are the projections of geodesic circles on the tangent plane, is generated. The carrier is named point fingerprint because its pattern is similar to human fingerprints and plays a role in discriminating surface points. Corresponding points on surfaces from different views are found by comparing their fingerprints. The point fingerprint is able to carry curvature, color, and other information which can improve matching accuracy, and the matching process is faster than 2-D image comparison. A novel candidate point selection method based on the fingerprint irregularity is introduced. Point fingerprint is successfully applied to pose estimation of real range data. 相似文献
3.
Ghayth Rigane Mohamed Bouaziz Nidhal Baccar Samira Abidi Sami Sayadi Ridha Ben Salem 《Journal of food science》2012,77(10):C1077-C1083
Abstract: A very simple method is proposed to produce hydroxytyrosol, a commercially unavailable compound with well‐known biological properties which justify a potential commercial application. The 2‐phase Chemlali olive pomace is selected as substrate for chemical treatment. Different conditions of chemical treatment, including concentration of acid and alkaline solutions, time and temperature, were assayed. A high amount of hydroxytyrosol (1360 mg/kg of fresh 2‐phase olive pomace) was obtained using water bath after treatment at 80 °C for 90 min with 1 M of H3PO4. However, treatment of 2‐phase Chemlali olive pomace using autoclave apparatus could produce a large amount of hydroxytyrosol (1993.60 and 1515.88 mg/kg of fresh alperujo, 1 M acid and basic catalyst, respectively). By taking into consideration practical and economic aspects, acid‐catalyzed treatment was more effective using autoclave conditions, whereas the alkali catalyzed conditions were not very suitable. This study could provide useful information for industry to produce the potentially bioactive compound. Practical Application: The 2‐phase Chemlali olive pomace is selected as substrate for chemical treatment. Treatment of “alperujo” using water bath or autoclave apparatus was carried out. A high amount of hydroxytyrosol was obtained using autoclave apparatus. 相似文献
4.
5.
Aishani Mazumder Chung Kim Nguyen Thiha Aung Mei Xian Low Md. Ataur Rahman Salvy P. Russo Sherif Abdulkader Tawfik Shifan Wang James Bullock Vaishnavi Krishnamurthi Nitu Syed Abhishek Ranjan Ali Zavabeti Irfan H. Abidi Xiangyang Guo Yongxiang Li Taimur Ahmed Torben Daeneke Akram Al-Hourani Sivacarendran Balendhran Sumeet Walia 《Advanced functional materials》2023,33(36):2303641
Miniaturization and energy consumption by computational systems remain major challenges to address. Optoelectronics based synaptic and light sensing provide an exciting platform for neuromorphic processing and vision applications offering several advantages. It is highly desirable to achieve single-element image sensors that allow reception of information and execution of in-memory computing processes while maintaining memory for much longer durations without the need for frequent electrical or optical rehearsals. In this work, ultra-thin (<3 nm) doped indium oxide (In2O3) layers are engineered to demonstrate a monolithic two-terminal ultraviolet (UV) sensing and processing system with long optical state retention operating at 50 mV. This endows features of several conductance states within the persistent photocurrent window that are harnessed to show learning capabilities and significantly reduce the number of rehearsals. The atomically thin sheets are implemented as a focal plane array (FPA) for UV spectrum based proof-of-concept vision system capable of pattern recognition and memorization required for imaging and detection applications. This integrated light sensing and memory system is deployed to illustrate capabilities for real-time, in-sensor memorization, and recognition tasks. This study provides an important template to engineer miniaturized and low operating voltage neuromorphic platforms across the light spectrum based on application demand. 相似文献
6.
Ultrasonic setting measurement is the study of how materials set or harden. Indeed, when mixed or combined, some materials undergo a change of their rheological properties if they are submitted to physical or chemical phenomena. Before use, these materials are liquid and they become solid when in use, at temperatures close to ambient levels, for example, hydraulic binding materials (cement, white-wash, plaster). For each particular application, users and manufacturers with to know the evolution such materials undergo, for three reasons: - the development of a new product (meeting a need), - the largest possible reduction of setting time (economic criterion), - the use of the material (moulding, transformation...) without risking a change of its properties (quality-and safety-related problems). The ultrasonic setting-measurement device provides solutions to such needs. The method is based on tracking ultrasounds through an interface during the process of solidification. Recording the change of transmissibility allows monitoring the rheological evolution of the material. Some examples of the use of the ultrasonic setting measurement device are provided, on the basis of laboratory measurements. A comprehensive study of the results of tests using hydraulic binders and acrylic resins allows the determination of characteristic times corresponding to the evolution of the material in question. 相似文献
7.
