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排序方式: 共有360条查询结果,搜索用时 31 毫秒
341.
A robust method for fingerprinting digital images 总被引:2,自引:0,他引:2
Saad Amer 《电子科学学刊(英文版)》2001,18(3):193-203
In this paper, a method to fingerprint digital images is proposed, and different watermarked copies with different identification string are made. After determining the number of the customers and the length of the watermark string, this method chooses some values inside the digital image using a characteristic function, and adds watermarks to these values in a way that can protect the product against the attacks happened by comparing two fingerprinted copies. The watermarks are a string of binary numbers -1s and 1s. Every customer will be distinguished by a series of 1s and -1s generated by a pseudo-random generator. The owner of the image can determine the number of customers and the length of the string as well as this method will add another watermarking values to watermark string to protect the product. 相似文献
342.
The NAND operation at 250 Gbit/s based on quantum dot-semiconductor optical amplifiers (QD-SOAs) is modeled. By solving the rate equations of SOAs in the form of a Mach-Zehnder interferometer (MZI), the performance of NAND gate is numerically investigated. The model takes the effects of amplified spontaneous emission (ASE) and the input pulse energy on the system’s quality factor into account. Results show that NAND gate in QD-SOA-MZI based structure is feasible at 250 Gbit/s with a proper quality factor. The decrease in quality factor is predicted for high spontaneous emission factor (N SP). For an ideal amplifier (N SP = 2), the Q-factor is 17.8 for 30 dB gain. 相似文献
343.
An all-optical logic AND gate based on two-photon absorption (TPA) in semiconductor optical amplifier (SOA) is simulated. By solving the rate equations of SOA in the form of a Mach-Zehnder interferometer (MZI), the performance of AND gate is numerically investigated. The model takes the effects of amplified spontaneous emission (ASE) and pulse energy on the system’s quality factor (Q-factor) into account. Results show that the all-optical AND gate based on TPA in SOA-MZI based structure is feasible at 250 Gbit/s with a proper Q-factor. 相似文献
344.
Hickey JM Keane MG Kenny DA Cromie AR Amer PR Veerkamp RF 《Journal of dairy science》2007,90(8):3900-3908
Calving difficulty is a trait that greatly affects animal welfare, herd profitability, and the amount of labor required by cattle farmers. It is influenced by direct and maternal genetic components. Selection and breeding strategies can optimize the accuracy of genetic evaluations and correctly emphasize calving difficulty in multiple-trait indices provided there are accurate estimates of genetic parameters. In Ireland, large differences exist in the age at which heifers first give birth to calves. The objective of this study was to estimate genetic parameters for calving difficulty in first-parity Holsteins and to determine whether these differed with age of the heifer at calving. Transformed calving difficulty records for 18,798 Holstein heifers, which calved between January 2002 and May 2006, were analyzed using univariate, multitrait, and random regression linear sire-maternal grandsire models. The model that 1) fitted a second-order random regression of dam age at first parity for the direct component, 2) treated the maternal component as a single trait regardless of dam age, and 3) fitted a single residual variance component was optimal. Heritabilities for direct (0.13) and maternal (0.04) calving difficulty were significantly different from zero. These 2 components were moderately negatively correlated (−0.47). Estimates of direct genetic variance and heritability were heterogeneous along the dam age trajectory, decreasing initially with dam age before subsequently increasing. Heritability estimates ranged between 0.11 and 0.37 and were higher for records with younger and older dams at parturition. Genetic correlations between the direct components of calving difficulty decreased from unity to 0.5 with increasing distance between dam ages at parturition. The results of this study indicated that heterogeneity of direct genetic variance existed for calving difficulty, depending on dam age at first parturition. 相似文献
345.
Tamer Rabie Baher Abdulhai Amer Shalaby & Ahmed El-Rabbany 《Computer-Aided Civil and Infrastructure Engineering》2005,20(4):231-241
Abstract: This article discusses the development of a mobile bus-mounted machine vision system for transit and traffic monitoring in urban corridors, as required by intelligent transportation systems. In contrast to earlier machine vision technologies used for traffic management, which rely mainly on fixed-point detection and simpler algorithms to detect certain traffic characteristics, the new proposed approach makes use of a recent trend in computer vision research; namely, the active vision paradigm. Active vision systems have mechanisms that can actively control camera parameters such as orientation, focus, zoom, and vergence in response to the requirements of the task and external stimuli. Mounting active vision systems on buses will have the advantage of providing real-time feedback of the current traffic conditions, while possessing the intelligence and visual skills that allow them to interact with a rapidly changing dynamic environment, such as moving traffic and continuously changing image background. 相似文献
346.