Direct-conversion radio transceivers for digital communications 总被引:4,自引:0,他引:4
Direct-conversion is an alternative wireless receiver architecture to the well-established superheterodyne, particularly for highly integrated, low-power terminals. Its fundamental advantage is that the received signal is amplified and filtered at baseband rather than at some high intermediate frequency. This means lower current drain in the amplifiers and active filters and a simpler task of image-rejection. There is considerable interest to use it in digital cellular telephones and miniature radio messaging systems. This paper briefly covers case studies in the use of direct-conversion receivers and transmitters and summarizes some of the key problems in their implementations. Solutions to these problems arise not only from more appropriate circuit design but also from exploiting system characteristics, such as the modulation format in the system. Baseband digital signal processing must be coupled to the analog front-end to make direct-conversion transceivers a practical reality 相似文献
8.
S. L. Abidi 《Water research》1982,16(2):199-204
Extremely carcinogenic diethylnitrosamine (DENA) was found to form in up to 75% yield from the reaction of nitrite with the two commonly used water tracing dyes. Rhodamine B and Rhodamine WT, DENA was detected at trace levels (0.13–7.02 μg −1) in river water samples after treatment with the dye and nitrite. Analysis of these chemically treated environmental water samples required extensive separation techniques prior to acquisition of reliable analytical data using highly sensitive instruments for detection. The occurrence of DENA in nitrite-rich water treated with Rhodamines may pose a health hazard to general populations. 相似文献
9.
Aicha Sifou Guiseppe Meca Ana Belen Serrano Naima Mahnine Abdellah El Abidi Jordi Mañes Mohamed El Azzouzi Abdellah Zinedine 《Food Control》2011,22(12):1826-1830
Seventy samples of rice purchased from local markets in six cities from Morocco (Rabat, Casablanca, Kénitra, Mohammadia, Tanger and Errachidia) were analyzed for the presence of six emerging mycotoxins: four enniatins ENs (ENA, ENA1, ENB and ENB1), beauvericin (BEA) and fusaproliferin (FUS). Samples were extracted with a mixture of acetonitrile/water (85/15, v/v) by using an ultra-turrax homogenizer. Mycotoxins were then identified and quantified with liquid chromatography (LC) coupled to diode array detector (DAD). Positive samples were confirmed with an LC-MS/MS. Analytical results showed that BEA was present in 75.7% of total analyzed samples. BEA levels varied between 3.8 and 26.3 mg/kg. The frequencies of contamination of samples with total ENs and FUS were 50% and 4.3%, respectively. Among the ENs, ENB was the mycotoxin much more found (30% of total samples), while ENB1, ENA and ENA1 were found in 24.6%, 22.8% and 5.7% of total samples, respectively. The high ENs value was registered in a rice sample from kénitra (448.7 mg/kg of ENA1). This is the first study that describes the presence of emerging Fusarium mycotoxins in rice available in Morocco. 相似文献
10.
Hecham Elhamri Larbi Idrissi Marina Coquery Sabine Azemard Abdellah El Abidi Mohamed Benlemlih Mohamed Saghi Francesco Cubadda 《Food Additives & Contaminants》2007,24(11):1236-1246
Coastal populations with high seafood consumption in the Mediterranean have a significant exposure to dietary methylmercury, and areas where environmental mercury pollution is an issue due to industrial activities are of special concern. The study was undertaken with the aim of assessing methylmercury exposure through fish consumption in a community of north Morocco and characterizing the relevant health risk. Concentrations of total mercury were determined in human hair, a biomarker of methylmercury exposure, and in locally consumed fish by cold vapour atomic absorption spectrophotometry. Based on consumption frequencies reported by the 108 subjects included in the study the weekly intake of methylmercury was estimated and biomarker data were evaluated in relation to the estimated intake and the sociodemographic characteristics of the population. Multiple regression analysis was employed for the interpretation of hair mercury data in relation to fish consumption frequency, gender and the age of individuals. Mercury concentrations in hair ranged from 0.22 to 9.56 µg g-1 (geometric mean = 1.79 µg g-1) and were closely related to fish intake. Fisherman and their families consumed fish three to five times per week and were the most exposed population subgroup. A high proportion of women of child-bearing age (50%) had relatively high levels of mercury in their hair (3.08-7.88 µg g-1). 相似文献