Yousif M. Hamad Tarek A. Hamad Abdulhakim Amer A. Agll Sushrut G. Bapat Charles Bauer Andrew Clum Nandish Shivaprasad Mathew Thomas John W. Sheffield 《International Journal of Hydrogen Energy》2014
Countries are trying to reduce their energy consumption, fossil fuel usage, and greenhouse gas emissions. Recent guidelines generated by various government agencies indicate an increase in the fuel economy, with a reduction in green house gases. The use of both alternative fuel vehicles and renewable energy sources is thus necessary toward achieving this goal. This paper proposes a hydrogen fueling infrastructure design for the Northeastern United States. The design provides an implementation plan for a period of 13 years (from 2013 to 2025). This design gives priority to customer convenience with minimum additional investments for its implementation. Extensive research has been conducted on generating a hydrogen supply from factories and other potential sources that can satisfy demand in the region. Markers (e.g. population density, traffic density, legislation, and growth pattern) have driven the process of demand estimation. 相似文献
347.
Sadeghi-Sefidmazgi A Moradi-Shahrbabak M Nejati-Javaremi A Miraei-Ashtiani SR Amer PR 《Journal of dairy science》2012,95(6):3406-3418
Trait-by-trait and multiple trait bioeconomic modeling were used to derive farm-specific economic weights (EW) for a wide range of traits under different production and economic circumstances to define breeding objectives for Holstein dairy cattle in Iran. Production parameters and economic data were gathered on 10 dairy farms from March 2008 to February 2010. The EW (economic values multiplied by gene expressions, in US dollars per unit of trait per calf born from sires of self-replacing females in planning horizon of 20 yr) were estimated to be $0.15 per kilogram of milk yield; $1.36 per kilogram of fat yield; -$1.02 per kilogram of protein yield; $4.59 per month of longevity; -$1.22 per kilogram of mature cow weight; -$105.67 for combined somatic cell score and clinical mastitis; -$1.35 and -$0.28 for percentage direct and maternal calving difficulties, respectively; -$3.98 for percentage direct stillbirth; -$0.76 per day of age at first calving; -$0.72 per calving interval day; and $0.91 for percentage 56-d nonreturn rate on averages across investigated farms. The coefficient of variation of economic weights across the 10 farms was lowest for direct calving difficulty and highest for calving interval. The proposed Iranian selection index was compared with selection indices of major countries exporting semen to Iran. Average relative emphasis for production, durability, and health and reproduction, across all exporter countries, was 41, 37.5, and 21.5%, respectively, whereas the respective values were 50, 14, and 36% for the Iranian index. Significant differences in selection indices may potentially decrease the utility of importation of semen as a means of achieving sustainable genetic progress in Iran. Results obtained in this study provide important information about economic values of traits that can be used to improve the Iranian national progeny testing program as well as importation rules for semen to Iran. 相似文献
348.
Short communication: Effects of feeding sweet sorghum silage on milk production of lactating dairy cows 总被引:1,自引:0,他引:1
The objective of this study was to determine the feeding value of sweet sorghum silage (SS) for dairy cows compared with alfalfa silage (AS). Two diets were formulated with a 50:50 forage:concentrate ratio. Sweet sorghum silage and AS constituted 70% of the forage in each diet (dry matter basis). Twelve lactating Holstein cows in early lactation were used in a crossover experiment. Relative to AS, SS contained 58% more neutral detergent fiber and 36.6 and 72.7% less acid detergent lignin and crude protein, respectively. Milk yield (33.0 vs. 36.7 kg/d) was lower for cows fed SS than for those fed AS. However, dry matter intake, energy-corrected milk, and feed efficiency were similar for both dietary treatments. Replacing AS with SS increased concentrations of milk fat (4.44 vs. 3.80%) and total solids (13.31 vs. 12.88%) and reduced concentrations of milk lactose (4.55 vs. 4.61%), milk solids-not-fat (8.88 vs. 9.08%), and milk urea nitrogen (10.0 vs. 14.0 mg/dL). We concluded that replacing AS with SS had negative effects on milk yield, whereas dry matter intake, energy-corrected milk, and milk efficiency were similar. 相似文献
349.
The performance of all-optical logic NXOR gate based on semiconductor optical amplifiers Mach-Zehnder interferometer(SOAs-MZI)is simulated.The effects of amplified spontaneous emission(ASE)and the input pulse energy on the system’s quality factor are studied.For the parameters used,the all-optical logic gates using SOAs are capable of operating at speed of 80Gbit/s. 相似文献
350.
We demonstrate the temporal evolution of terahertz (THz) wave propagation in one-dimensional periodic dielectrics. Distributed Bragg reflectors and a resonant cavity are investigated: The structures involve air gaps interleaved between polymer films. Transmitted and reflected broadband THz waves are measured by means of THz time-domain spectroscopy. The experimental results agree well with transfer matrix calculations. 相似文献